When To Choose A .308 Over 5.56?

[bzdog]

I would say that is a major oversimplification. With the exception of two limited production Barnes bullets a 300 Blackout with a 9-12 inch barrel will be at or near the minimum expansion velocity at the muzzle for every .308 bullet currently in production.

I'm not sure saying 300 BLK doesn't perform optimally with bullets not designed for it should be considered an issue.

For defense inside of 100 yards 300 BLK with the 110gr Barnes black tip is going to be hard to beat, even out of a very SBR. Make that 200 yards for a 16". With these combinations, the bullet is traveling fast enough for a rifle wound profile and you get reliable expansion and s barrier blind full copper bullet. I'd call this combo for this application cake and eating it too.

After that it gets a bit more gray as the 300 BLK slows down and drops faster. That said, the Barnes black tip reliably expands to 1300 FPS which ends up around 400 yards out of a 16".

And as for availability, the Barnes black tip has been pretty much the only premium ammo that was available through the BLK ammo shortage.

-john

[C-grunt]

I prefer 5.56 as my general purpose carbine. Low reoil, lots of ammo and pretty flat shooting out to 400 yards or so. The 308 I use as a support and precision round. My only 308s have always been precision bolt guns. Though there is a very good argument on using the 308 as a general purpose gun as well. To me the 300 BLK has finally legitimized the PDW concept (excluding the KAC thats not available). Up until now the PDWs have all been lacking in the terminal performance department especially at range. An eight inch 300 BLK has great close end terminal performance but still has some legs under it if the gunfight moves out to a couple hundred yards.

My personal setups (If I could afford all of them)

300 BLK. 8 inch barrel topped with a good red dot 0-250 yards

5.56. 11.5-16 inch barrel topped with a good red dot or low powered optic 0-400 yards

308. 16-24 inch barrel topped with a good low or high powered optic depending on the mission/terrain. 0-1000 yards

[bzdog]

308. 16-24 inch barrel topped with a good low or high powered optic depending on the mission/terrain. 0-1000 yards

While I don't disagree, why .308 over 300 Win Mag or such?

-john

[3ACR_Scout]

I would say that is a major oversimplification. With the exception of two limited production Barnes bullets a 300 Blackout with a 9-12 inch barrel will be at or near the minimum expansion velocity at the muzzle for every .308 bullet currently in production.

I'm confused - I was only comparing .300BLK to 5.56, not .308 (which I acknowledge is a little off the original topic). I was asking because I see a lot of references to .300BLK being ideal for suppressed sub-10.5" SBRs, but it's my understanding that it still offers ballistic benefits over 5.56 in SBRs even if you're not suppressing it. A lot of people feel that you start to run into reliability and terminal performance issues with 5.56 SBRs under 11.5", so I was just curious why people don't seem to recommend .300BLK even in an unsuppressed SBR:

5.56- 11.5-12.5; 200 & in, optimized for close work.
300- 9.5; suppressed badassery
308- 14.5-16, General Purpose

Is it just because there's no real benefit to a 10.5" .300BLK when you can go shorter and still have good performance?

Dave

[Failure2Stop]

I'm just talking about my personal use.
Agreed that 7.62 is not the answer for everybody, and that a 14.5 5.56 makes for a pretty good general issue individual weapon.

Perhaps for an experienced combat arms infantryman or cavalryman. For someone of the other arms (MPs, Engineers, perhaps artillerymen) the individual proficiency and competency of first-line NCOs (let alone the actual trigger-pullers) and sustainment and development opportunities may mean a 5.56 rifle or carbine might be a better option.

Although many troops are "Gun guys," not all are, and the opportunities for on-duty time development are fairly slim.

Not everyone is assigned to a Ranger company or Special Forces unit.

[Failure2Stop]

Yup.
300 Blk is interesting to me in that subsonic is great from a suppressed 9.5, and going supersonic makes the 9.5 viable.

I'm confused - I was only comparing .300BLK to 5.56, not .308 (which I acknowledge is a little off the original topic). I was asking because I see a lot of references to .300BLK being ideal for suppressed sub-10.5" SBRs, but it's my understanding that it still offers ballistic benefits over 5.56 in SBRs even if you're not suppressing it. A lot of people feel that you start to run into reliability and terminal performance issues with 5.56 SBRs under 11.5", so I was just curious why people don't seem to recommend .300BLK even in an unsuppressed SBR:


Is it just because there's no real benefit to a 10.5" .300BLK when you can go shorter and still have good performance?

Dave

[bzdog]

I'm confused - I was only comparing .300BLK to 5.56, not .308

The reason NV brought up .308 is a number of 300 BLK ammunition is made with bullets designed for .308. And, as he says, those combos aren't typically optimal for performance out of 300 BLK. On the other hand it opens the door for less expensive practice ammunition.

Is it just because there's no real benefit to a 10.5" .300BLK when you can go shorter and still have good performance?

Yah, you can go shorter. Should still get good performance from the 8.2" offerings.

-john

[bzdog]

but it's my understanding that it still offers ballistic benefits over 5.56 in SBRs even if you're not suppressing it.

Yup. 300 BLK doesn't lose much in even very short SBRs.

-john

[3ACR_Scout]

Yup.
300 Blk is interesting to me in that subsonic is great from a suppressed 9.5, and going supersonic makes the 9.5 viable.

Thanks, Jack. If I go the LMT MRP SBR route, I'll probably get the 10.5" .300BLK barrel just because it will be interchangeable with the 5.56 barrel, even if it's more length than needed for that round.

Dave

[bzdog]

To me the 300 BLK has finally legitimized the PDW concept (excluding the KAC thats not available). Up until now the PDWs have all been lacking in the terminal performance department especially at range. An eight inch 300 BLK has great close end terminal performance but still has some legs under it if the gunfight moves out to a couple hundred yards.

Over all a good characterization about the performance of the SBR 300 BLK when using good defensive ammunition IMO.

-john