Personally SharpShooter.. if I lived where you did, I would go with the .58 caliber. I am not saying that the .54 caliber would not take care of your business, but when hunting large animals, I like to push as much lead into them as I can. The .54 caliber roundball I cast weights 224 grains. The .58 roundball is 284 grains. That means your pushing 25% more lead down range. Also these Green Mountian Barrels you're looking at, I shoot 100 grains, but I can push it to actually 115 grains and still keep accuracy. There just is no need for me to shoot that large of a charge at a white tail. The 100 grain Goex 2f charge is plenty.

Sharpshooter,

I don't see what harm it would do to get either .58 or .54 caliber GMB. If I got a new one, for me, I think I would like the .58 better. But you know, considering the rifle is a gift from your granddad, and it is shooting well, I would be tempted to leave it just like it is, (like my .50 cal hawken my dad gave me). Taking an elk or deer with the rifle your grandfather hunted with sounds really cool to me.

My hawken has similar problems with looseness towards the breech. I found that a meal filler really boosted the velocities without hurting accuracy.Like your .54, it still shoots very well inspite of the pitting.

Good luck with your decision.

Lee, What is your load?

I know a guy on another forum who loads his GM with 120gr FFG KIK and it produces really good accuracy. A load like that would really be good for Colorado.

Another vote for the .58 Gm bbl. I load mine with PRB and 120grs Pyrodex RS. I am going to switch to real black powder after this can is gone though.

I have noticed alot of you guys like the 58 caliber. Please note I am not knocking the 58 caliber.

I would like to make a point and ask a simple question. I cast a 525 grain 50 caliber bullet, from an RCBS adjustable mold. I load 120 grains of 3F blackpowder in a Knight MK 85 rifle(1650 fps). The rifle wears a Williams target peep sight. I can consistently shoot 2 inch or less groups at 100 yards, and have shot deer and elk to 150 yards.

What possible advantage would a 58 caliber rifle have over this scenario? I do not feel any roundball load should be shot at 150 yards at an elk, or am I wrong? I realize that the 58 caliber would leave a bigger hole, but I can not believe 50 caliber hole from a 525 grain bullet is not big enough.

I will admit I have only shot a "Big Boar" TC a few times, so I really have no experience with the 58. But I sure am not above buying one and trying it, if you guys think I should(please tell me I should). I will also admit that my MK 85 kicks like a mule. The stipple on the bolt cuts the webbing between my thumb and forefinger every time I shoot it. But it is God awful medicine for an elk or whitetail. Tom.

Buy your self two green mountain barrels a 54and a 58 you can never have to many guns ask cayugad.

I'd have to say that your load is "some" medicine indeed . Wow. As far as advantage I would say there would be none. But then, there is little if any advantage with a bow, but many find it rewarding. So some want to use roundball.

Alot of bison fell to 45-70-500. Your load is 50-120-525 and in terms of a 2f BP conversion its 50-132-525. There was a Sharps rifle made in 50-140 and I think it shot a 525 grain bullet. It came a little late to kill many bison. In any event, this rifle weighed 20 lbs so probably had half the recoilyou've been experiencing. Thought some might be interested in the ballistics of your load.

Pretty amazing thump at 150 yards.

Head1,

Good God, I just calculated the recoil of your load (assuming 8.5 lb rifle) and got 76.3 ft-lbs. Almost 4 times a 12 guage clays load. You've been eating your Wheaties! The 50-140 sharps using the same bullet weight and charge would be around 32.4 ft-lbs or around 1.5 times the 12 guage load.

Pglasqow-As I stated, the load kills at both ends. It is not the load that I shoot every day in the rifle. However it is the load that I hunt with. I have shot two elk with this load. Neither elk went over 30 yards. You could tell that they were truly sick when the bullet hit them. Both were good behind the shoulder shots. It brings the blood to my hand about every time I shoot it. I also would not recommend the load to anyone, I believe I am overloading the rifle. It definitely kicks considerably harder than my 45-70's. I cast a 405 grain bullet for it. Thanks for your stats. I knew the load was stout, but truly did not realize it was that stout. The velocity was chronographed around one foot from the end of the barrel. I have a 45-70 load(405) grain that comes out at 1850 fps. It is also a very stout load. My normal load for the 45-70 comes out about 1350 fps. Tom.