SAR K2 45 Failing to Lock Slide After Last Round

[directdrill]

While at the range this weekend,  my SAR K245 failed to lock the slide back on an empty magazine. My K245 has about 750 rounds through it.  I was using factory original magazines, and only one of the five would lock the slide back. Any suggestions?

[jwc007]

Czech the Slide Stop Pin and make sure that the Slide Stop Pin Extension properly engages the Magazine Follower shelf.

Disassemble and Clean Magazines.

Check Magazine Spring Strength and if necessary replace with Wolff +10% Strength ParaOrdnance P14 Magazine Springs.
Note, I've not yet had to do the latter, at least not yet.  In general, .45's are particularly hard on Magazine Springs, regardless of Pistol Type or make..