I used a blow torch by inserting it in the area that would normally be occupied by the lifter and heating up the inside of the magazine tube where it is threaded into the receiver. It took a bit to position everything. I heated it up in "pulses" to not over heat one area but once it started smoking, like Sukhoi said whisps, I was able to unscrew the tube. No discoloration or damage to the receiver in my case.