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Adding a JP free-float tube to a Rock River 9mm upper?
4/5/2012 10:48:05 PM
Hey guys, I've got a RRA 9mm carbine that I'd like to add a JP 12" Free float tube to. I know I'm going to have to cut the front sight tower off as well as the delta rings from the OEM hand guards. My question is this, how hard is it to remove the barrel on a 9mm upper and install the JP tube. I'd buy a vise block from brownells as well as the required tools but I didn't know if the barrel removal/install was different from a normal .223 barrel. Also, anyone install a JP tube themselves? Is it pretty straightforward?
Any help is appreciated greatly as always.
Cheers623.
Any help is appreciated greatly as always.
Cheers623.
4/6/2012 1:52:36 PM
Barrel removal and installation on the 9mm is the same as a 5.56. The vice block will help, but if your gun has an oversized 9mm deflector, it probably won't fit in there without modification.
Never installed a JP handguard so I'm not sure on that one. I would guess it's pretty simple, like most FF rails.
Never installed a JP handguard so I'm not sure on that one. I would guess it's pretty simple, like most FF rails.
4/8/2012 5:31:23 PM
The only hassle with the JP tube is that the barrel nut has to be semi-permanently fixed in place with Locktite to keep it, and the tube attached to it, from rotating under torque.
It should actually be slightly easier on a 9mm build, as you will not have a gas tube to line up between the teeth on the barrel nut (sometimes they have to be ground down to index properly on rifle-caliber builds).
4/8/2012 8:27:30 PM
Installed many of the JP hand guards and never needed any kind of locktite and the receiver nut does need to
line up with the receiver lust like a normal AR that uses a gas tube or the hand guard tube will be not level/clocked at top center with the
reciver rail.
line up with the receiver lust like a normal AR that uses a gas tube or the hand guard tube will be not level/clocked at top center with the
reciver rail.
4/9/2012 10:15:42 AM
Redtazdog, nice looking builds.
The manual recommends the use of Locktite on the receiver extension nut, so I've always used it.
You are correct that the receiver extension nut should be lined up properly with the receiver, especially if you are using a top rail. I was referring to modification of the inner barrel nut.
As always, YMMV.
The manual recommends the use of Locktite on the receiver extension nut, so I've always used it.
Using the red Loctite 271, coat the threads of the receiver barrel collar and install the receiver extension nut, turning it down until it stops.
You are correct that the receiver extension nut should be lined up properly with the receiver, especially if you are using a top rail. I was referring to modification of the inner barrel nut.
Note: In some cases when tensioning the barrel retainer nut, it may not be possible to achieve alignment of the gas tube channel of the inner nut at an acceptable torque. The easy fix for this is to grind off the offending nub of the inner lock nut to clear the gas tube.
As always, YMMV.
