I am building a 24" upper for my AR-15 and wanted to have something light weight to balance the heavy weight of the barrel. I looked around for a carbon tube, but didn't like the idea of having one glued permanently to the barrel nut. I found this one on Brownells website and decided to call AP Custom and ask them about doing a full length rail on the top. They offered to send me one of their new ones with a full rail on top to check out.
this is what came in the package.
It comes with a trunion which attaches to a GI Barrel nut and a clamp piece that attaches to the trunion with 4 screws. The free float portion of the tube attaches to the trunion like the JP one does, but uses 3 set screws to hold the carbon tube to the trunion.
Here is the piece that it attaches with.
The parts are very well put together, everything is anodized, and the tube is flat instead of gloss finish.
The installation went very straight forward. In my case the Stag barrel is a little bigger than most bull barrels, and the inside of the barrel nut and the front clamp piece needed to have a total of .035" taken off to allow the part to fit properly. I called AP about it prior to taking the material off and they said there would be no issue doing that, and that they would incorporate that into their future designs to allow for all barrel makes to work.
To get started, slide the trunion on the barrel that has already been slipped into the upper receiver, then slide the barrel nut on after the trunion.
Tighten the nut like on any other AR to a minimum of 35lbft and tighten as need be to get the gas tube to line up. Then push the trunion forward and it will lock into the barrel nut with a small tab and place the clamp on the trunion and tighten down.
This is what the trunion will look like when fully installed and ready for the gas tube.
The tube will slide over most small size gas blocks and it held true with the PRI block I put on, so I went ahead and installed the block then the tube but it can be done the other way around if so chosen. The tube as stated earlier is clamped onto the trunion by 3 set screws that are loctited on with the blue stuff. I plan on doing a little shooting with this gun tonight, and hopefully it will shoot as good as it looks.
The tube and set up appears to be a very strong versatile set up, that one could transfer between projects. The reduction in weight helps to pull the weight of the gun back in to the shooter a little bit and helps to make this 24" gun feel more like a 20. It is rigid enough that one would have no issues shooting it off the bench rest, or hanging accessories off it. It came with two 2" Picatinny rails for accessories that are attached with screws and a backing plate.
Overall with the ease of install and the way that AP Custom was willing to accept suggestions on one the part that didn't fit my big barrel. I am already planning on using this same set up on one of my other carbines and will use it on a future build too. Their website can be found here at APCustom and they said they should be coming to market soon with this very same tube.
Here is the completed gun
Update time.
I just got back from the range with the monster, as the wife has started calling it. The AP Custom tube performed better than expected. It rides the bags like it was made for it, it is just as rigid as my Hogue tube on my other AR 15 and has no knurling so it can slide easily but doesn't. The vents in the tube not only allow for small Picitinny mounts to be placed on the tube, but also allow for good heat dissipation. Compared to the all aluminum design, if you shoot large amounts of ammo this one heats up but not nearly as quick as a metal one, and it cools very quickly.
Shooting off hand was a very easy proposition also. I shoot silhouette, so I took a stance from that discipline and adapted it to the AR platform. This tube along with the heavy PRS butt did in fact bring the weight balance back toward the shooter, leaving what I would say is a 60/40 balance to the front. The balance point with this barrel stock combination is 1 inch up from the mag well, and all of this allowed my 5'2" wife stand and shoot the gun off hand easily also.
I plan on getting at least one or two more of these things for my other AR's and future builds.
this is what came in the package.
It comes with a trunion which attaches to a GI Barrel nut and a clamp piece that attaches to the trunion with 4 screws. The free float portion of the tube attaches to the trunion like the JP one does, but uses 3 set screws to hold the carbon tube to the trunion.
Here is the piece that it attaches with.
The parts are very well put together, everything is anodized, and the tube is flat instead of gloss finish.
The installation went very straight forward. In my case the Stag barrel is a little bigger than most bull barrels, and the inside of the barrel nut and the front clamp piece needed to have a total of .035" taken off to allow the part to fit properly. I called AP about it prior to taking the material off and they said there would be no issue doing that, and that they would incorporate that into their future designs to allow for all barrel makes to work.
To get started, slide the trunion on the barrel that has already been slipped into the upper receiver, then slide the barrel nut on after the trunion.
Tighten the nut like on any other AR to a minimum of 35lbft and tighten as need be to get the gas tube to line up. Then push the trunion forward and it will lock into the barrel nut with a small tab and place the clamp on the trunion and tighten down.
This is what the trunion will look like when fully installed and ready for the gas tube.
The tube will slide over most small size gas blocks and it held true with the PRI block I put on, so I went ahead and installed the block then the tube but it can be done the other way around if so chosen. The tube as stated earlier is clamped onto the trunion by 3 set screws that are loctited on with the blue stuff. I plan on doing a little shooting with this gun tonight, and hopefully it will shoot as good as it looks.
The tube and set up appears to be a very strong versatile set up, that one could transfer between projects. The reduction in weight helps to pull the weight of the gun back in to the shooter a little bit and helps to make this 24" gun feel more like a 20. It is rigid enough that one would have no issues shooting it off the bench rest, or hanging accessories off it. It came with two 2" Picatinny rails for accessories that are attached with screws and a backing plate.
Overall with the ease of install and the way that AP Custom was willing to accept suggestions on one the part that didn't fit my big barrel. I am already planning on using this same set up on one of my other carbines and will use it on a future build too. Their website can be found here at APCustom and they said they should be coming to market soon with this very same tube.
Here is the completed gun
Update time.
I just got back from the range with the monster, as the wife has started calling it. The AP Custom tube performed better than expected. It rides the bags like it was made for it, it is just as rigid as my Hogue tube on my other AR 15 and has no knurling so it can slide easily but doesn't. The vents in the tube not only allow for small Picitinny mounts to be placed on the tube, but also allow for good heat dissipation. Compared to the all aluminum design, if you shoot large amounts of ammo this one heats up but not nearly as quick as a metal one, and it cools very quickly.
Shooting off hand was a very easy proposition also. I shoot silhouette, so I took a stance from that discipline and adapted it to the AR platform. This tube along with the heavy PRS butt did in fact bring the weight balance back toward the shooter, leaving what I would say is a 60/40 balance to the front. The balance point with this barrel stock combination is 1 inch up from the mag well, and all of this allowed my 5'2" wife stand and shoot the gun off hand easily also.
I plan on getting at least one or two more of these things for my other AR's and future builds.
