doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Longer shells in Short Chambers

i've not shot any shells with the hartin crimp but i did load up some dummy rounds just to see what it'd take and how they'd turn out and i'd say they'll open just as tightly as a folded crimp in the full length shell. while trying to dismantle them later they were no easier to get opened up than any other folded crimp shell i've tried to take apart.

Hi Nitrah,
Is you de real Hartin? I think your crimp idea is a very good one even though I haven't done it many times. I have lengthened the chambers on the guns I intended to keep. If anyone is interested I have pictures of two shell trimmers that I made from scrap stuff, one for paper and one for plastic. I haven't learned how to post pictures yet but if you send me a direct e-mail, I'll be happy to reply with pictures attached.
JL

The resistance to opening is in the folded area, not out in the folds themselves. Therefore, the Hartin crimp should offer as much opening resistance as a standard fold crimp.

I load 2 3/4" hulls with low pressure loads expecting to get the same performance as if I used a 2 1/2" hull. I've no interest in weeing higher up the wall with older guns.

Remember, and never forget, we are matching loads, not just hull length.

I've heard of people putting an over shot card under a normal crimp to keep the buffer from leaking.

Is the Hartin crimp a partial crip ?

In a double barrel is there any chance of the load coming out in the unfired barrel...from the recoil of the other barrel after repeated firings...say in a hunting situation.

Jim I still have the pictures you sent me of your trimmers. I'll be glad to post them for you if you like.
L.F.

Hi Joe,
The hartin crimp is a normal crimp, made at the same height from the base. The shell has been shortened by 1/4" before crimping. It therefore has a hole in the center that must be covered by an over-shot card. An easy and very clever way to make 2-1/2" shells that are loaded on a 2-3/4" loader.
I'd be happy if you could post my pictures. If I have pictures of the Hartin crimp I'll send you them also.
Thank you,
JL

Here they are Jim.

Here's the other pics of Jims trimmers

That's a pretty darned good, concise summary. Fact is, the reason US manufacturers intentionally short-chambered their guns is precisely because those slightly short chambers and slightly longer shells DID improve performance--IF, by improving performance, you mean achieving denser patterns. If the old paper case mouths opened into the forcing cone, they provided some cushioning protection for the shot charge (no plastic wad, remember!) on its initial contact with the barrel. Hence, fewer deformed pellets; hence, denser patterns.

As for the misquoting between Bell, Thomas, and Burrard . . . I can't speak for Sherman Bell. However, it's pretty clear from Thomas' "Gun Book"--if one reads the ENTIRE chapter entitled "Danger in Case-Length" rather than quoting selectively--that Thomas did not misquote Burrard. In fact, the two reached essentially the same conclusion, in slightly different words.

Burrard: "It will be realised, therefore, that the increase in pressure is the result of the longer LOADED CARTRIDGE rather than that of of the longer UNLOADED CASE." (Emphasis Burrard's.) He then goes on to explain that it's the load rather than the case length that causes the danger: "Since 1946 I have tested many more lots and these results have proved quite definitely that for all practical purposes any increase in pressure due to the longer cartridge case really does not exist PROVIDED THE CORRECT POWDER AND SHOT CHARGES FOR A NOMINAL 2 1/2" CARTRIDGE ARE USED." (Emphasis mine.)

Thomas: "But in the particular case cited by Burrard, the main danger arises, not from the constriction when the cartridge is fired, but from the fact that the longer-cased cartridges he had in mind invariably carried heavier loads; and heavier loads in a given gun, USING A GIVEN POWDER, of necessity involve higher pressures." (Emphasis Thomas'.)

Larry; Thomas did come to exctly the same conclusion Burrard did, that is true ( Your quote from burrard well shows that). However, Thomas "Did Not" credit Burrard with having reached that conclusion. If you read the paragraph ahead of the one you quoted he states;
"Burrard leaves no doubt in his readers' minds that the danger in question arises from the inability of the longer case to open up properly in the shorter chamber, and the higher pressure thus formed. It cannot be too strongly emphasized that it is indeed dangerous, in general, to use a cartridges whose "UNLOADED" case length exceeds that of the chamber of the gun". (emphisis mine)
This is quoted from page 261 of Gough Thomas's "Gun Book". If you read carefully the entire section from which you quoted, you will see he is very strongly inferring Burrard was wrong & he has proved it. I have carefully searched everything I can find in "The Modern Shotgun" & cannot come up with the exact quote Thomas cited. Burrard stated one should not fire cartridges having a "LOADED" length longer than the chamber. All Burrards warnings against the longer case were for loads heavier than the standard 2½ load for which the gun was designed. He specifically warns against those put up in the roll crimp case which would give a loaded length longer than the chamber. Thomas did in fact completely mis-quote Burrard & Bell simply echoed Thomas. He obviously didn't "Find Out For Himself" what Burrard had said.
Miller

Miller, Burrard says: "The effect of the mouth of the case being held in by the chamber cone is much the same as that of giving the cartridge an exceptionally heavy turnover, and the effect on the pressure will be obvious . . . If the mouth of the cartridge is compressed by being held by the chamber cone, the resistance to the initial movement of the shot charge will be greater and the pressure will be increased."

That's all from the same paragraph in Burrard's book, and nowhere in that paragraph does he say anything about the loaded cartridge being longer than the chamber. We know for a fact that loaded cartridges SHORTER than the length of the chamber can and do extend into the forcing cone, depending on how much shorter they are and how much longer the case is after it opens. And we also know for a fact--thanks to Burrard, Thomas, and Bell--that the longer case opening into the forcing cone does not result in a significant increase in pressure.

Thus, both Burrard and Thomas--if you don't read their entire sections on the subject--can be somewhat ambiguous, until you reach their conclusions, which are the same. In Thomas' para following the one you quote, he also clears up the "unloaded case length" issue, when he says: "It is, in fact, pressure that causes the danger: no gun was ever burst or damaged by a cartridge case . . . " That's the same thing Burrard cleared up when he says: " . . . any increase in pressure doe to the longer cartridge case really does not exist . . ."--then going on to specify that the correct powder and shot charges need to be used (as does Thomas).

Unfortunately, if one reads only part of what either Thomas or Burrard writes, or if they're quoted selectively, one can come to a conclusion that is 180 degrees off from that reached by both of them.