RE: which remington semi?
The Remington semi autos essentially beat them selves up simplly by shooting them. Some of this has been rectified with the newer models but it has not been eleminated all together. The rotating lugs will continue to rotate as the bolt reaches its rearward most point in the receiver thus beating themselves into the frame rails. Over time, if you shoot it enough they could beat up the frame rails bad enough to render the gun useless.
If you want a semi auto rifle get a BAR. Personally I won't own a semi auto rifle. They are much more prone to jamming than a bolt and they are succeptable to the bolt sticking in extreme cold weather.
Buy a bolt action and save yourself some possible headaches.