358-640 Gas Check – What size of gas check?

Hello,

I have been doing reloading for a while, but have been using pre-cast bullets.  I decided to use all the lead I had around, and make my own.  I am still learning the lay of the land on casting.  I see “gas check” and I think of those little aluminum or brass “gas checks” that get crimped onto the bottom of the bullet.  Although, I have also seen reference to a lube groove being called a gas check.

Looking at the drawing of the ‘358-640 Hollow point gas check’, it looks like it takes a crimp on gas check.  It appears that the crimp on gas check is smaller then the .358 diameter.  Does this take a .356 Gas check, or smaller?  I do not see any specifications which say what size of gas check to use.

Thank you