Subsonic loads enough to fully expand brass?

[too_many_hobbies]

I expect my 300-221 to arrive any day now. To use my OAL guage and headspace guage, I will need a couple of fire-formed brass from my weapon. The ammunition I have loaded are subsonic loads consisting of Sierra 220 grain HPBT bullets and 9.2 grains of Hodgdon H110. Will these subsonic loads fully expand the brass or will I need to shoot some supersonic loads to fully expand the brass within my chamber?

[lovdasnow]

I'm not an expert, but from what I've heard they will.
I'll keep an eye here for anything different, but think you'll be fine.

[pug]

I think you should be good to go also. I have been getting the cases to seal with 180s and up. Look for signs of blowby around the neck. Supersonics will definitely push the shoulder out so if you got the powder you might try them.

[jjmcrowell]

I have only shot subsonic loads with mine. It seems to form the shoulders.

I start with 223 brass that I resize, the shoulders look different after they are fired.