Pressure of my 12 bore?

[Blackpowder8bore]

I am inquiring about the psi of a rifled 12 bore muzzleloader shooting 250grs of 777 and a 600 grain conical or similar round ball. This is its max and common load for a 12 bore used in Africa. I'm choosing a steel for a similar rifle and need to know so i can pick the steel! 4140 or 12L14.

Anybody with knowledge of pressures in big bore muzzleloaders please help!

Please no negativity just trying to find useful info.
Thank you

 

[deerstalkert]

that load will make your babies be born naked!

 

[64Springer]

You're the one building the rifle.

Dig deep on the internet and find the answer to your question.

 

[Blackpowder8bore]

You're the one building the rifle.

Dig deep on the internet and find the answer to your question.

I'm not building it I'm ordering some of the parts for a builder who's doing it for me.and I am digging on the net..

 

[Comfortably_Numb]

I am inquiring about the psi of a rifled 12 bore muzzleloader shooting 250grs of 777 and a 600 grain conical or similar round ball. This is its max and common load for a 12 bore used in Africa. I'm choosing a steel for a similar rifle and need to know so i can pick the steel! 4140 or 12L14.

Anybody with knowledge of pressures in big bore muzzleloaders please help!

Thank you

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?

 

[64Springer]

I'm not building it I'm ordering some of the parts for a builder who's doing it for me.and I am digging on the net..

Then ask the builder what steel is required.

 

[tenngun]

I am inquiring about the psi of a rifled 12 bore muzzleloader shooting 250grs of 777 and a 600 grain conical or similar round ball. This is its max and common load for a 12 bore used in Africa. I'm choosing a steel for a similar rifle and need to know so i can pick the steel! 4140 or 12L14.

Anybody with knowledge of pressures in big bore muzzleloaders please help!

Thank you

Sam Falada shot a similar load in test in a .58 and it held with several 600 grain minies.

 

[Comfortably_Numb]

Sam Falada wasn't the sharpest knife in the drawer.

 

[Bunk]

Cunningham's Law: The best way to get the right answer on the Internet is not to ask a question, it's to post the wrong answer.
Respectfully
Bunk
P.S. what in Sam Hill are you planning to hunt with that thing. Tyrannosaurs Rex?
Makes my shoulder hurt just to think about it and I shot to zero an unmentionable .458 caliber with 500 grain solids over a MSL of IMR 3031 which I also can't talk about.
BUT spent a rainy afternoon casting 480 grain ring tail bullets for my Sharps.
Does that help?
held enter
hit center
never again
Bunk

 

[Blackpowder8bore]

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?

Thank you for your response. I use 777 in all my guns, why dont you like it?
The breech is 1 1/4 he says but I will ask him if it can go bigger,the barrel Wont be done for a year. I think it would be around 15 lbs. I'm going to deer hunt with it!
I already have an 8 bore that uses max 375grs and an 880gr ball! I just like big bores.its 12L14.
So you think 12L14 is ok? When looking up steel,the tensile strength of 12L14 is 67000 psi vs95000 psi for 4140.is that a good comparison do you think?

Thanks

 

[Blackpowder8bore]

Cunningham's Law: The best way to get the right answer on the Internet is not to ask a question, it's to post the wrong answer.
Respectfully
Bunk
P.S. what in Sam Hill are you planning to hunt with that thing. Tyrannosaurs Rex?
Makes my shoulder hurt just to think about it and I shot to zero an unmentionable .458 caliber with 500 grain solids over a MSL of IMR 3031 which I also can't talk about.
BUT spent a rainy afternoon casting 480 grain ring tail bullets for my Sharps.
Does that help?
held enter
hit center
never again
Bunk

Wow..
Yes i should've posted a wrong answer..
I'm hunting deer with it!. I'm having it built and I'm ordering some of the parts.
I have an 8 bore that uses max 375grs and an 880 gr ball! And I love my 458 caliber.
Thanks

 

[64Springer]

You already have an 8 bore rifle with bigger bore using a heavier projectile and more powder that is made from 12L14 steel, but you're asking if 12L14 steel is good enough for a 12ga rifle with a smaller bore and a lighter projectile and using less powder?

 

[Blackpowder8bore]

You already have an 8 bore rifle with bigger bore using more powder that is made from 12L14, but you're asking if 12L14 is good enough for a 12ga rifle with a smaller bore using less powder?

Smaller bore generates more pressure. .50 caliber uses way less powder and ball but generates significantly more pressure.i looked it up.so yes I am asking what people think.
Thanks

 

[Blackpowder8bore]

Sam Falada shot a similar load in test in a .58 and it held with several 600 grain minies.

That's a good bit of info as smaller bores generates more pressure in blackpowder

 

[Togo]

My friend who is now passed on had a custom made 72 Cal under hammer that had 2 nipples for musket caps built by a gun maker on the West Coast area. He shot and killed a cape buffalo and on other occasions 2 Red Stag that I can remember. It was loaded with 350gr of 2F 777 felt wad and patched RB. I got to shoot it, when the shot went off, I felt like I lost a couple fillings, but it punched the dead center of the bullseye offhand at 50 yards. It seemed to have parted the leaves on the ground for about 10 yards, pretty darn cool. I was also told the builder broke his collar bone proofing the rifle. My friend's son has it now.

 

[64Springer]

You said your builder already has a barrel with a 1-1/4 breech. What material is the barrel?

An 8 bore is .835 diameter. That gives you a breech wall thickness of .2075 inches.

If your builder is saying a .2075 wall is sufficient for a shoulder cannon, I would find another builder.

You'll need a huge lock too. Chambers makes a massive Virgina/Colonial flintlock that will work well on large breech rifles. They're rated for a 1-1/4 breech.

 

[Blackpowder8bore]

You said your builder already has a barrel with a 1-1/4 breech. What material is the barrel?

An 8 bore is .835 diameter. That gives you a breech wall thickness of .2075 inches.

If your builder is saying a .2075 wall is sufficient for a shoulder cannon, I would find another builder.

No sir the 1 1/4thickness is going to be for the 12 bore

 

[Blackpowder8bore]

My friend who is now passed on had a custom made 72 Cal under hammer that had 2 nipples for musket caps built by a gun maker on the West Coast area. He shot and killed a cape buffalo and on other occasions 2 Red Stag that I can remember. It was loaded with 350gr of 2F 777 felt wad and patched RB. I got to shoot it, when the shot went off, I felt like I lost a couple fillings, but it punched the dead center of the bullseye offhand at 50 yards. It seemed to have parted the leaves on the ground for about 10 yards, pretty darn cool. I was also told the builder broke his collar bone proofing the rifle. My friend's son has it now.

Wow 350grs 777?? That's heavy! Sounds really cool he took it to Africa..

 

[64Springer]

C-Num is right. 1-1/2 breech. .333 wall.

 

[Blackpowder8bore]

Then ask the builder what steel is required.

Really? Obviously thr builder and I talk and the shop uses 12L14 but I can try to find another.