I have a used mod 788 remington. The clip fits loose and will not fit up tight in the magazine well. I have to hold it up into the gun for the bolt to pick up the round.
The clip seems to be good, is theere a spring or some thing missing?

Can you post pics of the magazine?

Are you sure that the lips or ribs on the rear of the magazine are engaging the rail at the rear of the magazine slot. The magazine must click into place to feed properly, but I have never seen one that didn't feed perfectly - and I have about a dozen or so.

Is the magazine guide bar present (part #23 in the Remington 788 schematic)? If it is, it may need to be tweaked to hold the magazine in position. It is made of sheet metal and is easy to bend.