Ar15 Assembly (Installing Barrel Free Float & Mil-Spec)

Intro

Most military configured barrel assemblies come with the Barrel Nut, Handguard Cap, and front sight base installed. We will demonstrate how to assemble the delta ring assembly, the handguards and the flash hider. If you’re going to install a free float handguard then you can skip the standard barrel segments and watch the segments on installing a free float barrel. You may, however, depending on your barrel’s configuration need to watch the segment on installation of flash hiders. Here again it is important to follow the order of the steps as we present them. This will eliminate rework and allow you to align components with previously installed parts. You should have your parts organized on your bench. You’ll need a good bench vise, the upper receiver vise block and insert, a barrel wrench, a torque wrench, the taper pin starter punch, number 2 & 4 roll pin holders and punches, a 4 oz. pall peen hammer, and the front sight bench block.

Installing Delta Ring and Barrel Into Upper Receiver Mil-Spec

To install the barrel and handguard slip ring assembly and gas tube you’ll need the upper receiver vise block with the insert, a barrel wrench, a torque wrench, snap ring pliers, and a number 2 roll pin holder and punch. A small flashlight would be handy also. The methods for installing a mil spec barrel are the same for all barrel lengths.

• 1. From the rear of barrel, slide the handguard slip ring with the narrow end facing forward, the

  

• 2. Use your snap ring pliers to expand the handguard retainer ring and seat it into place in the cut on the barrel nut.
• 3. Place your upper receiver into the upper receiver vise blocks and install the insert into the back of the receiver. Put the entire grouping into your vise jaws up to the lips on the side of the vise blocks and tighten down your vise until you have a firm grip on the blocks.
• 4. Next slide your barrel into the front of the receiver making sure you align the pin on top of the barrel with the cut in the upper receiver threads.
• 5. Take your barrel wrench and attach it to your torque wrench which is set to 30 foot pounds. Pushing against the slip ring assembly tighten the barrel nut down to 30 lbs. 30 foot pounds of torque is the minimum amount needed to secure the barrel. We’ve typically found that you will achieve better accuracy with a minimal amount of torque above 30 ft. lbs. Make sure the cuts in the handguard retainer ring and spring are on top of the barrel. Look down the top of the barrel into the cuts of the barrel nut and into the receiver. It may

  

  be helpful to remove the vise block insert from the receiver and shine a flash light from the back of the receiver. You’re looking for one of the cuts in the barrel nut to align with the gas tube port on the front of the receiver. Typically this doesn’t happen with your first turn.

• 6. Note the distance that you’ll have to turn the nut to align with the next cut on the barrel nut and increase the torque setting on your wrench to 40 lbs.
• 7. Replace your insert back into the receiver if you’ve taken it out.
• 8. Tighten the barrel nut a bit more; it is always better to do this in small steps so that you don’t go past the next cut you’re trying to align. Check the alignment again. Keep repeating these steps and increase the torque setting on your wrench until you get visual alignment.
• 9. Once you have visual alignment, place your gas tube with the bend upward and the bulge

  

  towards the rear through the barrel nut into the receiver. It should pass through without any binding or resistance. If you encounter any resistance, remove your gas tube and turn the barrel nut either on or off to fine tune the alignment. A handy tool that prevents damage to the gas tube is to use the barrel nut alignment rod instead.

• 10. Once you’ve achieved proper alignment, you can install the gas tube into the front sight base.
• 11. Remove your barreled receiver from the vise block and place it into the front sight base block

  

  with the words PINS IN facing up. Align the gas tube with the roll pin hole in the front sight base.

• 12. Use your number 2 roll pin holder to start the gas tube roll pin in and finish driving in the pin
  with the roll pin punch until the roll pin sits flush with the side of the front sight base.
• 13. Finally, compress the hand guard slip ring and install each handguard front end first.

Installing Free floating Barrel / Hand Guard

While the installation of free float handguards is pretty straight forward, each manufacturer has some of their own specific methods; it’s important to read and understand the directions that are furnished with them. We are going to demonstrate how to install a free float, 4-rail handguard, a Tactical Shit modular gas block, and the standard front sight base in this sequence. We have already removed the front sight, flash suppressor, handguard cap and barrel nut. This will cover the basics and give you a reasonable understanding of what is necessary to do the tasks. Just remember to read and understand the directions that were furnished with your particular parts. Here again, it is important to follow the order of the steps as we present them. This will eliminate rework and allow you to align components with previously installed parts. The order of assembly is: installing the replacement barrel nut, the gas block and tube free float handguard, then finally the flash hider or muzzle brake. We have provided separate segments for installing an aftermarket gas block and reinstalling the mil spec front sight base in this section.

Now depending on the dimensions of your gas block you may or may not be able to slide your handguard over it. To test this simply slide your gas block onto the barrel and see if your handguard will slide past it. If it doesn’t, you’ll have to install the handguard first, then the gas block. If the handguard does fit over the gas block then you can install the gas block before the handguard and it will be easier to install the gas tube. For this demonstration we’ll assume that your handguard needs to be installed first. The tools that you will need are; a small flat head screwdriver, a number 2 roll pin holder and punch, the rifle bench block, a strap wrench and the upper receiver vise block and insert. A small level will be helpful to ensure that your gas block is on correctly. Different handguards and gas blocks may require different tools so check with the instructions provided by the manufacture.

• 1. Place your assembled receiver into the vise blocks and install the insert in the carrier way. Lock this into your vise with firm pressure.
• 2. Next slide your barrel into the front of the receiver. Make sure you align the pin on top of the barrel with the cut in the threads.
• 3. Slide the barrel nut down the barrel with the outside threaded portion facing forward, and then

  

  tighten the barrel nut down finger tight.

• 4. Set your torque wrench to 30 foot pounds and attach it to barrel wrench. Tighten the barrel nut down to 30 lbs. Thirty foot pounds of torque is the minimum amount needed to secure the barrel. We’ve found that you’ll achieve better accuracy by keeping the torque as close to 30 ft. lbs. as possible. Do not exceed 80 foot pounds of torque, you risk damage to the barrel nut and the threads of your receiver. If the directions that where provided with your free float handguards contradict our instructions follow the instructions provide by the

  

  manufacturer or you may damage the components.

• 5. Look down the top of the barrel through the holes of the barrel nut and into the receiver. One of the holes in the barrel nut must align with the gas tube hole on the front of the receiver. Typically
  this doesn’t happen with your first turn.
• 6. Note the distance that you’ll have to turn the nut to align with the next hole on the barrel nut and increase the torque setting on your wrench to 40 lbs.
• 7. Tighten the barrel nut until you have correct alignment to allow the gas tube to pass through

  

  without interference.

• 8. Slide the handguard down the barrel and hand tighten it onto the threads of the barrel nut.
• 9. Use your strap wrench to cinch down the handguard, but don’t apply too much force, you don’t want the barrel nut to turn down any further and cause the holes in the barrel nut to misaligned with the receiver.
• 10. Use your number 2 roll pin punch to help locate the through hole in the gas tube with the hole in the gas block.
• 11. Once you have these two holes aligned, use your number 2 roll pin holder to drive in the gas

  

  tube roll pin. Finish driving the roll pin with the punch so that it is centered in the gas block. If your handguards will fit over your gas block you can perform this operation while the gas block is on the rifle and the rifle bench block will be helpful to support the barrel.

• 12. Now insert the end of your gas tube with the two holes into the gas block with larger hole facing down toward the gas port on the barrel.
• 13. You need to be sure that the gas tube gas port on the inside aligns with the gas port on top of the barrel. Most aftermarket gas blocks come with over sized ports so this alignment, while important, does have some provisions for inaccuracy.
• 14. Now slide the gas block and tube onto your barrel and slip the gas tube through the barrel nut into the receiver. Adjust the gas block so that it is level and tighten the set screws. Once you’ve completed the assembly of your rifle, double check the level of the gas block in relation to the receiver. This is easy to do on an A3 upper receiver because you have two flat surfaces to compare. On this A2 you’ll need to establish level off of the top of the receiver and then on the gas block.