[brightcove video="1910733688001" /]
The Reaction Rod is a new armorers tool from Geissele Automatics. It's an alternative to other 5.56mm/.223-caliber AR upper receiver fixtures such as the takedown pin-based DPMS Panther Claw, or the clamshell style blocks, like Brownells Upper Receiver Action Block.
The business end of the tool mates up to the AR15 barrel extension locking lugs. This contains all the forces of torquing a barrel nut in the barrel extension instead of transmitting them through the aluminum upper receiver as other popular fixtures do.
The Reaction Rod has a few advantages over other upper action blocks. It works with any 5.56/.223 AR configuration, it's fast to set up, fast to use and nearly indestructible.
Fit: Some hand guards extend onto the sides of the receiver and prevent clamshell action blocks from closing. This makes torquing a muzzle device on a gun with an overlapping handguard or nonstandard upper impossible with a clamshell. I ran into this frustration when using a clamshell style block to change the muzzle device on a Daniel Defense upper with an RIS II handguard. The heads of the bolt-up system prevented the block from closing. I ended up carving out part of the fixture so it would close: an easy but time-consuming fix.
The Reaction Rod works by holding the upper internally on the barrel extension lugs. So the device is not bothered by external non-milspec features and flourishes. Using the bolt carrier group channel assures compatibility with every AR15/M16/M4 out there.
Fast to set up: It's a single piece, so set up is just clamping it in a vice at any angle that suits the work at hand.
Because the fixture is made from a piece of tubular steel, the flats have to be smaller than the diameter of the bar. This means the bar is going to want to twist in the vice jaws as you apply torque. The clamping pressure required to keep it from spinning in the jaw is pretty intense, and a hobby vice isn't going to cut it. The most important thing to know if you are considering one: They require a beefy vise. Also, don't use jaw inserts or pads in the vice. We realized we hadn't pulled ours halfway through shooting the video above when we noticed the rod spinning as the torque forced the red jaw pads to slip.
Fast to Use: There's nothing to assemble, adjust or clamp. Just slide the upper on and it's good to go. It's sized to fill the entire upper when it's locked into the chamber, so the upper is fully supported. It can't rock or rotate. It can only slide on and off. The fit is precise enough that it's not a bad idea to use some oil to keep things moving. When you're all torqued up, just slip it off. There's nothing to unlock. While any basement armorer likes to save time, professional armorers and production lines will really appreciate the time saved not having to mess with the fixture.
A novel feature is the ability to instantly re-orient the upper/barrel. You can slip the upper back a bit, rotate it into the best position for your work, then slip it forward to lock it back in that position.
Indestructible: It's a single piece of hardened and coated 4140 steel. They don't come with care and feeding instructions, but if they did the instructions would read, "Keep a little oil on it to stave off oxidation and don't drop it." Simple.
Downside: The Reaction Rod doesn't prevent the upper from sliding off, so be aware that you can't do anything that involves pulling on the muzzle end.
Some might be concerned about damage to the barrel extension lugs when sliding the upper into place on the fixture. It's not a big concern since the bolt is slamming in there under normal operation, anyway. Though, it isn't hitting the lugs directly, so just don't slam the lugs into the fixture and rifle will be fine.
I'll reiterate that you need a real vice to use the Reaction Rod. If you have a small vice you'll be better off with a clamshell style action block because they have a lot more area in contact with the vise jaws and provide more resistance to twisting.
The Geissele Reaction rod will cost $50 when they go on sale on Geissele Automatic's website next week.
