Arredondo mag extension fix for M&P9

[jaxman7]

Reading previous posts and discussions about these magazine extensions have either been love or hate. The vast majority of it love. There have been a few who have complained about the base plates slipping off and creating a shower of rounds out of the mag well. This same thing happened to me twice at a handgun class earlier this year. We were doing tap-rack-bang drills and when I tapped the base both slipped off as the day progressed. Keep in mind that I insert my magazines hard and the same way with tap-rack drills. Thank goodness something told me to bring the stock baseplates that day. A couple of times that day the plates also shifted forward slightly causing the follower to tilt and bind. There is small discussion about this same problem on the M&P pistol boards.
http://mp-pistol.com/boards/index.php?showtopic=27808

Just forward clarification purposes I have the new followers, extra power spring that comes with the kit, and I have the L-shaped base plate and it is put in correctly. What was happening was that the tip of the baseplate (at least my two examples) is made of very thin plastic. Here is what happens after many tap-racks and mag inserts:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_135054.jpg
Apologies for the pics. They are from my phone.

As you can see it is very chewed up. The lip was not giving much support and therefore the extension could easily slide slightly forward or completely off. I really wanted to use these extensions so I came up with an idea to make my own metal baseplates. First thing I did was go to Home Depot or as I call it occasionally, the Gun Mod Depot and purchase some angle aluminum:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_135012.jpg
Then I used the dremmel to cut the aluminum to roughly the same shape as the platic plate:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_135034.jpg
I don't have a good picture for reference but the lower leading edge of the factory plate is tapered on both sides. Obviously the angle aluminum is not tapered where the two sides meet and I could not replicate this on my version without some fancy metal heating and bending. I made the decision to cut an angled notch at the joint of the aluminum:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_142252.jpg

Next I had to also taper the inside portion of the vertical side of the aluminum to match the taper of the plastic one, pretty straightforward.
My next thing was to find a way to make a loop for the bottom of the spring to attach to. I thought about drilling 2 small holes in the bottom and cutting and reshaping and old 1911 recoil spring I had lying around. This would work I am sure but I ended up cutting off the bottom piece of the factory baseplate and JB Welding it to the new one and it works well. I put 3 mags through it so far have not had any feeding problems and the extensions have not slid off yet with live fire or dry fire:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101118_114813.jpg
Its not pretty, and I'll polish off the burrs but that's pretty much the final product. Here are a few more pics.
Before:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_142439.jpg
After:
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_142422.jpg
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101115_142358.jpg
http://i907.photobucket.com/albums/ac279/jaxman7/IMG_20101118_125252.jpg

I'll run some rounds through it this weekend and do a follow up but like I said, so far so good. I may go back and do my original spring loop idea. If anyone has had this same problem here is a possible solution. Thanks,

-Jax

[Heidevolk]

I can't believe noone ever replied to this

[Hmac]

Good to know. I run several M&P mags with Arredondo's for courses and training. I haven't had one disintegrate yet, but this is an illuminating post. Thanks.

[jaxman7]

That's because the OP is an idiot. Just ignore him. ;)

-Jax

[SteveL]

Since this thread is a couple of months old I'm guessing you've run some rounds through by now. How did they perform?

I currently have 5 mags set up with Arredondo extension kits and I haven't had any problems at this point, but I'd like to know how your fix worked out in case I do.

[jaxman7]

Steve,

Since the mod I haven't had any issues with the pad coming off or sliding forward. I have had one mag (I did this mod to 2 base pads) fail to lock the slide back on two occassions using the same setup but that's the only issue so far. The aluminum plate has held up well.

-Jax

[SteveL]

Thanks for the update.

[jaxman7]

Your welcome.