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4/6/2011 6:10:39 PM EDT
I got a used Mac 10/9 yesterday. I slugged the barrel and it came out to .3565".



I size my 9 bullets to .356. I fired 10 shots and got leading , no shocker there.



So I should size new bullets to .357?



If I do size to 357, should I expect trouble with tighter barrels that are .355 like my AR??



Or is the answer size and load for each gun?





Thanks

4/6/2011 6:29:16 PM EDT
[#1]
Try taking a sized case and put a good bell on its mouth (don't prime it).
Then get it it your chamber, either by the bolt or push it. Use a piece of
dowel or cleaning rod to push the case out. Measure case mouth and you should
have an idea of how big of a bullet you can go.
4/6/2011 6:45:58 PM EDT
[#2]
I would size to .357", load a few test rounds, and find out. The only issue you may run into is that the diameter of a loaded cartridge may end up being too big with a .357"+ bullet. The .357" bullet itself will not pose a problem at all.
4/6/2011 7:02:59 PM EDT
[#3]
Quoted:
I would size to .357", load a few test rounds, and find out. The only issue you may run into is that the diameter of a loaded cartridge may end up being too big with a .357"+ bullet. The .357" bullet itself will not pose a problem at all.


agreed
but because that's just too easy....

The "best" solution for minimum group size and maximum performance would be a different load, and probably even a different bullet, for each application.  Practically speaking, the above posters probably have the answers correct.
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