I’m trying to purchase a stripped lower from Sharp Bros/Rainier Arms, and I was wondering if the PSA lower parts kits would be compatible? Thank you in advance for you help.
It should be.
I have been trying to find a Sharps Brothers Jack 9 lower but they are out of stock everywhere. Going to do another 9mm build.
Yes the lower parts kit works well, and so do the PSA uppers.
I finally found the Sharps Bros Jack 9 billet 9mm lower and got a 9mm pistol build done. Pretty sweet little suppressed package. It took me a couple of hours honing the inside of the handguard and mlok connectors from 1.365 to 1.380". Now my suppressor fits inside the slimline handguard. This is my first specialty lower. All my other stripped lowers are regular lowers.
Those look great. I looked at the pdw expandable style stock that you have. I was curious about how comfortable you feel it is to shoot. I have a H&K 93A3 that has collapsible stock and two AK that are underfoldiers. I can shoot them pretty decently but keeping the same cheek weld is hard. They can also be uncomfortable to shoot for any length of time or in the cold.
They were very comfortable to shoot as a brace 
Sadly they went down in the boating accident