Best gas check shank size for 7.62 & 303 Fat 30-cal boolits size range 0.314"-0.317"?

[turbo1889]

If one where having a custom mold cut for such guns which size is the better choice and why:

0.284"-0.286" diameter shank to accept 30-cal size gas checks
0.301"-0.303" diameter shank to accept 32-cal size gas checks

One seems too small and the other too big so which way to jump?

[buyobuyo]

The one factory mold that I know of in that size (Lyman 314299) uses a 30 cal GC.

[Calamity Jake]

30 cal All the way

32/8MM gas checks are .335-.336 on the OD, that's a lot to try to size down to .313-314,
although I have done it to try an 8MM boolit in a warn out mosine, taken it down to .315.
The push thru boolit sizer rolled a burr at the bottom of the GC, that caused some seating issues until removed.

[Shiloh]

The .301-.303 will be too big. I think you will have seated checks that will be crooked when sized to fat .30 sizes of .312-.315.

Shiloh

[turbo1889]

Looks like the solution Ranch Dog came up with was to use a gently tapered gas check shank to open up a 30-cal check:

http://www.ranchdogmolds.com/store/bin/TLC313115RF/bullet/sketch.jpg

I suppose the trick with doing it that way would be making sure the taper is a gentle enough so that the check expands and you don't shave lead or bind up the check and get it off center or crooked.