Putting on gas checks tonight reminded me why I hate them. The new Lee 312-155 mold is dropping very large and you have to check them before you coat them. It doesn't help the bullets are coming out 0.3145" before coating. It seems its always too big or too small with Lee.
If Arsenal ever gets their web page working again I night get their version of this bullet. But a plain base.
I shared this quite a few years ago, and I don't really know why it hasn't caught on. I don't know if I've ever seen anyone else do it, and it's kind of ridiculous Lee hasn't done it themselves.
I've tried a number of solutions to oversized gas check shanks. A gas check expander is the commonly talked about solution, but those suck. I'm sorry NOE, but I would rather stick a fork in my eyeball, than expand gas checks one by one then force them off since they don't just fall off on that dumb expander set.
At least as of today, I have not encountered a mold that I could easily put a gas check on bare, but was tough when powder coated. For that to be the case, they would have to cast in that narrow .286" or .287" window. Any bigger, and you are forcing them on no matter what. Even .287" pushes on pretty hard if you get them started. Any smaller, and even with coating, they slip on with a gentle push. Of course we hope for an ideal world where all shanks are .283"ish diameter, plus or minus .001". We obviously don't live in that world. If you happen to have a mold that just barely makes it in that window, then maybe a gas check before coating can help. This is of course 30 caliber, other calibers would have different dimensions
I haven't been so lucky. My bad molds have all been beyond that. I don't know that I have ever had an undersized shank to where a copper gas check wouldn't crimp on tight. I've had a few that are oversized but quite a bit. I modified a tool to make the job easy. It's super easy to make, basically they are ready made.
They are called Lee Collet Crimp dies. All you do is find a cartridge that has a neck size about the gas check shank you want. These dies have quite a bit of adjustment, probably .010" each way, so it only has to be ballpark. For 30 caliber, I used a 243 WSSM. I would try a 308 one for a 35/38 caliber.
You could use these just as they are out of the box. To make it a little easier, all I did was cut some of the top off. You can't go fully flush with the collet, but leave maybe 3/16", now you can easily handle bullets. All it takes is an angle grinder. Just set the bullets on top, and pull the handle. You can adjust them to any size you want, bare, coated, anything. It doesn't get any easier.
