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Pressure of my 12 bore?

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I hunt with a 12 gauge smoothbore using a patched.715 caliber round ball over 120 grains of FFg black powder. Barrel is a Curly Gostomski Sitting Fox trade gun barrel. The charge is more than sufficient and actually overkill for white tail bucks. I carry it during bear and elk season too. The reason for the heavy load. It kicks like a mule with a walnut half stock.
James Gefroh (sp?) of northern Colorado made muzzle loading express rifles in 4 and 8 bore and some smaller. He and his clients successfully harvested BIG game in Africa. I don't have breech and barrel pressures for Triple Seven as I don't shoot anything but black powder. Maybe James does. I hunt for the meat and hides and have to get proper shot placement to keep damage to a minimum. Let use know which barrel steel alloy you choose.
It’s too expensive to ship to USA But in Holts March uk auction there’s a double 8 bore. Maybe not to expensive Tap in photo might get you to auction Great talking piece tempted
 

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The 12 gauge Curly Gostomoski "Sitting Fox" barreled (smooth bore) trade gun I hunt with works well with a .715 patched round ball over 120 grains for FFg black powder. Don't know what the breech pressures are. It is more than sufficient for white tail and mule deer and loaded this heavy for seasons where I have an elk or bear tag. Kicks like a mule.
James Gefroh of northern Colorado made and hunted 4 and 8 bore muzzle loading rifles. Both he and his clients were successful in harvesting really big game in Africa. He might be able to recommend a certain alloy of steel for your barrels. He had a machinist make breech plugs and tangs for those express gun barrels..
Thanks for the awesome recommendations
 
I know nothing of 777.

I do know black. Shooting a 0.990" ball in my 4-GA (1") 350 grains of 1F is reasonable. It pushes but is not violent. 350 Grains of 2F is very unpleasant. 350 grains of 3F will give you a concussion, at least it did me. Consider running 1F in large bores as was done originally.

If 777 accelerates the ball like 2F or 3F you might find yourself regretting it.
I don't find the recoil that jarring but im not pushing a ball like you.777 is just cleaner burning to me so i can see if the deer ran.i use 300 in the 8 bore for shooting and it's a big push.instead of a whipcrack like my .375i don't mind it.

I'll consider the 1f
 
for you big big bore guns what about a slug over 1000 grains and propelled by 12 drams of black powder.
Wat till the end when he shoots one. The "light" target load.
Not ML mostly but does talk about one ML Stopping Rifle and is interesting
ghttps://youtu.be/MDYtxxRU_cY
Thank you!!
 
12L14, leaded, was created for free machining screw making. Douglas Bbl stopped using it completely, years ago, and friend Jim K. who was the Metallurgist expert witness during the trials agrees - don’t risk using it with bullets.

I don’t believe Jason at Rice will cut you a bullet gun out of 12L14 either.

I built a 12b out of 4140 with no issues and shoot a mild load with a 850gr conical, I’m only shooting Whitetails..
Good luck, be safe.
Thank you for your response
 
I wouldn't put 777 in anything. I'm not afraid of 12L14 for muzzleloaders, but others wet their drawers at the mention of it.
I have no idea what the pressure is, but that many grains of real black powder and that weight of projectile will be safe with 12L14, depending on how big your breech is. I'd recommend 1 3/8" to 1 1/2" at the breech. Finished weight for the gun should go 14 to 18lbs or so, unless you want to pick yourself up off the ground a lot.
What beastie is it that you're going to slay with such a large projectile?
Well thanks for your advice! I called the barrel company and they gave me the option of 12L14steel or 4140 steel. I chose 4140 and have to pay more, but at least I'll know it isn't going to bust.
Thank you for your input.now I can use Sama Falada loads!
Oh,I'll be hunting deer.but I want to use the traditional load of 250grs as the African hunters used back in the 1800s.
 
Well thanks for your advice! I called the barrel company and they gave me the option of 12L14steel or 4140 steel. I chose 4140 and have to pay more, but at least I'll know it isn't going to bust.
Thank you for your input.now I can use Sama Falada loads!
Oh,I'll be hunting deer.but I want to use the traditional load of 250grs as the African hunters used back in the 1800s.
I'm an old man now. I have so much arthritis in my neck I can't even back my truck up by looking over my shoulder anymore. My arthritis is from all the pounding I received from hard recoiling guns. I sure wish I wouldn't have shot those things now.
 
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