AR Pistol Build

[johnlangdon]

My next build will be an AR pistol. I am a big PSA fan because the price and quality is tough to beat. Have any of you built an AR pistol? Did you have any issues with barrel length and bullet performance? Obviously a shorter barrel equals less velocity at distance but for a truck gun, backpack gun, or even CQB style rifle I think it's tough to not build one. Feel free to attached pictures!!

[panzer0170]

Definitely interested to see the outcomes of this. Will you be going down the route of getting a brace for it, as is the current fashion, or are you going for something else?

[johnlangdon]

Definitely going the brace route.

[Patriotic Sheepdog]

I did a lot of research on barrel length and found 12.5" to be the best when it comes to ballistics per the many charts I looked at and people I talked with. I chose the BCM Kino barrel with the sig arm brace. I'm looking at rail and optic now, but at the range this weekend it had no problems with the couple different types of ammo (55g) I fed it. It was eating up cola cans at 50 yds after I zeroed it. Did not try any further distances as the rifle range was full that day and I didn't have time to wait.
Here it up against my Daniel Defense 16" barrel.

Attachments:

[n517rv]

I built a pistol lower once... once. I'm in an SBR friendly state and was just waiting on a NFA form to come in on a registered lower.

As soon as my form came in I would up selling the pistol lower as I didn't have any use for it. It's not near as comfortable or fun to shoot as an SBR.

IMO, if you live in a state that allows SBRs just go that route or use it like I did as an interim solution.

[omnivorous]

I've never built an AR "pistol" (I hate the use of the term in this manner", but if I were, I'd go for .300 AAC Blackout. As much as I'd like to state to go with n517rv's advice, I wouldn't want to give the BATFE the satisfaction.

[johnlangdon]

I've already sent the ATF some tax stamp money for a suppressor and I'll probably do the same around bonus time this year but I wanted to avoid that for this next build.

[4track]

In the past years, I have assembled two AR pistols. One is my CCW, vehicle defense gun, and the other is my bedside, household defense gun.

I am very pleased with both of mine, and they fill their intended roles nicely.











For me, the pistol classification meets my needs better than a registered, stamped SBR, simply because I cannot legal keep a loaded AR pattern rifle hidden inside my vehicle or in my backpack, but a pistol, I can.

As for size versus velocity, I like 11.5" (the shortest reliable operation for 5.56" direct impingement, carbine gas systems). I get a good balance of compactness and velocity for my intended use: zero to 100 meters.




Shorter barrels will work on .300 DI guns, but the cartridge is too boutique and expensive for me. By staying in 5.56, I have complete GI parts and ammo interoperability with all of my other rifles and carbines.

One could reliably go shorter with 5.56, but only on piston guns, and their velocity drops considerably. Also, they all have proprietary parts.



I used BCM 11.5" uppers on both of mine, as well as Aero precision lowers. One upper is a hammer forged, with GI contour barrel, while the newest is a standard button rifled, with a light weigh barrel contour.

Both also have KAK receiver extensions and Sig SB15 arm braces.


Some have speculated that BATFE will eventually reverse it's stance on the misuse of the SB15 brace.  

Since realizing the usefulness of the AR pistol for my perceived needs, I have concluded that, if the bureaucracy ever does make this decision, then I will keep using my pistols without the brace on them.



To me, they are just too handy to not have around.

[johnlangdon]

4track - that's exactly what I'm looking to build. Thanks for the pics. I want to use a 11.5" barrel because my suppressor requires a minimum barrel length of 10.5".

[johnlangdon]

4track - in regards to the KAK extensions, do they basically keep the brace from moving forward as well as moving the cheek weld back to more of a standard AR stock position? I hope that made sense.

[USMC0331]

I went with the 12.5" because of reliability and compared to a 10.3 I did not see the added benefit in size verses reliability and velocity loss.

I cut down an LMT 16" 1:7 for my SBR and it has run 100% with the same system it had before doing so. I do run H2 buffers in my M4s though, so it has that benefit already going for it at 12.5".

[4track]

Oct 6, 2014 10:10:25 GMT -5 johnlangdon said:

4track - in regards to the KAK extensions, do they basically keep the brace from moving forward as well as moving the cheek weld back to more of a standard AR stock position? I hope that made sense.

Yes.

The KAK pistol receiver extension has a flange that prevents the SB15 brace from sliding forward.

It is a snug fit, however, if it is struck hard, the brace can still rotate on the receiver extension. A little bit of electrical tape wrapped around the receiver extension will all but eliminate this from occurring.


I am aware of another pistol receiver extension, from Phase 5 Tactical, which has a hexagonal design, which might eliminate any chance of the brace rotating, however, I have no experience with this product:

phase5wsi.com/hex-2-pistol-buffer-tube-hex-2.html



Mine measures nine inches from the receiver end plate to the rear of the KAK receiver extension. This is the same length as a carbine with the stock extended to the second position.





This gives my 11.5" upper pistol a total length of twenty nine inches.





KAK also sells a couple of spacers, which can extend the length a few more inches:

www.kakindustry.com/ar-15-parts/lower-parts/buffer-tubes-and-parts/pistol-buffer-tubes/sig-lak

However, I did not feel the need for these, as the stock length keeps my pistols nice and compact, for maneuvering inside my home and vehicle.


KAK sells several versions of their receiver extension, but the one I use and recommend is the KAK SUPER SIG SB-15 Pistol Buffer Tube:

www.kakindustry.com/ar-15-parts/lower-parts/buffer-tubes-and-parts/pistol-buffer-tubes/sig-super-sb15-pistol-buffer-tube

This is the only KAK model that uses standard GI receiver end plates and locking rings, and therefore, it allows the receiver end plate to be properly staked.








I spray painted one of mine, yesterday, and the rubber on the brace is taking quite a while to fully dry.









I expect at least another day, or two, before it is fully cured, and then I will be able to shoot it.

[winter]

Oct 6, 2014 17:26:04 GMT -5 USMC0331 said:

I went with the 12.5" because of reliability and compared to a 10.3 I did not see the added benefit in size verses reliability and velocity loss.

I cut down an LMT 16" 1:7 for my SBR and it has run 100% with the same system it had before doing so. I do run H2 buffers in my M4s though, so it has that benefit already going for it at 12.5".

Bad ass paint job. Not sure what you did, but it blends even in your bbackgrounds.

Weird.

[4track]

Oct 7, 2014 2:07:04 GMT -5 winter said:

Bad ass paint job. Not sure what you did, but it blends even in your bbackgrounds.

Weird.

Thanks.

I just did my normal Multicam-like paint technique.

Blending in with the background is the whole idea, right?

[johnlangdon]

4track - thanks so much for the info. Just ordered my lower yesterday and my KAK Super SIG tube a minute after reading your post. I really appreciate it! Sick paint job BTW.

How do you like the new Magpul SL stuff?