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

I believe my statement stated I shoot ammo that matches the chamber.
My blanket statement was a question.
L.F.

Joe I answered on the basis of the 2nd sentence which seemed to me to imply that any shell which did not exactly match the chamber in length was not the shell it was chambered for. This is simply not the case. Of much more importance than exact length match is to fire "The Load" the gun was designed & chambered for. This may very well not be an exact match in shell vs chamber length. One could very well put up too heavy a load in the shorter shell & a proper load in a too long shell. The point is there is much more to be considered than just length of the case. Many of the older guns are chambered for 2 3/4" shells, particularly in 12ga. This emphatically does not mean they should be fired with just any 2 3/4" load that can be bought, yet one might well say that it was "Chambered" for that length shell. The reason, I for instance, might decide to load 2 3/4 cases for firing from one of my damascus 2 5/8" chambered Lefevers would likely be my loader was set up to handle that length & I prefered not to be re-adjusting all the time. It is nice to have the knowledge that as long as I put the proper load inside the extra 1/8" of case is of no importance. & no it won't wee any higher up the wall or knock a squirell out of any taller a tree, just a matter of convenience.
Miller

I have been shooting 7,000 psi STS shells using the Harten Crimp, Clays, 1 oz. with 2 1/2" cut hulls. Since it takes much longer to make the Harten Crimp with overshot cards I compromised by reducing my loads to 5,500 psi in 2 3/4" STS shells using PB. I see no real difference in their effectiveness. The PB seems softer to shoot, though. The difference in the cost of the overshot cards makes up for the more expensive powder although I really do it to reduce the time I spend at the loader.

Builder, excuse my ignorance, but what is a harten crimp? Is it like a roll crimp

I believe the "re-inventer" of this crimp spells his name Hartin.

Not really important, but if you are going to be immortalized, it is nice to have your name spelled correctly.

Erik,

The Hartin Crimp uses an overshot wad and a fold crimp in combination. Shorten a 2 3/4" shell to 2 1/2" and a part of the original crimp remains.

Insert overshot wad and crimp as normal. Since you have shortened the hull the crimp would have a big hole in it that is now filled by the overshot wad.

One picture (anyone have one to post?) would explanin it alot better than I did.

Speaking of the Hartin crimp, I read recently that the writer used 16 or 20 ga. over-shot cards. Does anyone know why to not use 12 ga. OS cards? I've only made a few of these Hartin crimp shells but used 12 ga OS cards because that's all I had.
JL

I started with 20 ga over shot cards, but they moved around a bit. Switched to the 16 ga over shot card and got a nice snug fit, that wasn't too hard to insert. The reason for this method was it allowed me to make a 2 1/2" shell without changing or adapting my Mec grabber reloader in any way. I kept the pressures low, made myself feel good I was shooting a 2 1/2" shell, and seemed to get good performance. It is Hartin, thank you. I have since found a relatively easy way to cut the shell, using a piece of pvc pipe as a guide.

Jim, I'm assuming you used a 12 gauge over shot card in a 12 gauge. Which is fine. The only purpose for the over shot card is to cover the little hole in the center of the crimp, so shot doesn't leak out. Any size card that covers the hole will work.

So, the 'fact' that tight crimps are necessary for pressure to build and assure good combustion when using slow burning powders has been refuted? The Hartin crimp with half the fold crimp cut away would seem to be the very definition of a soft crip - overshot card or no.

Loading at the low pressures that you guys do with the low burn rate powders should, according to conventional wisdom, result in nothing but blooper city without a tight crimp.

What's the deal? Is conventional wisdom as passed down by generations of reloading experts wrong - again?

I do not use low(slow?) burn rate powders for my low pressure loads. I use Accurate Arms Nitro 100 according to the older Accurate Arms data for the older, compression formed AA 12 ga. shells. JL