Chris - have had them for many, many years - so might be able to shed some light. Mine are the originals from Harry Owen (Sports Specialties - CA) made decades ago from actual rifle barrels and brass stock - and I also bought some of his final inventory when he passed. A couple of companies later, and its MCA that makes them now up in Alaska. I think Harry's were better, but its pretty much a hit or miss thing as far as how well they really shoot. Some barrels shoot them well - others just the opposite. I've had/have 22 Pellet in 22 Hornet and 22-250; 22LR in 22 Hornet, 221FB, 222, 223, 22-250, 220 Swift; 22MAG in 222, 223, 22-250; 22 Hornet in 22-250, 220 Swift and way back when several for the semi-auto pistol calibers and a few for 308 and 30-06, probably a lot others way back I don't remember or didn't use. Many were made just for the Contender - others for most other firearms using a transfer piston. All actually work in the Contender/Encore - some in most other weapons - all a pain to reload except those for the Contender. Out of all of them, the ones shooting 22LR that seemed to do the best in almost any firearm used in were the 222 adapters. The 22 Hornet/22-250 is very accurate in my High Wall. Over the years I gave away or sold most of the extras - then the ones I was keeping for my collection but never used myself to where I am down to only a few now from about 200 of them I had at one time. Bottom line - are they worth the price of addmission? Not in my opinion, but then only bug holes interest me at the ranges I shoot diggers at. HTH - Larry