Max load

[ian45662]

I was wondering if 80 grains of 3F is to much for a 45 cal Green Mountain barrel out of a flintlock rifle 1-60 twist. Bullet is PRB. I dont like to shoot that much powder but the gun seems to like it and this is a hunting load so my 40 grain target load wont do.

 

[nkbj]

What size across the flats?
Thirty years ago I used to shoot the same load in a Japanese rifle and it would break the beak off of dinner a long ways off until the nipple flew off.

 

[ian45662]

13/16

 

[boar]

My .45 load is 40grs 3f for groundhogs and 70 for deer. Killed one deer with 40grs. Dilly

 

[Melton Kidd]

It could depend on how deep the dovetails for the rear sight and barrel tenon are cut. You could pull the barrel and check the depth of the dovetails to determine how much metal is under them. on a 13/16 inch barrel in .45 cal, you have .181 wall thickness in the barrel. Subtract the depth of the dovetails from .181 to determine if you have enough wall thickness to feel safe. One shot is one thing, but many is totally different. I shoot 70 grains in my Douglas 13/16 .45 cal. and would not shoot 80. The little bit of muzzle velocity gain is not worth the worry for me. It might depend on how much more accurate the gun is with eighty grains.

 

[ian45662]

It is the accuracy I am after. I wish it liked 70 but 80 grains makes the bullets touch at 100 yards. I was shooting 80 all day no problem but I guess that doesn't mean I wont have one in the future. I may just load it up one more time for deer season next week and pray every will be OK then next year get me a 54 or 58.

 

[JJB22]

I have the same barrel on my flinter and I shoot 50 for target and 70 for hunting and the 100 yard shots. Try 75grains, it doesn't seem like it would make a difference (5 grains) but I see a difference in my guns at the top of the curve so to speak.

 

[ohio ramrod]

If your rear dove tail is no more than .062 deep an it is at least 8 inches from the breech plug you will have no problem. The psi decreases as the ball moves out the barrel.The weak point on almost all guns is at the breech plug and slightly from it where the psi is the maximum. But then I am speaking from experience with a 13/16 numrich arms barrel ( considered inferior to the GM ) not as an engineer. ( Even though I do have my BS in Ind Tech ).I have used 13/16 fourty fives for over fourty years with no problems with charges up to 75 grain. I doubt that 5 more grain is going to put you ion a dangerous situation.

 

[ian45662]

I would love to try again but the wife wouldn't be to happy. I was gone all day today and I will be gone most of all next week deer hunting. Its a hell of a load though. It made clean holes through a cast iron frying pan at 100 yards. Maybe 70 grains would do that to but the holes wouldn't touch. Mine also loves a 40 grain load. Holes touch at 50 yards but they start to open up after that and that load would make me nervous shooting at a deer.

 

[ian45662]

Well that's good to hear!! My rear sight it actually farther than that from the breech plug and I don't think its that deep

 

[Skychief]

FWIW, I have a flinter with that barrel. I killed a big doe this morning at 60 yards with prb and 60 grains of 3f. The ball broke ribs going in and out and she was down in 50 yards. Maybe this will be of help to you. Good luck to you.

 

[Trench]

Check the Green Mountain Website. They have a generic statement that says you shouldn't load more 120gr in their barrels. I can't imagine that covers all calibers, but it's what they state.

"Exceeding maximum powder charge of 120 gr. Black Powder FFg by volume, or its equivalent, could result in extreme danger. Knight Rifles and Green Mountain Rifle Barrel Co. expressly disclaims any and all liability for the following: incidental or consequential damages due to the misuse or altering of these barrels and products; and mishandling (whether accidental or purposeful) of these barrels and products; exceeding the maximum load recommendations; or for rifles on which our products have been installed."

 

[hanshi]

I have a flinter with the same size barrel and have used 80 grains for years and taken quite a few deer with that load. The rifle really likes that load, too. Recently I've become more of a tightwad and have been convinced that I don't need that extra power. Since the rifle really likes 65 grains, too, that's what I now use. I used 65 grains (still do) in an underhammer rifle. That load seems to work fine on deer.

 

[chuck-ia]

Bullets touch at 100 yards. That is some shooting. I like to keep the powder charge in the low to medium range, I shot 55 gr. in my .45 flintlock and use 65 gr. (both 3f) in my .50 flintlock. I don't like stressing the barrel. It's up to you though. flinch

 

[ian45662]

well bullets were touching but that was off of a really comfortable rest. Off hand they start to open up.