Sizing Die sizes

[Peter74]

Hi, Im New to this and I have heard around the place different things about the size of the dies. on one hand they tell me to get for a 9mm a .356 die and others are telling me to go one up and get the .357 die. and also for the .357 cal get a .358 sizing die.

So I thought i would ask people that are in the know, could you please steer me in the correct direction please. Thanking you in advance.

[VHoward]

Actually, you should slug the bore of the gun you will be casting bullets for. That would determine what size to size your bullets to. If the bore slugs to .355, then the .356 size die would be fine.
https://www.youtube.com/watch?v=KuNoo4m6jso
https://www.youtube.com/watch?v=qPHypjU5alQ
These 2 videos will show you what I mean about slugging you bore/barrel and how to do it. Whatever diameter the slug ends up being, you want to get a sizing die at least .001" larger. Some go up by as much as .002 to .0025 over the slug diameter. This way, when you fire the bullet down the barrel, it seals it up and along with the bullet lube, it prevents the horrible leading of the barrel that can happen from a bullet that is too small.

http://castboolits.gunloads.com/showthread.php?110213-From-Ingot-to-Target-A-Cast-Bullet-Guide-for-Handgunners
I suggest reading the free book linked to in that thread.

[EDG]

Recommendations assume that you have a standard groove diameter. That is basically theory.

Dies can vary just like groove diameters. More theory
Reality is measure your groove diameter with a slug and make sure your die, regardless of what size it is marked, sizes the bullet at least .001 larger than the groove diameter.

If you do not have calipers and a good 0-1 mike get them.

[Peter74]

Thanks Guys that makes much more sense. I will be doing that.

[runfiverun]

if your 9 mikes out to 355 I'd be more surprised than if it were 357.
there is a few 9's out there that don't like 358 but they are fairly far apart.
my Para, CZ, Norinco, Hi-point, and I forget the other one, all shoot 358 without a hitch.
but then again so do all of my 38/357/358 revolvers and rifles.