Ran into a couple of troubles with build

[WelchyV90]

I am at wits end and could use some advice on where to go from here. So I am finishing my T-91 clone build and the upper receiver needs to be changed from the Wolf A1 to an unmarked receiver I got from here. Problem was that the barrel nut threading was messed up and the barrel nut would not come off. PB Blaster, heating it, cooling it, hammer, nothing would work. Took it to a local gunsmith and the only solution was to cut the barrel nut. Now its off and I have an extra barrel nut, however how the **** do I get it on? Is there a way to remove the FSB/piston housing without cutting it off?

[e292644]

There's tapered pin under the FSB, remove it and press the FSB out.

[WelchyV90]

Will that give enough clearance to allow the barrel nut down the barrel or will I need to remove the gas block too?

[e292644]

No, you will need to remove the entire FSB.