Subsonic data needed for 300 blk.

I have a stack of 2207. And the pills I have are jacketed 125 Speer tnt. And jacketed 190 sub x .. hoping someone can point me in the right direction. Thss as no u. It’s a bolt action rifle

Great Scott. First look up your sonic velocity by your altitude above sea level, it is on the web.
Then you must stay below the velocity at your location. My altitude is 247 feet so, the velocity is 1,000 to 1,100 fps.
You must increase the bullet weigh to increase energy as the velocity must always stay the same or below sonic.. I use 230 grain cast and 9 grains of H-110 for about 1,000 fps.
You need to figure the powders loads you have, out for yourself or change to pistol powder.

The 125s work with a super sonic load, actually too light for good effect at sub sonic velocities.

Easy tell, shoot at 100, if you can hear the bullet impact on the target paper clearly, you are sub sonic.

go to the Hodgdon's Data center on line.
Plenty of 300BO data, including Subsonic
beltfed/arnie

If you go to the adi website you will find with a small mag primer and 11 grns of 2207 should get you around what you want.they start at 220 grns jacketed and 11.2 grns but the pressure is low.
Check it out first thou.

125 grain subsonic is basically a 38 special load. Do you have pistol powders? 2207 is not an ideal powder for that load.

If shooting a bolt action, the options are wide open. I shoot the MP 311-410 subsonic using trailboss. It is significantly quieter suppressed using the 130 grain powder coated cast bullet compared to a 225+ grain bullet because you are using about half of the powder to reach the same 1050 fps velocity.

Book powders and charges are typically going to be with slower magnum pistol/very fast rifle powders to allow proper port pressure and cycling of ARs. You can use a bit less of a faster powder with a lighter bullet and get less muzzle pressure and less sound signature. (most or all of the book data will not tell/show you that)