....... ......


just checking the progress....

quote:

Originally posted by seafire2:
... just checking the progress....

Me too.

Still no defense of the HSGS "accuracy"! Imagine that.
-----

In defence of the finest Pressure Detection Methods ever devised - CHE & PRE - the knowledgeable reloaders know.

/

quote:

Originally posted by Hot Core:
[QUOTE]Question to Dr. Oehler:
5. If we consider the "Range" of variance you mentioned, 3%-8% with an average of 5%, if we consider the worst case situation with a HSGS, and if the system indicates 60.0Kpsi, are you saying the actual pressure could vary plus or minus 4.8Kpsi for a "potential Range" of 55.2Kpsi <-> 64.8Kpsi? But for most users who pay close attention to the Set-Up and follow the directions the average variance would typically be(5%) with a Range from 57.0Kpsi <-> 63.0Kpsi?

quote:

Answer from Dr. Oehler:
You've got it! That's much better than thinking you are at 50K and actually be exceeding 75K.

QUOTE]

Dr Oehler also said this on his web site.
http://www.oehler-research.com/m43faq.html

quote:

Does the measured pressure correspond to actual PSI or copper units pressure?

The pressure measured by the Model 43 corresponds closely to actual PSI readings. Copper crusher readings are so suspect that we hesitate to compare.

Questions can be asked and answers provided to prove/color ones point. Oehler answered as truthful as he could in both cases. The strain systems have great value when properly used, and that doesn`t mean they are restricted to a lab enviroment. They are much better as I read it to CUP and I wonder how CUP compares to CHE/PRE?

You say we need to "calibrate" the strain systems with SAAMI ammo. The SAAMI pressure loads used to "calibrate" the lab equipment, I been told, is ammo loaded to a SAAMI "standard" then sent to 1/2 dz or so labs with strain/piezo systems, fired and the pressure recorded and then the results are taken in and a "referance pressure" based on this data is then assigned to the ammo. The various powder, bullet and ammo makers then "calibrate" their - in most cases today - strain systems to agree with the pressure factor SAAMI gives with the ammo. There is no cut-in-stone SAAMI pressure unit anywhere to calibrate any system to yet that I`m aware of. If I`m wrong could you please point me to a referance of it?

The old PRE/CHE has been dropped by most writers still alive that used it, and not trusted by the new ones coming up as accurate enough to be trusted. I`ve used it (PRE) in the past and never had any pressure problems while doing so. I`ll be the first to admit I still feel it has some merit. I am though by nature a very conservative person, in reloading and other habits.

I feel the strain systems are more repetitive in their measurments then I ever was with a mic trying for 0.0001" accuracy. If I measured a case at random times and wrote the results down but never looked at them, I believe looking back, there would have been 2-3 answers in the end. My mic is listed as 0.0001" accurate according to the maker with 0.00005" resolution. That means I can be 0.00005" off either way and never know just due to tooling and this on a measurment we need to know of 0.0001" differences if checking CHE. Now toss in human error.......

I use a Pressure Trace, I feel it is the best check of the options available to me. I also at times DBL check with PRE. I also watch primers, compare velocities with the book, feel for extraction changes, compare data from multiple sources before starting with a new powder/bullet. I still to date -40 yrs at the bench- have had exactly one remembered primer leak -Knock On Wood. I`ve never had a primer "fall out" of the case. I`ve ironed a few out real well, and some cases didn`t last but a couple loadings. My velocities are almost always within 100 fps of the reports others post here for their rifles, even the "hot rodders". I`ve yet to have my rifle, target or game complain.

The PRE I used told me I was in the "ball park", but where in the park? PRE increases never matched up with gains in powder charge in my experiance. 1 gr extra may add 0.0002" then the next 1gr may add 0.0006", you never knew. I might have a measurment of .4700 on a fired cartridge and a previouslly set max figure of 0.4704". Can I add powder? How much? Am I within 10K or 5K psi from my max? What happens when I start with factory ammo measuring say 0.4650" and when resized the same spot on the case reads 0.4667"? Do I ignore the lost .0017" expansion the new case showed? is it important? If not, why?

BTW HC, I`m not taking sides, and you make some valid points at times.
I do have to ask though You tease Denton for suggesting tapping a live primer out with a sharp tool. I wonder how many of us have punched a live primer with a sharp decapping pin and never though twice about it?
You knew I couldn`t ignore this thread forever.....

quote:

Originally posted by Ol` Joe:
...BTW HC, I`m not taking sides, and you make some valid points at times.

Hey Pilgrim, What do you mean "at times"?

quote:

I do have to ask though You tease Denton(EDIT IN: the fool) for suggesting tapping a live primer out with a sharp tool. I wonder how many of us have punched a live primer with a sharp decapping pin and never though twice about it?

Let me suggest you go back and re-read The World's Most Ignorant Reloading Suggestion. Look for words which indicate the fool believes it is OK to Hammer on the Anvil of a Seated Primer. I see that as a good bit different than easing a live Primer out slowly with the Decapping Pin, while wearing glasses, having the entire operation wrapped in a towel, and keeping things I'd rather not have "shot" with a rapidly flying Primer Cup completely out of the way.

How `bout taking a new case with a Snug Primer Pocket and Hammer the un-fired Primer out following the fool's directions and letting me know how it goes. I do ask that you "do as he says" not as you think he said. DO NOT add anything he left out.

However..., I can NOT imagine the Ol' Joe I know, Hammering on the Anvil of a Snug Seated Primer with a sharp tool. If that is wrong, let me know.

quote:

You knew I couldn`t ignore this thread forever.....

You did right well to hold out as long as you did.

Perhaps you can help Kudude in his thread where he does not want opposing views. I can see how a fellow can win an argument that way though.

quote:

The old PRE/CHE has been dropped by most writers still alive that used it, and not trusted by the new ones coming up as accurate enough to be trusted.

In the newest Lyman Reloading Manual 48th Edition, in the chapter "The Mystery of Pressure" by Bryce Towsley (pg. 99), the last three paragraphs are dedicated to the CHE method of inspecting cases to detect high pressures.

They also claim that CHE is one of the best ways for the reloader to check, and that when its use was checked against the modern methods of pressure measuring, that it's proper use was proving correct.

While I admit I have not used this method to date, I would consider purchasing a micrometer for this purpose and see if I can make it work. But as has been stated by myself and others on this thread, one should not interpret the measurements to mean anything more than it does. It is a "go/no go" measure, a red flag that can be reliably heeded to mean "stop".

Gentlemen,

We wanted to see how our own loads on some of our wildcats faired "pressure wise"

So we bought an Oehler Model 43 Ballistic Lab.

We are going to set it up as the instructions suggest, and will shoot several rifles and report our results.

Our program is a bit busy at this time, so this is slated to begin around late April or early May.

quote:

Originally posted by Saeed:
Gentlemen,

We wanted to see how our own loads on some of our wildcats faired "pressure wise"

So we bought an Oehler Model 43 Ballistic Lab.

We are going to set it up as the instructions suggest, and will shoot several rifles and report our results.

Our program is a bit busy at this time, so this is slated to begin around late April or early May.

Saeed,

Thank you!! This will be very interesting in deed.

Will you be taking CHE/PRE measurements during your testing?

Posting pictures of the fired cases and primers at near max pressures would be interesting to see, too.

I wish I could be there to help!

Mike

Mike,

Yes sir we are going to take pressure readings. That was the whole idea of getting this instrument.

We've had a number of discussions, both in our workshop and on the forums, regarding some of our own loads.

There are people who think if a load exceeds published velocity for that cartridge, then our loads must have excessive pressure.

My own understanding is that both the rifle and the load work together.

Hence one load in a given rifle is might be too much or too little in another.

So, we load for each rifle until we reach what we think is its max. Then we stop.

This is particularly true of the older cartridges.

We have built modern rifles for some of these, and our loads have higher velocity than has been accepted in them.

We have not noticed any signs of high pressure at all, and both the rifle and the brass used are still intact and shoot very well.

We will just have to wait and see.

Neither methods (strain gauge and CHE) measure pressure. The best that you can do is make comparisons of indications of pressures compared to some other load in that gun and under those conditions.
If you want to measure pressure you need to have SAAMI calibrated pressure rounds to calibrate your type of measurement. Under these conditions the corrected pressures offered by a strain gauge can approximate pressures to a finer degree than the CHE method. WHY?
Because the strain gauge remains more constant than the cartridge case. If one case is softer than another or harder than the first then your "readings" are going to be further from the actual pressure than the strain gauge.
I have use the CHE technique in working up loads for wildcats that I had no other way to find a maximum load for but the final word was reducing the load to its first accurate load below the "maximum" and then testing it for the longevity of the case. If the case would not withstand at least ten reloads (neck sizing in my normal manner) then it was deemed over pressure for my firearm. It was further reduced to the next accuracy loading and retested for longevity. There is simply no way that measuring a deformed case can provide you with a close approximation of the actual pressure developed in any particular gun.
Using a strain gauge - compared to factory ammunition can give an indication of how the reload compares to that factory ammunition. Neither method is accurate enough to provide a shooter with real pressure figures. There are too many variables that are not taken in to account. Using a chronograph to find the pressure of a particular load is only slightly less accurate than the CHE technique because it doesn't take into account any of the barrel variables. A rough or tight barrel might give lower velocities and higer pressure than a polished or loose barrel. If you have a rough and tight barrel and try to load to a book maximum load by comparing the velocity you may end up blowing a gun apart before you get the same velocity listed in the book. Using hard brass could give indications of lower pressures when the pressure is in fact higher. A tight chamber can yield smaller expansion than a loose chamber would. There are too many variables the the shooter cannot measure or make up for to determine where a safe load is.
The best method that I have found is testing by using the longevity of my reloads. If cases last a very long time then I can be fairly sure that my pressures are below the level that will hurt my gun - even over the long term. I do believe that under the right conditions one can measure camparetive pressures better with a strain gauge than any other method available to the average reloader. (even though actual pressures cannot be measured without SAAMI pressure test cartridges.

This may be repetitive, but the best handling of this subject I ever read was "Chronographs and Pressure" http://kwk.us/chronographs.html 7 pages don't know the author.

/

Bartsche, Very good link, I`ve book marked it for future referance. It should be required reading for anyone that thinks they`ve a handle on judging pressure no matter what method they use.

quote:

Conclusions

The numbers suggest to me one can get into trouble by relying on chronographed velocity to gauge pressures.

But you have to ask, "Why would they want to?"

If you are a newbie, long time novice, or have a weak gun, then follow the load book recipes.

If you are more advanced with a strong gun, look at the brass.

Who cares what the pressure is?
Let alone measured with a chrono
Sheesh!

Bartsche:
Author of the article is:
Karl W. Kleimenhagen
http://kwk.us/

Pat

[QUOTE]Originally posted by pdpdad:
Bartsche:
Author of the article is:
Karl W. Kleimenhagen
http://kwk.us/Pat [/QUOTThank you. roger

quote:

Originally posted by Alberta Canuck:
........Heavier charges cause more pressure AND more heat. More pressure and more heat cause the powder to burn more quickly. Burning the powder more quickly causes even more pressure and more heat. It is a classic "ascending vicious circle"........ When loads get way over MAX, velocities often actually drop, and in the past some experimenters have described blowing up front receiver rings with excessive pressure loads which didn't even drive the bullet of the offending cartridge all the way through the barrel.........

Hang on there.....! It sounds like the bullet is upsetting in the bore, causing it to 'jam', which will most certainly raise pressure and temperature and still more pressure! We would use soft lead bullets in a revolver because they would upset and swage in the forcing cone to fill the bore real well, giving best accuracy.

quote:

Originally posted by Hot Core:

quote:

Originally posted by kudude:
HotCore,

Are you seriously suggesting that there is not a direct correlation between pressure and velocity?

Kudude

I am seriously saying no one can tell what the Pressure is from Velocity.

Surely there must be a very direct correlation between velocity and pressure? Mean pressure that is.

Just out of interest, brass case deformation can indicate a high peak pressure or a high mean pressure. (To a lesser extent 'though). This is because brass and other ductile materials deform under stress and time. On the down side, chamber pressure is not the main concern - it is bolt face thrust. Still worse, it is the rate at which the force is applied to the bolt face that matters most! A very rapid rise in chamber pressure of short duration will apply a severe shock to the bolt face with little pressure indication in the case itself.

JUST TO COMPLICATE THINGS A LITTLE FURTHER!

quote:

Originally posted by 303Guy:
...It sounds like the bullet is upsetting in the bore, causing it to 'jam', which will most certainly raise pressure and temperature and still more pressure! ...

Hey 303Guy, What you are describing is possible under some circumstances with "small" amounts of Powder, poor ignition, a Bore obstruction, and in some situatons with oversize Bullets. But that is not what AC is describing.

There are situations where a specific combination of Components in a specific Barrel causes the Powder to Burn in an Erratic maner as it approaches a SAFE MAX Load. Actually, it would be approaching an UN-SAFE Load, with that specific combination.

In those situations, as the amount of Powder is increased, it is very possible to see the Velocity, decrease slightly, remain the same, or have a HUGE increase.

I've see it with RL-19, 22 and 25 with both chronographs and good old CHE & PRE. I'd guess anyone could when the situation presents itself.
-----

quote:

...A very rapid rise in chamber pressure of short duration will apply a severe shock to the bolt face with little pressure indication in the case itself.

I'd suggest you somehow have this confused. Physics prevents this from being possible.

The Case will always indicate an Expansion when a Pressure is created inside it. The Pressure is omnidirectional and equal in amount from (basically) the Bullet's Base - aft - at any point in the Firing Sequence.

Surely Physics DOES NOT work in Reverse on your side of the Equator?!?!?!!?

Best of luck to you.

quote:

Originally posted by Hot Core:
.....

quote:

...A very rapid rise in chamber pressure of short duration will apply a severe shock to the bolt face with little pressure indication in the case itself.

.....

Surely Physics DOES NOT work in Reverse on your side of the Equator?!?!?!!?

We actually stand with our heels facing each other!

The question I'm raising here is to do with ductile materials flowing under pressure. Rockwell hardness testing is done by applying a sharp point onto the material under a specific load for a specific time duration, right? So what I am suggesting is that a pressure skike of short duration will 'under-read' while a low peak pressure but high mean pressure will 'over-read'. I am also saying that pressure that climbs very rapidly to it's peak will put a more severe shock load onto the bolt face than the same pressure that reaches its peak more gradually. (Suddenly applied load).

I have noticed some anomalities in pressure signs when looking at case stretch, case body expansion and primer flattening and primer cratering. Yes, cases work harden and primers have inconsistant material hardness but taking loadings into account, one sometimes wonders.

Good Shooting to You.

Hey 303Guy, As you are well aware, if the Firing Sequence works properly and you do not have a Primer Blow or a Case Separation, then all the Pressure that reaches the Bolt gets there because the Case Head is doing the Pushing.

So, there is no way the Pressure can reach the Bolt without initially causing the Case to respond to the Pressure. Any Pressure strong enough to toss a Bullet 50yds will create some amount of Expansion at the Pressure Ring whether it is a slow gradual rise or a sharp rapid rise.

As you also know, I'm certainly not a person who Defends HSGSs, but(gag)..., the Strain Gauge will also give an indication whether it is a slow gradual rise or a sharp rapid rise. That said(gag again), it is only Relative to the other Strain Gauge readings and is worthless - without Calibration - for knowing what the "Actual Pressure" during firing was.

Best of luck shooting upside down!

quote:

Originally posted by Hot Core:
[QUOTE]Originally posted by 303Guy:
...... possible under some circumstances with "small" amounts of Powder, poor ignition, a Bore obstruction, and in some situatons with oversize Bullets......

What I am suggesting is that under erratic ignition conditions, the peak pressure may be high enough to obturate the bullet, causing the bullet to bore drag to increase, which will exacerbate the pressure condition in the chamber (and produce a lower velocity). Obviously, there would be serious pressure signs on the case as well, if this is what is happening.

When a steady velocity rise is being observed with regular charge increases, then a sudden pressure rise, it could be that the bullet yield point has been reached. (And the poster very wisely backed off to a safe level!)

quote:

Originally posted by 303Guy:
...the peak pressure may be high enough to obturate the bullet, causing the bullet to bore drag to increase,...
... it could be that the bullet yield point has been reached. (And the poster very wisely backed off to a safe level!)

What do you think the Bullet would look like as it exited the Muzzle " if " this was happening?

quote:

Originally posted by Hot Core:
Hey 303Guy, As you are well aware, if the Firing Sequence works properly and you do not have a Primer Blow or a Case Separation, then all the Pressure that reaches the Bolt gets there because the Case Head is doing the Pushing.

So, there is no way the Pressure can reach the Bolt without initially causing the Case to respond to the Pressure. Any Pressure strong enough to toss a Bullet 50yds will create some amount of Expansion at the Pressure Ring whether it is a slow gradual rise or a sharp rapid rise.

As you also know, I'm certainly not a person who Defends HSGSs, but(gag)..., the Strain Gauge will also give an indication whether it is a slow gradual rise or a sharp rapid rise. That said(gag again), it is only Relative to the other Strain Gauge readings and is worthless - without Calibration - for knowing what the "Actual Pressure" during firing was.

Best of luck shooting upside down!

I missed this post - it must have been in the pipeline during my previous posting (probably still being ‘correctly orientated’).

You make a good point regarding the strain gauge. And the bolt face force being applied via the case head!

Maybe that even if the case smacks the bolt face real sudden, it will show sings of excess pressure - like shiny spots or flattening of the embossing. In which case we will see evidence of it anyway. It’s just that we do see damaged guns from time to time, including broken off bolt lugs.

quote:

What do you think the Bullet would look like as it exited the Muzzle " if " this was happening?

Well, this is an 'if'. I would say not very different from any other bullet. The bullet would likely not deform since the bore would be supporting it. I might expect to see more barrel groove marks between the rifling impressions than another bullet from the same barrel (as though the bullet was of larger diameter). This is not something we can explore. I am not aware of anyone ever mentioning this possibility let alone analysing it. I wonder whether we could ask a bullet manufacturer or someone? Anyway, we know that powders can produce erratic pressures and velocity when used outside their design range.

Good Shooting from Down Under(neath)

Hey 303Guy, Is the term you are describing "obturate"?

If it is, aren't " all " Bullets supposed to be designed to obturate at normal operating Pressure and fill the Grooves(thus sealing off the Gas pushing the Bullet) and prevent Blow-By.

I may be wrong, but I believe that was a problem with the Monolithic Copper Bullets when they were in the early Design stages. And I know it is possible to get a Cast Lead Bullet too hard for some Revolver/Pistol Pressure Levels and they will not obturate resulting in Blow-By Leading.

Was there a particular Cartridge you are thinking about, or just thinking about all of them at very Low Pressures?

Hi Hot Core. It was my 44 mag that made me think of obturation. I found it more a case of being difficult to cast a bullet soft enough to obturate at my pressures. Apparently, the bullet obturates in the chamber or at least before the forcing cone, where it gets swaged into the bore. I found exactly what you describe - Blow-By Leading. Some of my bullets would be flame cut so badly that the rifling impressions were the highest point on the surface!

It was the reports on this thread (as well as having heard about it over the years) - steady, expected pressure and velocity rise with incremental increases then a sudden and erratic increase in pressure and increase/decrease in velocity. And these were not compressed charges. So what could be happening? That's when I wondered about bullets being expanded under acceleration causing an increase in bore drag. But maybe it's simply the combustion becoming erratic at those levels? (I could scratch through the cobwebs and do a calculation, but, sheese, that's hard mental labour!)

Good Shooting!

Hey 303Guy, Ah yes, good old Lead in a Revolver, what could be simpler. HA

I really had no idea about just how many different types of Leading were possible until I was on my own for awhile. When I first got into Reloading for Revolvers and Pistols, all the tricky parts had been figured out by the older folks who taught me.

Then I got to experience Lead both too soft and too hard. And velocities too slow and too fast. Wrong Powders, no Gas Checks, incorrect Bullet Lube, etc. I remember looking in the Barrel and it appeared to be devoid of Grooves due to being full of Lead.

So, yes indeed, I do agree there are some strange things can happen with good old Lead. But once a person gets it figured out, it is very easy on a barrel and Kills just fine with a Flat Nose.

Best of luck to you.

quote:

Originally posted by Hot Core:
The Pressure is omnidirectional and equal in amount....

Hi again, HC. Before I go any farther, let me assure you I am NOT disagreeing with the use of PRE and CHE as useful warning flags; just wanted to toss something else in the mix...

...As to pressure being equal in all directions in the cartridge case....well, yes, some of the time it is, but supposedly not all the time during the burn, or even a bit after the burn is completed.

Much of the pressure is exerted in "wave" form (waves of super-hot gases, that is). When the initial wave of gas hits the base of the bullet it is at least partially reflected toward the head of the case. That reflected pressure (energy) is also in the form of a wave.

As that wave moves VERY quickly, the powder may still be burning (and creating new waves of super heated gas) while the reflected wave is moving aft.

When the reflected wave(s) of energy meet the new ones being sent down the chamber and/or barrel, the two waves interact with each other. Sometimes their energy acts to cancel each other out to some degree, and thus lower the pressure at that point. That's called "destructive harmonics". Other times, they re-inforce each other, thus making pressures higher at that point. Some call this effect "complementary harmonics". The study of both is known as the field of "wave harmonics".

And the waves do not just reflect from the bullet end of the cartridge...after they return to the head end of the case, they reflect again, going toward the muzzzle a second time...and so on...

There is some evidence that wave interaction contributes to such things as the "ringing" of chambers when the joining of the energies of two or more waves is complementary and adds greatly to the outward pressure at the point where the two waves meet.

And, of course, it may also affect velocity of the projectile, either making it greater or less depending on whether the waves are destructive or complementary. (It is one of the reasons I am reluctant to rely on velocities as a good direct indicator of pressures, too.)

It is also one of the reasons I am reluctant to buy totally in to the application of burn characteristics in rockets as being fully applicable to burns in contained pressure vessels of 50-75 or more calibers. Although rocket motor gases do compress and reflect off of the atmosphere at the exhaust point of the rocket, they are not confined in such a way as to redirect all the reflected energy back into the rocket motor.

Do you have any thoughts on this whole wave aspect?

If not, it is something to keep one's mind busy at night when they should be sleeping

Best wishes,

AC

303 Guy said;

quote:

The question I'm raising here is to do with ductile materials flowing under pressure. Rockwell hardness testing is done by applying a sharp point onto the material under a specific load for a specific time duration, right?

That is not quite correct, A hardness tester does not apply a load over time, A minor load of 10 kg is first applied to the indenter, which causes an initial penetration and holds the indenter in place. Then, the test machine dial is set to zero and the major load is applied. Upon removal of the major load, the depth reading is taken while the minor load is still on. The hardness number may then be read directly from the scale.
Other hardness machines, such as Vickers or Brennel testers, work in a similar manor.

Pat

Thanks for that pdpdad. I actually went to work after that statement and asked someone to check my accuracy. In the short time available, we were not able to come up with your explanation. I appreciate the correction.

Are you able to shed some light on my 'theory'? Does brass flow under the influence of pressure and time? (Well, we know it does but would the very short time durations within a rifle chamber make any difference)?

Do you have any thoughts on my 'theory' that a bullet might expand enough in a bore under adverse conditions to actually increase drag? Alberta Canuck's description of pressure waves could be a better explanation. Or add to the complexity!

quote:

Originally posted by Alberta Canuck:
...... it is something to keep one's mind busy at night when they should be sleeping
.....

Very interesting, Alberta Canuck. Is this a tested principle? What happens when the powder is compressed in the case? Would these waves result in bolt face loads we are not aware of? I expect these waves would influence barrel harmonics somewhat! Oh boy, I'm not going to be able to sleep tonight!

Hi there Hot Core. Have you ever loaded cast bullets in a hornet? That cartridge is made for lead! I've seen claims on the 'net for something like 2700 fps with lead (gas checked) and 3/4 MOA groupings. It's just a pity it's so difficult to cast those little .224 caliber beggars! (That would have something to do with pressures and chronographs wouldn't it)?

303Guy-

Yes, it is a long proved construction, taught since Heaven-Only-Knows-When in university physics classes...at least that is where I first learned of it. It is possible to apply it in engineering to prevent the destruction of tubes or other pressure vessels subject to sudden high internal pressure loadings.

Likewise, of course, one could engineer it to make contained explosions more powerful (and potentially more deadly). Takes some pretty complicated math to do it when working with propellants or explosives, but the principles are simple enough.

You can do it with your hand in a bath-tub or pan partly full of water.

Using your hand, create a wave traveling lengthwise...

Let it travel the length of the tub/pan, and when it stars to flow back toward your hand, start another wave. It doesn't take a lot of practice to learn how to time the waves to either get higher or lower wave peaks. If they were inside a tube instead of an open tub or pan, the higher waves would exert more pressure on the sides of the tube. The lower ones vice-versa.

If you do a lot of reading about internal ballistics, or the early days of reloading, you will sometimes come across reference to the phenomenon, but I haven't seen anything on it in some years now. Lots of things we used to learn the hard way, like how to use a slide-rule, and how to calculate by using logs, have fallen by the boards these days.

As to how the waves are affected when the case is full of powder, I don't recall, but logic tells me the waves would hit the base of the bullet instantaneously and reflect back. Shorter distance to travel, should equal less time to reflect back, or in other words, a higher frequency. Obviously, as the powder burns and/or the bullet moves, the frequency is also changed, so destructive or complementary nodes are constantly changing too.

So, I think it really complicates things which is one of the reasons I am always saying "Yeh, but...." when folks make absolute statements about pressures, burn rates, etc. They are DYNAMIC situations, never identical from one to the next, and almost never "straight-line" relationships.

That doesn't mean that PRE, CHE, or Chronos aren't useful, when read to indicate times to procede with caution. They are very useful indeed. When either one's brass or their cartridge performance changes negatively or unexpectedly, it is time to back off and ask "Why?"

One should just never assume things are as dead simple as much of what we read in the popular press may suggest.

Best wishes,

AC

quote:

Originally posted by Alberta Canuck:
...One should just never assume things are as dead simple as much of what we read in the popular press may suggest. ...

I'd sent a link to this thread to a buddy in Califoney who doesn't frequent this Board very often. And we talked about it on the phone a bit. Then he sent me a link to a thread from a Board he visits where some of the posters actually write for the Gun Rags. It is no wonder the people who read the Gun Rags are totally wrong about what works and what doesn't.

Once I saw what the people, "who should have known better - but don't", had written, it looked quite similar to some of the previous posts. One of the Gun Rag fools actually believes he knows what the Pressure in a Cartridge is by looking at a Velocity. Pitiful!

I mentioned to my buddy that the fool who wrote that bunch of ignorance wouldn't make it on this Board 5-minutes. The BIG problem is that some folks who really don't understand the dynamics of the process choose to believe those fools, and the ignorance spreads as if it were true.

quote:

Originally posted by 303Guy:
...Have you ever loaded cast bullets in a hornet? That cartridge is made for lead! I've seen claims on the 'net for something like 2700 fps with lead (gas checked) and 3/4 MOA groupings. It's just a pity it's so difficult to cast those little .224 caliber beggars! (That would have something to do with pressures and chronographs wouldn't it)? ...

I wrestled with various 22Hornets for 35 years and finally gave up on them. That was before Lil' Gun Powder existed. Never bothered to chronograph any of the Loads.

I was walking through a Charlotte, NC Gun Show and stopped at "Beanies" to get some Lead Gas Checked bullets for my 357Mags and 44Mags. There amongst all the stuff was 22cal 45gr Gas Checked Linotype Bullets. I still had some Hornets back then and got maybe 200. They did shoot as well as the Jacketed stuff in my Hornets.

So, I called him before the next Gun Show and asked if he was planning to bring any. He said he would bring all he had, but they didn't sell well. At the Gun Show, he mentioned he would make a 1000 for someone if they wanted them, but (exactly what you said) they were very difficult to cast.

I finally gave up on the Hornets and traded for a 223Rem. Gave the few Lead 22cal Beanies I had left to another Reloader in South Carolina.

As a side note, I can down-load the 223Rem to Hornet velocities, get much better "consistent" accuracy and the cases seem to last forever at those levels. Or, I can load it up to Varmint Blasting levels that are quite impressive on Dog size critters. Plus, I can load some with a particular Powder/Bullet it likes and "usually" enjoy a nice FREE BBQ Dinner when we shoot for the smallest group. I wish I'd done this 20 years earlier.

/

quote:

Originally posted by ALF:
...Im really trying to understand how we are all fools and so pitiful

Hey Alf, I never said everyone is a fool or pitiful. I have posted numerous times that a person who makes posts which are WRONG will be corrected by quite a few people on this Board. So, it always amazes me when someone makes a post where it is quite obvious they have ZERO first-hand experience with the subject. What gets them in trouble is when they do not mention they are guessing or simply copying stuff from a book they do not fully comprehend - like you do.

quote:

...pressure applied over time caused by the combustion of a mass of propellant imparts velocity to the bullet...

That is correct.

quote:

So please illuminate so as to protect the innocent and the "rookies" and beginners here on AR.

I've never considered doing otherwise.

quote:

And to make it even more degrading please, please bring those in California

Spoke to him last night. I thought the ancient old fellow was out snow skiing, but I caught him. He basically said he was not inclined to argue with people who really don't understand.

quote:

...who agree with you on board so they to may participate in setting us fools straight !

If you re-read the thread, that has already happened, quite a few times. Apparently you are unable to recognize where people have seen "first-hand" the answers to the initial questions I asked you. They did a fine job describing what they saw.

quote:

Because right up to this point you answer as supplied to 303 Guy regarding erratic or reversal in velocity trends when using Rl 19, 22 and 25 are in fact answered by the theories I proposed but then you refuse to understand what is written and implied by the rules of internal combustion.

You are blinded by Theory and a severe lack of first-hand experience observing what actually happens as a person approaches MAX when Reloading and using a chronograph. As has been said by numerous posters in this thread, once you approach MAX with some Powders, the velocity does not always go up. It is really that simple, but the reason why is complex.

I began to explain to you the dynamics of this about three times and erased it all because it appeared I could not Dumb-it-Down enough for "you" to comprehend what I was describing.

Erratic non-linear Velocity indications is one of the few places where a chronograph can be a benefit. AC described one of his first-hand experiences while seeing this very well. If you have someone(teenager or older) read it to you, they should be able to explain what he was saying to the point you "might" be able to comprehend it.

Perhaps some of the others are willing to take a shot at Teaching you. However, your best teacher would be actual first-hand experience by doing some actual Reloading.

The biggest danger for novice reloaders is not to heed careful increases in the charge as some of them believe that the MAX load is a tested one and therefore safe. Some will speculate that the Max load also includes a safety margin and thus it is OK to start there contrary to what Reloading Manuals recommend.

Every rifle should be viewed as a unique "pressure vessel" - having its own internal dimensions with regard to chamber and barrel. Furthermore bullets vary in diameter, length of bearing surface & hardness. Peak pressure is also different for various powders that are normally recommended for a specific caliber. Case capacities can vary quite a bit from brand to brand (for example Winchester vs PMP) and so combustion volumes differ, and the risk is when one changes to a case with a smaller capacity and not knowing it. Then we still have temperature issues when the gun & ammo is exposed to a long duration of heat.

For all these reasons one should start carefully and go up in half-grain increments, and when a chronograph is used in conjunction with astute observations, I belief a chronograph is a valuable tool - especially when we are nearing documented MAX velocities per Reloading Manuals. I much rather go by MAX VELOCITY limits as a datum than by MAX CHARGES, but as I have said, you must approach the Max position of your own gun with caution, as it may differ to published data.

Warrior

Real men don't wear women's underwear.

Real men work up a load in their strong rifles until the primer pierces, the primer falls out, or the bolt jams. Then they back off enough so that doesn't happen on a hunt.

Drama teachers in San Fransisco work up a load with strain gauges on their rifles so they never go above SAAMI registered pressures. Then they consult a load book. Then they consult a chronograph. Then they consult astrologers. Then they eat some Quiche. Then they worry that what beginner handloaders will do without the same "knowledge".

What does it all mean?
Don't tell me you wear women's panties because it is a better garment. I don't want to hear it.

Thank you for your reply, Alberta Canuck - this gets real interesting!

quote:

Originally posted by tnekkcc:
Real men don't wear women's underwear.

.

Maybe not, but some of us, even in our old age, keep trying to get into their pants