Consider building a "ramp" to the front of the magazine.
If you check out some of the Mauser conversions to .308 (or 7.62X51), they reduced the length of the mag follower and installed a "ramp" so the nose of the bullet does not free float too long. Go the full depth of the magazine.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)