I have found a great deal on a pre ban bushmaster upper receiver with the usual evil features, I.e. bayonet lug and flash hider.

I want to buy this upper but I do not have any pre ban lower receivers, could someone tell me the best way to make the pre ban upper legal to attach to a post ban lower? I have read the posts on cutting off the bayo lug and silver soldering a ATF legal muzzle brake I was wondering if there were any other options like replacing the front site post with a non bayo one and maybe cutting the last inch of thread off the barrel and recrowning. Anyone have any suggestions on this? How hard is it to silver solder the muzzle brake to the barrel.

If is a 20" barrel, you could cut and crown it.

I have one like that.

Yes it is a 20 inch barrel.
FirearmTom1 did you do this your self or did you send it to a gunsmith?

Remove the bayonet lug and install a brake that is permanantly attached.

You can take it to Harris barrel works and depending on the day they will do it for next to nothing.

The easy option is to change the FS.  You can go to American Spirit and pick on up.

Screw it on, drill it and set the pin.

Good luck.

What part of the State are you in.  I am in the Phoenix area.

i have had 2 de-prebaned uppers. i prefer to have the threaded section cut off, instead of just have the threads turned off.

Although I've never done it, I understand that instead of cutting off the whole bayo lug you can remove one of the "ears" of the lug and make it legal.  If you want to keep "the look".

Thanks for the responses I am even more unsure of what to do now than before. FirearmTom1 I live in Phoenix as well and am familiar with ASA in Scottsdale, I know Harris barrel is in the Phoenix area , but where?
Did shortening the barrel to 19 inches affect performance or accuracy?

How good of a deal are you getting on the pre-ban upper?