Slugged my bores….now what?

[fusil]

Hi guys,
I’ve slugged the bore of my revolvers and my semi auto. My revolvers are .357” and my semi is .356”. I used digital callipers as I don’t have a micrometer, is this accurate enough?
I’ve read you should have cast boolits .001”/.002” larger than bore size. The mold I was looking at is the Lee 358 RF 125gr.
Do I need to size at 358 if the cast boolit comes out the mold at 358?
I was going to buy a .356” Lee mold for my two 9mm’s, but they are .356” at the bore!
The other idea I had was to size the .358” RF down to .357 for the 9mm and use as cast for the revolvers.
Some please help as I’m beginning to annoy my wife (as usual) with all this talk of lead, molds and Alox!!!!!
fusil

[wiljen]

It is very difficult to get the kind of precision you need with a caliper. That said, lets assume you were pretty close. What did your revolvers cylinder throats measure? I would try to load a bullet as close to the cylinder throat size as will chamber. This may be quite a bit larger than the bore diameter, but will yield the best fit/results.

For the semi - size to .357 or .358 (if it will chamber).

[Cherokee]

If as cast idameter is 358, try that for the 357/38 loads w/o sizing. I guess you are using Lees lube if not sizing. Try loading a 358 bullet in the 9mm case too and see if that will chamber in your 9mm's (no primer/powder). If so, then load some for real to see how they shoot. Otherewise, size to 357 and try again. Depends upon how tight your 9mm chambers are.

[docone31]

I have the 150gn RF mold for my .357. It does drop at .358-.3585 depending on the alloy, and heat. I do size it at .358, even though it drops close to there. It evens up the lube, makes shiney lands.
For my 9mm, I size .357. So far, so good. I have a Star Modelo Super 9mm, not Largo. People have told me they are picky on useing only FMJ ammo. I have not found that to be so with my castings. I have not tried other jacketed profiles.
I must note, I have the TC120gn for my 9mm. It drops at .357 and I size it at .357.
A great performing casting.

[R.C. Hatter]

With respect to revolvers, you need to accurately measure the chamber diameter and make your bullets to that dimension. Don't worry about the bore fit in revolvers, when the big light hits the bullet, it WILL fit your bore. I doubt you can measure the chambers accurately enough with calipers, better to use a set of minus pin guages if you have them. If not, surely you can find a machinist who will measure them for you.

As to auto pistols, assuming you measured your bore slug accurately, you can size your bullets .001-.002" over groove diameter and be assured of a good gas seal with no gas cutting, which destroys accuracy. Use the larger diameter that will chamber OK when seated. You can make up dummy rounds for trial.