12ga+BP?

[Desertbuck]

Hi to you all I have been coming here for info for some time and decided it's time to join.
So! I have a project that has been buzzing around in my head, I want to build a mini breach loading rifled artillery gun based on the H&R 12ga slug gun.I know that sounds funny. But I plan on building a small wheeled carriage, with a recoil system, fine screw adjustment with horizontal and vertical read out using old calipers. I know sounds funny!

What I want to know before I get into this project is, Will the H&R slug gun and a 12ga 2 3/4 case handle say 650gr 700gr PP slug with a grease cookie and 180gr to 200gr by weight of 1F black powder?

Any advice yes or no is welcome.
Thanks DB

[UNIQUEDOT]

Welcome to the forum Desertbuck. As far as you inquiry goes I'm not sure, but if you are talking about the H&R 12 ga heavy barreled gun that's built on the 10 ga. frame i would imagine that it's probably able to handle more pressure than a standard 12 ga. slug gun, but I'm not sure how much pressure would be generated by a 700 grain slug being pushed by 200 grains of black powder in the confines of a 12 ga chamber. BTW have you given any thought to how you would be able to pack all that into a 2.75" case?

[Smoke73]

600 grain ball and 220 grains of FFg produces around 11400 psi. If I get time I will post a blackpowder pressure chart.

[missionary5155]

Greetings
I do know 135 grains 2F with a .685 RB repeatedly fired out of my Fox B 12 bore brings tears to my eyes. Recoil is a bit fierce to my 155 pounds. So my thinker says you better work up to that load in steps or a 20 pound (?) canon is going to be traveling somewhere.
Mike in Peru

[Combat Diver]

Just remember that when you take a shotgun and cut the barrel down to any length shorter then 18" and 26" OAL, doesn't matter to ATF that you put wheels on it or not. Just don't forget to get the tax stamp first. Good luck with your project.


CD

[Smoke73]

A .735 RB and 150 grains I could just hang on to in my husky 310 double. 150 grains of 777 and there is no way for me to hang on and I weigh 295. Looked like a fool on the 577 T-Rex videos on YouTube.

[JJC]

Smoke 73 where are you getting your data from? I am not having any luck finding info like this.

[Smoke73]

Found this spread sheet on the NitroExpress forum. Cant dig up the link at the moment but the info came from one of the old english double rifle builders. Recoil values will be much higher as these would have been measured on full on doubles weighing 13# plus. Hang on if your using a light weight rifle and remember that these heavy loads will even split poorly built stocks.

[Desertbuck]

Thanks Smoke73 that chart will help me a lot.

UNIQUEDOT-BTW have you given any thought to how you would be able to pack all that into a 2.75" case?


I planed on cutting off the crimp, filling the case with F black powder and leaving just enough room to place a pp boolit on top held in place by a touch of hot glue.

[Smoke73]

you'll be pretty much full around 160 grains in the 2 3/4 case. Some guys claim you can get the 190 grain load in the 2 3/4 but it just exposes their internet BS. 160 will get you rocking. You will notice at these higher levels the smoke lessons and the sound goes from a nice boom to something totally different. Goodluck and the best part is all these crazy heavy loads have no preassure concerns.