Guys I recently bought a pistol lower from PSA and I'm thinking about putting a 7.62x39 upper on it. Hoping to keep it around 7-8 inch barrel. What uppers and mags would you currently recommend?

d&h work for my pws diablo

The new CPDs run great in all my 7.62x39 builds, including a PSA & Radical Firearms upper. Since I run 20s more than 30s they're my preferred brand.

I still want to grab a D&H mag and give it a try, I read more bad than good about them but I like the fact they're built from heavy gauge steel. But the only place I see them for sale online is Atlantic Firearms and only in a 2 pack. Don't want to drop $50 just to see if one works when I already have CPDs and ASCs.

There's also a new kid on the block, the Unimag from RZE. One mag that takes multiple calibers like 7.62x39. I've seen positive posts for this mag running 7.62x39, 5.56 & 6.5 G.

I use CPD 30s and 5s (hunting limit) they run at least 99%. I wasted about $200 on 10 ASC 30s and they do not work at all. Maybe mine are defective, but the finish inside seems gummy and the rounds creep up so slow that they all jam. Hard to even load it as it requires so much pressure just to force rounds in.
As to uppers, I bought a PSA keymod upper black Friday 2015 with a phosphate barrel and it functions fine. All of my other uppers I've built my self because I wanted a1 or a2 uppers. One used a PSA nitride barrel, it's good also. I only use AIM surplus BCGs though, because they are about 50$ cheaper than the PSA. I did try a rguns bcg and I have had a few fail to fire and fail to go into battery. Not as smooth as the aim for sure.

I'm useing the MAS defense GTKLN 9" keymod with Aero slickside and it has been flawless so far
with LMT Bolt and RedXArms extended firing pin and GEN III CPD mags.

Are any bolts reliable and durable right out of the box or have you guys found the need to "enhance" them, firing pins, extractor, etc?

LMT has the best reputation, i don't have much experience with them personally other than 500 rounds on the X39 LMT bolt in my pistol.
In my rifle builds, I am also using a Givati X39 bolt and a no name X39 bolt.(almost 2000 rounds on each)
No problems with any of them yet but I also use as heavy buffer as possible so the lugs don't get beat up.

Edit, i have had to use RedX Arms extended firing pins in all of my builds to get 100% reliabilty with steel case ammo.

No extraction issues with the heavy buffer?

I have not had any extraction issues.
If anything, I figure it would help extraction by allowing pressures to drop before pulling on the case.
Do have any different experiences or thoughts?

My mistake might have been thinking the heavy buffer with weak or under charged ammo might keep the bolt from traveling all the way back.