Boolit size vs bore size in rifles

[XTR]

I've seen this referred to on occasion but nothing that seemed definitive or firm.

In order to get the best accuracy in a single shot straight sided cartridge like a 45-70 should cast boolits be +0.001, 0.002 or something else. (not talking about paper patching yet)

[btroj]

I like at least .001 over, .002 over isn't generally a problem if the cases chamber easily.
My Marlin slugged at .457 but I shoot bullets sized .460 and get very good results.

Over sized isn't generally an issue as long as it chambers. Undersized is a different story, that's often a guarantee of leading.

[XTR]

If you were going to run boolits through a sizing die, what would you choose a +0.001 or a +o.002?

[rbertalotto]

Slug the bore to be absolutely certain you need to size them.

Then measure a bunch of your as cast boolits to be sure of the size.

If they need sizing, size only so much as so they will chamber, but not more than
.002. If they need to be sized more than .002, you might want to consider a new mold.

Now this is for accurate, relatively long range rifle boolits. For shot range handgun boolits, do anything you like. It's not really going to matter at short range.

[felix]

Good advice! ... felix

[runfiverun]

anything groove diameter or somewhat larger will be adequate.
i use 358 in my 358 win
and 379 in my 375 win winchester and marlin375
i use 459 in my 45-70 but it slugs at 458.
i am not a fan of grossly oversized boolits.
but it seems marlins,and winchesters later 94's multi grooved bbls like them somewhat bigger.

[XTR]

I'm going to get a Lee .458 and make them all uniform, it will do a better job of crimping the gas checks on the GC boolits I have too.

[XTR]

I've got an 1885 that slugs at .456, I'm going to get a .458 Lee sizer. It will make everything uniform and it'll crimp the GC tight on my GC boolits.

[monge]

I have honed lee sizer with fine wet sandpaper to custom fit the boolits to my bore. Works great just keep checking size and go slow.

[stubshaft]

I've got an 1885 that slugs at .456, I'm going to get a .458 Lee sizer. It will make everything uniform and it'll crimp the GC tight on my GC boolits.

Make sure you measure a sized slug to insure that it is .458.