PMAGs not locking bolt open...figured out why
I've had random issue of my 30rd PMAGs not locking the bolt open on the last round. I was chalking it up to possibly the WOLF ammo just not always providing enough gas pressure until last weekend.
I was at the range and the first mag of the day didn't lock open, so I marked the mag. Went on to the next mag and it did lock open...same lot of wolf ammo. Then I loaded the first mag with some 5.56 and again it did not lock open.
When I got back to the table I compared this mag with the one that did lock open and the difference was immediately obvious....the follower was not coming up as far on the mag that did not lock open.
Didn't see anything blocking the movement so I pulled them apart and found two different follower designs, one with a shallower channel for the follower stop.
Pics:
Left is the one that did not lock open, right is the one that did.
http://farm7.static.flickr.com/6186/...c9dea13b_b.jpg
http://farm7.static.flickr.com/6171/...85c9c99e_b.jpg
http://farm7.static.flickr.com/6061/...543df9a2_b.jpg
The mags that have the shallower stop channel do not always fail to lock the bolt open, but it happens often. When I got home I emptied all my mags and checked them. I have 12 standard 30rd PMAGs and one windowed. 6 of the standards and the windowed have this shallow channel follower.
All of the mags with the issue are marked M7 and M8, W2 for the windowed. The others are mostly M3 and M4, but there is one M8 that is OK. All of the mags appear to have been made in various months of 2009.
I've emailed MAGPUL but haven't gotten a reply yet.
Just thought I would post my findings for any others who might be having problems PMAGs not locking the bolt open...may want to have a look at the follower.
I found one thread from last year with a similar comparison, but the posters issues were related to FTF malfunctions. None of these mags have caused any malfunction other than failing to lock the bolt open.