Slide locks back with round in magazine

[scattershot]

I have a M&P40c (Mod1). Lately I have noticed that the slide locks back With the last round still in the magazine. Any suggestions? By the way, this pistol rides in my truck and doesn't get shot much. Could having the mag loaded weaken the spring and cause that?

 

[Execpro]

Never heard that one before! Usually a weak spring will NOT lock the slide back. Option 1: I suggest with limited info, that you take the gun/mag down and give them both a GOOD cleaning/lube where appropriate. Put in NEW ammo and shoot it again.
Option 2: Stay tuned until someone far smarter than me comes along with different options/suggestions/answers.

Be SAFE and Shoot Often!

 

[Funflyer]

What ammo are you using in it? Could be the mag spring is weak enough to let the round move forward just enough so the bullet makes contact with the slide stop.

 

[merl67]

I had a Taurus TCP 380 that would intermittently do this with a loaded mag it was random might be 6 rounds in the mag might be two. The slide lock protruded into the gun just a bit too much, and a round coming up would occasionally hit it locking the slide back. A little file work on the stop cured it

 

[s2harry]

Make sure the bullet is not hitting the slide lock on the inside of the slide. Maybe youcan file the lock off a bit or use pointy bullets. Taking to a gunsmith is better than asking questions on here...

 

[jake1945]

I had that happen with my 1911 45acp. I was shooting reloads and occasionally the slide would lock open. Cause was bullet was not seated deep enough and tripped the slide lock. Seating the bullets a bit deeper was the fix.

 

[RobzGuns]

Springs usually don't weaken from lack of use. Repeated use is what weakens springs.

A majority of the time that your situation occurs (as well as the slide NOT staying open after the last shot), one of the shooter's thumbs is nudging against the slide lock lever. When shooting, it doesn't take much force to nudge the lever up (or down)

Everyone swears that their thumbs are nowhere near the lever, but the next time this happens, **Freeze** and without moving your hands, check your grip. You may find that one of your thumbs is against the lever. Been there... Done that!

 

[scattershot]

Thanks for the insight, guys. Factory Federal hollowpoints live in this gun, but I was shooting some handloads, too. The inadvertent pressure on the slide stop lever may be the culprit, I’ll check that next time out, thanks.