Barrel Test Gun (BTG) is what Mark Serbu calls his new project gun which unfinished version is today’s POTD. Overall, this gun is somewhat similar to the Serbu Q22 pistol except it is made to test barrels of many different calibers, particularly, the DIY rifled barrels that Mark Serbu has been experimenting with lately.

This receiver set will be fitted with a breech block and a break action barrel as seen in the CAD model in the above-embedded image. The trigger housing/lower receiver is borrowed from the Serbu Firearms BFG-50 and RN-50 rifles. It is machined out of 6061 aluminum, has a hard coat anodized finish and it is compatible with the standard AR-15 trigger mechanism. Here are some other features of the Barrel Test Gun quoted from Serbu Firearms social media pages:

The “upper” is machined 1018 steel which will be case hardened, and the barrel housing and breech will be made similarly.  For heavier calibers I may go to something tougher on the breech, and there’s the possibility of making a considerably larger barrel housing which locks to the breach at multiple points.  It uses an Uzi-style ratcheting barrel nut, has a little segment of 1913 rail for an optic, and there’s a little spring-loaded lever just forward and above the trigger guard to unlock the barrel housing for loading and extracting.

According to Mark Serbu, they are not going to sell the Barrel Test Gun, however, if there is enough interest, they may sell the drawings for those who want to put together their own BTG.