lee 390 150 flat

[thumb bum]

Want to shoot them as cast they drop at .3115 to .312 perfect win 94 slugs at .310. Can I run them through a .314 lee sizer to seat the gas check or is that to big?

[Texas Tinker]

I've tried using the .314 Lee sizer before, but it left the gas checks loose. So I ended up taking a .311 sizer and honing it out slightly. My end result is .312 bullets with a snug fitting gas check.

[fcvan]

Yes, your rifle will be fine. Another member here tested oversized boolits with I believe an Oehler 35P and pressure testing. If my search-foo was black belt level I would provide the link. In a nutshell, a boolit is resized to bore diameter within the first inch or bore travel but before peak pressure is reached in a rifle with slower powders. The test ran with a boolit 1 thou, 2 thou, 3 thou and then 4 thou over bore diameter. Pressures did not seem affected but accuracy did at 4 thou due to the greater deformation occurring under pressure in the bore. That being said . . .

If you seat your boolit with a .314 check and a .3115 ish boolit, your case neck may not have proper tension on your boolit. I suggest you pick up a Lee .311 push through sizer to finish off your sizing. I have that same mold (C309-150 F) and seat my own checks (made with a CheckMaker die). I seat/size to .311 for my 30 cal rifles with great success.

[ShooterAZ]

I just got that same mold and mine casts the same as yours. I size mine to .311 with my RCBS LAM2. If you are going to use a LEE sizer, Midway has the .311 on sale right now. I size all 30 Cal to .311 also. Works perfect in my Win 94 with Hornady 30 cal gas checks.

[thumb bum]

thanks for the replies. that's what I was wondering if the gas check was going to be OK size that big. I have a 309 lee sizer I might try to open that one up.

[ShooterAZ]

It's not hard to open them up. I used a tight fitting dowel with some fine emery cloth. A few drops of oil helped. Some guys use a drill, I did it by hand. Just go slowly and measure often.