My 300 Blkout rifle build

[Lumber_Jack]

BTW, I think the ballistic information is a bit optimistic, IMO.

So, you think they are just making up their data? I would believe a commercially produce round would have actual measured data.

[Guest nysos]

The more I look at the 300 blk, the more I am thinking that I will make the step into the class 3 realm with a 300 blk SBR and shortly after with a can....

[Dolomite_supafly]

The more I look at the 300 blk, the more I am thinking that I will make the step into the class 3 realm with a 300 blk SBR and shortly after with a can....

+1

A subsonic, actually any subsonic, load is pretty much useless without some sort of suppression. They are as loud as a normal round. The only thing they do not have is the concussive blast the shooter feels from full power loads.

The only thing that I have found to help with noise without the use of a suppressor is a long barrel. And when I say long I mean really long. I did have some 30 caliber subsonic loads that were as quiet as a 22lr without the use of a can but it took a barrel that was 24.5" long to get it to those levels. And at 24" it was an unhandy beast. My next build I used a 16" barrel and it was noticeably louder. I would guess they were about as loud as my wife's 9mm AR.

There is a problem with long barrels though. I have read that long barrels tend to cause problems with velocity consistency with subsonic loads. And with a normal, high velocity caliber, this inconsistency isn't as noticeable as with a subsonic load. Having a 223 drop from 3100 fps to 3000 fps isn't going to make that much of a difference in it's useable range. Now a subsonic load going from 1050 fps to 950 fps can have huge implications, as in a difference of close to two feet at 300 yards and six inches at 200 yards with a 100 yard zero.

Another problem with long barrels is factory loads that are listed as subsonic can go supersonic with the extra barrel length. I know this is true with most 147 grain 9mm rounds out of 16" barrels.

So for the optimal subsonic rifle I would consider a short barrel a must. If you don't want a short barrel then you will have to reload to get the velocities to where you want.

The 300BLK is the best thing to happen to subsonic shooters. Before this caliber there were never any real mainstream subsonic calibers. Bullet makers are testing and making bullets for subsonic performance. Even as short as 4 years ago we would have to compromise. I wish suppressor would become so mainstream that their regualtion would go away. Heck, back aobut 100 years ago you were considered a considerate shooter if you had a suppressor on your firearm when at the local range. One can only hope.

Dolomite

[William_Munny]

So, you think they are just making up their data? I would believe a commercially produce round would have actual measured data.

Not really... just overstating it. I feel because of the characteristics of the case capacity... unless of course they were using some proprietary hyperfast propellant but even then, I can't see it... I bet no handloader can mimic their published results...

...Which also begs the question, if they solved the .30 cal AR-15 platform problem with the .300 blackout, why did they (Remington) develop the .30 RAR... seems odd don't you think?

[Dolomite_supafly]

The 300 BLK was designed to be a subsonic round from the get go. Never was it meant to go super but they did make some factory supersonic loads. They also took into consdideration ease of use. You can use the same mags and get the same capacity in thos mags.

I would liken it to the 7.62x39 as far as energy levels and velocity levels. I have loaded the 7.62x39 with heavy projectiles in an attempt to do the same the BLK does. This was before the BLK came to market. Worked well but I had to handload. With the BLK it is not required to handload anymore.

Dolomite

[Lumber_Jack]

...Which also begs the question, if they solved the .30 cal AR-15 platform problem with the .300 blackout, why did they (Remington) develop the .30 RAR... seems odd don't you think?

the Remington website describes it as an hunting load in .30 cal that will function in an AR.

I think the 300 BLK is marketed completely different. As Dolomite said it's meant to be suppressed from short barrels. Not a long range killer.

Plus I would say Remington's main goal was to make money with it's own proprietary round.

[mikegideon]

Here's one I whipped up for giggles. Looks like a 110gr bullet hauls ass at close to max load...

[Lumber_Jack]

Here's one I whipped up for giggles. Looks like a 110gr bullet hauls ass at close to max load...

What about a 123gr similar to what the website lists? I that easy to run?

They claim 2315ft/s & 1462ft-lb

[mikegideon]

What about a 123gr similar to what the website lists? I that easy to run?

They claim 2315ft/s & 1462ft-lb

I looked for a 123. The point of this exercise is that you should be able to get close to those numbers with the available case capacity.

[Lumber_Jack]

I looked for a 123. The point of this exercise is that you should be able to get close to those numbers with the available case capacity.

Well I'm no ballistic guru. I notice the numbers were close with 110gr, but wasn't sure how much a heavier bullet would change things

[mikegideon]

There's more to it. I'm not familiar with the fine details of the caliber, so the seating depth is probably too deep. Also didn't play with various powders. The manufacturers can sometimes get a little more velocity using canister powders too. A 123 is gonna be a little slower, but not by alot. It was just a quick check. Looks like the 300blk is way more than a pistol round.

I may play with it some more. Quickload has a huge bullet library, but they're sorted by manufacturer.

[Guest rsilvers]

The 300 BLK was designed to be a subsonic round from the get go. Never was it meant to go super but they did make some factory supersonic loads. They also took into consdideration ease of use. You can use the same mags and get the same capacity in thos mags.

I would liken it to the 7.62x39 as far as energy levels and velocity levels. I have loaded the 7.62x39 with heavy projectiles in an attempt to do the same the BLK does. This was before the BLK came to market. Worked well but I had to handload. With the BLK it is not required to handload anymore.

Dolomite

I am the project lead on this. We designed it primarily as a supersonic round which would provide AK ballistics in an AR, while working with a normal bolt and magazine. The ammo prices will be much less than 6.8 SPC, and it has a bunch more energy than 5.56mm - not to mention it is legal for hunting in more states.

This is now a SAAMI standard - the drawing is on the SAAMI website. There are over 40 companies already supporting it.

Lots of info here: SilencerTalk • View forum - 300 AAC BLACKOUT OFFICIAL DISCUSSION AREA

[mikegideon]

The cool thing about the AAC is the .223 parent case. It's on my list to play with as soon as I get the SOCOM running well with my own loads.

[Guest rsilvers]

Yes, look how cheap brass is:

Advanced Armament Co (AAC) Brass 300 AAC Blackout (7.62x35mm) Box of 100 - MidwayUSA

[Guest rsilvers]

[mikegideon]

Yes, look how cheap brass is:

Advanced Armament Co (AAC) Brass 300 AAC Blackout (7.62x35mm) Box of 100 - MidwayUSA

That's cool, and there's a gazillion bullet choices.

[Lumber_Jack]

So the 220gr bullet passed straight through the melon but the 110gr exploded. Someone explain that to me.

[mikegideon]

So the 220gr bullet passed straight through the melon but the 110gr exploded. Someone explain that to me.

If the 110gr was a Match King, they tend to fly apart.

[Lumber_Jack]

Ahh I see makes sense

[Dolomite_supafly]

With bullets, especially rifle bullets, there is a happy medium where they work the best. Penetration increases as velocity drops at least to a point. I have viewed charts were Sierra Pro hunter bullets have penetrated over 60" (that is over five feet) when the velocity got down into the 1900 fps range. Now that same bullet only went 12.3" when at 3100 fps. And most modern hunting bullets act the same.

The reason some work better than others is bullet design as well as velocity. Bullets are designed to work within a certain range of velocities. If you get out of that range performance tends to go bad quickly, either too much penetration or too little. With that being said the 220 grain SMK's are probably stabilized to a point where they will not tumble and do not have enough velocity to cause them to come apart upon impact or inside the target. So the only thing they can do is just pass throguh without causing a lot of damage. Now if you push SMK's beyond their upper limits they will come apart very violently because of their thinner jackets. The 110 grain V-Max bullets on on the other hand are designed to come apart more readily and probably at a lower velocity. They were likely travelling within or at least closer to the velocity range it was designed for.

It is all about bullet design and velocity.

I have done a lot of testing on subsonic 308 bullets. Using various weights as we were trying to find a reliable HP that would expand at the subsonic velocities we were working with. We couldn't find any then a lightbulb went off. We decided to slow the twist down to a point where the bullets would tumble upon impact but would be stabile enough for flight. Using a 10 5/8 twist barrel shooting 180 grain Sierra Pro Hunters at subsonic velocities (~1050fps-1100fps) they would tumble between 6"-10" of water. And in the process cause damage that was substantially more than the same load out of a faster twist barrel.

The V-Max rounds exploded in the pumpkin while the SMK's didn't because they were travelling beyond the limits of their structural integrity. As a result the V-maxes were able to dump more of their energy into the pumpkin than the SMK's. It is not without issue though because I can also assure you that the V-Maxes have a lot less penetration than the SMK's. It is all about what you want to do.

the 300BLK is going to create a revolution in subsonic friendly bullets. Once it really takes off, which it has already for the most part, manufacturers are going to see a market for subsonic friendly bullets and begin selling them.

Dolomite

[Guest SMZRU275]

I ran two homeloads today through mine. A 110gr and a 147gr. Both in reformed 5.56 to blkout cases. Overall the 147gr performed better in feeding. I don't have a chrono yet to say what FPS they were, but both were loaded to supersonic load specs using H110 and the Hodgdon data sheet.

The rifle itself functioned fine and got the red dot pretty much dial in, but ran out of rounds to get the irons zeroed.

I spent A LOT of time on Silencertalk reading on the blkout info, especially the reloading thread.

[mikegideon]

With bullets, especially rifle bullets, there is a happy medium where they work the best. Penetration increases as velocity drops at least to a point. I have viewed charts were Sierra Pro hunter bullets have penetrated over 60" (that is over five feet) when the velocity got down into the 1900 fps range. Now that same bullet only went 12.3" when at 3100 fps. And most modern hunting bullets act the same.

The reason some work better than others is bullet design as well as velocity. Bullets are designed to work within a certain range of velocities. If you get out of that range performance tends to go bad quickly, either too much penetration or too little. With that being said the 220 grain SMK's are probably stabilized to a point where they will not tumble and do not have enough velocity to cause them to come apart upon impact or inside the target. So the only thing they can do is just pass throguh without causing a lot of damage. Now if you push SMK's beyond their upper limits they will come apart very violently because of their thinner jackets. The 110 grain V-Max bullets on on the other hand are designed to come apart more readily and probably at a lower velocity. They were likely travelling within or at least closer to the velocity range it was designed for.

It is all about bullet design and velocity.

I have done a lot of testing on subsonic 308 bullets. Using various weights as we were trying to find a reliable HP that would expand at the subsonic velocities we were working with. We couldn't find any then a lightbulb went off. We decided to slow the twist down to a point where the bullets would tumble upon impact but would be stabile enough for flight. Using a 10 5/8 twist barrel shooting 180 grain Sierra Pro Hunters at subsonic velocities (~1050fps-1100fps) they would tumble between 6"-10" of water. And in the process cause damage that was substantially more than the same load out of a faster twist barrel.

The V-Max rounds exploded in the pumpkin while the SMK's didn't because they were travelling beyond the limits of their structural integrity. As a result the V-maxes were able to dump more of their energy into the pumpkin than the SMK's. It is not without issue though because I can also assure you that the V-Maxes have a lot less penetration than the SMK's. It is all about what you want to do.

the 300BLK is going to create a revolution in subsonic friendly bullets. Once it really takes off, which it has already for the most part, manufacturers are going to see a market for subsonic friendly bullets and begin selling them.

Dolomite

The Barnes TTSX fully expands at 1000fps in .458 caliber. I'll bet it will in .308 as well. Not cheap, but good for low pressure stuff.

[Alleycat72]

All shot into wet newsprint @ about 1000 fps

Edited September 19, 2011 by alleycat72

[Guest chosinsteve]

Man, that does look good! I was at a gun show in Atlanta not too long ago and AAC/Remington had a booth and I fondled some of the samples they had and it felt just like any of my other AR's. The ammo is the only thing that's stopping me from diving head first in the 300 blkout, I haven't seen any at the 2 local stores where I am stationed.

[Dolomite_supafly]

I bet they, Remington, would sell a ton of bolt guns in this caliber. Build it like their AAC-SD with the threaded barrel except in 300 BLK. Make the barrel a 16" or maybe a 18". Bottom metal would be a great addition as well.

Although the AR's are quiet the ultimate is something that doesn't have to cycle, either a bolt gun or some other type of single shot. Or even a gas block on an AR that can easily be turned off and the bolt cycled by hand.

This has got my wheels spinning again. $200 stamp for a 30 caliber can, $80 in materials and barrel built for $250. I would use my Savage because I can replace the barrels on it in about 10 minutes. Might need to do that rather than the 9mm bolt gun I was considering.

Dolomite