Still figurin' out the GPR...
 

Dropped in to 25 yds and 50 gr T7 PRB, shot that for a bit just to check grouping then increased incrementally to 75 gr and back out to 50 yds. (OK, there were a few at 100gr just for kicks, actually felt recoil was very slight compared to both my Hawkens)

The grouping at 75gr was a bit tighter than at 50gr; not much difference due to yardage but tighter overall compared to my first few sessions. I tried this because shooting at 80 yds w/ 70-80 gr T7 I was having quite a few fliers if I did not swab every couple shots. I should mention that in my most recent sessions I swabbed every 5 shots.
So,having never owned a new, or in this case NOS, rifle before I can only assume that this is the break-in period? I planned to allow 100 rds or so before filing the front sight; at this point I'm @ 60.

Seem normal?

Take the T7 and put in away in the closet, its not worth a darn with patched balls.

Get some goex 3f or Pyrodex RS and run 100-110gr volume, .018" " blue and white stripe" patching.

Well I have the Great Plains Hunter and was shooting that today. And what was accurate a month ago, was terrible today for some reason. Ignition with the flint was excellent, but it just did not group like normal. So I finally got a different rifle out and tried that. It shot perfect. But then my White .451 always does.

I would also try some black powder or pyrodex (if percussion). But start at 75 or 80 gr and work up. If your having loading difficulty with the .018" pillow ticking try swabbing the bore with some JB compound and a good cleaning.
I am seriously thinking about getting me another Great Plains rifle. But I want a .54 flintlock.

That is an interesting statement, but you may be on to something. My .45 caliber TC Hawken groups a lot better with Pyrodex P than it does with T7 FFFG, when shooting PRBs.

Check your patches if the are blown to pieces switch powders to Pyrodex, most of us have found the 777 is not a good powder for PRB, if you feel you must use it then expect problem some can make it work by putting wads under the ball really more practical to switch powders to Pyrodex it was designed for PRB.

That was my experience also Lee. For PRBs it's either GOEX or Pyrodex RS. I'll also note that Pyrodex P did not work as well as RS for me.

Regarding the T7- I switched from Pyrodex 10 yrs or so ago & truly have had no complaints.
The patches, I've been purchasing pillow ticking by the yard (& recently found two different ones to try), look almost unused after the shot and, truth be told, I've reused more than a few w/no notable change in accuracy.

Again, I'm assuming barrel break-in here of 100 rds before filing the sight at all.

Hey 3 seasons, are you using stock rear sight or a peep and yours is a caplock right?

I thought about using t7 but I would have to duplex my load cause mine is a flinter. I just don't think that would be worth the hassle.

I picked up some Ultimate 1 Keith HP 350 gr to try out just for giggles. I think I'll start them off at 85gr Goex 3f with a wasp nest buffer. I'm going to lube them with bear grease. I'll post the results.

HA

HA- mine is a caplock & I'm using the buckhorn rear sight which I do like; growing accustomed to the front blade vs bead...

Why does the flintlock require a duplex load of T7?