300 blackout subsonic question.
- Thread starter JasonYuke
- Start date
I have not shot a bolt, but I have a semi. I was firing the 300 Blk with 220gr sub-sonic out of an AR upper set for 110-125gr super-sonic (heavy buffer and a mid length gas port), so it never cycled the bolt beyond unlocking the bolt head from the extension: as close as bolt as I have gotten. It is still a loud one: there may be no sonic boom, but the round still makes a big bang, even with the AR bolt only unlocking and not cycling.
You can "get your Google-foo" going and find some data: super sonic seem to suppress very nice, even as low at 115-110db. Sub sonic under suppression seem to be the toys of those using the 300BLK in an AR platform inside buildings with tight hallways and small rooms... like drug dens and gun-owning citizen's man caves.
You can "get your Google-foo" going and find some data: super sonic seem to suppress very nice, even as low at 115-110db. Sub sonic under suppression seem to be the toys of those using the 300BLK in an AR platform inside buildings with tight hallways and small rooms... like drug dens and gun-owning citizen's man caves.
arcstarter
CGN Regular
- Location
- Lethbridge, AB
I have 200gr 308win subsonics loaded with 10.5gr of trailboss shooting at 1050fps and they are pretty quiet and I'm sure the 300BLK is even quieter. I didn't measure with a dB meter but it can't be much if any louder then a .22LR
I've shot a fair number of subsonics through my bolt guns. By far the quietest rounds are those with light weight bullets and small amounts of fast burning pistol powders. A 90gr.-110gr. bullet with 4.5gr.-6.0gr. of Trail Boss is exceptionally quiet. Personally, I still wear hearing protection because my hearing is so very poor. You might be able to get away with it depending on your threshold for pain.
Not so much your threshold for pain, but your budget for hearing aides in the future.
Subsonic unsuppressed is still fairly loud. It will be in the high 150's range. For comparison unsuppressed supersonic will meter in the mid to low 160's range.
Powder choice can effect this. I have not metered any subsonics using Trailboss, which would be the quietest option.
Not a chance. Supersonic 300 BLK suppressed will meter in the mid 130's range while subsonic 300 BLK will meter in the mid to high 120's.
This video shows suppressed and unsuppressed with full sound data.
Powder choice can effect this. I have not metered any subsonics using Trailboss, which would be the quietest option.
You can "get your Google-foo" going and find some data: super sonic seem to suppress very nice, even as low at 115-110db. Sub sonic under suppression seem to be the toys of those using the 300BLK in an AR platform inside buildings with tight hallways and small rooms...
Not a chance. Supersonic 300 BLK suppressed will meter in the mid 130's range while subsonic 300 BLK will meter in the mid to high 120's.
This video shows suppressed and unsuppressed with full sound data.
I've shot 208gr A-max with 12gr of AA1680 through my 9.75 inch AR. That is the minimum charge that will cycle the action fully. It was quieter than a supersonic load but would still require hearing protection.
For 300 blackout and bolt actions I think Suputin has more experience testing than anyone around.
For 300 blackout and bolt actions I think Suputin has more experience testing than anyone around.
Unfortunately (well not really
) I do not have the option to test bolt gun loads unsuppresed. Mine only works in one configuration. If you brig your rifle here I will sound test unsuppresed loads for you.Unfortunately (well not really
I appreciate the offer! It's a bit of a trip from the East Coast to the Calgary area for that. lol.
Well I bought one today ? So I will report my findings with a rem 700 aac bolt 16.5 inch
It's a project do won't be anytime soon
But want to play with 208 AMax and trailboss or unique.
Should be interesting
It's a project do won't be anytime soon
But want to play with 208 AMax and trailboss or unique.
Should be interesting
Last edited:
Ideally, you want to be +/- 1,050 fps to be adequately stabilized and promote consistent ignition and velocities. You'll be WAY too low at 800fps. If you're at all tempted to try those low velocities, do so with cast lead bullets. And no doubt you've heard this plenty of times before but a chronograph is highly recommended when working sub loads. If you're not working off published data a chronograph is an absolute must have. I rarely deviate much from published data. Maybe a couple tenths of a grain +/-.
H110 is popular with gas gun users as they need to generate enough chamber pressure and gas volumes to cycle the action. Obviously, you've got far more latitude in load combinations with manual repeating actions. The .300 BLK is anything but a benchrest cartridge but you should be able to achieve acceptable results.
