While visiting TOS, I read several posts regarding a potential problem with the LMT MWS and the 20 round PMAG. The skinny from Magpul is here.....
The issue of concern is that the right rear portion of the spine of the PMAG could push the bolt catch up ever so slightly so as to rub against the BCG during cycling. I looked over my inventory of 20 round PMAGs and found a mark on the magazine here......
The slight wear mark is where contact with the bolt catch is occuring.
After breaking the rifle down and using the lower only to see what was happening I decided to make a small modification to my PMAGs.
I used a low powered, low speed "dremel" type drill with a grinder bit on it. I would NOT recommend a high speed dremel as this may shave off more material than is necessary. A file or a scapel would work as well. I shaved off a small amount of material and checked my work as I progressed. I disassembled my PMAGs and used the mag bodies with the lower to measure my work.
The finished modification is here.......
A small "shelf" was created and this was enough to prevent the magazine contacting the bolt catch. It works very well now.
Some of you may or may not be having this problem. My magazines are marked 04/09 and 03/09 and did cause the problem.
I believe newer Magpul PMAGs have addressed this issue and are GTG.
I hope this helps LMT MWS owners whom use the wonderful PMAGs.