Lyman Great Plains rifle. Got me a deal. I hope.

[Confederate rifleman]

Put her on layaway today. A percussion 50 caliber with a ball barrel. $165! Virtually new condition with a perfect bore. The crown is another story and a continuing drama with octagonal barrels. I' ve had 3 TC's and this Lyman with lopsided crowns. Very frustrating and I hope this one can be fixed without much fuss.
She's a handsome girl with some nice grain in the stock. The set triggers are very good and the unset pull is very nice as well. Love the balance and carry with the long barrel. The rear sight is positioned well enough that I can use it as is.
Is it just my bad luck, or have others had lopsided crowns? By this I mean one side of the crown is noticeably deeper than the other.
I love my inlines. But there are times when I want to take a long stick for a walk...

 

[Muley Hunter]

You got a great deal. I've had 5 GPR's counting the one being shipped to me now. All were good shooters. I don't remember seeing a bad crown, but the way they shot it wouldn't have mattered anyway.

 

[Semisane]

I have three Great Plains rifles and five TCs with Green Mountain octagon barrels. All have perfect crowns. I've never heard of a bad crown on a Lyman rifle - sharp crowns yes, bad crowns no.

Anyway, a lopsided crown is easily fixed.

 

[Confederate rifleman]

I'm guessing a lathe will be necessary to correct as a crowning ball will just follow the original crown. As i have had to deal with this 3 times now, I wonder why it happens. Perhaps the bore is off center or the final shaping was incorrect and the muzzle isn't square to the bore.
Will use a t square to see if the flats and muzzle are 90° to each other. In theory, as a ball can not pitch or yaw, a bad crown shouldn't have the same effect as it does on a bullet. Perhaps only causing a point if impact towards the offending side of the crown. The TC barrels wouldn't shoot after correcting with a crowning ball. 6 inches at 50 yards is pretty poor. Shot no better before the attempt to correct. Still, it will be worth some effort to make this girl shoot proper. Assuming testing shows an issue.

 

[Muley Hunter]

You could snip a little off the barrel and crown it if it's a problem.

 

[52Bore]

You need a piloted tool to crown similar to this. 5min fix.
I would be glad to send you this, brass pilots can be made for different bores, but unfortunately its only 1/2" in diameter and I do not have a larger one.

 

[junkman]

On my round ball shooter I used a countersinking tool to crown it after I shortened the barrel.

 

[cayuga]

I would take that to a certified Gun Smith or a machinist and have them look at it. If adjustment does need to be made, they could do it for a reasonable and professional price I would guess. If you muck this up you will have a real head ache.

 

[Muley Hunter]

I'd see how it shoots before doing anything.

 

[Confederate rifleman]

Well... Shot her today with a .490 ball, .018 ticking patch, bore butter for lube and 50 and 70 grain charges if 3f Swiss. Results were quite good for a first outing. Ignition was 100% and 3 rounders at 25 and 50 yards, with both charges were in the 1 1/4 - 2 inch range. Patches were generally in good condition, but one was a bit frayed and 2 were blown resulting in low hits that opened the group significantly. I was cutting patches at the muzzle and my knife wasn't a sharp as it could've been. Perhaps it caused some damage to the patch. The patch/ball combo is ok for hunting, but may be a wee bit loose for targets. Fouling was as expected and recoil very pleasant in this 9+ pound rifle.
So, at first blush I'm happy and hopeful that my new long stick will give good service. Once we get used to each other! Now to find a good steel aperture sight....

 

[GoexBlackhorn]

I've only owned two roundball guns in my lifetime and I have never blown a butter-lubed .018 pillow-ticker patch. Many of mine retrieved after shooting were still in very good condition.... some I had the urge to use again / 2nd time.

I'm glad to read that you are off to a good start with this most recent purchase.

 

[Confederate rifleman]

The ticking is old and well washed and the barrel is new, so the occasional cut/blown patch isn't exactly unexpected at this point. When I took her to pieces for cleaning I found something interesting. On the patent breech hook, there are 3 x's scratched on it. Also on the trigger plate, there are also 3 x's. I have seen this before. Cabelas does this on returned items. No matter. She's a good rifle.

 

[Muley Hunter]

The GPR is known for cutting patches when loading. Smoothing out the crown will help that. Your thumb and the right grit sandpaper will work for that.

It's also accepted it takes about 100 shots to get the barrel shooting it's best. You can speed up that process up by using some JB on the bore. 40-50 strokes will do it.