Cast bullet size

[Peter]

I just bought a Kimber 1911 Custom II, 10mm, I'm  planning on shooting PC'd cast bullets. My question is what size mold should I get. I did a chamber cast and it came out at .403, if I go the 1 or more thousandth over that, will that be to large. It just seems over sized since everything I've read about 10mm's is they are .401 - .402. I'm assuming that's for jacketed bullets so .405 +/- seems big. Any help will be greatly appreciated. I've never cast bullets for a semi - auto. Lots of other types but not a semi. New to this site but glad I signed up. Thanks. Peter

[The_Shadow]

Hello Peter and welcome to the forum!  Many of the 1911 barrel bores are 0.3990"  so 0.4010" - 0.4015" would be good.  Tighter chambers may not like much larger bullets as loaded.
However some Glock barrels work better with 0.4015" - 0.4020"...

Best regards!  Enjoy the forum!

[Sailormilan2]

My 10mm barrels(I have 4 by the same manufacturer) slug at .4007" and I size to .402". I don't believe I can go much bigger without affecting reliability. But. .402" seems to work very well. 
I think that you'd be better off tapping a bullet down the bore to measure the size than using a chamber cast.

Peter, PM sent.

[gnappi]

What diameter bullets worked in your barrels you want to PC for? There's your answer.

That said, your bigger issue / questions are what sizing die diameter should you get, and will you size the bullet first and powder coat, or powder coat then size. I tried both and now PC unsized then size to finished diameter.

Oh, FYI, you can get custom shorter sizing dies (for Star sizers, other brands I am not sure of) rather inexpensively made without lube holes specifically designed for sizing powder coated bullets.

[CtYankee]

You cast the chamber, for bullet size you want the barrel (or with revolvers, the cylinder throat). Lead bullets should be .001-.002 larger than the barrel. Most casters have .401" for their standard sizing, that works for me.

[Jayjay1]

You cast the chamber, for bullet size you want the barrel (or with revolvers, the cylinder throat). Lead bullets should be .001-.002 larger than the barrel.

There you go!
You must slugg your barrel, there are some vidoes on youtube showing it and it is easy to be done.

Then you add .0015 or .002 to the measured dia of your slug, that´s the dia you want for your bullet.

Barrel dias are very different even with the exact same gun model.
You must find your own and can´t overtake others.

The bullets always have to be bigger as the barrel, because otherwise they would slip over the twist, get damaged, lose accuracy and will lead your barrel immediately.

No magic, simple physics.