View Full Version : 9mm AR-15 upper

May 7, 2005, 01:01 PM
Me and a buddy where discussing the other day on how you convert an AR-15 to 9mm. Since I have no experience with a subgun/carbine M-16/AR-15, I figured I'd ask it here.
Are the 9mm uppers just like any other upper, in that all one has to do is slap it on the lower and be ready to go? Or do you have to make significant changes to the lower reciever?

May 8, 2005, 07:46 AM
I've been curious also. Once you convert it to a 9mm, can you just swap uppers and go back to .223? Could the same be done with a 45acp upper?

May 8, 2005, 07:59 AM
You can slap a pistol calibur upper on a standard lower, but in some cases you'll need to modify the hammer to accept both rifle and pistol cartridges.

You will also need a mag well block for the magazines, unless the magazines have been altered to fit in the mag well and lock up with the mag catch.

May 8, 2005, 12:04 PM
Just bought an RRA AR-15, and their website. www.rockriverarms.com, contains a short snippet of what you need to purchase to convert their rifles to 9mm.

Greenfurniture has the bulk of it, I don't remember the specifics.

May 8, 2005, 01:26 PM
Or you could just buy a 9mm dedicated AR...now me, Ive got this dark hiding place in the back of the finished guns waiting to be picked up room where one of those Coltwemakeemonceayear9mmAR15s is gonna hide for a bit for me to take home.....


August 20, 2005, 01:46 PM
here you go. if you want to just drop in a 9m.m. upper it must have a ramped bolt or you will wear out the lower or crack it. look at a M16 carrier next to a 9m.m. bolt (the hammer contact area is different). colt 9m.m. hammers are different for this reason. also your last round hold open won't work in a drop in. if you change bolt stops your magwell spacer can't be removed. i run an A.A.C. rate reducing buffer because it works with both systems! now the mag issue: colts 32 rd. are pricey, promag 32's are FAIRLY dependable, the uzi mag conversions wont fit all aftermarket spacers. and the 9m.m. systems are colt or oly. so the mags are also different. yes i have had to deal with these problems. go to AR15 .com forums this is covered nicely. your pal OTTO :confused:

August 21, 2005, 03:49 PM
you know its more dangerous to post where your hiding spots are now that i work for ya, right? i mean, the next time someone comes in asking for something cool, i'll know right where to go!

August 21, 2005, 07:41 PM
Bet there is an Colt M4 in there :D