I just have to say Wow...
I read that the handguards can be a pain to remove from our 450 BM's. So all week long since I ordered my new handguard, I've been putting some PB Blaster on the treads daily in anticipation to needing to remove the factory handguard.
I started the project this morning. The lock nut for the handguard actually came loose without much fuss. However after hours of not getting the dang handguard to budge (yes I used heat also), I finally had the bright idea of removing the gas block and gas tube first and maybe the entire barrel nut would come off (since I would need to replace the barrel nut anyways).
That ended up working for me! This may help any of you other gents out there that cannot get the factory handguard removed.
Unfortunately, I'll never be able to reuse this handguard now if I ever wanted to. It's fairly chewed up by this point.
I don't know if Bushmaster uses Red Loctite of some other epoxy, but I just wanted to thank them real quick.