First Shots fired in my new GPR

[Greenjoytj]

I fired my new Lyman Great Plain Rifle (GPR) .54 cal. yesterday.

I used the OEM supplied cut agate flint and the lock never failed to spark, the priming ignited ever time.

I dry balled the loading twice (back to back screw ups) but removing the lock and the vent liner I was able to pour in about 20 grains of 2 FG into the chamber area of the patent breach.
Reinstalled the vent and lock and the rifle fired, weakly but enough to launch the ball all the way to the 20 meter target I could see the bullet hole in the paper and I tested for an empty bore with my chamber cleaning wood dowel rod.

My first load attempt was with .018" pillow ticking patch lubed 4:1 water:Ballistol mix and a .535" ball.
The muzzle fit seem too tight it spooked me, didn't want to get a load stuck (I forgot to bring a hammer to pound a load). So I didn't use that load and tried the thinner .015" patch lubed the same and a .530" ball. This combo was easily seated and fired over 90 grains of 2 FG Goex.

I wiped the bore between shots with Butch's BP bore shine and was able to shoot until time was up about 15 shots.

Some shots went to the point of aim by putting the front sight even with the top of the rear sight notch and others went ~6" low. A shot using the top of the buckhorns went ~6" high.
I need more practice with the issue buckhorn sights and shooting this rifle.

The only mechanical trouble I encountered was using the set trigger.
On full cock I would pull the set trigger (must pull it very hard) and I feel and hear the "click". Moving to the front trigger I would press very lightly and hear a "click" again but the cock would not fall. Continue to pull the front trigger (very hard) and the lock would release the cock and the rifle fired.

I have a lyman digital trigger pull gage and will test the trigger and get actual pound pull numbers to see if the set feature is working, I don't think it is.


All shots were fired with 90 gr of powder as I wanted see and feel what a hunting load would be like and my Lyman BP book say this load should be about 1450 fps.
No way will I shoot this rifle through my chrono until I get the trigger problem fixed and can cause my shots to group.

I collected all the fired patches I could find (not many were found) most were ok, they sure get ragged around the edges after firing. I had a few that looked cut and a few with burn holes (.015"patch used).

My last shot of the day was with the .018" ticking patch and the bigger .535" ball.
I decided I would try to load this tighter combo. I had to hit the short starter harder and more times and the heavy solid brass range rod helped seat the ball over the 90 gr charge aimed and squeezed real careful and fired, that ball went 1.5" right of center but at the perfect hight with the front sight held even with the top of the rear blade.

Nice to finish the day on a good shot.

 

[jethro224]

The GPR is a good and accurate rifle. :thumbsup: You're in for lots of fun.

You might try the .535 ball with the .015 patch, and the .530 ball with the .018 patch, for a happy medium.
Also try some 3F powder if you can. Both of my .54 GPRs liked 3F better than 2F. One flint, the other percussion. I sold the flinter to help finance another gun but still have the percussion. The favorite load for both was 80 grains of 3F Goex, probably about equivalent to your 90 grain 2F load.
My .50 GPR liked 75 grains of 2F. :idunno:

Try some real flints too if you can. You'll probably get more and better sparks altho yours seems to be working well enough with the cut agate flints.
An extra piece of thick leather under the flint will get you a longer scrape down the frizzen face too. The flint GPR's I have seen all seem to have a too short hammer which strikes the frizzen about half-way up rather than 2/3.

Lots of folks, myself included, find the fixed primitive rear sight much better than the factory installed adjustable buckhorn one. If you try it you will most likely find it is way too loose in the dovetail and will need a bit of peening to make it fit tight.

Have fun getting your new GPR dialed in. :hatsoff:

 

[jethro224]

Oh yeah, the triggers...
You may need to do some adjusting to get the trigger pull right. The rear trigger is not adjustable and does take a pretty hard pull to get it to set. The front trigger can be adjusted by tightening the little screw between the triggers. just go a little at a time until it pulls reasonably light when set.
Some find a longer screw necessary to get it there.
The Davis triggers are a virtual drop-in upgrade and make a huge difference for about $40. They are listed for the T/C rifles but also fit the GPR's.

 

[ebiggs1]

I only have experience with two GPR's but they are similar to each other so that makes me believe they are representative examples.
My thoughts are, the lock needs work to function reliably. I prefer to install a “new” design TC hammer cock. The agate flints are next to worthless but I, too, have gotten them to work. But get real flints, soon! The Lyman trigger is difficult to get to work properly so I recommend the Davis replacement trigger. I prefer Bore Butter or plain olive oil on .018 pillow ticking patches. I shoot 70 grs of 3f GOEX almost exclusively in all my flintlocks. I use .490's in the 50 cal and .530's in the 54 cal. With just a little work you can turn this diamond in the rough into a real nice rifle. Enjoy your rifle. :grin:

 

[mykeal]

Agree with the Davis trigger, it's an easy install and worth the money. But, you can get the Lyman trigger to work pretty easily and it's a good trigger.

Hey guys, it's a brand new GPR. Has ANYONE EVER gotten a brand new GPR barrel to group acceptably in the first 50 rounds? The Lyman/Investarms barrels are famous for needing some break in/shoot in time, as much as 100 rounds.

So spend a hundred rounds just enjoying the gun (maybe fooling with new flints - cause you're gonna want new flints pretty soon - or something - heck, just making smoke and noise is good enough). Then get down to working up a load big time. Or, you could get some lapping compound and do a little polishing while watching Dr. Phil. (Just kidding about Dr. Phil, but lapping the barrel will also clean up those groups)

 

[jethro224]

Has ANYONE EVER gotten a brand new GPR barrel to group acceptably in the first 50 rounds?

Yep. :grin: My .54 caplock barrel shot great right out of the box. :thumbsup:
I changed out the rear sight before I ever shot it. First shot was with a .015 patch that pert near fell down the bore. Next shot was .018 patch that burned some. 3rd shot and every one since was a .020 patch. Shot 5 shots with 80g 2F a little low. Switched to 3F and she was right on the money.
Both my other GPR barrels needed some lapping out.

 

[majg1234]

yep lapping the barrel will help...and without all that noise ,smoke and mess.....naw just shoot it :rotf: she'll come around

 

[mykeal]

:thumbsup:
Well done, sir. You got a rare one, for sure.

 

[rancher]

I love my Lyman GPR .54 flint. It shoots great and I have just over 100 shots through it. I shoot 80 grains of Goex FFg in it under a pillow ticking patch and Hornady .530 roundball. Put the Davis deerslayer triggers in and what a diffence they made. It's like a whole new rifle. Good luck with your gun!

 

[Semisane]

Maybe I just got lucky. But the trigger on my .54 GPR flinter is just dandy. I wouldn't even consider changing it out.

 

[ODG34]

I use a .530 ball with .018" patch on top of 65gr of 3F. That combo works great in my GPR.

 

[trkyman1]

I have the .54 flint and stock trigger. It shoots great and I think the trigger is good also. What is the advantage of the Davis trigger? What does it do better than the stock trigger? [just asking]

 

[MSW]

by way of disclaimer, i've never actually used the Lyman trigger, but i am given to understand that they can be a bit finicky... sometimes you get a great one and sometimes not. I have put Davis triggers in the rifles i've built and they work very nicely. wouldn't hesitate to use them again.

the forty bucks is probably money well spent, depending on how much time you want to spend tinkering with the trigger set up (as opposed to how much time you want to spend doing something else, say, launching lead). if it were me, i'd plonk down the money and be done with it, but you might want to try taking the trigger out of the rifle and see if works properly uninstalled. If this is the case, you might be rubbing on something in the mortise, which is pretty easy to fix if you can figure out where the rub spot is. (Do the lipstick or soot thing.)

Your advice on real flint is well made: i'd get some Black English Flints of some of Rich Pierce's flints right away and you'll be amazed at the difference. Never had much success with cut agate, and couldn't get them to work at all most of the time, so you're doing much better than I on that score.

Welcome, by the way to the addictive world of rockbanging.

BWAHAHAHA (insert Mad Scientist laugh here)

ANOTHER ONE TURNED TO THE DARK SIDE!!

 

[rancher]

I have the .54 flint and stock trigger. It shoots great and I think the trigger is good also. What is the advantage of the Davis trigger? What does it do better than the stock trigger? [just asking]

Maybe my triggers were just a lemon in my GPR, but the Davis' eliminated the large amount of creep present in the stock triggers, and break much cleaner. The set trigger is much lighter. The old set trigger was awful to engage. I also like the aesthetics of the Davis triggers better and their feel.