Background: I have a new M&P FCP (9mm folding carbine) which came with two 23 round magazines and one 17 round magazine. After a short break-in (200 rounds), when using the 23 round magazines the bolt would intermittently lock open in the middle of a loaded magazine. I also purchased a third 23 round magazine thinking there were issues with the two delivered with the FCP, but it did the same thing bolt log in the middle of shooting. The 17 round magazine delivered with the FCP, worked without any issues, and all did lock the bolt open on the last round as normal. Investigating the issue, I open both the 17 round and 23 round magazines and compared and noted the followers on the 23 round magazines where NOT attached to the magazine spring, just rested on the top of the spring, however the 17-round magazine the follower was attached to the spring. Normally followers are attached, so I modified the 23 round magazine springs to enable attachment the same as 17 round magazine and ran several live fire tests. The Bolt Lock issue did not occur, all three 23 round magazines tested worked without issue; problem solved.
This issue maybe unique to the M&P FCP (9mm) folding carbine since I haven't seen any pistol complaints with this 23-round magazine.
Just wanted to make other FCP/ 23 Magazine owners aware if they experience the same problem.
This issue maybe unique to the M&P FCP (9mm) folding carbine since I haven't seen any pistol complaints with this 23-round magazine.
Just wanted to make other FCP/ 23 Magazine owners aware if they experience the same problem.
