AR-15 7.5" Heavy Barrel, .300 Blackout, 1:7, Stainless

This is a premium grade 7.5" AR-15 pistol barrel from a highly respected U.S. contractor / barrel manufacturer.
These premium barrels are renowned for their deep, crisp, and consistent rifling and extreme accuracy.

1 in 7 twist, gas port drilled at .076 and set up for pistol length gas system with a .750 gas block diameter
Threaded for any standard AR-15 compensator. 

Barrel Extension in rear with M4 feed ramps ready to install into any standard AR receiver.

Barrel is chambered as ..300 Blackout

1 in 7 twist tends to stabilize the heavier grain weight bullets better.  

These barrels are made from 4140 cold rolled steel and are rated at a barrel life of approximately 150,000 rounds. They are very top end. 

They are not chrome lined as most AR15 barrels are not. Chrome lining on modern rifles is typically used where there is a high probability of corrosive ammo being used such as AK type rifles chambered for foreign calibers... 

Since chrome lining may slightly affect accuracy, and since most AR-15 rifles are designed with accuracy as a benchmark, 
and since virtually all .223 / 5.56 NATO is non corrosive...most AR manufacturers do not chrome line barrels.