So far in previous posts from our easy AR15 build series we’ve planned out our new rifle, figured the cost of parts and gotten the tools organized. Now we’re ready to take the first big step in assembling our upper, installing the barrel and gas block. For this build, we’ve chosen the POF Puritan barrel in 5.56. Since we’re building an emergency preparedness oriented rifle, this barrel has a feature set that really works well for our needs. The Puritan comes in at 16.5″, which is short enough to keep the rifle handy. It is built with 5R rifling, which “rounds” the leading edge of the lands, so that they don’t try to shave material off of the bullet as it travels down the barrel, contributing to easier cleaning and accuracy. The nitride heat treating is a modern upgrade to the traditional chrome plating found in many military barrels. Also, something unique to POF is the E² extraction technology. This uses a little of the gas pressure from firing a round to help get the spent brass casing moving back out of the rifle. E² makes the extractor’s job easier and also contributes to a more reliable rifle, which is all the more important in an emergency, when this might be the only means of defense at hand.






We paired the Puritan barrel with the DIctator Adjustable Gas Block for our mid-length gas system, since they can come from POF as a matched set. The common way to adjust the gas system of AR type rifles is to switch out the buffer for a lighter or heavier unit. However, by upgrading to an adjustable gas block, there are nine different levels of gas pressure available at the turn of a dial. This allows the gas system to be easily tuned as needed, such as when adding a suppressor to the end of the barrel. The DIctator also comes with a straight gas tube. Removing the bend in the gas tube reduces the heat buildup along that section, further contributing to the long term reliability of the rifle. The gas system is designed so that it can be adjusted with a flat head screwdriver, 3/32″ hex wrench or the included tool, which fits nicely on a keyring.





Before trying to install a barrel, the smart money is on firmly securing the upper receiver. An upper receiver vice block is not expensive and it fits around the upper like a clamshell. Then, this block can be easily secured in a vice. Don’t get carried away when tightening the vice, as our goal is just to hold the upper firmly in place.






Once the upper is secured, we can prep for installing the barrel. The upper receiver should have two holes on the front side. The large threaded one will hold the barrel, and above it is a smaller cloverleaf shaped opening. This smaller hole allows the end of the gas tube to go inside the upper and mate with the bolt carrier. Take note of how there is a square notch cut into the threads of the larger hole. When sliding the barrel into place, the indexing stud on the top of barrel sleeve should sit inside the notch. Aligning this properly makes an AR barrel install difficult to mess up.






Before installing the barrel, it is a very good idea to “grease up” the threads on the upper receiver. This will make the barrel installation easier and help prevent galling of the threads. The proper way to do this is with Aeroshell 33MS grease. This is a molybdenum disulfide grease that does not contain copper, aluminum or anything else that can cause problems later on down the road. A small container is not expensive and will be enough for multiple barrel installs.  I will usually wipe a little on the barrel sleeve as well, before inserting it into the receiver.






Once the barrel has been pushed all the way into the upper receiver and the indexing stud is in its notch, tighten the barrel nut down to hold everything in place. At this point, hand tight is plenty. Our barrel nut is less complex than the standard GI unit, as it is part of the Midwest Industries Free Float Handguard package. Part of this free floating handguard design removes the need to index this nut, which further simplifies our barrel installation.






The Midwest Industries package also includes the wrench to properly tighten the barrel nut. However, a 1/2-inch drive torque wrench is still required. The proper torque range for installing the barrel is from 30 ft lbs to 80 ft lbs. The trick to doing this properly is to first set the torque wrench to 30 ft lbs and then tighten the barrel nut. (Most torque wrenches with “click” when they hit the specified limit.) Then, loosen the barrel nut and unscrew it from the upper receiver. Now, adjust the torque wrench up to 35 ft lbs and tighten the nut back down. Then, loosen and torque down the barrel nut one last time. We do this three times to help make sure that the threads on the upper receiver and barrel nut are properly mated.






Once the barrel nut is snugged down for the last time, carefully slide the DIctator gas block over the end of the barrel. The end of the gas tube should go about two inches into the upper receiver. Make sure to align the hole in the top of barrel with the hole in the bottom of the gas block. Draw a line with a pencil on the top of the barrel, through the middle of the gas hole, if you need a reference line. Now, just tighten the set screws on the bottom of the gas block to hold it in place. It is a good idea to use a higher temperature thread locking compound on these screws. Another possibility is to pin the gas block to the barrel, if you don’t mind a bit of extra work and drilling. Now that the hardest part is done, in our next installment of this series, we will finish building the upper and complete our AR15!



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