I heard of this before but, I am not sure what they use? Some type of silcone I think..Black?? I have a 700 Lss in .300 Ultra that is just giving me fits and I would like to try this... I think?? Any body know how stable this stuff is??? Kinda think it would have to have some variance in denisty between temp range of say 15.0 to maybe 115.0...Any body try this??I have lready floated the bbl, bedded the recoil lug and tang...then full length bedded the action, left the bbl floating..Then a pressure point above the front stud... some promise but not what I want...Damn thing shot under .75 @ 3800 with a 125 b-tip....got a muzzle brake screwed on...and now the harmonics are screwed up unless some thing else went wrong???? Will not do better than 1.5 with the above mentioned bullet no matter where i seat the thing and at vel. between 3600, 3800F/sec ....Tried a 180 partition.... 1.5" at 100........ well look on the bright side right??? That barrel will make a neat lookin tomato stake with the muzzle brake!! HELP!