I see three barrel types commonly included with the complete uppers or the build kits.

stainless steel
Phosphated or nitrided 4150 (no chrome lining)
CHF, double chrome lined

I'm looking at picking up a kit or another complete upper, and wondering what the pros/cons are?

I don't see a down side to a nitrided barrel sans chrome lining if the rifle will be rarely used.

In my experience the CHF barrels have been accurate and consistent.
The Nitrided barrels tend to be kind of a hit or miss deal.

I have one of their CHF barrels and it is the least accurate barrel in my safe.

As to nitride vs chrome, both are good.

well there ya go.... both ends of the spectrum!!!

Chrome lined barrels tend to be less accurate due to the chrome lining in the barrel. Remember, you're adding the chrome to the inside of the barrel which can affect accuracy. With nitride treatment of the barrel, nothing is added. It's merely a salt water bath treatment. Every nitride or melonite treated barrel I've owned has been more accurate than chrome lined barrels I've owned. The nitride bath also makes the steel harder and rust resistant. Stainless barrels are also usually more accurate than chrome lined barrels. I prefer a nitride barrel over chrome or stainless.

It is interesting to see the different experiences that people have with similar products.

All the FN built CHF barrels that my friends and I have received from PSA are very consistent and hold tighter groups than the other PSA barrels that we have.

I was out at my range last weekend and we were trying out a bunch of different PSA uppers and that was the general consensus.

Freedom and PTAC barrels seem to be hit or miss. You get what you pay for. You might get a good one, but maybe not

I've had good luck with PSA CHF barrel on my sbr. Normally I use ballistic advantage barrels but I'd give PSA a thumbs up.

The last I checked into it the CHF barrels were made by FN with machine gun barrel steel. This is what I have always purchased,and the accuracy has been good.