Thursday, March 21, 2013

SBR-Basics of the Short Barreled AR-15

A recent and popular trend in the "AR-15 world" has been the manufacturing and use of rifles with shorter barrels.  Like any modification made to the original/typical AR-15, there are costs and benefits to this particular configuration.  This blog post will highlight some of these considerations and offer basic information in regard to the legality and options one may have in building or purchasing a SBR in the AR-15 platform. 

I remember being quite thrilled when my unit began to issue 14.5 inch barreled M4 rifles.  The reduction in weight and ease of movement in tight quarters with the weapon were major benefits from my perspective.  Before my time in service ended, we were using the AR platform with a barrel just over 10 inches and the same benefits were even more noticeable and appreciated.  The main "negative" associated with a shorter barrel is the difficulty of successfully engaging targets that are at a greater distance.  With the loss of every inch of barrel length comes a reduction in velocity of around 100 FPS (many other factors are involved here, thus the use of the word "around").  Velocity affects energy and both affect terminal ballistic performance...if your "target" is affected by terminal ballistics and is at a longer distance, a SBR may be something to reconsider. It was rare that our mission/application necessitated using the weapon at longer distances, and if that need arose there were other weapons better suited to be used for such an application.  Any choice in the particular configuration of an AR-15 should be made with your application (how you intend to use it, most of the time) in mind.  If your predominate use of the weapon would be to engage distant targets and you have no NEED for a compact weapon, an AR-15 with a longer barrel would better serve you.

In regard to legality, any rifle with a barrel shorter than 16" is considered to be an SBR.  The same regulations that pertain to barrel length also apply to the overall length of a weapon.  A rifle must be at least 26" long from end to end.  The buttstock of the rifle can be full extended if it is collapsible to achieve this minimum overall length.  These regulations were part of the NFA (National Firearms Act) of 1968 (an earlier NFA act of 1934 was voided by changes made in the more recent legislation).  In order to own/build/possess an AR-15 SBR  you must obtain approval from the BATF.  This includes having the Chief Law Enforcement Officer (Sheriff or town/city chief of police) sign off on the ATF form, passing a federal background check (to include fingerprints/photo), and registering the rifle with the ATF.  Many other regulations exist in regard to the SBR (such as interstate transportation), even after you have waited for and received approval to purchase/own one.  For complete information about the process of acquiring or owning a SBR, visit this link :

There are ways of owning an AR-15 with a shorter barrel without receiving NFA approval...such as permanently attaching a muzzle device onto the short barrel that ensures the barrel is the necessary length.  This includes drilling a hole through the muzzle device and partially into the barrel, inserting a pin, and then welding over the inserted pin.  For a modification like this to be legal, the muzzle device must be permanently attached in a manner such as this. A 14.5" barrel can easily be brought to the required 16" length if a flash hider/compensator/muzzle brake of the appropriate length is permanently affixed.  The same can be done with an 11.5" barrel with a 5.5" flash hider.  While this configuration "looks cool" (a lot like the Colt Commando/XM177 Vietnam era configuration), the benefits like weight reduction and maneuverability are lost with the longer muzzle device length and there is no gain in distance capability (it would make more sense to have these extra inches in rifling).  The 14.5" barrel/pinned extended flash hider is where this method of owning a shorter barrel has the greatest benefit.  DTI offers these short barrels and a few muzzle devices from Troy and YHM that, when pinned and welded, will bring a 14.5" barrel to the necessary length and allow you to avoid all of the NFA hassle.

Thanks for reading our blog.  If you have any questions about SBRs, the parts we mentioned in this post, or any of the parts and rifles we make and sell here at DTI, please feel free to contact us.


  1. Maybe you shouldn't have your guns at a photo shoot with improperly timed flash hiders.

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