Call Remington at 1-800-243-9700 and order "Barrel Seal" They are heat resistant and last about
5,000 to 10,000 rounds depending on how hot you make the gun get from shooting
and cost a couple of dollars each
The nickel-dime hardware store rings will burn up and put caked residue in your gas system
Buy a few so you have them on hand, the shipping cost will be too high to buy them individually or, go to a shop speacializing in bearing assemblies; Detroit Ball Bearing, or something similar. I think you can get the same thing there.-Jerald
021 works for 12 Ga 1100 and SX-1s. I would bet a LOT of money that "barrel seals" are not made specifically for Rem and are, in fact, a standard chemical and heat resistant o-ring such as the Buna-N or Viton. I just bought 100 Vitons on-line and, incl shipping, they were about 14 cents each.