For a working gun, I am a big proponent of pinning the gas block to the barrel. Yes, there are excellent factory guns, such as those offered by LaRue Tactical, that attach the gas block via set screw. Having been at the LaRue shop more than once, I can say that their QC methods are better than 99% of anyone slapping together rifles in their garage. I have not seen a LaRue OBR or Stealth come apart at the gas block, but I have seen gas blocks on other rifles work their way loose on the range. These days, gas blocks are typically hidden underneath an extended hand guard and checking the set screws for tightness is not easy. Suffice it to say, for a gun that I am building myself, I want my gas blocks pinned.
Unfortunately, in the past, this meant sending my barrel off to a shop to have the gas block pinned. This wasn’t too expensive, but sure was inconvenient and didn’t satisfy my need for instant gratification. Thankfully, 87 Industries has come onto the market with their end-user-installable Pinblock Pro. This kit includes a very nicely machined, low profile gas block machined from super resilient 17-4 Stainless Steel, which is then blackened before shipment. The kit also contains a set screw to secure the block for indexing, a hex wrench for the set screw, a 1/8-inch cobalt drill bit, a cross pin, gas tube roll pin, and some Loctite.
A while back, the folks at 87 Industries sent a kit out to me to prove how easy it was to install. It languished in my parts drawer until the next build project. I started with a service grade complete upper receiver from Palmetto State Armory. I have had great success with these inexpensive uppers, which come with either a button rifled or cold hammer forged barrel made by FN. I have found the button rifled barrels seem to shoot a bit more accurately than the cold hammer forged ones, and I have enough guns now where it isn’t conceivable that I will wear out all my barrels before my time on the planet is up.
So I disassembled the upper, first by removing the A2 flash hider and then pushing out the taper pins on the standard front sight post. Then it was time to set up the gas block. I slid the block onto the barrel until it butted up against the shoulder, ensured the top was at top-dead-center, and tightened the set screw. The Pinblock has a nice flat machined into it along with a small pilot to get the bit started. Using a hand drill, I was able to drill a straight hole right through the Pinblock, barrel, and clear the opposite side. It took just a few minutes of careful work.
I haven’t shot this particular upper yet, as I am waiting on a few more parts to get the thing together. However, the hard work is done. The Pinblock comes with a grooved dowel pin to secure the gas block. Pretty easy. Actually, the hardest part of this project was getting the freaking barrel nut off. The folks at Palmetto State Armory torqued that barrel nut on there to about 6 million ft-lbs. After much swearing and cranking, I ended up having to cut the barrel nut off, but that is a story for another day.
If you find yourself building another rifle or upper receiver, and you are in need of a low profile gas block, don’t settle for one that is secured with just a set screw or a clamp. Get it done right. If you don’t want to send out your barrel, check out the Pinblock Pro from 87 Industries and do it yourself!
SOURCE: 87 Industries