Sizing Dies

[chas8008]

I have been shooting for 15 years, reloading for 2 years.

I have been Picking up WW here and there. I have about 400lbs:bigsmyl2:

The time has come when I need to start casting.

I sluged one of my 9mm barrels and got .355 land to land, and .350 grove to grove.

I believe I would need a sizer larger. But how much? 1/1000th 2/1000th?

I think I need a .357 sizer. But I would like to be sure.


Thanks

[docone31]

I use a lee Push Thru at .358 . You might get the .357, and if it is too loose, hone it to .358.
I use the same one with my .357 with great results also. The .357 casting is definately tighter in the sizer, and it does real well.

[AZ-Stew]

Chaz,

First, the groove diameter of a barrel is always greater than the bore diameter. The bore is drilled, then the grooves are cut, swaged or hammer forged into existence, with the bore diameter as the starting point.

When you measure your slug, the grooves in the slug represent the lands in the bore (bore diameter).

For our purposes, the groove diameter of the barrel (the largest diameter of the slug) is the diameter we want to deal with. It is what controls the seal made by the boolit in the bore. If the boolit is too small in diameter to seal the groove diameter of the barrel, gas blow-by will occur, resulting in leading.

Only your gun can tell you whether .001 or .002 inch larger than the barrel's groove diameter will shoot best. In addition, you can't always rely on the number stamped on the sizing die to be precise. To measure the die correctly you'll need a set of plug gages and you'll need to completely clean all oil/grease from the die and plug gage. The mere existence of finger prints on the surface of micrometer anvil tips will offset the measurement by .0001-.0002, so keep this in mind.

Now, you may not have to go through all these gymnastics. Size up some boolits you've cast, load and shoot them. If you don't get the results you want, try a different size lube/sizer die. You might even want to try some that are cast and lubed without sizing. You'll eventually find the sweet spot.

Regards,

Stew

[RayinNH]

We size to .357 for my son's Springfield XD...Ray