minimum pressure for 4831 with dacron filler

[bmortell]

I been using some 4831 for my 30cal loads around 2k fps with polyfill on top, I seen quickload data that says it should be around 27k psi. I was wondering how much it can be downloaded for lower speeds before I should switch to a faster powder?

also im using it to push 220gr bullets im assuming that helps burn slow powder a bit, and my book don't have data for 4831 or similar slow powders

[DonMountain]

Reloading manuals for Cast Bullet Loads are produced and have been produced by two of the larger reloading companies in the business, Lyman and RCBS. And in these manuals optimally burn rate powders are shown as they worked out the best for these loads. Obviously you wouldn't use 4831 in your 38 Special loads because of very much less than optimal burn rate. And you wouldn't use Red Dot in your 338 Win Mag either. But I can see where one might develop Red Dot loads for target shooting in your basement due to a desirable burn rate for real low pressure loads. but I can't imagine a real slow burning powder doing the opposite for you with cast bullet loads. I experimented with using 50 BMG powders for regular rifles like 30-06, even with the use of Red Dot to get it started. But I just couldn't get it to work out when I could just put in 34 grains of IMR-4895 and get what I wanted. Slow powders just don't function opposite fast powders.

[bmortell]

well I know 4831 for 2kfps in 30-06 with heavy bullets works. and experienced people here said to use filler under 80% fill, but what are the signs of when to switch to a faster powder? does velocity lose consistency or what happens

[john.k]

It was worth mucking around with slow surplus powders when they were $3 a lb,but now they are full price seems an exercise in futility.........in any case ,when you are getting too low pressure for a proper burn,you get brown smoke in the fired case,and a trail of powder grains down the bore.......this generally leads to powder grains crushed between case and chamber.....I also keep in mind that brown smoke and white ,bleached grains might be getting some way towards a S.E.E.,also called a kaboom.

[toallmy]

I am currently working on a similar project , trying out IMR 4831 in a 7x57 with cast . I have gotten to the point of using a filler to keep reducing the powder charge any further safety . So far so good . The group's will hopefully keep getting smaller as I keep decrease the velocity .

[Rick B]

Have mentioned this several times before in other threads. P. O Ackley talks in his books about standard hunting rifles and military sporters filtering into his shop over the years, Rifles all suffered catastrofic failures. Common denominator at the time we’re handloaders using reduced loads of very slow burning powders. 4831 is the first powder he mentions. I really like 4831, I never load a cartridge with anything less than the published starting load. Reducing loads further put’s one in jeopardy.
Rick

[Larry Gibson]

Have mentioned this several times before in other threads. P. O Ackley talks in his books about standard hunting rifles and military sporters filtering into his shop over the years, Rifles all suffered catastrofic failures. Common denominator at the time we’re handloaders using reduced loads of very slow burning powders. 4831 is the first powder he mentions. I really like 4831, I never load a cartridge with anything less than the published starting load. Reducing loads further put’s one in jeopardy.
Rick

As much as I respect P.O. Ackley that is 70+ year old hypothesis. It has since been proven incorrect. Smokeless powders, especially slow burning powders, do not "detonate" in cartridges. What causes S.E.E is well known and is reproducible. It is not from the powder "detonating". The use of a Dacron or polyfil filler with the reduction of slower burning powder charges is also a "game changer" in the realm of "reduced" charges.

As to the OP's question; there are numerous variables that affect " how much it (4831) can be downloaded for lower speeds before I should switch to a faster powder? I have not tested for an answer to that specific question. With the 311284 and 311299 bullets I have reduced both IMR 4831 and H4831 to 50% load density and used a Dacron filler in the 308W and the 30-06. I was always working up from there for higher velocity with accuracy so I do not know where it was burning inefficiently with a lower charge. That was all pre my ability to measure pressures and knowing the accuracy level of 50% load density with either 4831 I prefer to use 4895 with those cast bullets because accuracy is better.

However, looking through some previous pressure testing of H4831SC with 178 - 180 gr cast bullets in the 308W it appears that powder does not begin to burn efficiently in the 308W case with a Dacron filler until around 25,000 psi.

[vernm]

You say the cause of S.E.E. is well known. I can't find anything new in Google. Please enlighten us. What causes S.E.E. and who has reproduced it?

[Rick B]

In my comment above , I never mentioned any of P. O. Ackley’s hypothesis. I stated that over the years he saw a number of rifles that had catastrofic failures using reduced loads of slow burning powders. In Ackley’s heyday military surplus 4831 was the most commonly used powder. It was sold in paper sacks for .25-.50 a pound.
Rick

[MT Chambers]

The only way I would mess with it, other than full charges in large cases, is some usefulness in large BP cartridges, compressed somewhat, seems to act like BP (similar vel.). I would only try it if I had lots of it laying around.

[Larry Gibson]

In my comment above , I never mentioned any of P. O. Ackley’s hypothesis. I stated that over the years he saw a number of rifles that had catastrofic failures using reduced loads of slow burning powders. In Ackley’s heyday military surplus 4831 was the most commonly used powder. It was sold in paper sacks for .25-.50 a pound.
Rick

Yes, that is what you said and while you did not directly state such what you said infers it. You inferred such when you brought Ackley into this thread and stating what he talks about in his books ["P. O Ackley talks in his books"]. Here is what Ackley "talks about" in his book Vol I/Handbook For Shooters & Reloaders on page 91 "Reduced Loads"; "In this writers opinion (his opinion is the "hypothesis") there is sufficient evidence that reduced charges of slow burning powders cause detonating. effects.......". Ackley continues with his hypothesis as to what occurs causing the blowups (since proven incorrect) on page 93 and continues in that chapter quoting an article by Jack O'Conner. The incorrect hypothesis is summarized in the last paragraph on page 104.

I simply followed your lead and also mentioned what Ackley "talks about"......incorrectly because he did not have the test equipment available at that time to determine what really was occurring. He was simply hypothesizing about what he thought (in his opinion) was occurring. With the modern test equipment available in the last 25 - 30 years +/- we now know what actually occurs during an S.E.E. It is not what Ackley hypothesized about.

[Larry Gibson]

You say the cause of S.E.E. is well known. I can't find anything new in Google. Please enlighten us. What causes S.E.E. and who has reproduced it?

vernm

Sorry to mention this to you but google is not the end all of information. The Subject of S.E.E phenomenon has been discussed numerous times on this forum. I have posted the documentation (report on testing of Hercules Bullseye in 38 SPL target loads and A laboratory test of 6.5 ammunition involved in S.E.E as published in Handloader Magazine). You might do a through search of this forum for those discussions and documentations. The articles can be posted again if necessary but you should be able to find what has already been posted.

I also have been directly involved in two S.E.E.s over the years and have directly observed the end result of several others. Additionally since being able to measure pressures I have verified the test results of the tests mentioned by replicating them. Other ballisticians understand the phenomenon and can easily reproduce it.

[bmortell]

everything I did with 4831 is within minimum load pressures listed on other calibers, it just wasn't on my specific calibers, so I was using quickload charts I found to infer what the data would be and it was working fine around 1900fps in 30 cals with polyfill, but ive since acquired h4895 and would use that in the same circumstances because accuracy seems better.

[PAT303]

I've been getting very promising results in my 303's with AR2213SC which is the Mulwex equivalent to 4831. I started low at 40grns under a 228grn hitek coated CBE boolit and both my competition 5 groove Mk111 and two groove No4 have shot consistent groups at 100 meters, I'll be shooting more tomorrow with 42grns up to 45 with puff lon filler and dacron.

[swheeler]

Have mentioned this several times before in other threads. P. O Ackley talks in his books about standard hunting rifles and military sporters filtering into his shop over the years, Rifles all suffered catastrofic failures. Common denominator at the time we’re handloaders using reduced loads of very slow burning powders. 4831 is the first powder he mentions. I really like 4831, I never load a cartridge with anything less than the published starting load. Reducing loads further put’s one in jeopardy.
Rick

I've read all of Parker Otto's writings over the years, very interesting, intelligent gentleman.

[Larry Gibson]

I've read all of Parker Otto's writings over the years, very interesting, intelligent gentleman.

Yes, Ackley certainly was and I respect his writing highly. However, his hypothesis was in line with current "thinking" at the time in attempts to quess what was causing the blowups. The "wave/detonation" theory also prevailed into the '60s when numerous PPC revolvers were blown up with a supposed load of 2.7 gr Bullseye under a 148 gr WC in the 38 SPL. Those loads were tested considerably by Hercules and it was found the culprit to be a double or triple charge of powder over a deeply seated bullet. The cause was the use of an inline progressive loader that became popular for use in the mid to late '60s and early '70s by competition shooters.

The actual cause of S.E.E. was discovered after some factory 6.5x55 rounds loaded with a new slow burning powder blew up several rifles. The factory a reduced load of the slower burning powder which was developed initially in a C.U.P devise with a pressure barrel made to SAAMI specs. The load was developed by the factory to keep load under the SAAMI MAP. It was when used in milsurp 6.5 Swede Mausers with larger chambers and longer throats that S.E.E manifested itself.

The use of strain gauge pressure measuring equipment on an issue 6.5 Swede Mauser enabled the lab technicians testing the factory ammunition to see what was actually happening by the data measured and the time/pressure curve. Basically the cause is the bullet becomes a bore obstruction as it is pushed into the leade (usually rough or fouled) by the primer explosion and the pressure dropped before the powder the begins to burn efficiently enough to keep the bullet moving so the bullet sticks there in the throat. The powder then began to burn but before the stuck bullet gets moving again the pressure rises to a catastrophic level with the case rupturing and other nasty things happening.........

There is no "wave" and the powder does not "detonate" but burns progressively as it should. Without the bullet moving forward or moving forward fast enough the pressure can get extreme. Thus is an S.E.E. The old writers, whom we think of with reverence as experts, could not know what was actually happening because they did not have the pressure measuring equipment we have available today.

[303Guy]

Other reported SEE's have been with faster powders in rifle cases in which the foolproof method of seating a bullet immediately after powdering the case, in one sequence. I used that method too and had a near SEE. I never had any double charges but I did have a few powdeless cartridges.

The near SEE was with a 303 Brit. The powderless cartridge pushed the bullet into the throat and thinking I hadn't reloaded, I chambered another round.

Picture a bullet hard into the leade with another bullet hard behind it, pushed back into the case, reducing case volume on a full pressure load ......

Well, the bolt wouldn't quite close so the gun survived. When I extracted the round that wouldn't chamber and saw the bullet pushed back into the case, hard onto the powder, I went cold. Luckily it was not a reduced charge of slow powder so there was no room for the bullet to push back far enough to chamber.

I suspect this to be the cause of the majority of so called SEE's with reduced charges of slow or not so slow powder. But true SEE's are real and occur as Larry explained. Also the double or triple charges.

[Larry Gibson]

Definitely a "bore obstruction" there.....glad you caught it before something bad happened.

Yes, S.E.E. can occur with what we think of as a "fast burning powder". There have been a couple I know of with Contender pistols using light charges of 2400 (or similar burning rate powders giving low load density) behind a 300 - 350 gr jacketed bullets. The pistol is held muzzle down and raised up to shoot with the small charge of powder still forward against the bullet. On firing the primer pushes the bullet into the leade where it sticks before the powder begins to burn......then the powder burns and an S.E.E. can happen before the bullet can move quick enough.

BTW; If you ever get a "click.....bang" you might give thought to not shooting anymore of that load. It's not always a precursor to an S.E.E. but it is a symptom that one may happen.