Although I have several of the older 300-series guns (and I like them), I haven't used them as much as a 391. The problem you describe is common with a 391, and I can only assume it is also common with the older models. I haven't had that problem with an older model, but that is probably because I learned how to avoid it with the 391.
In the 391, it is often caused by putting the bolt into the receiver at a slight angle, rotated just slightly to the shooter's right side (i.e., clockwise). In that case, the bolt will go back about 1/2", compressing the recoil spring a little bit, before it stops. The solution is to take the bolt out, rotate it slightly counter-clockwise (as seen by the shooter) and put it back in.
Another possible cause, which would make the bolt stop as soon as it enters the receiver, is that the end of the connecting rod is not in the cup on the end of the recoil spring. It is a lot easier to get the rod in the proper position if you have the trigger group out of the gun when you put the bolt back in.
That discusses the 391 only, but the older models are very similar.