Most of these bolts are shared manufactures. Very few of these shops have the resources to design and cut their own bolts. Fortunately, I have had the opportunity to see a good number of them. The PSA bolt is a great utility bolt. It's limitation is the extractor and the rear weight. The extractor, if not seated properly will extend the face and bounce on the barrel causing premature breakage. The rear weight is a limitation because you can't run any sort of captured recoil spring. I have brought this up and there is a new design in the works. I hate the gas key being screwed in too ( like most of them do ) and there is one being designed now that is a solid body with removable weight. In the defense of the breaking gas key saga, many cases were due to improper buffering. Guys would get parts, put them all together and not really knowing the difference, use a carbine spring and light buffer. It is just a 9mm right? This caused the bolt to extend too deep into the buffer tube and bang on the lower. Over time, the screws would vibrate loose, the bolt would keep battering and then they would shear. I can't blame the users. The industry should do a better job informing folks but in their defense this market came on so quick I think sometimes they didn't know either.
ADK Arms has one that has the removable weight and had the weaker extractor. The finish was great and the bolt was solid. The issue I had with it was that the fluid used in the coating process was not flushed properly and penetrated the gas key screws. It weakened them and caused premature breakage. The firing pins early on were weak so after the first batch or so they used a stronger tool steel and the issue went away. They also started coating separate and then installing the key from what I was told.
Faxon Gen 1 was great. The one piece design was much stronger. The gas key was gone however they used the same 1911 style extractor. I had early firing pin issues with them but they quickly resolved it. The Gen 2 Faxon bolt used the more traditional AR style extractor which works great. It eliminated all the issues above BUT they went back to the 2 piece design. I have used both, they both have a lot of rounds through them and they work well. The 2 also has a much stronger firing pin. I have not had one of those break.
UM Tactical has a great bolt as well. It is very similar to the Faxon. The finish is great and it used the AR style extractor with removable gas key. This bolt was tested during the design phase of the LeadStar Barrage PCC and I hate to know how many rounds ran through it. They offer a fancy NiB BCG now that I am waiting to get my hands on. They are great folks to deal with. As a matter of fact, all of these companies are great to work with.
I have not used JP or QC10.
Right now, in my personal PCC, I am using the UM Tactical. I have 4 matches and maybe half a dozen practice sessions through it. No issues at all. The next few weeks as I get ready to go to the East Coast Steel Nationals, I will really hammer on it. If something happens I will update this post. All the ones listed above are good bolts.
Hope this helps at least on a few of them anyway... It seems like everyday someone is posting another variant of a 9mm BCG.