AR Build info/help...

Tgoody14

Member
Feb 28, 2013
172
18
Lake Amistad
I have been reading up on all the forums (ar-15, m4carbine, chatterbox, and here...) for about a week straight trying to get ready for my 1st build. Figured I keep my questions for you guys (my local forum)

Little background:
1st Ar was an Olympic Arms - Sold
2nd BushMaster Carbon15 - Feed Problems/Sold
3rd Colt 6920 - Current Rifle and I also carry one of these on duty. I have my personal 6920 rigged up for long range/coyote rifle and it drives tacks at 200 yards.

What I'm looking to do is to build a 14'5 barrel, low profile gas block, with a Colt lower (YES, I drink the juice... Haha) This will be my close range/on the 4wheeler/ridin the farm rifle

So my questions are:

1) If I can't find a complete Colt lower, what other brands are compatible on kits for a stripped Colt lower? Am I right in thinking that as long as it is "Mil Spec" it will work? Or are some "Mil Spec" not really Mil Spec...

2) Also, is this the same for the Upper (mil spec)? What brands for an upper and barrel will be compatible with my Colt lower?

3) If you have some useful links that you think I could benefit from reading please post em up

4) If you have a Colt Lower or know where I might find one, please post as well!

Thanks in Advance guys!
 

jtw2

Active Member
Dec 5, 2013
276
28
Cedar Creek
essentially anything that has a description of "large pin" should work. You can also get some small to large pin adaptors and then anything will work. I've gone that route but honestly it's a pain in the ass to take it down.
 

Shorts

TGT Addict
TGT Supporter
Mar 28, 2008
4,594
38
Texas
OP, GandRTactical has complete lowers, both BCM and Colt. You can pick up uppers from Grant as well. Or order a complete upper from BCM. Both the best options IMO if you want guaranteed milspec without a second thought. You said you drank the koolaid and if you've been reading M4C then you have already heard the things I mentioned.
 

Tgoody14

Member
Feb 28, 2013
172
18
Lake Amistad
jtw2 - thanks for the info

OP, GandRTactical has complete lowers, both BCM and Colt. You can pick up uppers from Grant as well. Or order a complete upper from BCM. Both the best options IMO if you want guaranteed milspec without a second thought. You said you drank the koolaid and if you've been reading M4C then you have already heard the things I mentioned.
Yea GnR is out of stock on everything. I almost sent them an email just to see what kind of time frame Id be looking at for a Colt complete lower. BCM is probably my first option for the upper as well.

I just want to make sure and stay away from whatever brands you guys know that I'll run into problems so I don't waste any money.

Thanks for info
 

Shorts

TGT Addict
TGT Supporter
Mar 28, 2008
4,594
38
Texas
No way, I just looked doing a little dreaming/shopping. Could have sworn there were still lowers there. I was looking at stripped lowers. Maybe that's why I'm thinking they were in stock.

Oh here's one:
Colt Magpul Lower
Colt 6920MP Magpul Lower at G and R Tactical


The BCM is a good deal and a solid choice. I've grabbed one of these and would recommend, (not purchased from G&R though):
BCM Lower at G and R Tactical


I've seen this LMT lower recommended before but can't vouch for it personally:
Rainier Arms™ | Browse | Receivers - Lowers | LMT Defender 2000 Lower


I'll keep my eye out and post it up. Send Grant an email, I'm sure he knows what's coming in and can at least forecast for you.
 

Tgoody14

Member
Feb 28, 2013
172
18
Lake Amistad
No way, I just looked doing a little dreaming/shopping. Could have sworn there were still lowers there. I was looking at stripped lowers. Maybe that's why I'm thinking they were in stock.

Oh here's one:
Colt Magpul Lower
Colt 6920MP Magpul Lower at G and R Tactical


The BCM is a good deal and a solid choice. I've grabbed one of these and would recommend, (not purchased from G&R though):
BCM Lower at G and R Tactical


I've seen this LMT lower recommended before but can't vouch for it personally:
Rainier Arms™ | Browse | Receivers - Lowers | LMT Defender 2000 Lower


I'll keep my eye out and post it up. Send Grant an email, I'm sure he knows what's coming in and can at least forecast for you.
Yea I saw that one, but I'm not really a big fan of Magpul stuff.

I actually just ran across a complete Colt lower that just got thrown up on M4C an hour ago! Talk about timing!!!! Prolly going to pick it up and go from there. Just need an upper, barrel, and rails now!

Are there any restrictions on barrel length? Is 14'5 as short as I can go without a stamp? Saw a real nice 12.5" barrel with 10" rails, looked sharp! Exactly where I'm wanting to go with this build...
 

Shorts

TGT Addict
TGT Supporter
Mar 28, 2008
4,594
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Texas
That is good timing (and how I came upon the BCM lower one Saturday morning) :D

Yup, a 14.5" is the shortest you can go without going the NFA route. You will need the muzzle device pinned and welded. IMO you don't gain much in that configuration over a 16". Instead I feel some "modularability" is lost because the pinned MD limits the work you can do to the upper. Likely you've already considered this and I respect your decision to go with it. Also on the 14.5" double check the length of the MD that it is long enough to bring the OAL over 16".

I'd like to get to get a 11.5" length. I hear you on the SBRs with full rails looking good. They have good proportions :D
 

M. Sage

TGT Addict
Jan 21, 2009
16,326
36
San Antonio
That is good timing (and how I came upon the BCM lower one Saturday morning) :D

Yup, a 14.5" is the shortest you can go without going the NFA route. You will need the muzzle device pinned and welded. IMO you don't gain much in that configuration over a 16". Instead I feel some "modularability" is lost because the pinned MD limits the work you can do to the upper. Likely you've already considered this and I respect your decision to go with it. Also on the 14.5" double check the length of the MD that it is long enough to bring the OAL over 16".

I'd like to get to get a 11.5" length. I hear you on the SBRs with full rails looking good. They have good proportions :D
And for the ATF's sake, make sure the muzzle device is pinned and welded BEFORE you take possession. As far as the feds are concerned, a complete AR rifle and a <16" barreled upper in your possession equals an SBR. I know it's stupid, but it's how federal LE works (stupidly).
 

Tgoody14

Member
Feb 28, 2013
172
18
Lake Amistad
I still can't decide whether I want to go 14.5 or 16. Any real deal breakers between these 2 lengths!? (Besides the pinned flash hider)

I know for sure I want to go with at least 12" rails, maybe longer if I go 16 on the barrel. I want to keep this as lightweight as possible. Like I said in my 1st post, I already have a heavy long range set up so this will be more for mobility/close range! I shoot 64 grain ammo if that matters.

Any info is appreciated. Thanks!
 

Big Phil

Well-Known
Feb 20, 2013
1,187
38
SATX
For rails the keymod is the new "hot" thing, I have a Noveske NSR, however I just got my Centurion CMR and I am very impressed. The CMR has holes that are already tapped for their screws and accesories. Supposedly the new BCM keymod rail is lighter than the Noveske. Which weighs 11 ounces for a 14 inch rail.

As far as the quality of forged uppers/lowers what you're really paying for is how well a particular company mills and anodizes the receiver.

The reason is, there are only 17ish (can't remember the exact number) that actually forge the uppers/lowers. From there they are sent as nothing more than a paperweight to all the different companies, big and small. Some companies have rejects, often called 2nds, that aren't up to snuff in appearance but are perfectly functional. Some companies like Noveske will reject uppers that you have to look hard to find an imperfection, whereas another company would not reject it.

In general most forged uppers and lowers are the same, however companies like BCM, Daniel Defense, Colt and Noveske have made a name for themselves by only accepting the very best uppers and lowers.

Billet is a whole other story, but the cost/benefit ratio really isn't that big a deal for me. I haven't found billet receivers to be any more accurate or functional than forged. The cost is generally much higher but you can get more of a "custom looking" AR that way.

Just as an FYI, Colt trigger pins are .169 inches while most other companies use .154 in. pins, as far as I know. This won't affect you as it pertains to quality, only the choice of a few (not many) aftermarket triggers. That is if you're into that kind of thing.

As far as barrel length, I prefer 14.5, no scientific data just preference. It just feels right.

Hope that helps.
 
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