doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Tom Roster SSM article re low vs high pressure

I was surprised after reading this article that Tom believes low pressure shells are no safer in older guns than high pressure shells as long as the shells are within the pressure designation for which the particular firearm was proved. I also think he said higher pressure loads render less perceived recoil based on slower burning powders. Did I read that right? Does that make sense?

I read the article and I could not believe it was printed. I didn't see the article address older proofs. Nothing in the article addresses vintage gun proofs and how it relates to today's shells for use in older guns.

Ken

The article surprised me too. I don't have the technical expertise to second guess it, but maybe one of the experts here will chime in.

re: quantifying "felt recoil". It's impossible, too many variables, but here's a scholarly attempt by Dr. Matt Hall
https://www.researchgate.net/publication/223811001_Measuring_felt_recoil_of_sporting_arms

The issue is debated on Trapshooters.com regularly, and Neil Winston would strongly argue perceived recoil has nothing to do with fast vs. slow powder
https://www.trapshooters.com/threads/recoil-test-of-powders-part-2-winston.79801/

Here's one of the latest; Tim is an engineer
https://www.trapshooters.com/threads/recoil-aaaah-our-favorite-subject.834949/
and
https://www.trapshooters.com/threads/powder-burn-rate-vs-recoil.651777/
https://www.trapshooters.com/threads/perceived-recoil.493105/

Blame it on Wallace Coxe - from "Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics", 1931
There is another factor which makes the recoil of a gun feel different with different powders, even when they are loaded to the same velocity and that is the rate of application of the recoil. It will be remembered that this was pointed out under the discussion on Characteristic Pressure Curves where it was shown that some powders burn up very rapidly and reach their point of maximum pressure in an extremely short time interval. This affects the rate of recoil, for the gun will begin to recoil at a higher rate of speed when the powder burns at a higher rate of speed.
The time required between the ignition of the powder and the time it reaches its maximum pressure is much shorter than the barrel time. Any phenomena that occur during this initial short time interval is only reported to the brain as a stimulus and does not leave any time for reaction to the stimulus. The mind can therefore only retain a subconscious reaction to impressions received during this short time interval.
It would be very difficult for any shooter to fire one shot of one type of powder and compare it with one shot of another type of powder and definitely say which powder gave him the feeling of greatest recoil unless of course they were loaded under entirely different circumstances.
During the course of a day's trapshooting, however, the shooter may be called upon to fire 50 to 200 shots. During this period the effect of acceleration of recoil is accumulating and by the time he has finished all the events there is hardly any doubt that the experienced shooter can readily identify peculiarities of differences of recoil that his subconscious mind had received from the accumulated impulses of each individual shot.

It should be noted that this was written in promotion of DuPont MX Smokeless, a Dense Multi Base Powder introduced about 1930. 25.5 grains was a 3 Dram Eq. and it was promoted as a 1 1/4 oz. Trap load. It was replaced in the 1954 with IMR PB.

Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in the �Field� Newspaper, Relative to Firearms and Explosives, 1897
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA197
�Some Notes on Recoil�

https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA254
It has been asserted that this or that powder gives �absolutely no recoil.� If one were to believe all that has been written on that point, there are various powders that possess this inestimable quality; but unfortunately�these statements are absolutely untrue.

It is a fundamental principle that action and re-action are equal and opposite; therefore, at the moment when the shot leaves the muzzle of the gun, the momentum (or weight x velocity) of the shot will be equal to the momentum of the gun. This is strictly true from the tune the shot first commences to move until it finally leaves the muzzle, but only up to that instant.
On no subject in connection with gunnery are there more erroneous ideas�superstitions one might almost call them�than on recoil. Many men will tell you that certain guns, with precisely the same ammunition, will give much more recoil than other guns of exactly the same weight. It will generally be found that these men are either novices in the art of shooting, or else they do not hold their guns properly up to the shoulder. Once and for all, it may be laid down that the recoil of guns, rifles, and arms of every description, from the smallest pistol to the heaviest piece of ordnance, proceeds from the same causes and depends upon the same elements.

https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA266
�judging of the weight and nature of recoil by the feeling alone one is apt to be misled; for according to the state of bodily health at the time, so will be the sensation produced by a normal recoil��

I am not one bit surprised at his first observation, in fact, have "preached" it for some time. Essentially if you push the same amount of shot to the same velocity you have done the same work or approximately the same "Average Pressure" over the length of the barrel.
The So-Called Low-Pressure loads have not truly lowered the total pressure, just redistributed it to give a lower peak with a "Slightly" higher pressure spread out over the rest of the barrel. When smokeless powders became common the Gunmakers knew what they were doing, they Beefed up the chamber area of their barrels to contain these higher pressures.

I think you may have misread the part about the recoil. Higher pressures are the result of faster powders, not slower ones. assuming the same ballistics. I have never been much impressed by many of the so-called Felt Recoil statements. Most, in fact virtually all, simply do not have enough certified data to defend the statement. Data for the loading manuals are generally taken from new hulls & fired through a test barrel having minimum dimensions to ensure a reloader if he follows the "Recipe" will have no higher pressure than what is listed. He may well have lower, which also may result in a slightly lower velocity than listed in the manual. A load using a slow burning powder, taken out of the shot weight class for which it was truly developed, is MUCH MORE apt to be adversely affected.

For most of my older guns, I generally try to stick to loads of around 8K, unless they are true Light Breeched guns made in the strictly Black Powder era. In that case, I stick with Black or at least very light loads with which I can bring the pressure down to around 6K while still using a fast powder.

My personal opinion is that the slow powders were optimized for either heavier shot loads, higher velocities or Both & should not be used at pressures lower than around 8K. The slow burn characteristics are achieved either by a varied shape which deters burning, a heavier deterrent coating, or both. Neither of these conditions is an asset to efficient burn at low pressures.

Recoil has nothing to do with pressure. It the reaction, to the shot payload being pushed down the barrel. The faster it moves down the barrel the greater the recoil. One vector is equal the other. It�s velocity and payload not low enough r high pressures.

We use low pressure and lower velocity loads to reduce forces likely to cause stock failure as well as barrel failures. Modern factory loads are 10-11K psi , pushing 1 1/8 ounce at 1200-1275 FPS or 1 ounce loads being pushed at 1300 FPS. Most British doubles were made for loads more like 1 ounce 1100-1150 FPS in British proofed guns. American doubles would have seen 8-9K at 110-1200 FPS with 1 1/8 ounce shot. Our doubles are often a bit heavier made. Modern ammo has higher pressure to work semi automatic guns reliable. But that 2-3K psi is not needed in a double. And doubles work perfectly with 1100 FPS loads. Few semi automatics will.

I�ve read others who claim my low pressure loads actually increase pressures near the muzzle because they peak much later. But I wonder if that�s as true as much as they claim. High pressure loads generate peak pressures within the first inch and drop off from there. Can low pressure not peak within the first few inches? And would they also not drop off a rapidly as well? And from a lower peak. So I take all these pressure articles with a big grain of salt.

I'm guessing RST and Polywad just refused to pay the "protection" to Roster...Geo

Jon;
Pressure curves have been posted here from time to time showing loads of the same ballistics, IE shot weight & velocity with various burn rate powders including Black. Peak pressures for all of them occur within the first inch of travel. The faster powders have a higher peak. The curves cross between from around 2 3/4" to 4" & the faster then have a "SLIGHTLY" lower pressure from there forward.

Note that total barrel time from ignition to exit will be on the order of 0.003 of a second. An acceleration curve begins with a steep climb upon ignition & gradually lessens as it goes down the barrel. All this would tend to lead to the conclusion that the total time the peak pressure could be higher with the fast powder at the Utmost would be on the order of 0.0001 of a second & for a total travel distance of no more than about a � inch. It doesn't take a big difference in the pressure level for the rest of the barrel to offset this difference in peak pressure. Not enough to be concerned about.

Bottom line is that pressure is really only of concern in the chamber itself. Reaction, IE shot weight & velocity is what affects the stock & primarily frame stress. It was not the increased pressures that cracked lightweight Flues frames it was the increased back thrust from the higher velocity loads with heavier shot loads.

Using the "Super-Low" pressure loads will of course not harm the gun as long as it goes off adequately & clears the bore of all components, but also is not doing it a great favor. The risk of inadequate ignition does become greater though.

Using a sensible load of shot at a reasonable velocity level with a proper load of the powder which was "Designed & Developed" for this type of load is the best way to go, in my opinion. If the chamber area itself is not constructed adequate enough for an 8K load, shoot Black or Hang it on the wall or sell it to Cracker Barrel. I have followed this rule for some 40+ years now & have never encountered a problem thereby.

I pay little to no attention to Tom Roster�s drivel. I�m still mad at him for foisting still shot on us.
JR