New Muzzleloader Question


Pat M
March 2, 2010, 12:22 PM
Greetings, I just received my first muzzleloader in the mail yesterday, and I have the first of what will probably be many questions. It is a Lyman Great Plains flintlock in .50 cal. The manual says I can use round balls in either .490 or .495.......which is best for this particular rifle? Or does it depend on the patch thickness? Should I simply try both, and see which shoots better? Thanks in advance.

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March 2, 2010, 01:38 PM
It really depends on each individual barrel.
Of course the patch thickness matters too, but some barrels just won't like loading with .495 balls. They do usually load noticiably tighter even if using a patch thickness that is .005 smaller than when using .490 balls. That's simply because there's not as much patch material to compress to fill in the rifling grooves.
It boils down to a compromise between the accuracy desired and the amount of loading difficulty that you want to encounter with your ramrod.
For the typical .50 caliber bore, start with a .490 ball and a lubed .015 patch. Then based on the performance and loading difficulty, you can decide whether to try the .495 balls with the same patch or a thinner lubed .010 patch.
Some folks might try a .490 and an .018 pillow ticking patch first before switching ball size because it's recommended to just switch one component at a time to properly evaluate the effect.
But obtaining shooting experience with that rifle will help you to judge for yourself what you should try next. A tighter load might require swabbing more often between shots. But that can also depend on how much powder is loaded.
By starting at the lower powder charge of ~50 grains at 50 yards and then increasing it in 5 - 10 grain increments, you'll find the powder charges that shoot the most accurately for that combination of patch and ball.
Then repeat the process for whichever new combination that you eventually decide to try.

March 2, 2010, 01:51 PM
Good advice from arcticap.

One more point: The Lyman barrel needs to be 'broken in' (I do NOT mean 'seasoned') before you settle on a particular ball, patch and lube. It usually takes about 100 rounds to accomplish this. Nothing wrong with trying out ball/patch/lube combinations right from the start, but don't be discouraged by the results at first. You may find it just won't group well with any combination. Once you've gotten to 100 rounds, start over and seriously search for the right combination for your barrel. If you'd rather just shoot one combination until you reach that magic number, the .490/.015 or even .490/.010 is a good choice.

March 2, 2010, 01:59 PM
GPRs also have a patent breech which has special cleaning requirements. After cleaning the bore with soap and H2O, I use a .32 or .357 bore brush on a ramrod and clean the smaller patent breach area near the chamber. I change to a patch tip and clean with a patch.

This may not make much sense but the breach looks like a funnel (maybe Mykeal or someone can come up with a picture). but it is important to do this on Lyman GPRs.

Good luck and good shooting.


Pat M
March 2, 2010, 02:39 PM
Thanks for the advice. I think I'll go with the .490 ball and the .015 patch until I get the hang of it and get at least 100 rnds through the barrel. Lyman also mentions that this rifle tends to shoot high and front sight may need to be filed down a bit, but I'll wait until I can be sure where the groups are going. This will be an interesting learning experience.

March 2, 2010, 05:26 PM
What works for me might not for you but here is my 2cents. I shoot a GPR slow twist barrel 1:60" I use a .490 round ball. For patch material I use pillow ticking. Pillow ticking is just one of probably a thousand types of fabric one could use for patches. I pick mine up from a local gun store pre-packaged in 1sq/yd sheets. I cut it into 1' wide strips and tie off a strip to my shooting bag when I am getting ready to shoot. I have also seen ticking in pre-cut patches both lubed and unlubed. The stuff I use mics at @ .018. but it has varied between .009 and a whopping .022! I do not use lube. I use spit. Yep, spit. I put an end of the strip tied to my bag in my mouth and after pouring in my powder charge I place the moistened end of the strip across the muzzle. Now I do not slobber all over the patch, just moisten it. Then I place the round ball on top of the patch and seat it with my ball starter. A patch knife is then used to cut the strip from the seated bullet. A quick strike on the short starter again and then I seat the ball home with the ram rod. Prime the pan and then shoot. I've been using this method for about 20 years and it works for me. Mykeal, Articap and Higene also have great pointers for your GPR. I find the patented breech easy to clean with a brush I get from DGW. http:// (

March 2, 2010, 05:29 PM
Before you take it out to shoot.... Give the barrel a good cleaning. You want to get out any oil that was used in the manufacturing process. A good degreaser and a few drying patches should do the trick. Now you've got a dry barrel. At this point it would be wise to run a jag with bore butter down the barrel and let the barrel sit awhile. First time you take it shooting, use well lubed patch's...clean every few shots and pay attention to how well the ball/patch are seating. You might find a few "dry" spots that make it hard to load between shots. Each time you do, after you fire your current load...take a few moments and clean the bore before loading the next shot.

I think you'll be well served with the .490 ball and a .015 patch for the first go around...and you can experiment from there. Wouldn't worry about touching the file to the front sight until you work up a reasonably accurate load.

March 2, 2010, 07:22 PM
Another name for the patent breech is Nock's Breech:

This isn't exactly the same as the GPR patent breech, but's it's in the ballpark.
Unfortunately I don't have a reference for the above pictures, so if anyone here is author, please excuse the posting without attribution - it's strictly due to ignorance.

March 2, 2010, 09:25 PM
Also, with all iron sights, the front sight should be moved in the OPPOSITE direction of the strike of the bullet. i.e. If one wants to Raise the strike of the Bullet, one Lowers (files) the front sight. If you want to Lower the strike of the bullet, you Increase the size or height of front sight. A taller front sight lowers the strike of the bullet. The same opposite logic applies to windage when adjusting the front sight.

One adjusts the rear sight in the same direction as the desired change in the strike of the bullet. (Think M16).


My GPR came with adjustable rear sights which do a good job. Relatively inexpensive aperture sights are available and GPRs are tapped for them.


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