Hello all, quick questions I hope you can all answer... I was looking to buy some more mags for my M&P 40C yesterday and saw something that says you can use the full size mags in the compact frame? Can someone confirm this?
I also saw a grip extender for it, to make it appear smooth and protect the mag, would this be required on each mag, or could it be attached to the grip. Has anyone ran a full size mag in a compact with or without this piece?

Yes, you can use full sized magazines in your compact. They'll just hang out the bottom of the magazine well.



The spacers from places like X-Grip are designed to fill that gap between the bottom of the magwell and the baseplate of the full sized magazine. They're installed on each magazine individually, not fitted to the handgun's grip.

I have one of those sleeves for a P320 Carry 17 round mag in my P320 Compact 15 round gun. It affords for a nicer purchase on the grip. Around $6-7.00 from Midway. Since I only have the 1 mag, I glued mine in place, but if I had more than 1 mag, I wouldn't go the glue route again.

Just be aware if you use the full-size mags without A filler sleeve, you can bend the feed lips If you seat it with too much force.

I have been using the full size magazines in my compact for years now

As long as you are not carrying the compact as a backup to the full size M&P, the X-grip sleeves work great

When I carried a C as an issued gun I carried full size mags as spares. I didn't bother with spacers because I have no class. Just having the mag hanging out didn't interfere with my grip at all.