08-13-2011, 02:38 AM
The cracking has nothing to do with the temperature. The cracking is caused by the same reason a glass jar cracks when you fill it to the top with water and put the lid on and put it in the freezer. If there is too much of a difference in size, something is going to have to give. You can temporarily reduce the size if the barrel and temporarily increase the size of the upper, but when they return to roof temperature, the upper is going to be too small and the barrel is going to be too big to fit together, The thin aluminum receiver is the weaker of the two and it either going to have to remain stretched or if it shrinks too much, it will crack. I would make Mega fix the undersized upper and I would not let them sand or turn you barrel extension to fit their non-standard part.