Looking to build a small AR

[Bowdog]

I just got a bug to build a small AR. I see that Palmetto State Armory sells 10.5 inch uppers. I do not want a pistol ,but would like an AR about 24-30 inches long. My question is what size buffer and tube can I use? Will a carbine size work with a 10 inch barrel? Can I use a pistol buffer and tube with a carbine adjustable stock?
As you can see I am not an expert on AR's but I know where to look. I live in TN and I do not want to brake any state or Federal law.

[marine6680]

Any... ANY rifle... With a barrel shorter than 16in is considered a short barrel rifle (SBR) and is regulated... Meaning you must apply for a tax stamp to own one.

A rifle has a buttstock... That is the difference between it at a pistol. If your firearm has a buttstock on it, it is a rifle.

Unless you go through the background check and paperwork, and pay the stamp fee, then you can not build an SBR. The current wait times are over 6 months I believe.


There is only one way to build an AR with a barrel shorter than 16in and it not be an SBR... And that is to build it as a pistol. (You can build an AR with a 14.5in barrel, so long as you use a muzzle device/flash hider that is pinned and welded in place, and that is long enough to make the whole assembly 16in or more... Once welded on, the muzzle device is considered part of the barrel, as it is "permanent")

Technically you can build a pistol AR using a carbine buffer tube, so long as you do not put a stock on it... Bit that opens you up to questions and attention from law enforcement.


So if you want an AR with a 10.5in barrel... You must build it as a pistol, or first apply and be approved for the SBR tax stamp.


The new pistol braces are well designed and shouldering a brace is not prohibited.

[Bowdog]

Thank You, marine 6680

[Wyosmith]

Speaking of light ARs, my friend's wife had surgery and wants me to make a supper light AR for her. She loves to shoot, but now weights 91 pounds and has a bent spine, so something of extremely light weight is needed.

I know Bushmaster used to make one called the Carbon 15 and some weighed only 4 pounds or so. My idea is to make something like one of them, but I am not familiar with any companies making fiber or plastic uppers and lowers that hold up to a good deal of shooting, and have no problems with the butt socket or the barrel nut threads.

Anyone out there have resent info for me? Do such things exist? Are they good, or have they still got problems with the threaded parts that hold the buffet tube and the barrel nuts.

Fire away gentlemen.

[zukiphile]

She loves to shoot, but now weights 91 pounds and has a bent spine, so something of extremely light weight is needed.

I believe that the upper receiver isn't a great place for CF or polymer. I do have a gaggle of uppers built on Anderson "Lightweight Sport" AR uppers. I bought them because they don't need a forward assist or dust cover to be added, and I've yet to have a problem with any of them. They are $40 at Aimsurplus.

On my lightest AR, I used a 16 inch pencil barrel from Faxon. Faxon does make a 14.5 inch pencil barrel. When I bought mine it was $150-ish.

CF hanguards have proven durable, but I don't sling up very hard with them, just a hasty sling position in the standing position.

I also used a polymer lower. The weight savings is only a few ounces, but I am fond of these items. The CF has lower thermal density so it isn't cold to the touch. I put a drop of locktight on the threads for the castle nut.

If recoil will bother her, I find that a 5 ounce buffer gives very gentle function.

I hope some of the above is useful. My AR with all those pieces, a two stage Del-ton trigger, MFT minimalist stock, A2 flashhider, scope, sling and rings comes in at 5 pounds, 14.9 ounces.

[marine6680]

There is a company that makes reinforced polymer upper and lower sets... Fiber reinforced polymer with metal in key areas. They are not perfect though in my eyes. They shaved weight by making the metal reinforcement smaller than I think it needed to be for maximum benefits. Basically I think they should have expanded the reinforcement further to other structures, to maximize interlocking rigidity. Like making the front takedown pin location and barrel collar be one piece of reinforcement.

They are expensive though. A set costs something like $600... I can not remember the name of the company at the moment.


With light use, and especially with 22lr uppers, the standard poly lowers work ok. They are reinforced but not as sophisticated as the ones I mentioned above. I wouldn't trust them to last though... Not more than a few thousand rounds tops.

There is another poly lower that has an integral fixed buttstock, and I hear good things, but it is hard to get apparently, and you are stuck with the buttstock as is. It saves weight by eliminating a lot of parts though. No buffer tube or castle nut, etc.


The problem is... The poly lowers don't really shed that much weight compared to something like a titanium receiver set... And the aluminum ones that are trimmed down don't gain that much over the other options. The skeletonized sets shed more weight but at the expense of exposing the internals.

Most of the weight savings you can gain are in various small parts, BCG, and the barrel.

To get below 5lb, it gets expensive in a hurry... Figuring out a target weight and then selecting parts with that in mind is the way to go. You may find ways to save money by shedding more weight in one area, and buying a less expensive part somewhere else. Like BCGs... The really light weight options (the ones with the most weight savings) for BCGs are expensive. Making the BCG light, and using a light carbine buffer makes an adjustable gas block a necessity. Light weight barrel profiles can shed half a pound or so. Titanium small parts here and there. I am not so sure about titanium in the bolt carrier, as titanium has a higher coefficient of friction, and is strong but softer than steel in many of it's temper/heat treat forms. (A quality knife maker that uses titanium for the grip, will put a piece of steel at the point the blade locks, to prevent deformation of the locking point... I have a ZT that does this for the liner lock)

Building a lightweight AR can be a fun but expensive endeavor.

[T. O'Heir]

"...something of extremely light weight..." Chambering is more important. Lower weight will increase the felt recoil. Not that it has anything to do with Bowdog's bug.
"...to brake any state or Federal law..." You won't stop anything. snicker.

[FrankenMauser]

It is possible to build a ~31" AR rifle and remain legal. But that's as short as you can go.
That's minimum legal barrel length, and minimum length required for a carbine buffer system to work (in a pistol-length tube, for that matter). My numbers: A pistol-length carbine buffer tube* and standard AR receiver set locate the case head about 14-3/4" from the end of the buffer tube. Add a 16" barrel, and you're at 30-3/4". But, no one makes 16" barrels; they're all 16.25" or 16.5", just to be sure they're legal. So, you're at 31" (or more).

*(I can't provide a link at this time, but I have seen pistol-length tubes that accept an adjustable stock. I know they're out there. I just can't cite an example right now.)

Any shorter means one of two things:
1. The barrel length is too short, and requires an SBR stamp.
2. You've gone to one of the 9mm pistol buffer systems that are super-short and won't allow a stock to be installed.


Light weight:
I've gone through quite a few TAC-15 lower receivers. They're a reinforced polymer lower with brass inserts. Fairly light. I haven't damaged one. But they're quite bad, dimensionally, and require too much fiddling, fitting, and shimming.
I am not a fan. I wouldn't recommend them.

Unless you go through the background check and paperwork, and pay the stamp fee, then you can not build an SBR. The current wait times are over 6 months I believe.

The Eastern US seems to be stuck at around 6 months; but many Western states have had a big uptick in shorter turn-around over the last couple months. I recently got a Form 1 (SBR) approved in just 3 months, for example (Idaho - 3 months, 5 days, including time in the mail).
I had the receiver engraved, assembled in SBR configuration, and firing, less than a week later.

There are, of course, additional legal considerations for SBRs, though.

[Uncle Malice]

I highly recommend the 10.5" PSA upper with the fluted can and slant rail. I have mine with a PDW 'brace' with a Spike's H2 buffer and spring with a Toolcraft nitride BCG. It's honestly one of my favorite AR's... even though it's the cheapest one that I own. It runs very well. I have a Geissele BG-RF trigger in with a Primary Arms micro red dot. Super fast. Very controllable.

[imashooter]

Bowdog, you'd be best served doing a 10.5" pistol. Some manufacturers make collapsible "pistol braces". For all intents and purposes, same/same as a SBR less the 200.00 federal stamp and restrictions accompanying SBRs. This lower is good value with its SBA3 brace and the PSA EPT trigger. Have your cake and eat it too. https://palmettostatearmory.com/psa-...165448150.html

Several PSA 10.5" uppers to choose from. I would suggest one with a 1:8 or 1:7 twist.

https://palmettostatearmory.com/cata...=10.5%22+upper

[Rob228]

Wyosmith, I've heard good things about Tennessee Arms:

http://www.tnarmsco.com/ar15-tac-9-complete-lowers/

Polymer reinforced lowers, they do not make uppers though. The company was started by a few Marine vets.

[FrankenMauser]

Wyosmith, I've heard good things about Tennessee Arms:

http://www.tnarmsco.com/ar15-tac-9-complete-lowers/

Polymer reinforced lowers, they do not make uppers though. The company was started by a few Marine vets.

I mentioned them earlier:

"I've gone through quite a few TAC-15 lower receivers. They're a reinforced polymer lower with brass inserts. Fairly light. I haven't damaged one. But they're quite bad, dimensionally, and require too much fiddling, fitting, and shimming.
I am not a fan. I wouldn't recommend them."

[Wyosmith]

I may look into Tennessee Arms.
I wonder is there is any real advantage to a carbon upper. I have not seen any in years, so I can't maker any side-by-side comparisons.
As far as barrels go, I have no problems with them. I make my own, so I can do anything I'd like.
The goal is to come up with an AR or 4.5 pounds or less and not give up any degree of longevity. A carbine with normal life expectancy of rounds fired.

[marine6680]

I don't think a poly lower will give you the longevity requirement. Not the TN Arms, or the other similar lowers.

Those ones I mentioned before are the closest to the old Bushmaster carbon receiver sets, probably better made though.

I would look at ways to save weight in other ways, and then determine if you need special receivers to reach your goal.

[SamNavy]

There are a couple dozen different pistol braces out there now for sale... and about 1/2 dozen that are nigh indistinguishable from a regular buttstock from a shouldering functionality standpoint. Unless you live in a state where it's illegal to own a "assault pistol", like in Hawaii (where I live) or California, it's almost a no-brainer anymore to go with a pistol AR for general use.

And with the prices in the 9mm AR industry falling almost daily, it's REALLY a no-brainer to build one of those to plink with to cut your ammo cost in half. There's a company out there now selling kits for regular PMAGS to convert them to 9mm that require no modifications to the lower... just use these coverted mags and a 9mm upper. LRBHO works normally too.

[Rob228]

I mentioned them earlier:

"I've gone through quite a few TAC-15 lower receivers. They're a reinforced polymer lower with brass inserts. Fairly light. I haven't damaged one. But they're quite bad, dimensionally, and require too much fiddling, fitting, and shimming.
I am not a fan. I wouldn't recommend them."

Didn't catch that. Good info about the fitting, thanks.

[Charlie98]

I built an AR rifle a few years ago, my goal was to make it sub-6#, and I made it pretty close... 6# 7oz. Lightweight 16" barrel, fixed shorty A2 stock (for something different, for all I know a slider might be lighter,) no optics or anything. If I really worked on it I probably could have gotten it down to 6#.



...and here it is compared to my A2 H-bar...



Thing is, without trying to straddle the line between BATFE rules, and the whole AR pistol vs rifle thing, you can build a lightweight rifle without the fear of getting gigged for something.