[jeri534]

I have an M&P 9, and for some reason I can load 18 rounds into my 17 round magazine, has anyone else noticed this?

 

[PatM&P]

i cant remember if it was in the owners manual or on here...but that is not recommended

 

[jeri534]

yea I wouldnt do it, it just seems odd, I wonder if it would fail to feed with 18 in there

 

[YukonGlocker]

I doubt it would fail to feed; but it might weaken the spring from over compression.