9mm AR build

TheSwampFox · Jan 26, 2014

I am thinking about doing a 9mm AR build. I was hoping that someone might have some pointers and could answer some simple questions.

1. Is the 9mm buffer a necessity or not? I'm not shooting full auto (sadly :cry: ) and probably will shoot less than 500 rounds per year.

2. What about the extended brass deflector? Since there is no forward assist I was thinking about using a slick side upper for the build but I'm left handed so if this is going to result in getting smacked in face with hot brass every round I'll go ahead on put it on.

3. If I go with the brass deflector do I need to plug the forward assist or can it be left open?

Since there is no gas system I wasn't going to waste time and money on a gas block and I'm going to use free float hand guards probably YHM.

Any help is greatly appreciated

fordnut · Jan 26, 2014

This is something I have often though about doing..Just haven't taken the step...I wait patiently fort answers, also.

Steve

Tigerstripe · Jan 26, 2014

i believe you need the heavy buffer. without it and no gas system the bolt would come back pretty hard.

shooting mine i can tell its a different animal without the gas system.

if the bolt you get has the ridges for the assist you can put on the assist or not. i had an upper for 556 without the assist for a while. got one and have a door ordered now.

when you get a 9mm barrel it wont have the gas hole on it and its not needed to close the one on the upper if that is the one you mean. mine is open and has the deflector cause it is an upper that came from the complete 22 upper i bought. i put the slick side upper on the 22 barrel.

i would say yes you need the deflector. and dont forget the mag block. depending on where you get the bolt it may need to be ramped. that could be a full auto thing though. not a big deal. works better ramped i think.

Sooooo, ive been debating for a long time, still not sure, selling the COLT A-2 9mm upper i have. it was a complete Colt and i switched the reciever for the flat top 22 reciever with deflector and foward assist. the Colt doesnt have assist but has a deflector. i dont remember dropping the 9mm gun so it may be because of the heavy recoil. the walmart red dot on it was broken last time i went to use it. looking inside you can see, looks like a snap ring came loose. that might be a reason for me to keep this upper and just have open sights.

TheSwampFox · Jan 27, 2014

Tigerstripe, thanks for the input.

I plan on getting my upper parts here
http://rockriverarms.com/index.cfm?fuse ... ory_id=244

My BCG, buffer and flash hider here
http://yhm.net/index.php?main_page=inde ... 96f425cefb

Spikes Tactical has some nice 9mm stuff but its all out of stock with no eta.

Fordnut, here is more info I found from the internets
http://www.ar15.com/forums/t_3_15/10826 ... R_FAQ.html
http://www.m4carbine.net/showthread.php ... parts-list

Now here is the million dollar question. Do I just build a standard rifle and call it a day or do I go for it and do a form 1 and make a SBR?

Tigerstripe · Jan 27, 2014

SBR

they told me to make a list of the different bbls i would put on my SBR.

just make up a list and cover yourself.

i put 5.5 inch 22 so anything longer would be ok but i did put 10.5 22, 556, 9mm also.

and they told me i could just revise the list if i wanted something else and send them a copy, they would send it back ok, something like that. the list was on a seperate paper than the stamp but it had ATF numbers on it.

Clicker · Jan 27, 2014

The other option is the Olympic pattern instead of the Colt. I stumbled into a deal on an Oly upper years ago and have thousands of rounds thru it. The Oly's bolt is ramped and a little easier on the lowers FCG.

The down side is the goofy ejector and a somewhat weak extractor, I've broken a couple of each. I've busted some hammer and trigger pins but I can't blame all of those failures on the 9mm upper. The heavy buffers serve to slow the carrier speed down and reduce the hammer bouncing off the disconnector and eventually breaking FCG pins.

On the up side these Olympics shoot softer than the Colt due to the ramped bolt and with a hydraulic buffer its really as good as it gets for an AR in 9mm.

Tigerstripe · Jan 27, 2014

also

i would not go for a 3 lug bbl. a friend had his suppressor fly off, luckly not doing any damage.

ill bet you could find an upper on one of the sites. thats where i got my mag block and buffer.

ill find out which mag block we have. Andy said he would sell you some mags but they have to have a little work. the catch has to be cut in and if you want a hold open it has to be put in. i got mine from him. they wouldnt be $50 either.

we ramped mine, piece of cake.

TheSwampFox · Feb 5, 2014

Well I got a deal on a 16" 9mm barrel that I could not pass up. Looks like the SBR is going to have to wait for another day. I have all the little parts and pieces I need to convert one of my 5.56 Ar's but I'm still lacking the mag block and BCG.

First, I'm looking at the BCG from CMMG and YHM. Does anyone have any preference or know if there is any difference between the two? They seem to be evenly priced.

Secondly, other than plastic construction are the promag mag blocks really any different from the ones that cost 3-4x as much? The guys at AR15.com seem to like the promags okay.

I would rather not deal with the pain in backside of having to remove the bolt catch to install the mag block but if it will save me $150 I can put up with it. Does anyone know if the spikes magblock is top or bottom loading?

Tigerstripe · Feb 5, 2014

remove bolt catch? didnt know about that.

mine slides up into the magwell and i tigthen a set screw. just make sure its even with the top of the reciever. its aluminum. some have two set screws.

how much are you talking? i think mine was $40 or $45. used though, barely.

TheSwampFox · Feb 5, 2014

Most of the mag blocks I have seen are called top loading and go in from the top of the magwell which requires the bolt catch to be removed first. There are a few that say they are bottom loading and are easier to take in and out. The promag mag block cost in the area of $50 but all the others including the bottom loading cost in the neighborhood of $200.

Do you know what make your mag block is?

Another thought I had today was the CMMG dedicated 9mm lower is only about $150. That is cheaper than most of the mag blocks and I wouldn't have to give up my 5.56 lower.

YHM says their BCG is ramped and uses the standard AR15 hammer and is a completely drop in piece and will work with Colt pattern mags. CMMG does not have any info on their BCG whatsoever so I don't know if its the same or not. I could save about $20-30 with CMMG but if it wont do what I need it to then that doesn't matter.

I don't mind spending a little more for something better but I do mind spending more for the same thing.

Tigerstripe · Feb 5, 2014

i talked to Andy. he is the pro. he says the plastic mag blocks are junk. do not buy.

the top loading block would be good if you dont plan on switching cals with the lower. so in that case you are going to have a dedicated 9mm.

the $150 lower might work best, BUT find out what kind of mags it takes or it may cost you in that way.

i didnt remember but he says i paid $85 or $90 for my mag block. at the time they were around $150 new. it is a Rock River Arms.

so for the bolt you also need to know what mags the 9mm lower takes. and if it is already ramped $30 more is less than having machine work done to ramp it.

dont forget though if you use an AR lower you can SBR it and buy a whole new set of bbls in every cal and shorten them . :lol:

TheSwampFox · Feb 11, 2014

I have ordered the last two parts for this build. The mag block and BCG should be in by Thursday which means I'll be hitting the range by the weekend.

I will post pictures and specs once I get it slapped together.

TheSwampFox · Feb 16, 2014

Here she is

Specs:
Brownells 16" Barrel
Working Mans Armory upper and lower
YHM BCG
Brownells 32 round mag (worked like a charm)
Omega free float quad rail
Magpul BUS
Magpul CTR stock
Strike fire red dot
Promag mag block (I went the plastic one because of the price. I plan on getting a hahn when I can afford it.)

The only hiccups were when I tried to shoot some hollow points and I was expecting a few feeding issues which is exactly what I got. 4 failure to feeds in 10 rounds. Anyone have any suggestions of a good self defense round I could use in this?

Here are the results with the strike fire @50 yards

I would also like to plug a website I found for the build. http://www.9mmar.com/StoreHome.html has decent prices and super fast shipping. The selection isn't huge but its good enough. Also huge props to forum sponsor Working Mans Armory. Their upper and lowers are fantastic. Probably the only ones I will get from now on. Their gen2 lower looks even better than my gen1. I can't wait to get my hands on one. I wish they would set up a booth at the local gun shows.