I’m playing around with subsonic 300 BO rounds through my ruger ranch. My current load is running right around 1045 fps and movie quiet. Groups are decent at 50 yards but open up quit a bit at 100. If I push them just over supersonic, say 1150-1200 fps will I loose that movie quiet noise reduction or will the sound jump straight to full load level? Trying to tighten it up at 100 yards just a tad. Shooting 190gr Hornady SubX heads with 12.5 gr of CFE BLK.
Subsonic vs Supersonic
- Thread starter scmoose
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I wouldn’t push them just over supersonic as they’ll then go transonic in first 100-200 yards...which is more likely to negatively affect your groups. I’d want them well above supersonic or not, but the heavy projectiles aren’t optimal for supersonic.
1045 on a cold day is probably good to ensure it stays subsonic on hot day. But you’d have some room to experiment w slightly higher charge weights while keeping it subsonic. can also try different powders / to eeek out whatever accuracy is desired. since you’re not cycling an action, powder burn characteristics won’t much matter. BTW I’ve had the best results with AA1680 for all my 300 blk loads, especially subs cycling a suppressed AR, but the powder options for 300 blk are enormous if you’re in a bolt gun.
regarding sound, supersonic will just have the crack. It’s not a huge deal, but somewhat defeats the purpose of this loading. Supersonic 300 blk is also a great cartridge but apples to oranges IMO. More like trying to replicate a 7.62x39. Load a 110-150 gr and push it as fast as possible.
1045 on a cold day is probably good to ensure it stays subsonic on hot day. But you’d have some room to experiment w slightly higher charge weights while keeping it subsonic. can also try different powders / to eeek out whatever accuracy is desired. since you’re not cycling an action, powder burn characteristics won’t much matter. BTW I’ve had the best results with AA1680 for all my 300 blk loads, especially subs cycling a suppressed AR, but the powder options for 300 blk are enormous if you’re in a bolt gun.
regarding sound, supersonic will just have the crack. It’s not a huge deal, but somewhat defeats the purpose of this loading. Supersonic 300 blk is also a great cartridge but apples to oranges IMO. More like trying to replicate a 7.62x39. Load a 110-150 gr and push it as fast as possible.
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Biggest rounds that will shoot a 3" group at 75 yards that are movie quiet are perfect. 1045 on a 35 degree day is good.
You will be suprised at how differrent bullets not know for accuracy does really well below transonic speeds.
You will be suprised at how differrent bullets not know for accuracy does really well below transonic speeds.
sounds like you need 8.6 blk
Have you tried a longer or heavier bullet? Not speaking from blackout experience but from shooting transonic ELR it seems the longer the bullet with good design the better it transitions and flies in subsonic ranges. I switched to solids from bergers for that reason when shooting extreme ranges.
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I have always heard that it doesn’t. The reason being that the bullet makes the crack along its entire path as long as it remains supersonic, so the target will hear as much of it going away as toward it, and it all happens pretty much instantaneously.
