How much over groove is ok

[MotelAlpha]

My as cast bullets are .615, and my barrel slugged reads .621x.615. I have pressed some into .622 to .624 as my accuracy at original casting .615 gave me poor accuracy. Do you believe these new larger one to be ok to shoot?
Thanks

[Old Dawg]

My experience with cast bullets is that as long as they chamber they are okay. Of course one should always work up the load from start using the large bullets.

[uscra112]

Size to fit the throat, and ignore groove diameter.

[MotelAlpha]

Ok, will be at the range this week, and give it a go...Thanks all!!

[runfiverun]

woa back it down a click.
you size over groove diameter not bore diameter.
bore diameter is for dead soft lead with black powder.

for smokeless you go over groove, the 622- 624 should be fine if you have them equally
622-24.

[MotelAlpha]

Those number are pretty much spot on, as I do not have a sizing die for them. If they were near .625 or over too much, I rolled them on my work bench until I was at the lower sizes. Completely uniform, well maybe not 360 degrees, but I was able to fit them into my cartridge without lead peeling.

[runfiverun]

now I'm interested in what you are shooting them in.
there ain't a lot of 621 diameter rifles out there.

[swheeler]

I'm curious too, rifled 20 ga?

[MotelAlpha]

Its a 10ga. SxS in.600 cal. conversion. I use 20gao Magtec brass shells slightly tapered. We call this a 600 express. shoot a 650 slug at 1350-1500 fps..a real interesting gun to shoot for sure.

[jonk]

While I agree with what has been said so far, sometimes you CAN go too fat. Just because it fits the throat nicely doesn't mean everything; case in point, I have a Steyr 8X56R that will chamber a bullet measuring .340 (the fattest my .338 mold drops, a chamber cast suggests it could take a .342), but the grooves on it past the very worn throat are .334". I run them through a standard .338 sizer and seat in neck turned brass, and they shoot a lot better than unsized .340s do.

[MotelAlpha]

I have tried many rounds in the as cast size (.615) but accuracy is not what I want, so this is why I am trying a larger more closely matching the upper bore dimensions. Hopefully this will get me closer in groups. These large double rifles are quite temperamental as far as powder, bullet weight and size. This is a continuing adventure for this round.

[runfiverun]

bore sized boolits only work when they are dead soft, sitting [mostly] in the bore to begin with, and are booted with a super fast powder [like black]