300 Blackout Barrel Twist Rate

[Odd Shot]

What are people's thoughts on the twist rate for 300 Blackout?

I was on SIG Sauer's website checking out the MC Virtus SBR in 300 Blackout, and noticed that it comes in a 1:5 twist rate.

 

[just having some fun]

I a not a big expert on Bullet Stability/ barrel twist

7-8 twist is the more common twist for the Blackout

But the fast twist might be better for the sub sonic Bullet Stability

not sure.. it is one of those things... it might work

the worst case i could see would be a 220g vld at .... its the length/ twist/ speed combination

 

[greg olmstead]

1:7 to stabalize the long bullets like 210 or 220 at subsonic speeds. A bullet need to hit a certain rpm to stabalize. Doesnt matter how fast it's going it just needs to spin. 1:5 seems a little aggressive

 

[cr5]

I own 7 and 8 twist 300BLK rifles (have owned 5 different 300BLK rifles over the last few years) and shoot 200+ grain projectiles subsonic with them, accuracy has never been stellar with the heavier stuff (2-3 moa ish) but they've all shot lighter supersonic loads sub moa.

I lost interest in shooting the heavy loads subsonic, we can't use a suppressor so you still have to use hearing protection and since the lighter projectiles are cheaper and more accurate I just shoot them.
I do have a 150gr subsonic load for my bolt action that shoots very well but it won't cycle my semi auto 300BLK.

The hardest thing I found when trying to run the 200+ grain projectiles subsonic is finding a load that will cycle the action of a semi and still remain subsonic. It's a very fine line when loading for the rifles. I guess I should mention that this was easier when I had shorter barrels on my AR's but now I'm running an 18.6 inch on my semi so it's a little harder to keep the velocity down and still cycle the action.

I don't think I would bother with a 5 twist unless all you planned to run was heavy subsonic loads, it doesn't sound like it would be a good "all around" twist rate even though I'm not one who subscribes to the spin too fast theory. I don't think you can overstabilize or spin a bullet so fast it loses stability, I have spun thin jacket varmint bullets so hard they've come apart in the air from a 7 twist 223 but until you get to that point I haven't seen any evidence that you can over spin a bullet.

Powder selection is very important with the 300BLK, I own but haven't tested 4227 and CFEBLK but one of these days I'll get around to it.
From my experience with the powders I've used so far.
H110 is used for 100-150gr projectiles
Lil'Gun is my go to for 140-168gr supersonic loads (155gr sub moa in both my rifles).
A1680 is my 200+gr subsonic powder.
I also have a supersonic load with A1680 and a 155A-max that shoots sub moa in both rifles as well.

Something to note as well, not all factory ammunition will cycle a semi auto, I had a PWS 10 inch piston driven AR for a couple years and even though it would cycle my 208gr subsonic handloads it wouldn't cycle Hornady 208gr subsonic factory loads. If you have issues with factory ammo it may not be a problem with your rifle.

In my opinion I would skip past anything 300BLK in a restricted rifle unless you don't care about ammo costs, 300BLK is a very versatile round but if you're just sitting at a gun range shooting from a bench at paper and steel you'll get a lot more pleasure from just shooting a 223 instead, you'll be able to shoot accurately further out with less compensation for trajectory and you'll shoot more rounds for the same money. Away from the range is where it shines, I can load it for varmint/predator control and also for deer hunting, and when I feel like it I go target shooting with any weight of projectile. It's a great round, I just see very little benefit at a range with it.

Also, don't believe for one second that the 300BLK was "optimized" for a 9 inch barrel. That is total and complete garbage. The 300BLK benefits from a longer barrel just like any other cartridge gaining velocity the longer you go. It is better than a 223 with a short barrel when velocity loss per inch of barrel is concerned but there was no optimizing or tuning the round for a 9 inch as some people like to spew.

 

[ColinD]

I own 7 and 8 twist 300BLK rifles (have owned 5 different 300BLK rifles over the last few years) and shoot 200+ grain projectiles subsonic with them, accuracy has never been stellar with the heavier stuff (2-3 moa ish) but they've all shot lighter supersonic loads sub moa.

I lost interest in shooting the heavy loads subsonic, we can't use a suppressor so you still have to use hearing protection and since the lighter projectiles are cheaper and more accurate I just shoot them.
I do have a 150gr subsonic load for my bolt action that shoots very well but it won't cycle my semi auto 300BLK.

The hardest thing I found when trying to run the 200+ grain projectiles subsonic is finding a load that will cycle the action of a semi and still remain subsonic. It's a very fine line when loading for the rifles. I guess I should mention that this was easier when I had shorter barrels on my AR's but now I'm running an 18.6 inch on my semi so it's a little harder to keep the velocity down and still cycle the action.

I don't think I would bother with a 5 twist unless all you planned to run was heavy subsonic loads, it doesn't sound like it would be a good "all around" twist rate even though I'm not one who subscribes to the spin too fast theory. I don't think you can overstabilize or spin a bullet so fast it loses stability, I have spun thin jacket varmint bullets so hard they've come apart in the air from a 7 twist 223 but until you get to that point I haven't seen any evidence that you can over spin a bullet.

Powder selection is very important with the 300BLK, I own but haven't tested 4227 and CFEBLK but one of these days I'll get around to it.
From my experience with the powders I've used so far.
H110 is used for 100-150gr projectiles
Lil'Gun is my go to for 140-168gr supersonic loads (155gr sub moa in both my rifles).
A1680 is my 200+gr subsonic powder.
I also have a supersonic load with A1680 and a 155A-max that shoots sub moa in both rifles as well.

Something to note as well, not all factory ammunition will cycle a semi auto, I had a PWS 10 inch piston driven AR for a couple years and even though it would cycle my 208gr subsonic handloads it wouldn't cycle Hornady 208gr subsonic factory loads. If you have issues with factory ammo it may not be a problem with your rifle.

In my opinion I would skip past anything 300BLK in a restricted rifle unless you don't care about ammo costs, 300BLK is a very versatile round but if you're just sitting at a gun range shooting from a bench at paper and steel you'll get a lot more pleasure from just shooting a 223 instead, you'll be able to shoot accurately further out with less compensation for trajectory and you'll shoot more rounds for the same money. Away from the range is where it shines, I can load it for varmint/predator control and also for deer hunting, and when I feel like it I go target shooting with any weight of projectile. It's a great round, I just see very little benefit at a range with it.

Also, don't believe for one second that the 300BLK was "optimized" for a 9 inch barrel. That is total and complete garbage. The 300BLK benefits from a longer barrel just like any other cartridge gaining velocity the longer you go. It is better than a 223 with a short barrel when velocity loss per inch of barrel is concerned but there was no optimizing or tuning the round for a 9 inch as some people like to spew.View attachment 301305

This is some great Info.

I'm building a MS with 300BLK for hunting mainly. I have very little knowledge about the round, but would like to use some 223 brass to load.

I'm going to start a 300BLK thread for NR semi rifles if I can't find one in the search menu.