300AAC pleasant surprise!

[jimb16]

Yesterday I mounted an old Herters 3x scope on my AR15 .300 Blk. I took it to the range this morning to sight in the scope. I placed it on a sandbag and with the lower dropped down, I sighted thru the barrel at a 25 yd target. After adjusting the scope to the same point of aim, I fired a single shot. Line was perfect, but low. Adjust up: shot was same distance high. Split the difference and the shot hit dead center in the bull! 3 shot zero! But that was only the first surprise. The second was when I moved the target to 50 yards. I had thrown together some test loads using the 311413 bullet and 14.0 gr. of H110. The bullets were all "seconds" that I just didn't feel like recasting. I loaded 5 in the mag and started shooting. Couldn't see where I hit. After 5, I went down to inspect the target. With a thrown together load and a 3 power scope I had managed to stack all 5 shots in a single hole just right of dead center. I really love that 300 black out!

[308Jeff]

Noice!

[osteodoc08]

I love all my 300 BLK guns. They are accurate and fun to shoot

[Smoke4320]

Yes they do shoot well
With the right twist and gas system length you can go from 110 to 247 gr bullet

[SciFiJim]

Yes they do shoot well
With the right twist and gas system length you can go from 110 to 247 gr bullet

I am selecting parts for a 300 Blackout AR-15 build. Which twist and gas length would be best? I am thinking a 1 in 8 twist and pistol length gas system, but I am always open to new ideas and info.

[wlc]

From what I've been reading the current recommendation is 7 twist and pistol gas. I've got an 8 twist carbine gas 16" barrel. The 8 twist shoots everything I've fed it so far including 230gr cast. I wish I had pistol gas though. It would give me more options on powders as the amount of gas required to work the action wouldn't be so high.

[Loudy13]

I was also impressed with the BO, I didn't expect the accuracy and accuracy at a distance that it is capable of. Being able to cast for it and having a large amount of options bullet wise was also a nice surprise.

[HeavyHev]

Correct me if I am wrong but aren't all 300BO gas systems pistol? If I recall correctly, the cartridge reaches full burn potential at about 8inches...

[BK7saum]

No. Most 16" barrels and longer are carbine gas. If you want to run subs, most prefer the pistol gas on even a rifle length barrel

[Smoke4320]

Go Pistol length gas and 1-7 if you want to shoot the 247's and/or subsonic easily

[Texas by God]

I have no use for subsonic so my 16" 1-7" carbine gas .300 suits me fine. I'm having a blast with jackets & cast. Best, Thomas.

[Moonie]

I love subs, I have a 16" carbine length gas 1-8" and it cycles 245/247gr at subsonic velocity and they are completely stable. And they are extremely quiet through my can.

[jimb16]

Gas tube length and twist rate depend on what bullet weights you want to shoot.
Shorter bullets at higher velocities generally do well with slower twist rates and carbine length tube. Larger and subsonics do better with a pistol length tube and a fast twist. A 1:8 twist is kind of in the middle and is a good compromise. Mine is 1:8 with a carbine length tube. But I really don't expect to be working much with subs.

[sparky45]

Mine is a 1:7 and it loves the NOE 247gr pile driver.

[dogmower]

I shoot the lyman 311413 sized .309 over 18.5 grains of aa 1680. shoots baseball sized groups at 200 meters (in 20 mph winds). haven't chrony'd it, but should be good for 1750 fps or so.