Gpr accuracy

[Hota]

Hey folks,

Any tips on tightening up groups on a gpr? I have had this rifle for years and is currently my only flintlock now while i am awaiting delivery of my custom build i started and is being finished by Paul Allison. But this gpr rifle groups 5" at 50 yards. Horrible accuracy which precludes me from participating in woods walks and other events. Just too embarrassing. My southern poorboy i had was super accurate.

My sights are tight, barrel is tightly fitted to the stock, lock screws are tight and alinged with the touch hole, triggers feel ok, not great but ok enough. I may clean up the lock channel some, barrel is clean but i cant attest to if there is any rifling damage. Its a .54 and i am using hornady round balls. .535 with .18 prelubed patches. 90 grains of 2f goex with 4f pan powder. Good ignition. All conditions side by side i was grouping 1" with my tvm, 5" with my gpr. Maybe that is good for a gpr and mynstandards are high?

[prairie dog]

It should shoot better than that. My experience with GPR's is that they can be very picky about the load.

For example; my 50 would not group with 490 balls.  I had to go to a 495 ball with a 20 thick patch.  It also refused to shoot good groups with bore butter.  It does like Tracks mink oil or moose milk.

They sometimes shoot better with a heavier load than most would want to shoot targets with.  My friend has a 54 that will only group with hunting loads and mine shoots it's best groups with 80 grains of 3-f.  Fortunately, it will also shoot well with a 40 grain load.

I would check the muzzle crown for damage then do a through load work up. I might also consider glass bedding the tang and barrel.

I won first place in my gun clubs yearly aggregate last year with my GPR and I am on the way to doing it again this year.  I know they will shoot and I see plenty of guys doing well with them at rendezvous shoots.  

I' do a lot of experimenting with your load before giving up on it.

BTW- I also did considerable work on my trigger and changed out the factory sights.  Those are too coarse for target shooting in my opinion.

[Roaddog]

My GPR 54 cal. flinter likes the 530 ball and a .15 pach, Ol' Thunder Lub with 60 gr. 2F for target and 90 gr. for hunting. It was a stinker to site in. Keep working with it and it will come around. I get the Ol' Thunder Lub from Flecher here on the frorum.

[Uncle Russ]

Darren, I am somewhat surprised that a an ol' Muzzleloader like yourself is having problems, especially with the GPR.....but, I have heard it before, and even know of fellas trading off their GPR because of it.
I suspect my dealings with the GPR have all been very positive.....straight out-of-the-box accuracy with only a bit of experimenting.

My own GPR was "pretty good" right out of the box. But after a dozen or so fire-lappings it was never a problem no matter what the powder charge, seemed to have always had a preference for the .530 swaged and a .012 pillow tick patch. To say one lube was more accurate, from spit-patch to Moose-Milk, to Hoppes would be splitting some mighty fine hairs, but Hoppes did, and still does, seem to give me more shots in between wippings.

Something to think about;
For Fire Lappings I simply use a patch well soaked in Mineral Oil, with a large dab of #11 Valve Grinding Compound on it, load the ball with the Compound to the outside, touching the barrel, ram it down over about 50 - 55gr FFFg, and touch it off....then clean up your mess in the barrel. (The reason for the small powder charge is because it seems to create less of a mess to have to clean up).
Do this a dozen or so times, maybe even more if you have the time and patience, and your barrel will sparkle like new money, and most likely shoot a little better.
I amd also told a very tight heavy cotton patch, with the same concoction, and 50 or more strokes between cleaning will do the same thing.

The very best way to lap is with a conical lube grooved bullet, .001 overbore size, (Mini or Maxi) ...then mount the conical to the base of a good stout dowel rod, with the compound embedded in the grooves by use of a heavy lube like Bore Butter or 1000 Natura,....... using constant long, even strokes, run the slug in and out of the bore a couple of dozen times....clean the barrel good with Mineral oil, bump-up another slug and go at it again.

I hope you get that thing shooting. The GPR is one of my all time favorite toys.

Uncle Russ...

[Hota]

Thanks for the confidence Russ. And to be honest i am surprised i'm having problems with it too. I'll keep working with her and see what happens. Thanks for the fire lapping suggestion. I'll give that a try. I'll have to keep notes on all the different things i'm doing to get this one dialed in. Never had this much of an issue sending a ball straight down the pole.

[Swamp]

Hota, my GPR that I had liked .530's over the .535's! I also used and 80gr charge of FFF and pillow ticking with my own Swamp-Juice lube. That baby was so accurate it was spooky! I should have never sold it to Beaverman!

Good guns they are, and when you find the right load, they are shooters!

[Stormrider51]

Have you miked the bore for size?  It may be marked ".54" but what it really is depends on how worn the cutter was when it was made.  I also second examining the crown at the muzzle.  The most important part of a barrel is that last little bit that releases the ball into freeflight.  Seemingly small imperfections there can cause big problems.

Storm