The 742 and 740 wear out such that they actually jam open. I had a 742 that I used for target shooting in the 1970s and sent it back to Remington with this problem. They fixed it and sent a statement that it was near the end of its useful life. I had 2,500-3,000 rounds through it, but have no idea how many the original owner had shot, but suspect it was not a lot as he was a typical hunter that perhaps shot 3 boxes a year in prep for the season. The newer 7400 (I own a Carbine in .30-06) should be more durable by virtue of its design. I have about 500 rounds through mine and no problems. The magazines seem to suddenly fail, but this is remedied by a new one. I have seen some hunters complain of the trigger mechanism wearing out such that the magazines are not held properly in the firearm. The entire trigger guard assembly is a pot metal that certainly could wear faster than steel and allow tolerances to get out of spec, but I have not experienced this in mine or any I've owned. As far as I know, those are the main serious complaints besides those related to accuracy (and one sees those for any rifle). The seller should be willing to field strip the rifle for you and allow you to check the gas mechanism for wear and rust. I would take dummy rounds and try cycling the action by hand to insure that the magazine and its locking mechanism work. Usually, failures here are indicative of problems that will be expensive to fix. My 742 cycled by hand yet failed to function under the rigors of true cartridge recoil.
