My upper has arrived

[leakytanks]

I just received my Model 1 300 whisper. Ordered on 1-5-09 received on 7-14-09. Its a plain upper with a target crown and I tried a few 175 grain match kings with 14.4 grains of W-W 296.

Is that a good fire form load using 221 brass?
and
It has no adjustable gas block, will it work with sub sonic loads as is?

Thanks