Shiloh Rifle Forums

No definitive answer from the Shiloh folks on the forum - so best to ask the home office ... Thanks

Postby John Boy » Thu Dec 22, 2016 2:46 pm
Poster on the ASSRA forum stated he contacted Shiloh and qas told their 1874 Sharps had a maximum pressure of 70,000 psi ... Fact or Fiction?
Regards
John

PLEASE, PLEASE, PLEASE I do NOT work for Shiloh, but I shoot their rifles, you CANNOT believe everything you see, read, or hear about on ANY forum. That is unless it is backed up by MUCH experience. Falling Block rifles are strong, but I would not even attempt to go anywhere near 70,000 PSI in ANY rifle!! This is the stuff that make disasters happen!!!

Well said!! Shilohs are made to shoot and load standard 45-70 ammunition!!!!! To date I know of no loading manual recommending 70,000 pound loads for 45-70, so it's just a ridiculous statement for the guy to even make!!!

I use copper clad 405 grain slugs and smokeless powder in a Marlin 45-70 guide gun. Slugs are leaving at about 1,750 fps and per the loading data pressures are in the 28,000 CUP(August 2007 Handloader). I find no agreement on CUP:PSI conversions. It is not pleasant to shoot. Suffice to say, I will never get behind a 45-70 doing 70,000 psi regardless of make or model. That is the realm where cartridges are starting to fail, and rifles won't be far behind with any sort of error/overload.

Pardon the blunt response, but only an idiot would load ANY rifle of vintage design, whether original or new construction, to 70 KSI. If you want a .458 Winchester Magnum, buy one, but don't try to hot-rod your 1870's design. If you want to want to punish yourself, hot-rod the Marlin, but be fully aware that the Marlin design has a very thin area between the barrel threads and magazine tube; I guess you could get yourself in trouble before 70 KSI even with that design, and as another poster indicated, the recoil is brutal at 28 KSI.

Clarence

That's the silly thing about this pressure deal, there are no saami spec cartridges that operate at 72k psi or cup. Even the 458 win mag tops out around 51k cup.

Here is a little something to ponder on about this pressure subject. I'll put it in a more visual way and relate it to something most of you will have seen a time or two and that is Top Fuel dragsters in drag racing. Right now the the fuel guys are claiming 10,000 HP @ 8500 RPM out of their 500 cu in engines that converts to a little more than 8,000 PSI BMEP "(brake mean effective pressure)" on a 4 7/16" piston. So if we take that 70K number for a rifle and change it to HP it would be about 65,000HP out of that 500 cu in engine! If you have seen the drags and seen some of the engine blow ups it gives a real visual picture of how much boom that 8,000 psi makes. The driver is sitting in front of a big bomb! Pictur3e in your mind what happens in the gun? Nut those pressures are just instantainous numbers as they reduce quickly as the piston and or bullet travels down the cyl. The gun gets the speed of the bullet because it is in a longer cylinder 28" vers the engine at 2.5" when the EX valve opens.
Back to the real world per say a real good hot 454 chevy has a little more than 100 psi BMEP!

Jim
"