Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Site Notices
6/25/2018 7:04:05 PM
Posted: 9/20/2004 3:10:55 PM EDT
Being reasonably mechanically adept, is there any reason I should not install my own PRI midlength FF tube? Are there any special tools needed, or anything I should know or be wary of going into it? If it matters, it's going on a RRA Midlength A4 upper.

Thanks, all!
Link Posted: 9/24/2004 8:33:29 PM EDT
Link Posted: 9/24/2004 9:25:09 PM EDT
You will need the barrel nut wrench, and punches to remove the front sight pins, and gas tube roll pin. Other than that it should not be a problem for you!

The front sight pins are tapered so you will need to drive them toward the larger end to get them out. I use a 1/4 inch drive socket that will fit around the front sight pins and rests on the front sight base to drive on the pins so the pressure from the hammer blows is not on the barrel. After you get the front sight and gas tube off take off the barrel nut, and slip on the freefloat tube tighten it down and then tighten further till the barrel nut slot lines up with the gass tube hole in the upper. Be carefull aligning the front sight, and you should be there!

Hope some of this helps!

Link Posted: 9/25/2004 3:51:33 AM EDT
[Last Edit: 9/25/2004 3:57:52 AM EDT by mongo001]
FSB removal is really the hardest thing, for most. See here: FSB Removal.

You must clamp the receiver in a vice, I recommend using the proper vise block set as pictured below. Other than that, you need a armorer's wrench to remove the barrel nut from the original setup and to install the PRI barrel nut, although I use a separate FF tube wrench for all FF tube nuts. The FF barrel nut is installed, then the tube is installed and it's nut tightened. I used a strap wrench to tighten mine. Reinstall the FSB with the gas tube and you should be good to go.

On a side note: You don't have to remove the gas tube roll pin. You can remove the FSB and gas tube as a unit and reinstall it the same way.

List of tools with pics:

Armorer's multi wrench:

Vise block set:

This is the FF nut wrench I use on all FF tube nuts:

My PRI middy setup with different optics and buttstocks:

Link Posted: 9/25/2004 12:10:31 PM EDT
Thanks for the info, Starsil and Mongo!!

Mongo, nice ride! My end product will be similar to the lower rifle with the ACOG. I'm going to go with a TA11 or 31 (undecided.) Same tube and front sight, but I have a Magpul stock, instead of the CAR or Crane stock.
Top Top