Interest in 300 AAC Blackout?

[Nwcid]

Sorry I will rephrase why is 1:7 better then the 1:8? The 1:10 is not fast enough for slow long bullets.

Here are PAGES of info all suggesting 1:8, what twist for .300 whisper - Google Search

As I posted in my first comment I never said the 1:7 was bad, but the 1:8 would destabilize on impact.

 

[Burt Gummer]

The Liberty Leonidas seems like a great internally suppressed 300Blk. I don't think they are shipping them until November, or so I've heard. Full AR, upper only, or convert your AR. Dan Dee Sales here on the forum carries Liberty products. Since the overall length of the 'barrel' is over 16" it is OK in Washington which is great.

 

[Mecanik]

I've been looking for a .300 BLK barrel for months now. Who has one actually for sale. I have no interest what so ever in suppressed loads and I'm looking mainly for a "deer capable" AR-15 with .30 cal bullets. The .300 blk seems perfect.

 

[del_and_bones]

I built a 9" 300BLK SBR as a range toy (subsonic suppressed) and a deer rifle (supersonic suppressed). She tips the scale at 7lbs with an Aimpoint T1 and a 762SDN6. It's as heavy as a comparable bolt-action, has great balance, and relatively low recoil. The velocity loss for short barrels, even with 110gr bullets, is fairly low IMHO.

Muzzle energy using graph below for 110gr:
16" ~2450 fps - 1470 ft-lbs
12.5" ~2300 fps - 1290 ft-lbs
9" ~2150 fps - 1130 ft-lbs

12-13" seems to be the sweet spot to me.

Graph: 110gr bullet velocity vs barrel length posted by Robert Silvers on various forums

 

[SIG383]

What kind of velocity and energy be given with an 18" barrel? I'm looking for a 300BLK to be used for deer and such and don't have much interest in the subsonic/suppressed use for the time being(might build a shorter one down the road for this). If there is not much difference between the 16 and 18" I'll go with the 16. Thanks!

 

[del_and_bones]

You won't gain a lot of velocity going 16" to 18". The efficiency of the cartridge is extremely high, meaning that in a short barrel you have a relatively complete powder burn. Using 110gr ammo, going from a 16" to 9" barrel you will only gain ~300fps MAX or about 43fps per inch of barrel (this is a non-linear relationship but for all practical purposes it can be approximated to one). If you use over 110gr bullets, the difference shrinks to ~200fps between a 9" and 16". After 16" you get diminishing returns, that 2" might get you around 40 - 80fps. Plus everyone and their mother makes 16" barrels and uppers.