When shopping for a buffer tube, the first question is whether your stock is commercial or Mil-spec, because commercial and buffer tubes are not the same. The question we hear most here at Hojan.net is what is the difference between these buffer tubes?
It is very important to know the difference between commercial and mil-spec buffer tubes. Purchasing the wrong buffer tube will not fit into the oppositely designed stock or can create damage to your buffer tube.
The first way in which these buffer tubes differ is in the shape of the tube itself. This is the easiest way to tell the difference between commercial and Mil-spec buffer tubes. Commercial buffer tubes will have a slanted back at about 5 degrees while Mil-spec will not have this slanted feature. A Mil-spec tube always has a flat back.
The second way that a commercial buffer tube differs from a Mil-spec standard buffer tube is in the diameter of the tube. A Mil-spec standards buffer tube has a diameter of 1.148”, while a commercial buffer tube has a diameter of 1.168”. This difference may be small but if you were to hold a commercial buffer tube in one hand and a Mil-spec buffer tube in the other, the difference can be felt and seen if put side by side.
So make sure when purchasing a buffer tube that goes with your stock that you know which type of stock you have and that you purchase the correct buffer tube.