Fine tuning Tapco polymer magazines.
Once you are sure that the mag is fitting into your stock without binding and it is still cramming shells up against the end of the barrel, you may have to change the feed angle of the magazine lips to elevate the round.
The widest point of the chamber hole is where you want the bullet point to hit. This has the best chance of going into the chamber without jamming.
Elevating the entry angle keeps the bullet off the 8 to 4 area.
The curved feed lips of the mag will also slightly angle the round toward the chamber centerline if the angle is tipped up a little.
Up and in is what you want.
If your mag jams when full, try it with 10 rounds, then just 2 or 3 rounds. Some just don't want to work well when full. Some may feed from the left stack, some from the right. Only fix what is broke. Stretching doesn't do any good. No matter what all those emails say.
Start with just a couple rounds in the mag and some 400 to 600 emery paper. Take just a little material from the front of the lip at a time. Slide the emery paper fore and aft with the bullet in place. You want to concentrate on the forward half of the lip but you want to end up with a smooth taper.
Clean up the area and try to manually feed the rounds.
I TAKE THE TRIGGER GROUP OUT, REMOVE THE HAMMER AND SPRING, THEN PUT THE TRIGGER GROUP BACK IN WHEN PLAYING WITH LIVE ROUNDS. ALWAYS POINT THE MUZZLE IN A SAFE DIRECTION.
Let the bolt fly and see if there is any improvement, noting which side works best.
This has fixed the feeding issues on every one I have tried.
I also spray a little dry lube inside the mags to help.
This is where to sand.



You can see how little material was removed.

After sanding, the round heads straight for the chamber. Even a Hollow Point.
