Minimum load for Lyman GP .50 cal.

[diego_m]

I am starting to shoot my Lyman Great Plains .50 cal. percussion rifle 8 months after triple bypass surgery. Even though my surgeon says it's okay to go full bore (pun intended) I want to start off with a reduced load before going to a full hunting load. The manual gives only maximum loads so I'm looking for advice about how much powder to use to start with. I prefer to use FFFg Pyrodex or Triple Seven. Your advice is appreciated!

 

[azmntman]

I vote 35, no recoil lotta smoke!

 

[mooman76]

Start low as you want and work up a little at a time as long as you feel comfortable. There really is no lowest you can go. Even a few grains will spit out the ball. I'd start at about 20 or 25 and work up.

 

[BrownBear]

I'm using 35 grains of 3f for superb small game accuracy. Don't even have to change the sight from their regulation with a heavy hunting load.

My GPR doesn't care or seem to notice whether it's shooting Goex, Pyrodex or Triple Seven. It likes them all equally well. Guy would have to be a politician looking for an argument to find any difference between them in accuracy or performance.

 

[Semisane]

The absolute minimum load is 4.3579 grains. :grin:

 

[Tom Compton]

Oh WOW, I was told minimum was 5.4 grains.

 

[azmntman]

4.5 will bounce off wood, MAY penetrate one side of a soft aluminum pepsi can, wont blow through.

I used to load down my ROA so my then 2 1/2 year old could shoot it (with pop behind him makin sure no barrel swing in such was goin on). 4.5 (ok 5) gr would send it into one side of the can and we could "pour em out" when done. He was a crack shot too :redface: (at 3 feet). He thought all that corn meal was smoke :blah:

 

[stronics]

I have good luck with 40grs. 3F in my 50's.
David

 

[charlie b]

My GPH likes 30gn, but, it is the faster twist.

 

[charlie b]

I was reminded in another forum.

The Lyman rifles have a patent breech with a smaller dia chamber at the rear.

The powder charge should AT LEAST fill this smaller chamber. If it does not you will have an air gap, which is not good.

Not sure how big the chamber is but I would bet that mine would hold about 20gn (about .32 dia and 3/4 or 1" long).

 

[mooman76]

Yes, and how many here have forgot the powder before the ball, and put a few grains of powder under the nipple to launch the ball out?

 

[azmntman]

:shocked2: no powder before ball? NOW WHO WOULD DO THAT :hmm: More than twice per range trip i mean..... :rotf:

 

[BrownBear]

I was reminded in another forum.

The Lyman rifles have a patent breech with a smaller dia chamber at the rear.

The powder charge should AT LEAST fill this smaller chamber. If it does not you will have an air gap, which is not good.

Not sure how big the chamber is but I would bet that mine would hold about 20gn (about .32 dia and 3/4 or 1" long).

Years back someone pulled the breech and measured the capacity. Don't recall who did it, but I'm pretty sure it was Zonie who posted the results.

My memory is geezerly at times, but I do remember stuff that registers as important. I'd been shooting 20 grains of 3f until then. Zonie (or whoever) reported that the patent breech on the Lyman GPR holds right at 30 grains.

Did some testing, found out mine preferred 35 grains rather than 30. Tossed my 20 grain measure in the drawer and made a new one for 35 grains. Never looked back.