Not sure what heating it is supposed to do.
It doesn't need heat to cure.

I use 609 and 620 at work all the time.
620 is for high heat applications.
If you really want it to set just clean and use the activator with it.

I just use moly lube on the barrel.
After messing with stuff that's been glued in properly with 609/620 I would think the upper would be a consumable if used.