Newsletter – Vol. 5 / Issue 12

With suppressor use on the rise the use of an adjustable gas block to control the operation of the rifle makes a lot of sense for those who are using one. In the case of the .308 it is usually necessary for reliable functioning of the rifle when shooting suppressed. Too much back pressure from the suppressor in the powerful .308 cartridge will often cause reliability issues as the rifle will run way too hard as the rifles are tuned to be fired unsuppressed. I have fired 5.56 caliber rifles suppressed successfully with no adjustable gas block but even in that caliber it usually makes sense. It is a lot easier on the rifle and more pleasant to the shooter to dial the gas pressure back a little.
In the following tutorial, I show the installation of the POF Midlength .308 adjustable gas block on one of our 16″ .308s with the 15″ Midwest Industries free floating handguard.

With a center punch put a punch mark in the hole at the rear of the factory gas block in the dead center. This is where the gas port is located on the top side and you will use this mark to line up the adjustable gas block.

With a wide flat punch and a hammer start both of the taper pins. You will be hitting them left to right. Note one head of the taper pin is smaller than the other. You want to drive them out from the small side. Once they are started, use a smaller punch to drive the pins all the way out.

With a wooden or plastic mallet drive the gas block and gas tube assembly off the barrel. Once it is off degrease the barrel and also the insides of the POF gas block where it will contact the barrel.

Slide the POF gas block assembly on and line up the rear punch mark with the back screw hole. It should line up with the gas block pushed all the way to the rear (if you are installing this on a rifle that had a standard handguard and handguard cap the gas block will be slightly ahead of the shoulder on the barrel. In this case this gas block can only be used if you are also installing a free float handguard like the Midwest industries)
Once the punch mark is visible put another punch mark through the front screw hole in the dead center.

Before I go further I want to mention that I’m showing how to put divots in the barrel to correspond with the set screws. I am showing this as this is the method POF instructs it to be done. When I first tested one of these I did not do this. I simply used the Loctite as I will describe below and the gas block held on just fine. So the divots may be unnecessary. But if you want that added step of confidence that the gas block will not move, put the divots in. Also note that sometimes the screw holes may line up with the taper pin holes where the steel is very thin. In this case the set screw will really just bend the steel in a bit where you are installing it and that really will do the same thing as putting a divot there. You will see in one of my pictures where the divot was actually starting to break through that area anyhow.

When drilling the divots use a carbide drill bit for best results. I used a .170″ carbide drill bit in this case. All you want to do is put a pretty shallow divot in the barrel.

Put green 680 Loctite on the two areas of the barrel where the gas block contacts. Slide it on and line up the back divot again so it looks dead center in the hole. Let the gas block set for a while. After 15 minutes or so you should no longer be able to move the gas block by hand and it should be at 12 O’ Clock with the upper receiver.

Put a little red 262 Loctite on the screws and screw them into the gas block. Wipe off any excess Loctite.

Reinstall handguard with some fresh 680 Loctite around the barrel nut. Torque the handguard screws down to 28-32 inch pounds.

A little wrench comes with the gas block that can be used for adjusting it, but when a long free float handguard like this is installed it can’t be used. There are also slots in the gas block adjuster so you can just reach in there with a screw driver to adjust the gas block.
In this case I turned the adjuster in all the way and turned it back out until the rifle ran perfectly and locked back on every empty magazine on the last shot. When shooting unsuppressed you will have it turned out quite a bit. With a suppressor you will adjust it in more. There are nine positions on this gas block so you can adjust it perfectly for your suppressor and loads. When adjusting it in the field though just make sure that between firing and making adjustments you unload the rifle each time and lock the carrier to the rear so you can visually see there is no round in the chamber. When adjusting your hand will be in front of the muzzle so this is VERY important. You don’t want to lose a hand or worse.

As with all of our items, these can be installed here at the factory if you don’t want to tackle it on your own. There is no labor charge. Just call customer service at 1-855-808-1888 to set it up.