This concern about fully loading a magazine applies to any magazine fed weapon.
The top round in the magazine is touching the bottom of the bolt, if the bolt is closed. This makes fully seating the magazine more difficult.
That being said, it is more of an issue for some weapons. On an M14, it would be less of an issue than it would be on an M16. The M16 locks up like most semi-auto handgun magazines lock up with a cut out in the mag body. That cut out has to be aligned with the magazine catch. The M14 locks with a lug on the back of the mag. The M16 mag also is pushing straight into the mag well and the M14 mag is sort of rocked into postion.
The top round in the magazine is touching the bottom of the bolt, if the bolt is closed. This makes fully seating the magazine more difficult.
That being said, it is more of an issue for some weapons. On an M14, it would be less of an issue than it would be on an M16. The M16 locks up like most semi-auto handgun magazines lock up with a cut out in the mag body. That cut out has to be aligned with the magazine catch. The M14 locks with a lug on the back of the mag. The M16 mag also is pushing straight into the mag well and the M14 mag is sort of rocked into postion.