Lyman great plains

[Smokey Plainsman]

The simplest way would be to use a micrometer to measure the land-to-land diameter at the muzzle. You can get cheap but good digital ones from Harbor Freight or Amazon.

If I was a "bettin' man" I'd say it's a 15/16" .54 caliber barrel, just like on my GPR. It looks almost exactly the same from the pictures but I'd mike it before ordering or running balls.

 

[jefftx]

Land to land at the muzzle I'm assuming is outside edge to outside edge?

 

[Grenadier1758]

It will be money well spent to get a cheap dial or digital caliper. My digital caliper from Harbor Freight is accurate enough to measure bore diameter. Until you measure the bore, you won't know the caliber.

 

[Grenadier1758]

You need a caliper to measure inside diameters. A micrometer measures outside diameters.

 

[jefftx]

I just took a piece of paper and marked outside to outside on my .54 Cabela Investarm. I also marked inside to inside. It looks like an exact match to the rifle in question. I have a harbor freight close by for a caliper, but it looks like I now own two .54s.

 

[jefftx]

I just measured with a caliper the inside of the barrel. My new purchase was .556. My Cabela .54 measured .550.

Thank you guys for catching that and the missing clean out screw. This forum is full of great, knowledgable fine fellows.

I really wanted a .50 cal to go with my .54, but with all the powder and molds I'm still happy with the deal I made.

Once I get the clean out screw, I'll shoot it and see which one shoots better groups. My Cabela is still being broken in, less than 100 round balls thru her.

 

[Zonie]

Glad to hear you figured out what the caliber is. :thumbsup:

For folks who want to get a close estimate of the caliber of their guns without buying a caliper, they can use a good ruler or tape measure.

Eyeballing the actual bore so they are not measuring the crown or corner break on the muzzle, place the ruler/measure on the muzzle lining up one of the inch lines with one side of the bore.

Figure out what the distance to the opposite side of the bore is on the ruler/measure.

If the measurement is about 7/16" the gun is a .45
If it is 1/2" the gun is a .50
If it is about 9/16" it is a .54 and 5/8" would be a .62 caliber.

 

[fishmusic]

Jeff, you can probably get that screw at your local hardware store. It is a M4-.7 x 5mm set screw, pretty common stuff in metric sizes. When you screw it in it won't stop until it hits the nipple. Go gently until it stops and then back it off 1/2 a turn. That way you won't goober up the nipple threads.

I usually remove to clean but it is'nt necessary.

 

[fishmusic]

BTW, what part of Texas you located in? I am in Hutto just a little east and south of Round Rock.

 

[azmntman]

MUCH better than 1. I have 3 :grin:

 

[jefftx]

I called Lyman yesterday and they sent one out free. Nice folks.
I'm down in Laguna Vista, near Port Isabel.