Well the couple I've gotten in the past that were new in the package had a white ink stamp DOD eagle on them. This weres off quickly. The most common fakes are the cast ones. A real 37 will be all milled. The one place I look in the cut out for the gas plug. The cast ones have clear spur line on the edges as the mold comes apart along these edges. All the real 37's I've seen you can see the milling lines in this cut out on the bottom of the flash hider. the cutting tool used leaves milling marks 90 degrees to the length of the flash hider.
great appear I have a legit one , may come in handy when the flesh eating zombies attach, wonder what the difference in length between the GI & foreign cast T37 ??
I was taken early on by a couple fake ones and I've owned a dozen or so real ones. As far as I remember there is not much of a difference in length, but I can't say I've held a fake and real one up side by side. If your fighting the zombie hoard you can't use a bayonett with the t37 on the rifle, just pointing that out.