My 300 BLK upper is great, but I have an impulse to try a different barrel. I like the 10" handguard and stuff. The website says the barrel (1:8 ) is carbine gas but it's 4" from the barrel nut so I assume it's pistol. I'm thinking of trying a carbine gas with a 1:7. Other than that, what do you recommend? Without a suppressor, I'm mostly not interested in subsonic. Classic Firearms has some inexpensive barrels but their shipping of course is almost as much as the barrel. I'm also thinking of CMMG. https://ironcityarmory.com/shop/barrels/cmmg-cmm-mk4-mr-4140cm-300blk-16-1/ 

I have a CMMG complete upper in 300 BLK. I like it. It has been reliable and accurate with Speer 130gr Hot Cor, Sierra 125gr SMK and 130gr SMK. It has been accurate with other bullets as well. But the Speer's are the best. I tried lead boolits and they are good enough for practice at close distances (Like when I shoot with HDF or HRA in the action bays) but not accurate enough at 50yds+ for my taste. So I stick with the above referenced bullets. The Speer bullet is really short making for a really short cartridge. As weird as it looks being so short it has been 100% reliable.

If you are not in a hurry I will let you know when I bring it out and I'll let you try it out for yourself.

Appreciate it.