I recently acquired a A&K M249 Mk. II Para with a feeding issue.
The box mag adapter and any M4 mag I threw it would not feed, as they were not being held up far enough inside the magwell to keep the retainers pushed clear of the feed nipple. They would also wobble side-to-side badly.
To fix this, I modified Squen's M249 mag latch, as it had the same problem, to a lesser degree.
The mag catch protrusion has been made taller, moved back to seat the mag further in, and the pivot pin hole size reduced (3.8 to 3.2mm). This works great in my M249, feeding flawlessly now.
To kill the wobble, I printed this simple shim at 0.1mm layer height in ASA (you could use PETG or ABS, also) so it came out at 0.7mm thick and glued it to the right side of the magwell. Pictures show this location clearly.
Print this out of tough stuff only. PETG or CF-PETG at a very base minimum, preferably ASA or CF-ASA. CF-Nylon would likely be the best.
Keeping with Squen's contribution, I've included STEP files if you'd like to make your own changes.
| M249_Mag_Latch.STEP | 90.6KB | |
| M249_Mag_Latch.STL | 264.9KB | |
| M249_Mag_Slot_Shim.STEP | 14.2KB | |
| M249_Mag_Slot_Shim.STL | 684.0B |
