I am developing a new hunting load for my 308 using 165 grand slams I am using 210 primers and varget for a powder. Heres the deal, my groups are really starting to tighten up at 44gr.(just under an inch at 100 yards) two of my manuals say that this is a max load. Will there always be signs of pressure before somthing really bad happens?

I don't have a chrystal ball but with a slower single base powder such as Varget I believe you will set flat primers and or sticky bolt lift/extraction before you get to Kaboom. I wouldn't bet somebody else's gun or eyes or life on it but have pushed one or two other calibers such as 243 Win. to the point of these excessive pressure signs using a similar powder without it blowing up. BUT, when the bolt became sticky to lift I quit shooting and didn't shoot this hot load again. With the 243 we (my S-I-L and myself) didn't approach tack driving accuracy with the 55 grain Nosler BT bullets before this. He switched to the 58 grain V-Max and it is a tack driver (one ragged hole at 100') without excess pressure.

The thing about reloading data is it varies from test rifle to test rifle. The Hogdon site has 46gr as a max. load (diff. bullet manuf. though). You rifle may or may not be at max. Pressure signs like sticky bolt lift, excessive flattened primers or case head smearing mean you have gone too far. Rifles seldom go KB w/o some pressure signs appearing.

All of the loading I have done with Varget has shown me a very linear powder. I have pushed it pretty hard with an '06 and 130 grain Barnes TSXs looking for a sweet spot I would expect Varget to show you the beginnings of over pressure on the way up.

44 grains of Varget pushing 165 is right up there but still safe for a modern bolt. If you are using a modern bolt you are in the proceed very cautiously range.

Were it me I would either stop right there or move in .1 grain increments until I saw the first signs of pressure. Since you didn't say what rifle this is being shot in or if you are seing any pressure signs No one is going to be able to know more than you do about this.

Unless you know how to read pressure signs well, do not proceed.

Is this a strong rifle?
In strong rifles work up to the threshold of trouble:
a) primer pockets loosen*
b) primer pierces
c) bolt gets hard to lift

Then I back off 6% in powder charge, ala Vernon Speer 1956.


*1) Brass life can be measured at the range by reloading at the range. I have fired 5 shot groups with a single case. It is a pain to haul all that stuff to the range.
2) Some primers fall out of loose pockets and some don't until the pocket is very large. Working up until primer pockets are loose at the range by watching for primers falling out is sketchy.
3) My best system is to have dial calipers at the range. I measure the extractor groove before and after. If the groove increases .001", the primer will not fall out, but the limit has been reached.


Here is some 308 brass [necked down to 243] I shot in a Turkish Mauser I re barrelled. All three sequential rounds were the same load. The throat was getting Copper fouled.

quote:

Originally posted by 1in10:
... Will there always be signs of pressure before somthing really bad happens?

Hey 1in10, Normally speaking, with a Powder well suited for the Cartridge, you will get the standard Pressure Indicators prior to getting the Pressure way too high.

However, there are other conditions that will give a different answer to your question:
1. Too much Lube in a Barrel can act as a Bore Obstruction and create high Pressure. Just wipe it with a dry patch before you start.
2. Never cleaning the Barrel can eventually result in high Pressure, but it is normally accompanied by patterns instead of groups.
3. Shooting an underload which results in a Bullet remaining in the Bore and then shooting another Cartridge.
4. Using a Powder which has proven to be Erratic with some Cartridges has the potential to create unexpected high Pressure.
5. Using less "Slow" Powder than recommended in a Manual, in some Cartridges, can create a Secondary Explosion Effect(Detonation).
-----

However, in regard to your Developing Loads, this is excellent information

quote:

from tnekkcc:
My best system is to have dial calipers at the range. I measure the extractor groove before and after. If the groove increases .001", the primer will not fall out, but the limit has been reached.

I prefer good old time proven, CHE & PRE. PRE works on all Cartridges, even the old low Pressure ones. CHE is very similar to what tnekkcc described.

So, you can learn to do it correctly and not be concerned about Pressure, or just keep guessing.
-----

By the way, Velocity doesn't tell you anything about whether the Pressure is too low, just right or too high. Never has, never will.

Best of luck to you.

I care about the signs of pressure, i.e. the effects of pressure, but I don't care about the pressure it self.

So if the weak link is the brass, I care about the effects of pressure on the brass.

So I measure the brass.
I look at the brass.

what does it all mean?
When it comes to the signs of pressure, I really do care about what is best for my brass.

Hot Core, when you say -

quote:

By the way, Velocity doesn't tell you anything about whether the Pressure is too low, just right or too high. Never has, never will.

Do you imply that:
1. velocity is not dependent on the amount of pressure applied to the bullet when launched out of a rifle?

woops I forgot to mention the rifle has Sako A2 action and has a 22" Shillen barrell with a 1 in ten twist. As for barrell I always baby it since it is the only custom rifle I probibly will ever own, its always clean. I usually run a bore snake down the barrell in between groups. I know its a somewhat of a modern action as for how strong it is i'm really not sure.

I almost forgot, thaks for all the help.
Hot Core I read CHE and PRE info there is a lot of helpful info there but I have one question, when you say measure the pressure ring. Is this the area where you would find a belt on a belted magnum?

quote:

Originally posted by Jagter:
Hot Core, when you say -

quote:

By the way, Velocity doesn't tell you anything about whether the Pressure is too low, just right or too high. Never has, never will.

Do you imply that:
1. velocity is not dependent on the amount of pressure applied to the bullet when launched out of a rifle?

Velocity is a result of work under the time/pressure curve. When people talk pressure limits, there speaking of only the initional "spike", not the sustained "push". It's the "push" that get's you your velocity.

I can find you a powder that will blow your rifle apart and still leave the bullet inside the barrel (0fps) and another powder that you can't physicly stuff enough into the case to get into a over pressure situation with.

quote:

Originally posted by 1in10:
... Is this the area where you would find a belt on a belted magnum?

Hey 1in10, If you will go back and read the Details and Explainations, you will find:

1. On Belted cases (7mmMag, 375H&H, etc.), CHE is measured across the Belt.
2. On Non-Belted cases (223Rem, 7mm-08, 30-06, etc.), CHE is measured just forward of the extraction groove (where the Belt would normally be located) with special "Thin Blade" Micrometers.
3. On Straight Wall cases (9mm, 357Mag, 444Mar, 45-70, etc.), CHE is measure just forward of the Rim with special "Thin Blade" Micrometers.
4. On a "fired" Belted case, PRE is measured across the “widest diameter†of the case body forward of the Belt.
5. On a "fired" Non-Belted case, PRE is measured across the widest diameter on the case body forward of the Extractor Groove.
6. On a "fired" Straight Wall case, PRE is measured across the widest diameter on the case body forward of the Rim.
-----

I know it is a long read, because it was written for people who have never measured CHE & PRE. It might be best to print it out, sit down with it, and think about it with a Case and a 0.0001" capable Micrometer in your hands.

If it is still confusing, let me know and I'll try my best to explain it.

Tailgunner wrote:

quote:

When people talk pressure limits, there speaking of only the initional "spike", not the sustained "push". It's the "push" that get's you your velocity.

What would you suggest creates this "push" you are referring to?

/

Alf,

Your opinion on this
please.

Appreciate.

quote:

Originally posted by Tailgunner:

quote:

Originally posted by Jagter:
Hot Core, when you say -

quote:

By the way, Velocity doesn't tell you anything about whether the Pressure is too low, just right or too high. Never has, never will.

Do you imply that:
1. velocity is not dependent on the amount of pressure applied to the bullet when launched out of a rifle?

Velocity is a result of work under the time/pressure curve. When people talk pressure limits, there speaking of only the initional "spike", not the sustained "push". It's the "push" that get's you your velocity.

I can find you a powder that will blow your rifle apart and still leave the bullet inside the barrel (0fps) and another powder that you can't physicly stuff enough into the case to get into a over pressure situation with.

Tailgunner, I don`t think anyone suggests measuring velocity of a random load and trying to compare it to a specific loads velocity from a manual. Varying the powder type will definatly alter the pressures and very possibly the rifle too.
The only time the velocities will or should compare closly is if all components used in the manual are also used in the load being tested, and barrel lgt is the same.
IE; Speers # 13 lists a load composed of their 168gr SPBT, with a CCI-200 primer in W-W brass over 59.0gr of IMR4350 as giving 2782 fps. Note, this bullet is the only one listed with this data as they do not make another style bullet of this wgt.
Now if one loads the same components and finds at a charge of 57.8 gr he is getting around 2780 fps he can figure he is in the ballpark of the pressures Speer had with their load of 59.0gr.
Will they (pressures) be exact? No!
They will be near enough to each other though that prudence tells us we should stop adding powder unless we have other means of measuring presure, or we are not concerned with SAAMI pressure specs.
Most bullet manufactures offer multiple styles of similar wgt bullets such as a 30 cal 180 gr SP, SPBT, RN, ect, and lists one set of data for the bunch. The velocity the book lists is only valid for one of these bullets, as is the max powder charge. The problem now is we don`t know which one is the true max or which one gave the listed velocity. In this case you can`t rely with much certainty on the velocities in your gun being relevent to the one listed in the manual.
A experianced loader will possibly ignore velocity while working up a load and after finding his max based on other criteria then worry about the velocity. New comers or less experianced loaders though I feel should still pay attention to velocity and understand that although it tells nothing exact it does point out possible pressure ranges that should be taken in account with other factors in deciding where we are.

Joe
This is what I was refering to:

quote:

Do you imply that:
1. velocity is not dependent on the amount of pressure applied to the bullet when launched out of a rifle?

And yes, I was going to extreems to make my point IE: "EG Pink" (it's a powder that was used to make blanks) or Bullseye on the fast end, and with a pull down powder from 20mm Vulcan rounds on the slow end.
Even with powders that are in the "normal" burn range for a given cartridge, just because you reach 60Ksi dosn't mean your velocity will be the same with all of them, or just because you hit X velocity with all of them it dosn't mean the pressures are all the same. On this point I think that you, Hot Core and myself (along with many others) are in agreement.

As far as matching ALL the components (down to the exact lot # of each one) goes, I still remember seeing a 270fps variance between 2 different chambers (same receiver, same barrel, the higher velocity came from the tighter chamber/throat) even though the ammo came from the same "lot" (hell, it came out of the same box of reloads). Side note, the tight chamber velocities were within 15fps (2995 vs 3007 IIRC) of what Nosler claims they got with the same combo (but different lot #'s). Do I care about the actual velocity? Hell no, that load is grouping in the 5's which IMHO ain't bad for a deer rifle. Were the pressures the same in all 3 chambers? I highly doubt it, but I'd also bet that 2 of them were damn close.

I agree with Tailgunner's posts - as usual.

quote:

Originally posted by Ol` Joe:
...New comers or less experianced loaders though I feel should still pay attention to velocity and understand that although it tells nothing exact it does point out possible pressure ranges that should be taken in account with other factors in deciding where we are.

Ol' Joe, I understand what you are saying. The problem I see is the Beginners and Rookies interpolate a lot of this into believing by looking at the Velocity they can tell what the Pressure is(which no one can).

Each component in a Cartridge(Case, Primer, Powder and Bullet) is different from what is shown in the Load Manuals. Same with the Bore, Grooves, Rate of Twist, Barrel Length, Smoothness, and all the Chamber Dimensions. And the kicker is that even if the Cartridges were from the exact same Lot(as Tailgunner mentioned), the actual Pressure differences between rifles which appear to be exactly alike can have a w-i-d-e variance in the Velocity.

Those of us who have had multiple rifles chambered for the same Cartridge, and have wasted a lot of time measuring Velocity, can verify the results are not the same.
-----

So, then the question gets back to what you are suggesting that the Pressure "should be OK". Maybe it is and maybe it isn't. In the initial post, 1in10 stated he is at a MAX Load shown in two Manuals. Looking at the Velocity will not tell him if he is at 52k-cup, below it, or above it.

For example, lets say with three different rifles using that same Load he got:
1. 2550fps
2. 2750fps
3. 2950fps

One has a Chrome Lined barrel, one has had 40k shots through it, one is a Win, one is a Rem one is a Savage, one has a Gain Twist Barrel, one has 5R rifling, one has 4-grooves, and one has a 22" barrel.

What do you know about the Pressure?

Nothing without CHE & PRE.

Way too many variables to cipher Pressure from Velocity, can't be done. Never has, never will.

"More Power to you." - Briscoe Darling

quote:

In any case, the handloader should remember that the cartridge case itself is the wimpiest thing involved when a cartridge is fired in a strong, modern action, and excessive pressure will begin to show there first. Keep an eye on your brass, and if you see signs of excessive pressure (extreme primer flow and flattening, case head expansion, cracked or otherwise damaged cases, etc), stop shooting that load and back off your powder charge until the high-pressure indicators are gone.

With the above truth in mind, the following certainly makes absolute sense:

quote:

GS Custom's logical and proven reply:
"I have taken same caliber rifles to the range for load development and testing, more times than I care to mention. Invariably, identical start loads on three to five rifles of the same caliber, will result in different speeds. As you work up the scale, such a set of rifles will show pressure at different powder levels, but at similar speed levels, if barrel lengths are the same.
It is quite clear to me that the relationship between maximum pressure and muzzle velocity, is closer than the relationship between maximum pressure and powder charge.
A load that is safe in one rifle may blow a primer in another and will always result in more speed as well.
However, if you bring the two rifles to the same muzzle velocity with different powder charges, pressure levels between the two will also be closer. Once a powder charge has been decided on, check it by loading and firing the same case with it until the primer pocket loosens. If you get more than five or six loads from a case, pressure is not over the top."

"Load data that specify a maximum powder charge always carry the caution that the loads are only applicable to the test barrel used. It makes more sense to me to specify a known safe start load and a maximum speed that should not be exceeded.
Such a maximum speed will occur at differing powder levels from rifle to rifle but will be closer to the correct maximum pressure for that rifle than blindly following a stated maximum powder charge."

It once again underscores the necessity to control your loading by use of a chronograph and loading to the expected velocities, but never exceed the specified maximum velocity.

That is why velocity is a clear indicator of excessive pressure and/or less than excessive pressure simply because of the direct correlation between the two sets of results and one's effect on "the wimpiest thing involved" in the process, namely the brass case!!!

We all know that velocity can be determined much easier and more accurately than pressure, so why keep on BS'ting oneself?
Accept the hard facts and learn something here, namely: Velocity does tell one about pressure, enough to know when to load down or not!

I have an acquaintance who got one of these:
http://www.shootingsoftware.com/pressure.htm

He did not, however, just attach it to a rifle
and begin shooting unknown loads. He acquired
all known pressure testing from Savage. Then he
used known loads to compare his testing from
that which was known, using the results as a
base line. (Seems as though he did have to
reposition sensors on the barrel until the
pressures read same as the factory's pressures.)

There are some who distrust this equipment
because no holes are drilled into the barrel,
but what reloader wants to do that to one's
barrel?

I trust his results because my field testing
gave me accuracy results that would have
otherwise never been realized.

My guess is that the companies getting such
different results from their pressure testing
were using various types of equipment and that
the holes for pressure testing are placed in
different places in the test barrels.

/

Once again Alf, I have enjoyed your 'terribly' technical posts!

quote:

But and with this I have a problem, if it does not deform I'm still in the dark, because of the false negative possibility!

This is where my problem lies. I do not even get primer 'flattening' to warn me of excess pressure. CHE does not mean a thing to me. Nor does primer pocket expansion. I am loading a low-pressure hornet! But by examining loading tables and checking for consistent 'pressure' development, I have been able to load up some pretty decent cartridges. I determine 'not enough', 'enough' or 'too much' pressure by inconsistent primer .... ummm .... 'flattening', consistent 'flattening', and case length growth. Zero length case growth and consistent primer flattening is all I have to go on.

Is this argument...er...discussion a form of eternal life?

Jagter, I think what HotCore is trying to caution you about is that there are two important kinds of pressure involved in accelerating a bullet.

1. There is the total amount of pressure under the burn curve for the cartridge and charge. All of the energy represented by every bit of that "pressure" contributes to the acceleration of the bullet until the bullet is a (very) short distance out of the bore. To that extent, yes, pressure causes and is directly related to velocity.

2. There is another entirely different, but even more important pressure...the PEAK pressure reached at any single point in the bore. The peak pressure usually, but not 100% always, is reached while the bullet is in the chamber end of the barrel where you and I CAN'T measure the bullet velocity. If the powder is quick enough burning, that peak chamber pressure can be high enough to destroy the barrel, regardless what the velocity might have been, had the powder burn and bullet flight down the bore both been completed before the barrel was destroyed.

So, from a practical point of view, velocity alone is of limited use to handloaders in analysing pressures to determine maximum safe loads, regardless what the best, most modern, "theory" will tell you. The speed of the bullet really tells you nothing useful for handloading about maximum "peak" pressure.

Trying to measure pressure by measuring velocity is kind of like trying to measure horsepower by measuring the speed of a drag-racer in MPH as it flys through the final trap. Sure, it may be doing 306 MPH, but it may have already lost the race to another ride which blew through the quarter at "only" 301 MPH, but .03 sec. faster from start to finish. Which one applied the most HP to the pavement consistently? Which one had the highest peak HP? Which one had the best balanced set-up for that track? The final speed in MPH will tell you none of that. Just noting which one won the race will answer at least one of the questions definitively (best race set-up), and give hints regards the other two. It's the same with bullet muzzle velocities...they really do not tell you what some folks think they do.

A better, more direct way to ascertain when you are reaching a maximum working pressure, to MY mind, is to observe what is happening to your weak link, the brass. If your brass, whatever make or lot it is, is not injured by the load, then you can be almost certain your stronger, steel, rifle isn't injured either. So for that lot of components, it is a safe load.

What you are presumably after is a good "working" load. If it "works", i.e. doesn't harm brass or steel and produces a reasonable velocity for your needs, then both maximum pressure and pressure under the curve become irrelevant as anything other than just numbers.

If one starts to get unreasonably early brass damage from his reloads, then that "load" is NOT working out, and he doesn't have a good, safe, "working", load. Again, it doesn't matter what either the actual total pressures, or the peak pressures are, it still isn't a good load. If he can, he probably needs to use more of a slower burning powder to get more velocity, at a lower peak pressure.

I guess I am only about the 4,700th person to say that on THIS forum.

As far as comparing your rifle or my rifle with a naval rifle, I think that is also of very limited use. Naval rifles velocites may be used for a variety of things, but as they may also use different techniques for sealing the breech, obturating the bore, adjusting the sights, etc., they are different machines. Though the few similarities are interesting and fun to play with mentally, they are hardly directly applicable to our circumstances.

quote:

Originally posted by Alberta Canuck:
......I guess I am only about the 4,700th person to say that on THIS forum.......

That may be so, but you said it very well!

firearms companys put heavy triggers on rifles out of the factory to save themselves, reloading manuals too save themselves by being a little conservative with there max loads. assuming you have a reasonable new rifle that is in good condition with a decent action on it, most times you'll be able to go over the max listed load by a grain or 2. sometimes you wont see any noticable pressure signs then the next grain up and your taking off your shoe to hit the bolt open.

/

Alf -

I do not know whether you can't understand what I said, or simply refuse to do so. I hope it is neither, but don't know what else it might be.

Would it make you happier if I said there are at least two measurements of pressure which can be quantified and stated...one being the pressure peak and the other being the total amount of applied energy in whatever units you care to use, but basically referring to the various pressure levels during the bullet's acceleration and their dwell times against the bullet's base...the area under the burn curve, if you will?

At any rate, your dedication to mathemematically displayed theory is impressive, but in my opinion absolutely impractical when it comes to determining whether the peak pressure at any given time or point in the bullet's trip is actually SAFE.

First off, you are depending on pressures measured by other than velocity (they were actually determined by firing cartridges in pressure guns), and later correlated to velocity, when you cite the Dupont data. What substantial reason is there to assume the same correlations will be valid when the same charges are fired in any other gun barrel? Do you understand why everyone with practical experience knows that no two guns are necessarily alike or perform alike, even if we try our damnedest to make them exactly alike?

No one has said (or thinks) you are trying to measure pressure from a single shot, and I doubt that anyone disagrees with your statement that if the trend is suddenly and significantly violated, one should look for the cause. But looking for the cause would then involve other tools, if we suspected excess pressures to be the problem.

So, what I am saying is that the chronograph, although it does give some useful information (in this case that "something" is wrong), it does NOT tell us what that something is, or to what degree it is a problem. (Heck, the problem might be a bullet starting to come apart in flight, and rapidly losing velocity between the chrono screens, not a chamber pressure problem at all)

In other words, the relationship between velocity measured at the muzzle or 12 feet or so beyond, and peak pressures, is not solid enough as a "chain of evidence" for us to usefully conclude anything specific about pressures by reading velocities. All we can do is fall back to other tools.

If we suspect pressures to be the problem, and are without a pressure measuring device (another tool than a chronograph) which produces both valid and reliable readings, my experiences lead me to conclude that disciplined looking at the fired brass tells us more useful info than the chronograph does.

If you want to spend your time reading charts established with guns other than your own, feel free, and enjoy yourself. I hope they never lead you to far astray.

Alberta Canuck wrote:

quote:

A better, more direct way to ascertain when you are reaching a maximum working pressure, to MY mind, is to observe what is happening to your weak link, the brass. If your brass, whatever make or lot it is, is not injured by the load, then you can be almost certain your stronger, steel, rifle isn't injured either. So for that lot of components, it is a safe load.

Exactly what Gerard, myself and others are saying as stated in my post above dated 29 February 2008!
WATCH your BRASS, the wimpiest thing involved!!!

Alberta Canuck, read in my above post very carefully again what Gerard from GSC said there about different rifles, even if they are of the same calibre and barrel length, as well as relationship between muzzle velocity and pressure, please.

Handloading with the 'velocity as pressure indicator method' is still a carefully worked up action. When using GS Custom bullets one starts off with a known safe, maximum load per a reloaders manual for a specific calibre and bullet weight in lead/copper jacketed bullets. Then gradually built up your load from there with the help of a) the chrono and b) the careful watch of your brass cases.
Reason to go beyond that 'safe max load' stipulated: GSC's light travelling through the rifle bore drive band technology makes that possible!

This is very important as is confirmed here by Alf:

quote:

Just to make a point very clear, I am not claiming that we take a cartrdige fire it over a chrono and that single reading will give us an indication of pressure ! as I have stated before the chrono measures velocity, not pressure ! But if we work up loads and fire series of shots over the chrono for each increment is charge mass increase we will see that there is a linear upward trend in velocity, if suddenly there is a deviation from the trend it should be a warning because it can only happen at the hand of pressure change.

Yes, it all started with this little bit: E = mc^2, Alf!

quote:

Originally posted by Jagter:


by Alf:
[QUOTE] But if we work up loads and fire series of shots over the chrono for each increment is charge mass increase we will see that there is a linear upward trend in velocity, if suddenly there is a deviation from the trend it should be a warning because it can only happen at the hand of pressure change.

Jagter- Unfortunately, that statement by Alf is not correct. Many things other than significant pressure changes can cause chronographs to return fallacious upward readings. A sudden glint of light is one.
A bug flying simultaneously (or almost so) through one of the screens is another. A faulty chip is a third. A loose connection "rocked" by muzzle blast is still another. The list goes on and on.

There is no doubt it should warn a person something is wrong, but once again, that "something" may or may not be related to chamber pressure.

And BTW, I did read your posts carefully...that's why I used the expression "weak link"...I knew you would recognize it.

quote:

Unfortunately, that statement by Alf is not correct. Many things other than significant pressure changes can cause chronographs to return fallacious upward readings. A sudden glint of light is one.
A bug flying simultaneously (or almost so) through one of the screens is another. A faulty chip is a third. A loose connection "rocked" by muzzle blast is still another. The list goes on and on.

Alberta Canuck, we have used chronographs to the full extent in normal daylight conditions and never had any of those 'funnies' you have mentioned happened to the readings. If it did, we would have recognized it as being such and either correct the fault or simply continued with what we were doing!

However, chronograph readings always had indicated very definite trend changes in instances where the powder charge loaded was causing signs of high pressure. Simultaneously we've found tighter bolt lift and on close inspection in such instances the brass cases showed something wrong somewhere. That is when you load down and work back to the perfect load.

The 'perfect load' is then further tested like Gerard described it:

quote:

Once a powder charge has been decided on, check it by loading and firing the same case with it until the primer pocket loosens. If you get more than five or six loads from a case, pressure is not over the top."

With experience it is no longer necessary to go that far, you do notice sudden velocity deviations very early in the process.

We do play it safe, based on velocity mainly and a few other observations!

One thing that will effect a chronograph is muzzle blast. If you suspect that back off another 10 feet and shoot again.
What measuring brass (where ever it is done)
tells is that the brass is being stress into
yeild. That is a very good thing to avoid no
matter what the velocity , or the bolt lift
tell you.
Good luck!

quote:

Originally posted by 303Guy:
Once again Alf, I have enjoyed your 'terribly' technical posts! ...

Hey 303Guy, Only from a purly comical standpoint. The problem is that alf knows nothing about Ballistics and has - as he alsawys does - posted non-relevant, transcribed

His post value is the same as tossing "Reloading a STUN Gun" into the discussion. The thing that makes it comical is he really believes he understands what is going on. Feel free to quote me on this as it pertains to alf's and jagter's Ballistic knowledge -

quote:

Originally posted by ALF:
Two pressures, one peak and one total ? methinks not!...

I'd say that once anyone reads that, they now fully understand alf's actual Ballistic comprehension is nonexistant.

quote:

Originally posted by Alberta Canuck:
Alf -

I do not know whether you can't understand what I said, or simply refuse to do so. I hope it is neither, but don't know what else it might be.
...

I'm a bit surprised that you would actually try to "discuss" Ballistics with either alf or jagter. Surely you have read enough of their posts to realize they only post

1. I'd place a bet that you quickly tire from the nonsensical posts they make.
2. I'd place a bet that you become angry with yourself for "trying" to talk rationally with them.

Already been through it myself. One thing is for sure, they NEVER learn.

/

This discussion is obviously polorized; those who find chronographs useful when working up loads and those who don't. I'll add my 2 cents worth;

Before I got my first Oehler in '75 I worked up loads using the "look for classic signs of pressure and then back off a grain or two" method. I ended up with numerous examples of enlarged primer pockets, extractor/ejector marked cases, stiff/stuck bolt handles and even several blown primers. Many were not at what was listed as "max" loads in several publications. When I got my first chronograph (Oehler M11 with M61 Skyscreens) one of the first things that became apparent was that when I was into the above "classic pressure signs" velocity was always above, sometimes well above, what it was supposed to be. I learned to interpolate published velocities of manuals when taken in real rifles and compared barrel lengths to what I was testing in. I added or subtracted velocity for the differece in barrel length and this gave me a reasonable velocity to watch for. I never expected to get the same exact velocity but found that when approching that interpolated velocity I was getting close with the attendant pressures. Using the appropriate burning rate of powder was also a careful consideration. Also the chronograph began to tell me when the powders were burning efficiently. That most often indicates you should continue to work up carefully even if below the expected veloctiy.

Some where back in the late '70s or early '80s PRE/CHE came into vogue. I quickly found that PRE was useful when used in conjuction with the chronograph to duplicate factory pressures while equaling factory velocities if similar bullet weights and powders were used. CHE was found to be useful only in telling you if maximum pressure had been reached with that lot of cases using a specific powder/bullet/primer combination. CHE told nothing about loads of lessor pressures.

Let me give a recent example of why I have found chronographs to be very valuable tools. Last year a friend had a custom '06 with 26" barrel built by a very reputable custom rifle maker using all the appropriate quality materials. The chamber was cut to minimum headspace. He had been working up loads using WW cases, WLR primers, IMR4350 and Hornady 180 gr SPBT bullets. At 55.5 gr of 4350 the primer blew (these were new cases) and the bolt was very difficult to open. Since 56 gr of 4350 is generally thought to be a safe max load it appeared something was amiss IF his loads were correct.

We pulled the bullets in the remaining 3 unfired shots of that string and the all had exactly 55.5 gr of powder. I checked the specification sheet the riflesmith sent with the rifle and it was not only chambered to minimum headspace but chambered with a minimum spec match reamer. The owner of the rifle had also brought his loading componants so we loaded up another batch going from 54 gr of 4350 up through 55.5 gr in .2 gr increments.

A quick trip to the range and set up the Oehler M35P and we began testing. At 55.1 gr the bolt lift was getting difficult but the primers were not unduely flattened nor was there any measureable CHE. However, the velocity for the 3 shots averaged 2807 fps and the 3 shots of the 54.9 gr load was 2778 fps.

Since 2800 fps with a 180 gr bullet in a 26" barrel is a pretty healthy max load (but most often a safe load if the correct powder is used, sometimes 2800 fps is not a safe load however) the chronograph was telling me the loads were max regarless of what the powder charge was. He settled on the 54.9 gr load. We did not fire the 55.3 and 55.5 gr loads. It was obvious the combination of a new barrel with a tight chamber caused higher than "normal" pressures. Had my friend used a chronograph as he and I did it may not have told him the pressure but it would have (as it did to me) told him he was treading in high pressures with a velocity over 2800 fps with a 180 gr bullet in his '06.

That is how a chronograph works for those of us who know how to use it and interpolate the data. However, I now have an Oehler M43 so relative pressures in most of my firearms will be known. The use of a chronograph is still much more accurate in developing loads (especially those loads that are not near max pressures) than is CHE or just group shooting. Of course the user must use appropriate references, loading componants and understand what the chronograph is or is not telling him.

Larry Gibson

Okay guys, I can see where the gist of this whole conversation is fragmenting.

First of all, Jagter, I am not disagreeing in particular with anything you are saying, just with the "absolutes" that Alf was postulating. Whether it seemed that way or not, I have actually been supporting your position through this whole thread.

I have always suspected Alf knows far better than to put things in absolutes, but for the sake of any lurkers who do not have extensive experience, I think it is essential to point out that there are few absolutes in handloading. That you can determine safe or unsafe pressure trends by using a chronongraph is not one of them. Some believe you can, but that is an act of faith as much as anything else.

Second, Mr., Gibson, if you have concluded that I am in a "camp" which does not believe chronographs are useful in handloading, you are mistaken. I DO believe chronos are useful in handloading, but I do NOT believe they are useful in telling you any substantive information about your load's pressures. In the 55+ years I have been chronographing loads, I'll bet I have done as much chrono work and interpretation as nearly anyone here. So it is barely possible I do understand how to use chronos and to evaluate the info they give me. I also undestand there is no solid, definitive, tie between velocity 6 feet from the end of a gun barrel and the peak pressure in the chamber.



Chronos certainly CAN tell you sometimes that something is off track, but as to exactly what or how much, well that is something else entirely.

How many of the folks here, using a chrono, have clocked ammo where there were occasional rounds which showed 100-to-150 fps or more velocity than the others fired in that same 5-round group (batch)? What does that indicate to you? Is it a indicating a pressure problem? If you are sure it is, what kind of a problem? Is the load too hot or is it maybe too low (so that only one round of the 5 burned fully as it should)? Was it a truly errant round (in velocity), or was it a variation in the reading of the velocity by the chrnograph?

I have NEVER said a person would find a chrono useless in working up a load. All I have ever said is you cannot RELY on one for your safety by assuming anything it tells you is directly linked to the safety of the pressures you are creating.

Even very consistent loads, in terms of velocity, may be either consistently excessive in pressure for the long term good of your brass & rifle, or they may be consistently just into the intended low end of the burn envelope for your powder (in that case, with that bullet). If they are at the low level, no harm probably, but if you are running consistently at the top end, it may end up something like constantly driving your car with the engine revving ight up next to the the tachometer red-line. Works fine for a while, but doesn't do much for the safety of the engine.

For reading whether pressures are safe, I still say, don't depend on a chronograph to tell you. Look at your brass.

If you want to know if your loads are safe, that's something you can do with every round you fire, wherever you are, if you want to.

With that, I've go a life to live elsewhere, so will try to leave the rest of the detail and debate to you guys. You know whare I stand.

1) Stay inside min & max loads as per your reloading manual.
2) Work your loads up and chronograph the velocity
3) Compare your velocity with the book velocity, so you know where you stand.
3) Check the normal tell-tale signs as you increase the loads.
4) Try to find the rifle's sweet-spot as you are loading up.
5) Once you find the sweet-spot there is no point in loading up
6) Never exceed the max load/velocity as the incremental velocity is academic and of little practical value.
7) If you stay inside the max load you will always be within Saami/CIP spec
8) In this band of min to max velocity you will experience essentially a linear relationship to pressure
9) If you so wish give your load to a Lab and have it tested to get a better fix at the pressure level relative to industry standards.

The system is actually dead simple, even for novices.

Warrior

quote:

Originally posted by Larry Gibson:
...That is how a chronograph works for those of us who know how to use it and interpolate the data.

Hey Larry, I also wasted a good number of my 50+ years of Reloading shooting across a chronograph. That is how I know they don't tell a person anything about Pressure.

quote:

However, I now have an Oehler M43 so relative pressures in most of my firearms will be known.

Actually all you have purchased is Fool's Gold. If you read the questions to and answers from Dr. Oehler in that thread, he explains they are intended for Test Labratories. By that, it is clear to me that means a place that can get Calibration Ammo, or Reference Ammo as Dr. Oehler prefers to call it.

Basically that translates into any Haphazard Strain Gauge System being non-calibrated if a person buys one for use at home. And non-calibrated means misleading and worthless data.

quote:

The use of a chronograph is still much more accurate in developing loads (especially those loads that are not near max pressures) than is CHE or just group shooting.

I disagree completely. CHE & PRE can keep anyone out of Pressure Problems if both are used properly and together. The chronograph only tells velocity.

quote:

Of course the user must use appropriate references, loading componants and understand what the chronograph is or is not telling him.

I do agree with this statement, but it is only because I know a chronograph only tells Velocity - not Pressure. Stating otherwise has mislead many Beginners(and people who really don't have a clue about chronographs) to False Assumptions, Incorrct Interpolations and Totally Wrong Conclusions.

Best of luck with the guessed at chamber dimensions, random fudge factor adjustment, and non-calibrated M43.

Hey 1in10, I hope the above pissing match didn't dissuade you. "pressure signs" seems to be fightin' words, and once "PRE/CHE" rears its ugly head, some folks seem to get personally insulted sooner or later, and the threads veer off into arguments.

My down-n-dirty answer to you is look at a few primers in fired factory fodder from your firearm, see how flat they are, use that brand of primers, and don't load so that they get much flatter. the 308 and similar cartidges work at a pressure that takes the rounded corners off of primers, but doesn't make them too flat. compare them to a few factory 30-30, 35 remington, or similar cartidges and you will see what I mean.

the trick here is not to try and estimate the pressure from the primers, but to keep your loads withing a safe neighborhood.

I have noticed a general trend of better roups at higher pressure, I suppose that the higher pressure translates to more uniform burning. so I am not afraid of working up a bit.

In my limited experience, I have never blown up a gun, and rarely see things like sticky bolt lift or smeared case heads. some may think I'm not worth reading because of that, but I am pretty proud of it, actually.

quote:

First of all, Jagter, I am not disagreeing in particular with anything you are saying, ....... , I have actually been supporting your position through this whole thread.

Thanks Alberta Canuck, appreciate.

What's more, I think we all know very well what everybody else are really meaning with their comments. It is just that some of us are more willing to try out new developments/ways of doing with success as well, than others who are perhaps a bit against the idea to change their old and proven methods of doing things.

If there is one certain thing in this life, then it is that nothing will ever remain the same, things, methods and whatever always change - if not to the good most such changes don't take place at all or don't last long afterall!

And this I think is a change to the good of all reloaders.

Just a question of time and we will see and accept the benefits of it - including the fact that velocity + the state of your brass are an easy observable tell-tale mechanism to the benefit and good health of us all untill such time we all accept the new ways to determine that ever important pressure.