9mm AR upper on a Colt lower

[vf111]

I am looking into finally building up a 9mm AR and am seriously considering using my registered Colt lower. I know I need to change out the hammer to either a DPMS or a 9mm specific hammer (RRA probably since that's what seems available). However, I recall reading that Colt uses different pin sizes than everyone else - does this create an issue w/ the hammer? TIA.

[studiojon]

I use the DPMS hammer so I can change out my uppers. I run .22, 556 and 9mm on the same lower, you can order them at garrisonmfginc or various plces on the net.. not sure about the pin holes but you can search over at ar15.com and I recomend the KNS pins cause 9mm can be a lil rough on the trigger and hammer pins or stock up on extra OLL so you dont have to worry bout wear. I hope this helps a lil

J.


Oh ya you might wanna get your 9mm carrier ramped its about 55 bucks but makes the 9mm run smoother

[redcliff]

Supposedly a ramped 9mm bolt allows you to use stock AR15 hammers in a RRA conversion so swapping between calibers is easy. It also is supposed to drastically reduce the stress 9mm conversions can cause on the hammer pin hole in the receiver. This is the route Im taking with my registerred AR15 sp1. Im also adding the heavier 9mm buffer, which supposedly works fine in 5.56 also. All my parts arent in yet, so I can't tell you for sure how this will work out.

Given that your registerred AW receiver is irreplaceable at this time, the ramped bolt sounds like the way to go, but perhaps someone with more experience can add more information.

[vf111]

Given that your registerred AW receiver is irreplaceable at this time, the ramped bolt sounds like the way to go, but perhaps someone with more experience can add more information.

I was thinking the same thing and may go w/ a buttet button/ fixed mag build on an OLL. I just have this stack of Sten mags stocked up (loved the Sten ever since I first saw "A Bridge Too Far") I was hoping to use with an Olympic upper and the reg'd Colt will let me go w/ detachable mags.

To change gears, anyone have a 45ACP AR upper? Are all the changes the same as 9mm (buffer, spring, hammer, etc.)?

[Bladewurk]

for 45 acp need a Cavarms lower and greasegun mags....

[redcliff]

I was thinking the same thing and may go w/ a buttet button/ fixed mag build on an OLL. I just have this stack of Sten mags stocked up (loved the Sten ever since I first saw "A Bridge Too Far") I was hoping to use with an Olympic upper and the reg'd Colt will let me go w/ detachable mags.

To change gears, anyone have a 45ACP AR upper? Are all the changes the same as 9mm (buffer, spring, hammer, etc.)?

I also have an Olympic Arms 9mm conversion dating from back in the early 90's and it uses the stock AR15 hammer just fine. I just have a lot more UZI mags since I have a registerred model B also, so I'm converting to a RRA type upper with a hytech mag well so that I can use unmodified uzi mags in it. I also prefer the dual feed uzi mags to the somewhat finicky and harder to load sten mags. Be sure to get a good magazine loader for those Sten mags!

Good luck on your project, I find shooting 9mm very enjoyable as I have access to a private outdoor pistol range with a lot of reactive steel targets that would be damaged by .223, plus its a whole lot cheaper than shooting .223 or 5.56.

[krim]

I am looking into finally building up a 9mm AR and am seriously considering using my registered Colt lower. I know I need to change out the hammer to either a DPMS or a 9mm specific hammer (RRA probably since that's what seems available). However, I recall reading that Colt uses different pin sizes than everyone else - does this create an issue w/ the hammer? TIA.

If you have a large pin lower like I do, RRA does not make a hammer for you. AFAIK, your options are to send out the bolt to be ramped, or buy a large pin colt 9mm hammer from places like numerich, brownells, etc.. (~ $70)

[redcliff]

Since he's going to use an Olympic conversion unit I don't believe a new hammer is needed purely from a function standpoint. My old unit works fine with a stock hammer, although bolt ramping would be easier on the rifle.

He will however need to find a mag well adapter for using Sten magazine, as Olympics stock setup utilizes modified sten magazine.

[krim]

i see that now... that's what i get for posting before morning coffee.

[trinydex]

is the bolt in a the latest rra 9mm uppers ramped?

http://thegunwiki.com/Gunwiki/AnalysisAR9mmRRA

from the gun wiki it appears it is somewhat?

[gunsmithcats]

That specific one is not ramped. In fact, my personal upper was used for that analysis

[trinydex]

so how important is this bolt ramping? how come there's a huge thread about it over on arfcom and no real talk in all the threads about 9mm ars here?

[vf111]

I had my bolt ramped by a well-known 'smith on this forum and am still waiting for the frickin' thing to show up at my door 1.5 weeks after I asked this guy to send it back to me. I sure wish he'd respond to my PM's.