GM .54 Bore Size....................

[Pioneer2]

I talked to a ladytoday atGM about the.54 GM barrel measurements.She told me that the bore is between .540-.542" and the groove is between .560-.564".They recommend patches between .015-.018".Also a .535 ball for hunting.Do you have to double the patch dia. and add it to the ball size?Seems a little tight to me but I'm still learning.I have a .530 mold so I'm hoping it's not usless.A buddy gave me 50 or so .535 balls to try.I can't fathom getting a .020 patch down the pipe.Any ideas what to order or loads for this barrel.Our local gun store has squat for BP stuff so I'm mailorder only.............Got a wack of snow today so I'm not sure if it's worth going bear hunting today as planned? Thanx Harold

[cayugad]

Remember when you figure the patch thickness you have to figure it twice since it wraps around both sides of the ball where it engages the barrel. So even with a .530 ball and .018 patch you have .530 + .018 + .018 = .566 which in a .560-.564 on the grove should still engage the rifling fine.

[cayugad]

Just so you know, I have a .535 LEE mold that I casted two hundred roundball out of. They were so hard to load, I never made another batch. They did make dandy ammo for my wrist rocket sling shot thought. I use a .530 becauseI am not driving nothing down the barrel with a mallet. You should of seen my friend and I that day trying to load them .535 ball. We had to ram atree with the ramrod in order to seat the first one. The second one, I used a ball puller and removed. I bought the mold because some "expert" told me that was the size ball they shot. Try the ones you got. Loading these rifles should not be a major project.No I am not saying the person at GM is wrong, but try those .535 you got and then judge what is better.

[lonewolf5348]

I favor using a 530 hornady RB and .017 pillow patch material in my 54 cal. barrel
I think I would start with the 530 dia: and go from there,I read a post that you have problems in buying pillow patch material from walmart in your location,I can if you like the next trip I make to walmart pickup 3 yards of the stuff and mail it to you if you like :
you can send me the funds later

[roundball]

It must also be remembered that you can't simply add the various measurements...patches compress to half their initial measured thickness when started into the bore