CAUTION:
For everyone who buys the "Ultramatch" barrels from Rainier - the latest batch was rushed, and has some really serious quality issues. I couldn't get a muzzle device on my latest barrel from them, and they gave me the runaround on an exchange. First, they sent me a shit barrel, and then wouldn't make any concession on swapping it out. Wanted me to send the barrel or my upper in, on a build that was slated to go out the next week. I purposely delayed the build, until I had barrel in hand. They wouldn't send me either a washer, or a new barrel, with a return label to swap the old one, given my situation. They lied to me, told me they had no more barrels, and didn't know when they would be back in. (they're still in stock) Gave me every excuse, and inconvenienced me to the max, after sending me garbage. I sent them pics, and it was confirmed to me that there was a defect. I got the general impression from the conversation, that the whole batch had the same defect.
Any other company that I've done recent business with, makes these kinds of mistakes right.
Not only this, but when I posted a negative review of the product, they didn't approve it on their website. (they have blocked it)
I should have paid attention to all of the complaints on the sub-Reddit about the customer service. Never again
BUYER BEWARE!!!