I was looking at getting into a 300blk bolt gun for subs, but with the cost of everything, I was wondering if there’s any difference really in the round vs a 308 subsonic? I’m already set up to load 308.
- Thread starter Jmccracken1214
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Let see, both shooting the same heavy bullet at subsonic velocity. Nope. The difference is the size of the action required.
If you are already reloading 308 it will certainly ease logistics.
The BO was designed for subsonic so the case capacity is optimized for that function. The 308 case capacity is really too large but can be "made to work" so to speak. Ultimately it depends on your intended use. I would choose the BO if I expected to shout this gun often and wanted accuracy.
You have about 150 more choices of powders with a Blackout. The case capacity of the 308 would make it possible, but a lot more difficult to have consistent subsonic rounds.
No matter how you slice it powder shift is definitely a thing. If you are not familiar with what that is it means the space left over in the case will allow the powder to shift around inside the case. One round will be 1300fps and the other will be 900fps. This is solely due to the powder being in a different orientation inside of each case.
No matter how you slice it powder shift is definitely a thing. If you are not familiar with what that is it means the space left over in the case will allow the powder to shift around inside the case. One round will be 1300fps and the other will be 900fps. This is solely due to the powder being in a different orientation inside of each case.
Yep, that’s why high volume powders like Trailboss are the go to for .308WIN subsonic.
300blk or .223 is fine for 300yard paper punching. .308 is overkill in that application IMO. If it's just a toy then I would go .223. Super cheap ammo! However 300blk will be a lot quieter with subs. You need to see the video of Travis Hailey shooting a 9' ar15 suppressed 300blk at 750yards with a stupid aimpoint! Personally I think he's a witch.
Same bullet, traveling the same velocity, with the same BC, makes zero difference what size cartridge shoots it. Same results.
Except with .300 BLK, you don't have to use special powders, and with .308 Win subsonics, it's a big pain in the ass, and you have to use Trail Boss powder, drill-out your flash holes to 9/64", and use magnum primers. I've made lots of .308 Win subsonics over the years, and I built a .300 BLK AR15 years ago. I want to buy a .300 BLK bolt-action next, and I'll stick to supersonics in my .308 Win.
Thank you. Thats the kind of info I was wondering about.
^^^ this
This thread sparked me to do some more (deeper) hands-on research with my .308 Win subs... Checkout the subsonics thread in the reloading section if you're interested... I will definitely be playing with this much more in the future. Plus, I was getting bored because all my load development has been completed with my commonly-used range guns and hunting rifles, and this gives me something new to fuck with. 
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