I took my stock bars in the house and ran hot water over the left grip. It slid right off. While it was still hot, I put it on my Buckhorns and when it cooled it was stuck tight. There wasn't any adhesive on it - it just fit perfect.
Something else to consider - the stock bars have inserts in them that the tiny allen screws thread into to hold the end caps on. These inserts also help dampen vibrations. If your new "M" bars are completely hollow, you may notice some vibration in them - they will "ring like a bell" at certain rpms...
That was the case with my Buckhorns. I cured the problem with these....
weights
During my research I also found that a similar effect could be had by filling the ends of the bars with small lead shot and sealing it off with RTV.
Then again, you may already know all of this...
