Arrendondo M&P45 extension

[MCS]

So I decided on the full-size M&P 45, and want to try the Arrendondo extension. Looking on Midway, Brownells and Arrendondo's site I don't see different part numbers for the different sizes. I realize the 9mm/40 use the same kit, but don't see a different part number for the 45. My question is, do the 9/40/45 all share the same sleeve and base pad?

[andrewcdub]

Not 100% sure but I think they are different. You have to file down a ridge toward the bottom of the mag for it to work if i remember correctly. Honestly I would just go with the factory 14 round mags but to each their own.

[SteveL]

I had 5 (I think) Arredondo kits on some of my M&P9 mags for a while. They worked well enough and never caused any malfunctions. I didn't have to file anything for them to work. It's my understanding that the 9/.40 and the .45 do not use the same kit. Ultimately I ended up removing them, though, and going back to the factory springs and floor plates.

[andrewcdub]

With regards to the filing, I was talking about the .45 mags. At least that's what their website says needs to be done. That's pretty much the only reason I didn't go that route.

[MCS]

New .45 mags don't have the notch that needs to be filed down. I took apart a new M&P .45 mag and it did not have the little notch. I can't seem to find a different part number for the .45. From what it looks like on their site the .45 is not a kit, just a base plate.