by Jim in Houston » Sun Dec 22, 2019 7:24 pm
The angle of the round between the lips of the mag have been a problem for others in the past. Since the second and subsequent rounds load properly, it may be that they are positioned differently from the first round due to the recoil and "jolt", when the first round is fired pushing the second round up at a slightly different angle.
If you anticipate the problem again, take an image of the loaded mag with the first round in position. Then pull the mag after you fire it and take an image of the second round in the mag. The difference, if any, may not be very noticeable.
As an alternative, before putting the loaded mag into the rifle, give it a firm tap on the bottom against the shooting bench to make sure the first round is firmly in the mag lips. Also, use the bolt release and allow the bolt to slam home. I do this routinely on my 5.56 AR.
Life Member, Texas State Rifle Association; Patron LIfe Member, NRA