doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com TOM ROSTER'S COLUMN

Jim: here is another one:

http://bbs.shootingsportsman.com/viewtopic.php?f=2&t=36569

Before Sherman Bell; Before Gough Thomas; In the year 1938 the fold crimp shell was introduced to the British trade. Wadding had to be adjusted to get the same load in the "Nominal" 2½" shell (actually about 2 9/16"-2 5/8" long). The length of the loaded shell was much shortrned & there was Legitimate concern they would be mistaken for 2" shells which actually went to about 2 1/8", but of course loaded much lighter. Very shortly experimenting began on putting the same load with appropriate wadding in a nominal 2 3/4" case, which when closed with the fold crimp gave a "Loaded" shell length virtually identical to the roll crimped 2½" case. It was found that both pressure & velocity were for all practical purposes "Identical" between the "3" methods of loading (2½" RC, 2½" FC & 2 3/4" FC) all loaded with the same load. WWII prevented extensive testing at the time, but was continued immediately following. To the best of my knowledge from that point forward "ALL" British shells of a "Nominal 2½" length, closed with a fold crimp "Have been Longer than their Chambers". If you disagree give me proof.
All this was reported on by Burrard. Burrard did mention testing some few shells himself, but essentially reported the work of the British Shotshell industry. Previous to this he had warned against using 2 3/4" shells in 2½" chambers. This was two fold; First the longer "Roll Crimped" shell would actually enter the cone "Before Firing". There is a strong possibility of this delaying the opening of the crimp thus increasing chamber pressure. Second these shells carried a heavier, higher pressure load than the 2½" chambered gun was designed for.
Unfortunately both Thomas & Bell in their reporting honed in on statements Burrard made on using these heavier loads & totally ignored the actual facts of using appropriate loads in the longer "Fold Crimped" case. Bell was not even sure that Thomas' tests were conclusive & needed him to "Prove" them.
In point fact the matter was settled in 1938 & the "Billions" of British long hulled, fold crimped shells marked "For use in 2½" chambered guns" (paraphrased) should be sample enough.
To the best of my knowledge none of the current testers have addressed the question of using a shell which is actually long enough to enter the cone prior to being fired. Until such testing is done "Personally" I would strongly advise against doing so. One powder makers handbook stated that pressures could be varied very widely by simply changing crimp depth, thus strength. The hull being squeezed by the cone prior to firing has the effect of increasing crimp strength.
The testing which has showed no pressure concerns has all been done with shells having clearence prior to firing & the hull only laps into the cone after opening in a normal fashion. By this time the shot is already beginning to move, but without the space & speed to create an obstruction condition.

Miller, although Bell does not tell us in his article, I'm guessing that when he fired 3" magnum hulls in Armbrust's 2 1/2" pressure barrel, those unfired hulls likely extended into the cone. There was an increase of about 700 psi--from 10,953 to 11,665--from the 2 3/4" chamber to the 2 1/2" chamber using those 3" shells. But I agree with you that shoving an unfired shell into the cone is likely to be risky business.

As Mr. Bell points out there are always those who profess the "my mind is made up, don't confuse me with the facts" philosophy.

JC(AL)

Thank you, df. That's the one I wanted to read. I am happy to see there was some intelligent discussion over there. Some of it was "intelligenter" than some of ours. I'll add that "other board" to my favorites.
Thank you,

df - note that there are a number of people on this board that do have the background and inclination to read Mr. Bell's work, word for word, and to review his data and conclusions. His articles have stood the test of time. They are several years old and have been the core of many discussions, both here and off this board. If there was a fundamental error, it would have most likely been pointed out by now. However, if you think you see a scientific error, please point it out.

Mr. Roster's statement may be true for limited cases, but I've seen way too much credible data to accept his statement as the general case.

The shell manufacturers are stating a liability limiting warning that has a foundation of erring on the side of safety. They are correct to do so. But, once again, this is not a general statement for all situations; it is a warning for the shells in that box.

Larry;
The thing I noted about the 3" shells Bell fired in the 2½" chamber was first, they were low pressure reloads, at least in the article I read, maybe I missed another. As you noted he gave the pressure increase from a 2 3/4" chamber to a 2½" chamber. What he did not give us was an actual pressure when fired in a 3" chamber, thus we do not know how much actual pressure increase he had from the design chamber. In this aspect it all depends upon just how much the cone retards the opening of the crimp. As long as there is clearance between the end of the shell & the cone the crimp can open in a normal manner. Pressure rises "Very Rapidly" until the charge begins to move. It would not take much retardation in the opening of the crimp to prove disastrous. If there is any resistance with a shell chambering fully, "Yank it Out" & find out why. It may just not be fully resized, but if it is being jammed into the cone "Don't Shoot IT" is my advise.

Miller has reminded us of something brought up by an earlier poster (I think) who brought up some pressure figures involving loose versus tight crimps. The pressure differences between the two are more than we would have thought. Miller further mentioned the consequence (tighter crimps) of running a crimped shell into the forcing cone. I, personally, take Sherman Bell's testing only to the point he tested, in other words, 2 3/4" shells in 2 1/2" chambers. I'm not worried about putting 3" shells in 2 1/2" chambers because I'm just not going to do it. Let's face it, only about one in a hundred of us has a reloader set up for 3" shells and the factory shells are too off the scale for use in bird guns.

You're correct, Miller, in stating that Bell and Armbrust did not lengthen the chamber to 3" to get "normal" readings on the 3" reloads they tested. However, Bell did not describe the reloads as "low pressure". In fact, he described the lighter of the two as "too hot" for another test he had planned, and "scheduled for dismantling". The other one, even hotter, did come close to producing Roster's jump of 1500 psi--but that was when fired in a 2 1/2" chamber. I don't think any of us are nutty enough to shove a 3" shell into a short-chambered gun, at least not intentionally!

Larry;
Been awhile since I read that article. You are likely correct that "Low Pressure" was not really the right term. As I do recall though it was a lighter load than factory 3" "Magnum" loads, both as to shot weight & pressure. I also recall he strongly advised against intentionally firing one of them in a 2½" chambered gun, but tested it just to see what it would do "If" he accidently did fire one in the short chamber. Problem is it could only take one shell in which everything went "Just Wrong" & until far more testing has been done I will stick to my refusal of firing a loaded shell longer than the chamber. I do fire 2 3/4" low pressure loads in my nominal 2½" & 2 5/8" chambers.
It is well to note that Bell strongly recommended "Only" proper loads for the gun in question. Seems at least some are taking it he recommended firing any 2 3/4" shell which is definately not the case. I find no fault with the tests he carried out & applaud him for bringing to the attention of modern shooters. Just think he really should have stated he was "Re-Affirming" what had been proven 60-70 yrs ago, rather than leaving the impression he "Discovered" it, at least that was my take on it.