Rem 700 BDL in 300 WM w/ floor plate. All of a sudden quit holding rounds in the mag. The first just pops back out of the mag. If I hold the one and get the second in it'll stay but the 3rd will not. Tried several pieces of different brass also. Is this a trip to the smith or could it be something simple? Gun is only 3-4 yrs old and kept clean.