I've been working with the folks on the Yahoo CB-L and a fellow from Hornady on gas check fit. I've got 7mm and 22 molds where the gas checks don't fit the shank on the bullet.
Hornady now makes Lyman and RCBS checks, they're the only game in town.
I have the Hornady gas check drawing with dimensions. I'll send it to whoever wants it in .jpg.
If you have gas check fit problems, please tell me the mold #, bullet gas check shank diameter and gas check lot number. Maybe we can get this fixed. Somehow the checks got smaller over the years.
Thanks;
joe b.
Joe Brennan, joeb33050@yahoo.com

Joe - thanks for the prompt response!

I wonder if there are other manufacturers out there that could produce checks competitively that would be interested in doing so.

Joe, do you know if Hornady is making the Lyman checks to Hornady specs or to Lyman specs?

Well done Joe! Gas check fit is the difference between 3moa and 1 moa on full power loads.(Assuming everything else is right.) I made a tool to "spread" the checks like Col. Harrison(?) talked about. That fixed the problem but you have the correct answer! Fix the checks. I made my own .30 cal checks and they worked great. Email me if you would like pictures.hmh56@wabash.net

OK, who was making the dies to make gas checks out of soft drink can aluminum?

Ah! Found it: http://hanned.com/mrkIIPB.htm

Kind of pricey. I can buy a lot of Hornady gas checks for that.