The MEN 147gr shoots pretty good for me too.

Federal brass, CCI No 34 primers, IMR 4064. OAL 2.790

Best groups were with 44.2 gr, 45.0, and 45.4 (the 44.6 wasn't good, maybe shooter error?)

Sierra's manual has OAL around 2.775 and so does hogdon's but that is for the regular MK. I load a little longer since there is no actual data for the TMK. I had a primer pop at 46.6 gr (.9 under hogdon's max) but it was a hornady case that I must have mixed up. I did not fire the rest in that charge weight.

I was jumping .4 gr between charges, I plan to go back to 44 gr and try smaller steps to see what I get and get some velocity data.
I should also have a better optic mounted by the, So that may help. Then it's on to 200yrd groups.