I recently acquired a Remington 742 30.06. The rifle came with a scope, sling and a factory 4 round mag. The mag it came with slides perfectly into place and locks in right in every time. While on a trip to the Kittery Trading Post, I decided to purchase a second magazine which was aftermarket. This magazine was made to accept a few different calibers of ammo, and has a difficult time sliding in and won't fully lock into place. So, I decided to purchase an original 30.06 magazine, identical to the one that came with the rifle. This too has a difficult time sliding in and won't fully lock into place. I stripped the rifle down, cleaned and oiled it, and inspected the innards for signs of wear. I also compared the two factory magazines and they look identical. After reassembling the rifle, I am still having the same problem. Any suggestions?