Lyman Great Plains Rifle...

[sooter76]

So I know I recently asked about Pedersoli's Kentucky Longrifle, but after reading the comments, some other threads, and some messages sent my way I've been rethinking my direction towards the Lyman GPR. That said, for those that have the .54 1-60 twist versions...

1) What powder and charge do you use and find most accurate?

2) What size ball do you use?

3) I know some people make cartridges for flintlock rifles and use that paper as wading instead of patches; does anyone do this for their GPR? How does it work?

And in general what accessories do you find important to have?

Thanks...

 

[AJumbo]

In my testing of my Dad's GPR, I found charges of 70-80 grains of FFFg black powder, pushing a .535 round ball patched with .015 pillow ticking to be capable of 75-yard cloverleaf groups. For plinking and small game hunting, charges of 50 grains were plenty accurate; hunting charges upward of 110 gr. of FFg still kept 3 rounds in a 2" - 2 1/2" group. Hard to beat that from an untuned production rifle.

In the interests of science let me point out a few things:
-.535 balls and .015 ticking were all I had on hand, so maybe another combination of materials would better in another rifle. My eyes back then were pretty dang good, too, so I'm not sure I could wring that kind of performance from any iron-sighted rifle these days.

-Dad prefers Pyrodex over black, and never complained about accuracy or performance when using it in the GPR.

-Sometimes a rifle barrel with a slower twist needs to be loaded more heavily than one with a faster twist in order to start really throwing nice groups, and that seemed to be the case with this rifle; that being said, the practical difference between 50 gr. and 80 gr. charges was pretty much negligible when plinking.

All these rifles need some personal involvement from the shooter in order to really shine. Whatever rifle you pick, be prepared to try different powders, patches, balls sizes, even lubes, in order to find what it takes to make it purr.

 

[robert garner]

What AJumbo said.
The only thing I would add is that wadding is used in conjunction with patches ,not instead of.
I love dangling the occasional participle.
Start low and work your way up,keep records of groups ,when you change your variables remember to ONLY change one at a time.
Mainly get out and have some fun, these rifles are generally a law unto themselves, and must be finessed by you to bring out their potential.
robert

 

[BCRider]

I can't really comment on the .54 since mine is a .50. But I do know that I was getting very nice groups with it when I was using .490 RB with cotton cleaning patches as patching. Then I ran out of .490 and had to switch to .495 and try a lighter patch. So far this isn't working so well. Groups have most certainly opened up although I have not found time to try it on paper to get an idea of just how bad it is.

I was getting such good results with the .490 that I think I'm simply going to melt down the .495 and re-cast it in the .490 mold I've since gotten and go back to my cotton cleaning patches.

If you do not have a set of calipers for measuring the cloth I'd suggest you pick up a cheap digital set. Or spend slightly more and by a dial version which never needs batteries. Or if your eyes are still those of an eagle then one of the super inexpensive vernier style calipers.

 

[mykeal]

Both my flintlock and percussion .54 GPR's like 70 grains/volume real ffg black powder (Goex) with .018 pillow ticking dry lubed with 1:7 water and Ballistol and a .530 round ball. Both required 100 rounds to come to the point where they would group consistently.

 

[MEHavey]

My 54-GPR/Percussion did require those 100 rounds to knock the sharp edges off the lands.
On the other hand, my 50-GPR/Flint shot well right off the bat.

Two-dozen full strokes w/ some 600-grit clover lapping compound on a Tight patch would probably knock the edges off just as well.

 

[OrangePwrx9]

1) 90 gr. Pyrodex RS
2) .535 Roundball with .018 pillow ticking patch
3) ?

Try to get a look at the rifle before you commit. I bought one new (gunshop got it for me) and it went back for warranty service twice. First time for a variety of cosmetic issues; second time for a set trigger problem. It's a shooter, but the trigger guard is still slightly cockeyed viewed from the muzzle.

Second one I bought (used) was cosmetically perfect. Luck of the draw I guess.

Interesting quirk: The rifle will shoot 295gr. PowerBelts accurately and to the same zero as the PRB. Makes for a fast field reload if you carry a few in your pocket when hunting.

 

[MEHavey]

but the trigger guard is still slightly
cockeyed viewed from the muzzle

Now that I look at it, so is mine. But then I realized that the stock itself
was designed with deliberate cast-off away from the centerline.

 

[Iggy]

Start with the number of grains of powder the same as the caliber of the gun.

Work up at five grain increments. THe group should tighten up and then start to spread.
Back her back down to the sweet spot.

Same thing with ball size and patch thickness.

The old timers called it learnin' the gun.