I never heard of that and my 100 ATR never came with any papers stating such a guarantee, so I wouldn't bet on it. As someone mentioned the Marlin XS7 will be available in .243, but from what I've heard they are just getting their long action production to finally meet demand so it may be tough to come buy unless you find someone taking oreders right now. My Mossberg shoots great, I can touch 2 out of 3 holes at 100 yards. I have never done that before. Is it the gun or did I just learn to shoot better ?? I don't know, but obviously the gun is pretty accurate. I am not trying to sell the Mossberg I feel it's kinda spliting hairs. Go with price and personal comfort and you can't go wrong. I agree with Stalkingbear, that a 7mm08 would be a great option to the .243 also.