Lyman Great Plains Rifle

[Hornet22savage]

My Dad has an older Lyman Great Plains Rifle. He has been toying around with loose Triple Seven powder. I beleive that he has gotten upto 120 grains and it seams to blowing his hammer back to full cock. I forgot to mention that it is a .54 cal. and I beleive that it has a 1:48 twist. He shoots 400 grain conicals. Is this a sign of an over charge or just a weak hammer spring?

 

[cayuga]

My Dad has an older Lyman Great Plains Rifle. He has been toying around with loose Triple Seven powder. I beleive that he has gotten upto 120 grains and it seams to blowing his hammer back to full cock. I forgot to mention that it is a .54 cal. and I beleive that it has a 1:48 twist. He shoots 400 grain conicals. Is this a sign of an over charge or just a weak hammer spring?

The Great Plains Rifles had a 1-66 twist and then later went to a 1-60 twist. The Lyman Trade Rifle has the 1-48 twist. The Great Plains HUNTER had has a 1-32 twist for shooting conical. I suspect your father has a Great Plains Hunter if the rifle was meant to shoot conical bullets.

120 grains of Triple Seven and a great plains conical is too much powder and bullet for that rifle. He's lucky he did not crack the stock. Also the recoil must have been brutal. I am not surprised it cocked itself.

If the barrel is a GPR, tell him to try a roundball. In the Great Plains Hunter, a conical and up to 100 grains of powder would be a max load.

 

[Hornet22savage]

He purchased this rifle back in the 80's i want to say after I was born so it would have been around 84. He is on his second barrel and that is why I say it's 1:48. It came from Italy thats all I know. He is crazy I have seen him shoot 200 grains of pyrodex with a 425 grain conical and that half cocks his hammer. It shoots the conicals great my concern was the charge and pressure saftey.

 

[Semisane]

Cayuga: 120 grains of Triple Seven and a great plains conical is too much powder and bullet for that rifle.

Dang right it's too much. That's pushing the limits of safety and is probably a waste of powder anyway. What are his typical shot distances in a hunting situation?

 

[mrlnfshr1]

200 grains of Pyrodex? Is he a glutton for punishment? I shoot 110g 2F real Black in my 54 and most traditional shooters say that is overkill.
Lyman lists 120g 2F under a round ball and 110 gr 2F under a 450g conical as max loads.

 

[Hornet22savage]

Yeah he's crazy like that. I want to say tht his normal load was 110 grains but then he switched to triple seven and stepped it up a bit. I'll let him know today that 120 is way too much. I know that most loads for a .54 are down around 90 grains and he does too. Just trying to gooutside the relm of normal.