Exactly right. The 4-H club was using O-rings from a local hardware store tray assortment in Rem. 1100's when I got there. The shotguns worked with new O-rings but the O-rings crapped out pretty quickly. Switched to the proper high temp rings (Brownell's). Between that and keeping where the rings seat free of carbon buildup the rings last a long time. It's trap shooting and I'll replace an O-ring every year or two depending on use. Eventually the heat will rob them of their elasticity. The rings are of a high temperature elastomer of some type, there are several, with Teflon.
