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Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Sun Mar 27, 2011 9:31 pm
by daviscustom
Was just reading about a bolt gun project in 7.62x25 using heavy bullets similar to the 300 blackout and it made me start to wonder about other options for .308 cal bullets that are already around. I am interested in mostly subsonic anyway and may not do anything on an AR platform any time soon, so I wondered what would be wrong with loading 220 grain bullets in 30 Carbine. Wouldn't you be able to get away without lubing cases since it isn't a bottle necked cartridge? I've never reloaded 30 Carb.....wondered if you could seat the bullet deeper to reduce case capacity and hopefully interference with the rifling in a standard 30 carbine chamber. I'm guessing maybe the 300 blackout would be a heavier case and handle higher pressure loads...any concerns about the 30 carbine case with heavy bullet loads?

Just curious about any other pros and cons I am not considering for these options. Of course being able to get factory loaded ammo would be a big pro for the 300 blackout when it is more readily available, but wondered if there was anything else I'm missing. Just being able to easily convert an AR eventually is a plus but as I said I don't know when/if I will. I like the .308 cal options mainly because I already have a good supply of bullets to play with so that is my focus at the moment.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Sun Mar 27, 2011 10:04 pm
by 300Blk
7.62x25 is something, as far as I know, some guy did because he had a source of cheap ammo. I don't think anyone would want to go into it long-term.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 8:07 am
by daviscustom
I'm actually a bit more curious about 30 carbine since it is not a bottle necked cartridge.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 8:12 am
by 300Blk
30 Carbine: 110 grain at 2000 fps from an 18 inch barrel, 1:20 twist standard.

300 AAC BLACKOUT: 110 grain at 2450 fps from a 16 inch barrel, 1:8 twist standard.

300 AAC BLACKOUT matches the 18 inch M1 Carbine from a 7 inch barrel.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 8:25 am
by daviscustom
Hadn't thought about the standard twist for 30 carbine being so slow, so it would have to be custom barrel.....getting less interesting. What about the case design on it's own as a custom project for subsonics, is there really any downside to 30 carbine? I realize from a marketing standpoint it would be better to create a new cartridge for many reasons, but I'm just curious about this as a custom project.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 9:12 am
by 300Blk
Why bother when 300 AAC BLACKOUT is out?

300 AAC BLACKOUT brass can be made from 223 brass, and there is factory subsonic.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 12:06 pm
by Overton-AR
daviscustom wrote:Hadn't thought about the standard twist for 30 carbine being so slow, so it would have to be custom barrel.....getting less interesting. What about the case design on it's own as a custom project for subsonics, is there really any downside to 30 carbine? I realize from a marketing standpoint it would be better to create a new cartridge for many reasons, but I'm just curious about this as a custom project.

Sounds to me like you are looking for ANY excuse NOT to build or buy a Blackout.

Silvers said it best......Why bother with the others when the BLK is available???

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 12:34 pm
by curious sam
Will the 30 use a 5.56 bolt?

Will the 30 use a 5.56 magazine?

How much is 30 brass?

How available is 30 brass?

How much do we appreciate AAC for making the 300 BLK so that we don't have to answer any of those Q's? :wink:

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 6:11 pm
by snipecatcher
silencertalk wrote:30 Carbine: 110 grain at 2000 fps from an 18 inch barrel, 1:20 twist standard.

300 AAC BLACKOUT: 110 grain at 2450 fps from a 16 inch barrel, 1:8 twist standard.

300 AAC BLACKOUT matches the 18 inch M1 Carbine from a 7 inch barrel.
I'd like to know how you are getting 2000 fps from a 7" barrel. I could get that with my 10", but it's a hot load, and certainly not something I'd feel comfortable shooting much of.


To the OP: The 300 BLK is the best all around choice of the cartridges in question.

Re: Pros/cons of 7.62x25 vs 30 carbine vs 300 Blackout

Posted: Mon Mar 28, 2011 6:14 pm
by 300Blk
I have not verified 2000 fps from a 7 inch barrel, but it should work at 55,000 psi with H-110 powder and a 110 grain bullet - in a real 300 AAC BLACKOUT chamber.