Thoughts on the Short Barreled AR15.


Some years back I decided I would convert one of my AR15s to a short barreled rifle.  After paying a 200 dollar tax stamp and waiting a long time, I started with a LMT 10.5 inch upper.

The first time I shot that short upper I decided I wanted a suppressor.  That ended up costing me a great deal of money.

That picture shows two products I ended up having issues with.  My Eotech 512 had the battery contacts fail on me.  I also found out that the threads on my LMT upper were not cut concentric to the bore.  That issue lead to a 10 minute of angle point of impact shift between suppressed and unsuppressed.

My first silencer was a Gemtech M4-02.  The can performed great but it was a thread on can.  Each time I screwed it on or off the rifle I was worried about damaging the threads and I had to keep a flash hider or thread protected around for when I wasn’t using the can.  So I did more research on suppressors and I ended up buying a Surefire 556K can.

I found I preferred using ACOG optics on my SBR.  The ACOG gave me better target recognition and the bullet drop chart aided in shooting farther distances.

In the above photo my rifle has a Surefire muzzle break.  That break stayed on my rifle for one whole range session.  I find the increased flash and blast of a muzzle break on a short barreled rifle not worth the minimal amount of reduced recoil.

Around the time I decided I would have to do something about the major point of impact shift with my LMT upper I found out about a new rail on the market, the Daniel Defense MK18RISII.  I bought one along with a 10.5 inch medium contour match barrel.

When the above photo was taken I was trying out an early production Magpul UBR.  Many people on gun forums were claiming this was the ultimate rifle stock.  I found it to be awkward and heavy and very quickly got rid of it.  They don’t seem to be that popular any more.

Since then I have had a SBR AR15 in 9mm, 5.45.  I also had a LWRC PSD in 5.56.  The pistol caliber carbines are fun, but lack the usefulness at longer distances.  The LWRC with its 8.5 inch barrel and piston system was heavier then my 10.5 inch direct impingement uppers.

The 10 inch 5.56 SBR is the shortest I prefer to go.  Shorter then that you give up a great deal in ballistics and terminal performance.  A longer rifle starts to get awkward when using a suppressor.

I really love the short barreled AR15, but it is not something I would recommend to everyone.  Unless you are using suppressors I don’t think SBRs are that worth while.  If your thinking about getting into a short barreled AR15, look at the Colt 6933 and the Colt 6945.  I’ve purchased a Colt 6945 and am eagerly awaiting it.


  1. I’ve been toying with the idea of a SBR for a while now. It’s going to have to wait until I move back to a free state, though. I’ve gone up and back trying to decide on a barrel length. I had settled on a 12.5″ due to dwell time and slight velocity gains, but the 11.5″ just keeps tugging at me.

    I was also trying to decide between my TR24G, a TA33, or a TA44

    • You know what I did with my first tax stamp? I spent it on a SBR Vz 61.

      I wish I would have stamped one of my lowers, but at the time the Skorpion looked way more fun.

      The concussion is what has kept me away from the 5.56 in SBR form… But they are tempting considering the fragmentation capability of the heavier match loadings are still quite good out of shorter platforms.

      I would probably go with a 9mm just to reduce ammo costs and less concussion despite the loss of utility at distance.

      Those are nice weapons!

      • There is always the option of a second SBR upper in 6.8 SPC II or 300 BLK, which were both designed to work better out of short barrels.

        The other option, of course, is something like the Tavor , which is just about as long as a 10.5″ AR even though it has a full 16″ barrel.

  2. I have a 9″ 300AAC upper on a Noveske lower, with the AAC can. It is a cartridge designed for short barrels and cans. Works great. If I think I may need a longer shot, I have a 16″ DDM4 in 6.8, unsuppressed.

    At work I use a 10″ 5.56 Crane upper with a KAC can on a Colt lower. I always run it suppressed. Works great. If I want more reach, I take a SCAR17, unsuppressed.

    SBRs and cans are tools in the toolbox. Select the right tool, no issues. Select the wrong tool, you may be dissatisfied.

  3. RE: Your EOTech 512

    Don’t know if you have already solved the problem, but they have an improved battery connector in the battery cover.

    I just had a problem, where my AA batts had corroded while in the unit and messed up the battery cover and the main unit. Emailed EoTech CS and they were awesome. She offered to send me out a whole new battery cover at no charge or I could send it in. I told her that I’d go ahead and send it in. I was expecting a pretty high price to fix it, but she said it would only be $78 to completely fix everything that was wrong with it and send it back to me.

    Give them a shout, if you haven’t already.

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