Just a tip.....
From what I've read regarding gaschecks lately, Hornady produces them for just about everyone now.
Lyman included.
So if you're gonna buy them, just look for the cheapest price. 99% sure you'll be getting Hornady's now matter where you buy.
Lyman's old style (designed to fall off in flight) were dismal sellers, and accuracy was usually the same, dismal. They were distinguishable by their different, brass colored appearance, rather than the nice copper color.
Take care,
Bob