Beginning to find a subsonic load for my 300 BO Ruger American. Tried a load with 10.5 gr of 4227 under a 175 gr Sub-x. First shot was subsonic and the next 4 went super. I guess I was right on the threshold of subsonic velocity?

Probably. If you work something up at the edge of the threshold at this high temp, it maybe supersonic when it gets back cold.

4227 might burn a might too 'slow' Naturally you don't have any 200/220 gainers handy to try just guessing a heavier bullet would slow down to Sub. I think that Ruger is 16.1 barrel see if you can find something at 1025/1040 fps. Sure is easy to fix everybody's issues behind a keypad.

I have several other powders available as well as some heavier bullets. Was wanting to get something working on the 175's

I’m loading cfe blk and 190 grain sub-x bullets for a buddy.

I'm using 9.?? of VV N110 with 180gr sp pulls from American Reloading. N110 and N120 are GREAT powders for subs

k bush, what were your velocities?

Didn’t set up Chronograph, I literally drove 2 miles to a gravel pit, threw up a target at 50 yards and shot off the hood.



I loaded 5 more test rounds at 10.0 of 4227 and 5 with 9.0 of 2400 to try. Will chronograph these if my junk still works, haven’t tried it in a couple of years

Using your chrono would definitely help.

I plan to set it up next time I test a few loads. Dug it all out and it still powers up, it's a Pact that has the sky screens that mount on a tripod.

Heck, yeah. Good luck with it.

be careful loading sub sonic loads, they can spike pressure sometimes.

Have y’all seen the “Reloading for AR” book?
It’s got some GREAT info on loading super and sub for AR’s…my biggest takeaway other than best powders already tested and proven…when loading for subs it’s totally backwards as far as safety.
On most everything else, you load low and work up…watching for signs of high pressure indicators.

On subs, NEVER start low. Start high and work down, but don’t go below recommended data.

when I first got into the blackout AA1680 was the best option for subs, with Lil' Gun and 4227 being the next best options. I've had good luck with 1680 and 4227, but I was always loading much heavier bullets (220-245gr). You might try bumping up to something heavier?

Try aa#5 or aa#7 for super quiet loads. Just be careful with those fast burning pistol powders. It is easy to double charge a case if you don’t pay attention.

My Remington 700 sounds like a pellet gun with a 225 grain eld