View Full Version : S&W M&P slide lock

August 5, 2006, 11:25 AM
My friend's new M&P .40 keeps locking the slide back with one round still in the magazine. I'd like to look like a hero and tell him what the problem is, but I can't see what's causing it. The mag looks fine to me, but my old eyes don't see what activates the slide catch.

Can U help? Many thanks.

August 6, 2006, 03:06 AM
Is it the magazine that came with the gun? If it's a aftermarket it may need a little tweaking.

This may sound dumb but I thought the M&P was a revolver? I still got a lot to learn;)

August 6, 2006, 11:28 PM
The slide stop should be activated by the follower on the magazine. ( I don't know if that was a question or not.) The slide stop may be the problem or the follower may be defective in the way it holds the last round and pushes it against the slide stop.

You might call S&W and ask them, they may be familiar with the situation.

August 12, 2006, 08:11 AM
Does it occur with different bullet weights?

August 12, 2006, 08:59 AM
Only one bullet and bullet weight was used on the occasions when I observed the problem. Some additional efforts: it occurred with both provided magazines, and, it only happens when shooting, not when cycling by hand.

My pal called S&W and was told " Hmmm, that could be frustrating". He's sending it back. I'm more of a fixer and always want to learn the solution to a new problem. My guess was maybe a weak spring on the latch, but that still doesn't tell me why it happens with one round left. Why not with two?

Many thanks

August 12, 2006, 09:19 AM
It is possible that bullet shape can affect slide stop, hence 'last rd only'.......

(Didn't Wilson have this problem with some of his 45s? I seem to remember somebody big-name having it....)

August 12, 2006, 10:19 AM
Great idea about trying different bullet. The ones he's using are flat nose fmj types which are not that typical. I'll suggest he try with another bullet. That will be instructive, but I would expect it to work with all factory and most handloads. Target guns are different, but my philosophy has been that if I can't get my autoloader to be 100% reliable I'll use a revolver (for defense that is). I know that rules out a whole lot of autoloaders and don't mean to offend auto fans. I like them too.

September 9, 2006, 08:32 AM
the follower touches the slide lock on the inside. I'm betting there is a burr on the metal causing this.