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The use of smokeless in the large capacity cases trying to duplicate low velocity loads can be extremely dangerous.
You will find references to this as far back as the advent of IMR powders in the 1930s, Phil Sharpe mentions this.

3031 at BP ballistics is poison in large capacity cases like the 45 and 50 3 1/4" cases.
The only Shiloh Sharps that was totally blown up while I worked for them was a 50-3 1/4" that a guy insisted on shooting 52 odd grains of 3031 in. AFTER I had told him at length that it was not to be used. He broke all major parts but the lock, breech block and trigger plate. Had he been shooting offhand rather than the bench he would likely have lost a hand.
He sent some photos of the remains.
Had he shot 100 grains of 3031 it would simply have leaded the bore and kicked him severely.
A Sharps *made of modern materials* chambered for a straight case is very difficult to damage with an massive overload of even 4198 which is a fairly fast rifle powder and a heavy jacketed bullet.

If shooting ANY smokeless in ANY cartridge and there are wild velocity variations or hangfires STOP SHOOTING IMMEDIATELY. Poorly ignited smokeless powder is extremely volatile and these are warnings that the load is right on the edge of major firearm and perhaps shooter damage.
This includes powders like Unique or Red Dot in 45 colt or 44-40 etc. Unique is shown in loading data for 45-70. But it rings chambers is really weird ways.
If you use smokeless in a large case use a very slow powder, my 45-100 2.6" will use all the powder that will fit behind a 540 grain bullet if I use AA8700 or 3100. Its closer to BP ballistics with about .2" airspace. Compressed loads will nearly equal 458 mag.
The only way to avoid this with BP duplication loads is to use a filler like Pufflon that compresses the powder tightly in the case and holds it tight to the flash hole so ignition is as it needs to be. But this usually requires a slight reduction in the powder charge. I have used it in 45-70 for some smokeless loads. But have only loaded a couple of loads this way and testing has been limited.

I am fairly confidant that more modern guns are blown with too light loads than with too heavy, especially revolvers and replica firearms.
For example.
I have it on extremely good authority that in 357 magnum cartridge a full case of Bullseye and a 158gr SWC will only bulge a heat treated revolver cylinder. Go under 3 grains with the same bullet and the cylinder will be blown in a few rounds of shooting when the factors get just "right".
This from a major manufacturers testing to see how people were blowing up their revolvers.

Dan

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