@ 06:49 am (GMT)
Thomas Kitchenhi john.
Nathan has been testing the tmk not sure which calibers he has done few comments on them but so far they seem like they perform well but i think there's more research to do.
from his blog
A quick Review of the Sierra TMK:
Recently I have been testing Sierras Polymer tipped Matchking (dont worry, Ill be into the new ELD-X range soon enough). This is a relatively new high BC bullet design from Sierra boasting a massive hollow point behind its big green tip. As a quick summary - it works extremely well as a long range hunting projectile. The 168gr .308 in particular has been a great bullet. As a testimony to its performance I made up a batch of downloads for Riley (now 9) with a hefty load of Trail Boss and a magnum primer yielding 1650fps. I zeroed at 120 yards and the load shot fairly flat in between and beyond, again thanks to its very high BC. Riley was able to shoot accurately at the range (as if I would let her get away with anything less) and also use the load in the field to bag two feral goats. Both went down immediately (one shot at exactly 120 yards and the other around 30 yards). Wounding was thorough and penetration excellent. Recoil was near nonexistent for the wee lass yet the pay load was emphatic for close range work.
The 168gr TMK works equally well at full velocities and can tackle reasonable body weights at close ranges without issues. Wounds are devastating.
This is a very long projectile and takes up good deal of magazine space with a COAL of around 2.815 / 71.5mm working effectively. I you are looking for something a little different to try in your .308 or .30-06, give this a go.
also check out this thread http://www.ballisticstudies.com/Resources/Discussion+Forums/x_forum/18/thread/8750.html
hopefully that helps it sounds like they are worth trying by all accounts