.300 Blackout Questions.

[ASP785]

Do you have velocity data for those two tests? (it is very relevant if we are looking at bare gel).

I do have the velocities but I disagree with you that the velocities are very relevant for Barnes bullets. For M193 and M855, the faster the better as those are bullets whose primary wounding mechanism is fragmentation and have a certain velocity range in which they will fragment. A bullet, such as the Barnes, whose primary wounding mechanism is controlled expansion, velocity is not so relevant, as long as impacts are in the velocity range where the bullet is designed to expand.

See the link for more information on this: http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/DocGKRData/223 Barrier Rounds.htm

The link shows Barnes bullets with a near 600 FPS velocity differential fired from multiple barrel lengths. Their is almost no difference between expansion and penetration in the 8" barrel and 20" barrel gel photos.

To answer your question, the data from my earlier post includes two SBR's. 2186 fps for the 9" 300 blackout and 2425 fps for the SBR 5.56.

 

[MoBoost]

The link shows Barnes bullets with a near 600 FPS velocity differential fired from multiple barrel lengths. Their is almost no difference between expansion and penetration in the 8" barrel and 20" barrel gel photos.

This is pretty amazing, penetration is identical, therefore energy dump is very efficient - just look at the temporary cavity difference!

Thanks for the links!

 

[aeropb]

If I wanted another 30 caliber SBR I might get a 300 blk upper and fool around with the 110's and 125's. Subsonic is a joke

 

[aestus]

Lol, didn't expect a thread on 300 blk would spark this much debate.

Wrong - once the bullet leaves the barrel only gravity, drag and gyroscopic stability matter.

Again, wrong - shape of the case has nothing to do with bullet flight (see above). There is indeed trivial difference in caliber (.308 vs .310) - but for sake of this discussion it is 100% negligible.

I didn't say shape of case. I said shape of projectile and yes it does matter. Higher ballistic coefficient = better performance, retained energy and accuracy. It proven that longer shaped projectiles not only have a better BC, but have better accuracy and retained energy in long distances. Here's a pic of a typical 7.62x39 rounds vs a 300 blk round. Notice that the ogive is longer in a 300 blk specific .308 projectile compared to your usual .308 projectile. This is what gives 300 blk it's higher BC. Could you load a 300 blk projectile in a 7.62x39 case? I suppose you could. Most AK barrels are usually .311 and I would also question how the 300 blackout specific .308 projectiles would function and group in a 7.62x39 case, since these seem to have a different ogive than the run of the mill .308 projectiles.

Again, this is ridicules - you can use the same darn bullet in either cartridge, one just had more boiler room and can shove the same bullet faster. Apples to apples.

Actually, not really. You can probably make the shorter, rounder .311 AK style bullet projectile work in a 300 blk case. Might run into pressure issues running a .311 bullet through a .308 bore and possibly feeding issues if it makes the overall length of the round too short. Loading longer and heavier grained .300 blk bullet projectile (.308) in a 7.62x39 case might not chamber correctly, since .308 loaded 7.62x39's already tend to run right up to bore. And then there's the question of the 300 blackout specific projectiles that are are typically longer in taper and ogive shape than your standard .308 rounds and also the use of pistol powders, which may mean having to run a shorter custom gas tube, piston and barrel for the AK to cycle correctly.

I actually started gathering numbers regarding 300 blk performance vs typical m193 and mk262 and was going to try and get numbers for the Barnes VOR-TX for .300 blk (which is absolutely brutal and too good to be true), but it's 3 AM and decided against it. We can spout numbers all day back and forth and it won't end. You will show numbers showing why 300 blk sucks and can be factually true. I can show numbers showing why 300 blk is awesome and be factually true.

What the numbers do show is that 300 blk achieves comparable and sometimes better performance than .223 or 7.62x39 when comparing them in supersonic loads and shines in shorter barrels. That's what it was designed for. It's not the ninja round made with unicorns blood that will replace .223, 7.62x39, or any other round. It has a niche and serves it well, it's icing that I can switch mags and run supersonic rounds instantly and get comparable results as .223 or 7.62x39. Comparable, not necessarily better.

To say that 300 blk is optimized for nothing is really reaching for straws. Even the most staunch nay-sayers will concede that out of a suppressed SBR, you'll be hard pressed to find better that runs reliably in an AR platform with the same performance. (Off tangent, but 300 blk is actually hotter than 300 whisper. You can shoot 300 whisper out of 300 blk chamber, but not recommended the other way around.) The performance of 300 blk compared to pistol caliber smg's can't even compare, since the 300 blk demolishes the pistol calibers in energy just due to the sheer size and weight of the caliber, offers superior barrier penetrating capabilities and it's just as quiet as the pistol calibers suppressed. And unlike pistol calibers running subsonics, you can easily just slap a mag full of supersonic 300 blk and engage targets out past 100 up to 300 yards with minimal reduction of effectiveness. You can't say that with a pistol caliber SMG.

Anyways, if you don't like 300 blackout that's fine. Some people think 6.5 Grendel is the absolute cat's meow, good for them. I find 300 blackout as a general use SBR caliber that gives me the option to be run suppressed in a AR platform using the same components, bolt, mags, ect. to be good enough to invest in. There's really not another caliber in such a common platform like the AR that allows such commonality of parts and .223 still isn't going to go away anytime soon.

 

[MoBoost]

Lol, didn't expect a thread on 300 blk would spark this much debate.

debate = info = everyone wins.

I didn't say shape of case. I said shape of projectile and yes it does matter. Higher ballistic coefficient = better performance, retained energy and accuracy. It proven that longer shaped projectiles not only have a better BC, but have better accuracy and retained energy in long distances.

Agree with everything except for accuracy - 6PPC uses short, fat, flat base bullets - and reigns undisputed short distance accuracy king.

Here's a pic of a typical 7.62x39 rounds vs a 300 blk round.

This is a picture of 1950 com-block FMJ bullet compared to a modern match bullet that went through a tipping die - apples to oranges, that raises all kinds of "bs flags" in my mind.

Notice that the ogive is longer in a 300 blk specific .308 projectile compared to your usual .308 projectile. This is what gives 300 blk it's higher BC. Could you load a 300 blk projectile in a 7.62x39 case? I suppose you could. Most AK barrels are usually .311 and I would also question how the 300 blackout specific .308 projectiles would function and group in a 7.62x39 case, since these seem to have a different ogive than the run of the mill .308 projectiles.

You can build 7.62x39 with 308 bore ... again you can compare bottom of the bucket AK barrel to a custom built barrel to a custom bullet - but we are back to apples to oranges.

And then there's the question of the 300 blackout specific projectiles that are are typically longer in taper and ogive shape than your standard .308 rounds and also the use of pistol powders, which may mean having to run a shorter custom gas tube, piston and barrel for the AK to cycle correctly.

Pistol powders are used because you have pistol sized case - 357 Magnum to be exact.

We can spout numbers all day back and forth and it won't end. You will show numbers showing why 300 blk sucks and can be factually true. I can show numbers showing why 300 blk is awesome and be factually true.

That's my whole point - it filled the niche that in my opinion doesn't exist.

To say that 300 blk is optimized for nothing is really reaching for straws. Even the most staunch nay-sayers will concede that out of a suppressed SBR, you'll be hard pressed to find better that runs reliably in an AR platform with the same performance.

5.56 the AR was designed for runs just fine suppressed.

The performance of 300 blk compared to pistol caliber smg's can't even compare, since the 300 blk demolishes the pistol calibers in energy just due to the sheer size and weight of the caliber, offers superior barrier penetrating capabilities and it's just as quiet as the pistol calibers suppressed.

I think you are forgetting that all pistol rounds (minus mouse guns) run bigger caliber AND heavier bullets. The energy/penetration of 300blk comes from velocity fired from a rifle @ 55000 psi.

And unlike pistol calibers running subsonics, you can easily just slap a mag full of supersonic 300 blk and engage targets out past 100 up to 300 yards with minimal reduction of effectiveness. You can't say that with a pistol caliber SMG.

a) 125gn@2200 vs 220gn@950 - POI is totally different - so slap a mag and go to range to re-zero, engage targets is the reality.
b) Past 100 yards, 1" drop every 2 yards is not exactly "effective" .... sorry man, if you are shooting subsonics past 100 yards - you are doing it wrong.

I find 300 blackout as a general use SBR caliber that gives me the option to be run suppressed in a AR platform using the same components, bolt, mags, ect. to be good enough to invest in. There's really not another caliber in such a common platform like the AR that allows such commonality of parts and .223 still isn't going to go away anytime soon.

As I said - 5.56 runs suppressed just fine, so why reinvent the wheel? Or the 300AAC sales pitch clouds your mind and you think suppressed = subsonic?

 

[ASP785]

The thing that really angers me about this thread is that I argued the side FOR the 300 blackout cartridge and after debating with MoBoost I am wondering if the cost for what I perceive to be as better performance is worth not having access to the 10000 or so pieces of 5.56 brass I have in inventory especially after viewing the photos in the link I posted....dangit! I do not want to have to fire form 300 blackout cases either.

I could care less about shooting subsonic suppressed. It just doesn't matter to me. I do have concerns about being able to shoot a SBR 5.56 bot unsuppressed and then suppressed without changing anything with the gas system. Perhaps these concerns are unfounded or that is what Noeveske invented the switchblock to deal with. I am glad I put 'Multi' on my Form 4. It was a rookie mistake but it gives me more time to decide.

 

[aestus]

The thing that really angers me about this thread is that I argued the side FOR the 300 blackout cartridge and after debating with MoBoost I am wondering if the cost for what I perceive to be as better performance is worth not having access to the 10000 or so pieces of 5.56 brass I have in inventory especially after viewing the photos in the link I posted....dangit! I do not want to have to fire form 300 blackout cases either.

I could care less about shooting subsonic suppressed. It just doesn't matter to me. I do have concerns about being able to shoot a SBR 5.56 bot unsuppressed and then suppressed without changing anything with the gas system. Perhaps these concerns are unfounded or that is what Noeveske invented the switchblock to deal with. I am glad I put 'Multi' on my Form 4. It was a rookie mistake but it gives me more time to decide.

Shooting 5.56 SBR suppressed and unsuppressed should be no issue. The only thing I can see (and this is a little on the extreme side) is if you're running a 7.5" barrel with an uber heavy buffer like an H3 AND extra power springs that's tuned specifically to run really hot 5.56 loads suppressed and then decided to change to uber weak steel cased .223 ammo in the next mag change unsuppressed. Then maybe you may run into issues, but most likely can be corrected in that particular case by using standard springs and using a lighter buffer.

Also, shouldn't really need a switchblock if tuned properly to cycle everything from hot 5.56 to weaker .223 steel cased. Sure it might mean your hotter 5.56 loads may "eject wrong" or pound you a little harder, but I would rather have a rifle that works than a rifle I constantly have to break out the tools and spend money to "tune." If you got loads of 5.56 brass that you don't want to turn into 300 blk, then a 5.56 sbr may be a better solution for you. Typically 10.5" aren't as finicky. 11.5" usually just works with little no tuning needed.

The 300 blk sbr I'm building is mainly going to serve as short range brush gun hunting / HD / fun gun. I won't be shooting carbine courses with it so having cheap bulk ammo by the thousands is not an issue for me for the 300 blk SBR I'm building.

 

[WideLoadTimmy]

debate = info = everyone wins.

This

Good grief! I'm gone for a couple days and I come back to this. Awesome info. This is tits. Can I try to steer the thread toward hunting? What about using .300blk to hunt hog/deer with? I imagine it would be a good idea if I wanted versatility out of my same rifle but lets take that out of it and focus on cost vs. return. Would I be better served building/buying a .300blk upper for an existing rifle or would it cost less (or give me more gain) to take MoBoost's advice and go with the bolt gun? I'm sure that if I wanted, I could find a used Remington 700 or Savage in .308 for a reasonable price but how would that price compare to building/buying an upper? We'll leave the glass out of the equation for now because I'd need that, regardless of the route I take.

 

[MoBoost]

Can I try to steer the thread toward hunting? What about using .300blk to hunt hog/deer with?

If you want to use your AR - find the 5.56 load that works and put them where it counts - on hogs two inches behind the ear drops them without squealing (aka instant death).

would it cost less (or give me more gain) to take MoBoost's advice and go with the bolt gun?

This year I hunted with Marlin XS7 in 7mm-08 that I picked up new on gunbroker for $206!! That's about the cost of the barrel alone ....

 

[aestus]

This

Good grief! I'm gone for a couple days and I come back to this. Awesome info. This is tits. Can I try to steer the thread toward hunting? What about using .300blk to hunt hog/deer with? I imagine it would be a good idea if I wanted versatility out of my same rifle but lets take that out of it and focus on cost vs. return. Would I be better served building/buying a .300blk upper for an existing rifle or would it cost less (or give me more gain) to take MoBoost's advice and go with the bolt gun? I'm sure that if I wanted, I could find a used Remington 700 or Savage in .308 for a reasonable price but how would that price compare to building/buying an upper? We'll leave the glass out of the equation for now because I'd need that, regardless of the route I take.

For purely for hunting purposes, going with a bolt gun can start out cheaper and get expensive pretty quick, depending on how custom you make your bolt gun. A standard bolt gun from Savage will run about $400 and go up from there. If you know how to shop around online and wait for the best deals, you can build a new .223 or 300 blk upper for about the same price. My 300 blk upper costs me $417 to build. Would actually be cheaper if I had gone with a 16" stainless steel barrel, but companies like to charge more for shorter barrels... >.<

Typically I think bolt gun are better for game hunting and would lean in that direction. For predator / varmint hunting I like semi-auto. Unless you already have AR upper parts lying around, it would probably be better to get a bolt gun in .308. That would give you 2 different guns (if you already have an AR) capable of a wide gamut of uses in between.