Scott is also correct. To simplify what he said, it is " dv/dt ", which I feel sure everyone os familiar with.

Thank you, Larry Gibson.

jeffo, let's not get rude. If you have "explained" this to me several times, you must have done a poor job of it.
If one takes a 30-06 case and puts some IMR4350 in it, the bullet will go xxx veleocity. If he puts a larger amount in the case, the bullet will go faster.
That's all a reloader needs to know. The aesoteric bullshit to show your style as a retorician only adds heat to the conversation, and certainly no light.
You and HC make a good pair.

quote:

Originally posted by wasbeeman:
Thank you, Larry Gibson.

jeffo, let's not get rude. If you have "explained" this to me several times, you must have done a poor job of it.
If one takes a 30-06 case and puts some IMR4350 in it, the bullet will go xxx veleocity. If he puts a larger amount in the case, the bullet will go faster.
That's all a reloader needs to know. The aesoteric bullshit to show your style as a retorician only adds heat to the conversation, and certainly no light.
You and HC make a good pair.

Yeah, i must have done a poor job.. a poor student always blames the teacher --

esoteric? hardly ... and not a bad thing for one to KNOW and understand ... sort of like your car gets worse milage at 60 than at 55, but the DELTA is worse comparing 65 to 60 ..


But, you are SO CLOSE to actually GETTING it ...

let's take that 4350 example ..
the bullet does IN DEED go faster .. but not as a direct relationship to PRESURE --

why? bc presure curves are non-linear ..

get it?
using quickload projections, just to help with the icky esoteric mathie bits...
(the loads below are NOT reloading data - do not USE)
with A bullet in a 30-06 and 4350
a 50gr charge goes 2398 at 31077psi
a 55gr charge goes 2637 at 40345psi

the delta in vel is?
239 fps

the delta in psi is?
9268

IF "pressure" was a primary force, an additionl 9268 psi would result in an additional 239fps..

so,, if wasbeeman was right, a pressure of 49613 would result in a vel of 2876

lets plug some numbers in, shall we, and simply prove who is correct.

a pressure of 49613, with h4350 results in a vel of 2828 ...

hey, wait a minute? i thought been felt strongly enough to insult me that it would be a perfect advancement?

where's the other 48 FPS?

well, its in work, then, aint it?

in fact, it takes 52292 psi, 28.9% MORE than a direct relationship with pressure, to make it go 2876...

oh, and powder increments change, too .. but that's for another time ...

So, mr wasbeeman, sorry to go all esoteric on you .. its just basic facts, really, to me ..

however, if you like reloading in the dark, and not understanding what's going on inside the case, i can not be accused of failure to warn.

btw, do you have any explaination for why we see both JUMPS in velocity as well as no gain and negative gain when increasing powders?

its not a touch subject, but one has to be willing to learn just a bit more than what one SEES ...

one of my college profs invented the formula
(the 1 and 2 are properly subscripts)
(mass, volume, pressure, temp)
M1+V1+P1+T1= M2+V2+P2+T2 for all conditions on the earth, not involving nuclear fission or plasma -- if you know the volumeteric expansion, burn rate, and time, along with weights and frictions, you can get amazingly close to, well, reality

its a really neat forumla, and like y=mc+b, amazingly useful ..

hope that's not to esoteric for you ..

Hot Core stated that I had totally missed the point when I stated that I really need a chronograph to see what is going on with my loads. He may be correct in believing that I don't fully understand all there is to know about the things under discussion in this thread.

However, I didn't mean that I needed a chronograph to determine pressure, for I think I see that a chronograph can only tell me what velocity the bullet has leaving the barrel of a rifle and to make a determination concerning what the pressure was is an inappropriate use of a chronograph.

But, it would seem to me that, without a chronograph, the only thing I can determine about different loads is how they group. You cannot accurately determine the velocity a load is producing by using what a loading manual states as the velocity of a certain powder, charge weight, and bullet weight will produce.
Because, what a reloading manual states as velocity with a certain powder, charge, and bullet isn't necessarily what one will get with a particular rifle. Using the same powder, charge, bullet, etc. in several different guns will result in different velocities. Correct?

Hot Core, if you think I don't really understand the relationship of pressure to velocity you are correct though in assuming that I don't

quote:

Originally posted by Red C.:
However, I didn't mean that I needed a chronograph to determine pressure, for I think I see that a chronograph can only tell me what velocity the bullet has leaving the barrel of a rifle and to make a determination concerning what the pressure was is an inappropriate use of a chronograph.

Hey Red C., I stand corrected, you do get the point.

quote:

But, it would seem to me that, without a chronograph, the only thing I can determine about different loads is how they group. You cannot accurately determine the velocity a load is producing by using what a loading manual states as the velocity of a certain powder, charge weight, and bullet weight will produce.
Because, what a reloading manual states as velocity with a certain powder, charge, and bullet isn't necessarily what one will get with a particular rifle. Using the same powder, charge, bullet, etc. in several different guns will result in different velocities. Correct?

That is correct. The thing you are missing now is that you can "guesstimate" the Velocity as close as a non-calibrated HSGS can "guesstimate" Pressure.

quote:

Actually, your last sentence says a lot:
Hot Core, if you think I don't really understand the relationship of pressure to velocity you are correct though in assuming that I don't

You are doing waaaaaaay better than those who still believe you can somehow mysteriously determine Pressure with a Chronograph.

Here is a "Key" you may be seeking. If you guesstimate the Velocity by comparing a Load to the Loads shown in a Manual, you may be off as much as ( + or - )250fps, but it doesn't matter. You just take the guesstimated Velocity and run that number through the External Ballistic Tables in the back of the Manual - to get a very raw "estimate" of the Trajectory. You create a Guesstimated Drop Chart and use it to get somewhere on the Target as you move it farther away. But, you really do not need the Guesstimated Drop Chart to do the same thing.

Once you actually shoot your Groups at distance, 300yds and beyond, you will probably realize the Load may need a bit more Fine Tuning. But, you will be close and already have a good idea of the Drop Rate.

If you Hunt and only take shots closer than 300yds, none of this amounts to a Hill-of-Beans. You simply sight in at 225yds or 250yds, take a few shots at 300yds if that will be your MAX distance and pay attention to how much it drops. Typically the Bullets we have available today when used in a Deer Rifle(including the RNs) don't drop enough from 225yds out to 300yds, to fall below a clean Kill area on the Deer if you aim at the top of the Shoulder.

The most important thing of all is being able to read Pressure Indicators and know when the Pressure is rising enough to begin changing the dimensions of the Case - CHE & PRE.. Some Pressure Indicators are better than others, but nothing beats good old CHE & PRE.

Once you really understand what Velocity is actually good for, you will realize it's importance is waaaay overrated.
-----

quote:

Whammed in by the BeeMan to Jeffe:
You and HC make a good pair.

Thank you!

I have a question too for you guys who are definitely more knowledgeable than me on internal/external ballistics.

As an example:

Why can we have a new rifle, with say, 50 rounds through it, where the shooter chose to "break-in" the bore and borescope showed apparent adequate cleaning....work up a load with the following:

sorted Lapua brass that weighs, say, within .01 grains of each other..you have 20 cases for our purposes.

You pick a good bullet and check and sort by weight and bearing surface.

You hand weigh each powder charge, cases are prepped as identical as you can do it, and each finished cartridge is measured to in length of head to ogive to identical length (in other words, every load is as identical as you can do).

go to range, and shoot this "identical" set of rounds, and sometimes depending on powder, you have very little velocity spread, and sometimes it can be well into double digits?

Are there just so many factors including potential glitches in chrony, fouling in bbl, etc?

I took some very meticulously loaded ammo to the range with everything being identical except powder and charges, where both were providing excellent velocity (IMO), but one powder outshined the other in terms of accuracy at 100 and 200 yards, but with bigger velocity spreads, where the other had very little velocity spread but groups were roughly 1" to 1.3" in 3 shot groups.

Why is this?

Doc

If you are just testing 3 shot strings then your comparisons, velocity, ES, SD and groups sizes, are not valid. Most ballisticians believe a 5 shot string is still not valid. Speer's ballistician in their manual #14 says the minimum shot string is 7 to be valid. Most use a 10 shot string.

Larry Gibson

Well I'm sure we were all wondering when HC would bring his CHE into this. He just can't seem to understand that the useof a chronograph is not about measuring pressure. It simply can be an indicater when one is approaching maximum safe pressure levels. He still puts his faith in the proven unreliable HE method. All CHE does is tell you when you'v exceeded the elasticity of the case. That means youarealready over pressure.

The use of the chronograph is an indication of pressure, not a measurement of it. Pity he can't understand something so simple. If youare recording 2700 fps with 56 gr IMR4350 in and '06 with 180 gr bullets you can bet you are approaching the SAAMI MAP for that cartridge of 60,000 psi. If you go on and lad more 4350 into the case waiting for CHE you will probably not get a measurement of "pressure" until the psi is well above that. The last test I ran did not give a CHE measurement until I was over the max load and above 68,000 psi. If you want to depend on CHE like HC does then have at it. For me I'll use a chronograph and be safe about it.

Larry Gibson

quote:

Originally posted by Larry Gibson:
Doc

If you are just testing 3 shot strings then your comparisons, velocity, ES, SD and groups sizes, are not valid. Most ballisticians believe a 5 shot string is still not valid. Speer's ballistician in their manual #14 says the minimum shot string is 7 to be valid. Most use a 10 shot string.

Larry Gibson

ok, but lets take what is unvalid and explain why it still occurs. What if I shoot 2 rounds only and there is a 37 fps difference. Why would this occur?

quote:

ok, but lets take what is unvalid and explain why it still occurs. What if I shoot 2 rounds only and there is a 37 fps difference. Why would this occur?

Because every bullet is different, every case is differnt, humidity level of the powder even one charge to the next can be slightly different.

Temperature between the shots will be different, and some variable within your barrel will be different as well. Bottom line, it's just the way it is.

A couple of points that I don't think have been made here yet;

The ideal pressure time graph to give the maximum velocity to a bullet with a given powder would be that showing maximum allowable breach pressure being reached as fast as possible (without detonation), and then most importantly, that maximum pressure being maintained constantly as the bullet accelerates down the bore.

As a bit of a comparison, take the catapault launch on an aircraft carrier. Hydraulic oil is not used as it is too slow to pump to fill the rams operating the launch. Even compressed air would not give the acceleration required but here steam performs this duty as it is feed into the rams and expands very similar to gun powder gas all the while maintaining the maximum allowable pressure during the launch sequence.

The theoretical trick with gun powder is to match the burning rate and gas expansion factor to the allowable chamber pressure, bore size, barrel length and the bullet weigh with the aim of getting that pressure up quick and maintaining it as close to constant as possible for the length of the barrel, and then burn out the instant the bullet leaves the barrel.

H380 & BLC2 are ball powders and they tend to be more sensitive to temperature. Also Lot variances can be common. W748 is quite similar as well. I have seen 200+ fps variance between hot & cold weather with these powders in some calibers. Given that these powders are very old technology, I avoid ball powders altogether. Very dirty burning too.

The one 22-250 I owned shot well with Varget & H4350 and 52 to 55 gr bullets. I suspect that a double based powder like N550 might be an interesting one for this caliber. John Barsness has done a lot of load development with Ramshot powders which are ball configuration but very modern technology (Made in Belgium I think). I wish we could get those powders here in NZ.

quote:

The last test I ran did not give a CHE measurement until I was over the max load and above 68,000 psi. If you want to depend on CHE like HC does then have at it. For me I'll use a chronograph and be safe about it.

Larry, this isn't meant to be argumentative, so please don't take it that way. This is a genuine question. How did you know the pressure was "above 68,000 psi"? How close to the actual pressure can you be without using actual pressure measuring devices (not a chronograph)? Could you state, again, how to determine pressure with a chronograph?

I suppose I'm more interested in having safe pressure than having a certain velocity. For me, the main reason for wanting to know velocity is to determine trajectory.

What I want is an accurate and repeatable/dependable load, with trajectory that is satisfactory for the distances I plan to hunt/shoot, with enough stopping power to humanely dispatch what I'm hunting.

To be honest, Hot Core's approach seems to be better for what I'm after, but I want to make sure I understand both sides of this issue.

Thanks in advance to your response.

P.S. I don't want to have to choose/take sides here, I'm just wanting to understand and be a better reloader.

quote:

Originally posted by larry:
... the useof a chronograph is not about measuring pressure.

Absolutely correct!

quote:

It simply can be an indicater when one is approaching maximum safe pressure levels.

Absolutely misleading!

quote:

He still puts his faith in the proven unreliable HE method.

Proven inaccurate by people who did not follow the correct procedure. So, that statement is Wrong.

quote:

All CHE does is tell you when you'v exceeded the elasticity of the case. That means youarealready over pressure.

Not if you follow the Procedure. And Wrong again.

quote:

The use of the chronograph is an indication of pressure, not a measurement of it. Pity he can't understand something so simple. If youare recording 2700 fps with 56 gr IMR4350 in and '06 with 180 gr bullets you can bet you are approaching the SAAMI MAP for that cartridge of 60,000 psi. If you go on and lad more 4350 into the case waiting for CHE you will probably not get a measurement of "pressure" until the psi is well above that.

Not real sure what he is talking about here.

quote:

The last test I ran did not give a CHE measurement until I was over the max load and above 68,000 psi.

But..., that 68kpsi is BOGUS. It comes from a non-calibrated HSGS which was proven to be a worthless misleading piece of trash outside of a Lab in this classic, time imortal, non-prejudiced Test. It is colloquially refered to as The GLOATING Thread for some reason.

quote:

If you want to depend on CHE like HC does then have at it.

Best advice I've ever seen given by larry.

quote:

For me I'll use a chronograph and be safe about it.

Wrong-O!!!

Well I can see Hot Core's ego is alive and well this fine Sunday morning...

evidently NO ONE has had a chance to piss in his corn flakes yet...

Boy, I'm glad I keept things simple. I just go shoot (with chrony), add powder til the bolt lift gets a little stiff, or primers look a bit flat or scarring begins to occur on the case head. No more powder and I back it down about .5 grains. Done. No problem with that method in 2 decades.

I don't have time to learn, agree with or disagree with all those who know a lot more than me about internal ballistics.

nahhh, Doc. You don't want to do that. If you do that (even quite successfully) you have to listen to a lot of condescending bullshit from Jeffo and his side kick HC whilst they debate how many angels can dance on the head of a pin.

Red C.:

quote:

The last test I ran did not give a CHE measurement until I was over the max load and above 68,000 psi. If you want to depend on CHE like HC does then have at it. For me I'll use a chronograph and be safe about it.

Larry, this isn't meant to be argumentative, so please don't take it that way. This is a genuine question. How did you know the pressure was "above 68,000 psi"? How close to the actual pressure can you be without using actual pressure measuring devices (not a chronograph)? Could you state, again, how to determine pressure with a chronograph?

I suppose I'm more interested in having safe pressure than having a certain velocity. For me, the main reason for wanting to know velocity is to determine trajectory.

What I want is an accurate and repeatable/dependable load, with trajectory that is satisfactory for the distances I plan to hunt/shoot, with enough stopping power to humanely dispatch what I'm hunting.

To be honest, Hot Core's approach seems to be better for what I'm after, but I want to make sure I understand both sides of this issue.

Thanks in advance to your response.

P.S. I don't want to have to choose/take sides here, I'm just wanting to understand and be a better reloader.[/QUOTE]

I measured the pressure of those via an Oehler M43 in 2 different rifles. I currently can measure the psi in 23 different rifles/handguns using 18 different cartridges. The psi's I have recorded have been 100% in line with SAAMI and CIP standards. The ability to measure the psi along with the velocity has also verified my own, and most every one elses, use of the chronograph when developing loads. Simply put, when the velocity is up where is is supposed to be according to the manuals then the psi is also pretty close to what the say it is. I've also discovered that the "fast and slow barrel" claims are simply a function of pressure. With a given load and equal barrel lengths the fast barrels have higher psi and the slow barrels have a lower psi. The internal specs are what affects this along with twist rate and bore smoothness. Load the slower barrels to the same psi and the velocity is then the same as with the fast barrels.

I'm sure HC is going to jump in about the M43 being haphazard, etc. but the M43 is not inaccurate in the least. I'm sure he will throw out the usual thread to "prove" it. However, in that thread the .223 rifle's owner improperly placed the strain guage in front of the chamber which is why the psi readings ere low. They should have been low compared to a proper placement of the strain guage over the chamber. The readings given were also probably correct for that location of the strain gauge on the barrel. HC can't comprehend that. I've offered to do the same test for him but he knows better than to take me up on it as my .223 barrel has a correctly mounted strain gauge and gives correct psi readings.

The M43 is an excellent and accurate tool. I have used specific lots of ammuntion with known psi (provded by Winchester and Federal ballisticians) as "reference ammuntion" so I know the M43 is accurate, or as accurate as most any pressure measuring device is. I have run CHE tests on .223, .308W, 30-06 and 8x57 and have found the CHE measurements do not correlate to pressure at all. In several instances I got excessive velocity and very high psi with no CHE increase at all. CHE was an excepted method for a while but with the advent of much better pressure reading technology it has been proven very unreliable. The manuals no longer advise it's use. BTW; HC's CHE method is incorrect; one should only use new, unfired cases. Not the once fired cases as his directions say. The once fired cases have already been slightly work hardened by the firing expansion and contraction. They don't reuse the copper cylinders in CUP machines either for the very same reasons.

If you want to stay safe then use the current reloading manual's loads as guidelines, use a chronograph to know when your velocities are getting where they should be and watch for the usual pressure signs as outlined in all reloading manuals. You don't have to take sides at all, just be safe. CHE is unreliable and has been proven so.

Larry Gibson

Thanks for your fast and thorough answer. I appreciate it.

Larry,

I couldn't agree with your last post more. I haven't used an Oehler M43, but have strain gaged barrels and using "normal" data acquisition software, material properties, and standard engineering principals calculated the chamber pressures based upon the measured micro-srain. It is much much more accurate than the bogus mythology of PRE or CHE!

quote:

Originally posted by ScottS:
Larry,

I couldn't agree with your last post more. I haven't used an Oehler M43, but have strain gaged barrels and using "normal" data acquisition software, material properties, and standard engineering principals calculated the chamber pressures based upon the measured micro-srain. It is much much more accurate than the bogus mythology of PRE or CHE!

That it is. Good to hear from you.

Larry Gibson

"I think the title of the thread ought to be, don't load a Savage 22.250 to max load manual data... start REAL low.."

IF you add to that the serial number of THAT Savage the statement would stand on its own legs.

Some arguments aren't worth winning. If you gotta explain the area under the time/pressure curve vs. speed, you gonna hit a stump everytime!

quote:

Originally posted by Jim C. <><:
If you gotta explain the area under the time/pressure curve vs. speed, you gonna hit a stump everytime!

amen!