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.