FTF with my MR1 using RRA LAR15 mag but not using G2 PMAG ... suggestions?

[Tikka223]

I was at the range today sighting in my new-to-me MR1 and noticed that when using the RRA LAR15 mag that I had on hand I was having frequent FTFs. The round seems to pop out of the mag too quickly, then get carried forward by the bolt causing the tip of the bullet to get hung up on the top of the receiver / barrel / chamber, and thus causing a FTF and damage to the bullet. I had no issues whatsoever with PMAGs. Has anyone else encountered this problem? Any suggestions? The same RRA LAR15 mag runs just fine in my AR.

I tried to replicate the problem to post a picture:

 

[Tikka223]

When this was happening at the range the round was jammed in a much more diagonal way with the tip of the bullet at the top of the receiver and the base still down by the magazine.

 

[Tikka223]

Almost forgot, anyone see anything physically wrong with the mag?

 

[Silveragent]

It's common to file down the edge between the lips so that the top round can no longer touch contact it.