Will a suppressor slow this down enough?

[bikemutt]

I just completed my first batch of 300BLK subsonic reloads using 220 grain projectiles and Hodgdon CFEBLK propellant. I have to say the reloading "book" for this powder was pretty close. I don't know what barrel length they used for the recipe but in a Cooper rifle with a 16" barrel I was very close to the edge of subsonic/supersonic, some shots had the telltale crack while others didn't. The average velocity over 20 rounds was around 1180 fps on a shady northwest pleasant day, according to my Magnetospeed chrony.

Anyway, since this was my first time loading for 300BLK I didn't want to mess with any more variables than necessary; the muzzle terminated in a JP brake, my ultimate intent is to shoot the rifle suppressed. I've heard it said a suppressor will slow the projectile's velocity, if that's true I wonder by how much? Should I leave the powder charge the same hoping suppressed shooting will result in consistent subsonic velocity, or should I back off the 12.1 grains of CFEBLK from the get-go?

Thanks

 

[TheDomFather]

The surpressor should add a little velocity not slow it down, from a velocity perspective it acts almost like a barrel extension, you might get another 20 - 25 fps, I would test it with your magneto speed but you likely need to take your charge down.