300 Whisper/Blackout loads?

[ch-pi-tu-ra]

My second thread on this forum
I recently bought a MGM 13" barrel for my TC G2 Contender.
Its accuracy has been marginal with the best groups being 2.5" @ 100 yards.
I have a 357 Remington MAXimum that gives me 1" groups @ 200 yards consistently.
Just stating that because I can shoot better than this barrel has performed so far.
I don't want to give up on it, just seeking some advice from others that has more successes than I have been having.
8 different bullets, 8 different powders 8 different loads per bullet.
So I am trying hard to get this to dial in.

A neck trimmer is on its way in the mail to obtain concentricity as another attempt to eliminate another variable.
My best load so far is a 178 Grain Hornady A-Max # 30712, with 10.0 grains of IMR 4227.
Slow subsonic at 1050 FPS, but it can keep the groups on the paper.
However I would like more terminal momentum.

Anyone have recommended pet loads to share?

Many Thanks

[ole95]

What twist is it? II have one that is 1/8
And have to run 168's up to 1200 to get them to shoot
Plain base more than likey will shot better

[MSLiechty]

http://up.sur-la-toile.com/iFsk

Heres soem sierra data based on the TC

ML

[ch-pi-tu-ra]

Lots of good pointers that are appreciated.
Especially the very informative Sierra 300 Whisper link that I did not know existed.
Thanks!

[MSLiechty]

16 grains N110 with sierra 125's is what I load at about 2,000 FPS and quickload says that should be over 60K PSI. apparently the case capcity is less in their model than in real world, according to the Sierra data.

ML