Building a light SASS and have decided on a 20in heavy barrel. I have contacted Obermeyer and the shortest I can get a heavy barrel for the AR is 24in with .920 diameter.
Now what twist rate would be optimum in a 20in for 4-600 meter target shooting/groundhog. Also I am wanting to have the 24in barrel cut down to 20" and threaded for a FH.
Obermeyer’s website states that all barrel blanks do not have threads, or chambers. Who should I contact/who do you all recommend to cut the barrel down, thread the barrel, and chamber it?
Do you have to go with an Obermeyer barrel? You should be able to get an accurate 20" barrel that you don’t have to cut & thread.
Twist rate depends entirely on what bullet you’d like to use and what range you plan to shoot. Will you be reloading or just shooting factory ammo?
For longer ranges you’ll want a bullet that balances a good ballistic coeffecient with enough velocity & explosive terminal impact for an assured kill. A longer barrel is better for longer ranges because it gives you higher muzzle velocities.
I would select a different barrel. I’d look toward somebody that makes complete AR bbls that are ready to shoot. I’d consider somebody like Satern, Shilen, etc.
For the bullets you intend to use, most would recommend a 1:7" or 1:8" twist rate.
Contacted Satern and Shilen already. Satern did not have any barrels in the diameter or caliber that I wanted on hand and had a long wait time. Shilen has discontinued the barrel that i wanted with the particular rate of turn. All they offer now in heavy barrel 223 is 1:12 in 24in. I would still have to have it cut down to 20 and have it threaded, if I still have to send it off I might as well get what I want.
Out of curiosity, why is the diameter the deal breaker?
I would take a look at Superior Barrels also, but if it were me, I would prioritize quality, twist, and length over diameter. There are plenty quality 1/7 or 1/8 20" barrels out there that are good to go.