300 blackout subsonic question.

That is all I am expecting is acceptable accuracy. And in hopes I can set my scope up using turrets for sub sonics around the farm and full loads at the range.

Minute and acceptable achievement is what I am looking for. I would rank that at 1.5-2 Moa at 100 with full loads and 1.5 inch groups at 50 with subs
 
JasonYuke said:
That is all I am expecting is acceptable accuracy. And in hopes I can set my scope up using turrets for sub sonics around the farm and full loads at the range.

Minute and acceptable achievement is what I am looking for. I would rank that at 1.5-2 Moa at 100 with full loads and 1.5 inch groups at 50 with subs
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A good supersonic load will average between .75-.85 MOA for (5) shot groups at 100 yds. 1 MOA subs under the same conditions would be exceptional with a good load being under 2MOA on average. As with any rifle, it all depends.
 
2bad4u2 said:
You won't get enough TB in the case to keep 200gr. bullets from lodging in the bore. For adequate powders, consider H110 or Lil' Gun to start out with (roughly 9gr.-10gr. if memory serves me correctly.
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Those powders are more suitable for an AR. In a bolt gun I use N320, HS6 and the like. These fast pistol powders are nicer in a bolt gun.

If you want to use Trailboss you need to go down to a 150gr or lighter. 6.5gr of TB will fill the case to the bottom of the neck so there is no room for the bullet to protrude into the case.
 
Suputin said:
Those powders are more suitable for an AR. In a bolt gun I use N320, HS6 and the like. These fast pistol powders are nicer in a bolt gun.

If you want to use Trailboss you need to go down to a 150gr or lighter. 6.5gr of TB will fill the case to the bottom of the neck so there is no room for the bullet to protrude into the case.
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Suputin, have you tried H110 or Lil' Gun in a boltgun? With subs, the noise isn't bad at all. I agree with you regarding fast pistol powders. Where the OP is presumably new to the cartridge and possibly subs in general, sticking with published load data is a good idea initially. Wouldn't you think?
 
2bad4u2 said:
Suputin, have you tried H110 or Lil' Gun in a boltgun? With subs, the noise isn't bad at all. I agree with you regarding fast pistol powders. Where the OP is presumably new to the cartridge and possibly subs in general, sticking with published load data is a good idea initially. Wouldn't you think?
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I've tried Lil Gun and W296 and they can be fairly quiet at lower velocities but by the time you get up around 1000 fps they get considerably louder. The problem is that my idea of quiet is quite different and for different reason. I also have the sound meter which tells me in no uncertain terms which is quieter and by how much. Going subjectively by ear can easily lead you astray due to how we perceive sound levels.

If we were talking about building subsonics in a larger case with a long barrel then it is safer to go with established data. However there is a lot of valid 300 BLK data that is not published and with the short barrels we use, the chances of getting a round stuck is pretty low. In a way the reloading companies are a bit behind the curve on this. You can see this by looking at the published data, the majority of it is for subsonics, especially where a bullet weight could be used for either.

As long as he isn't loading crazy small amounts of powder (I usually never go below 30% case volume) then he should be OK. It'd be pretty difficult to seriously overpressure a subsonic round. Even a double charge wouldn't come close and for powders like TB that isn't even possible.


Looking up my data I got the following out of my 12" special bolt gun YMMV:

200gr Lapua bullet:

N320 6.3gr (70% load density) 997 fps [123.3 dB]

HS6 7.0gr (50% load density) 981 fps [125.9 dB]

Trailboss 5.7gr (100% load density) 613 fps [116.7 dB]

Blue Dot 7.0gr (60% load density) 965 fps [124.0 dB]

AA#5 7.0gr (45% load density) 978 fps [121.6 dB] note this load tends to throw wild flyers


150gr FMJ-BT:

Trailboss 6.0gr (100% load density) 791 fps [117.8 dB] - I am fairly certain that 6.5gr can be gotten into the case with this bullet which would give a bit more velocity.


The Trailboss loads are ludicrously quiet
 
id think a longer barrel and subsonics would make things sound like a suppressed rifle at least that's how it works in a .22 with a 30"+ barrel. at most pistol powders are all burned out at about 12"-16" or so
 
2bad4u2 said:
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.
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In my AR I've found that H110 will only cycle the action with bullets up to about 130gr then I need to switch to LiL'gun for the 130-170ish gr then switch to AA1680 for the heavier stuff like the 208gr. In a bolt gun you would have a lot more room to play but in the piston operated AR with 9.75 inch barrel that is all that has worked for me in order to get reliable cycling.
My 110gr V-max loads with 19.4gr of H-110 are doing pretty much MOA at 100yds with a 1-4x24 scope. I think it will do better if I put something with more magnification on it.
 
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