This is what is state regarding headspacing with the Wilson Combat Recon Tactical .458 SOCOM Upper Receiver Build Kit. "Since our build kits and rifles are set to minimum headspace to allow for slight headspace growth over time, you may have failures to completely chamber or close for several rounds after building your upper. As your chamber burnishes and bolt and locking lug surfaces mate together your SOCOM will start to feed as designed. This is a very powerful cartridge and we have engineered it to have very tight tolerances for long-term safety and reliability. "
The gas block in the Wilson Combat Recon Tactical .458 SOCOM Upper Receiver Build Kit requires a 1.55"-1.60" internal diameter handguard.
If you’re referring to the recoil buffer, I would highly recommend the Armaspec “BB” model Stealth Recoil Spring. The BB is for “big bore” riles and has worked very well in all of my big bore rifles.
Unfortunately, Wilson Combat does not provide that information. The state it includes a complete Bolt Carrier Assembly (NP3 Coated). I suggest reaching out to the manufacturer to request more information.
This has a muzzle thread of 11/16" x 24.
This will include:
Barrel
Complete Bolt Carrier Assembly (NP3 Coated)
Adjustable Gas Block
Gas Tube, Straight
Q-Comp or Whisper® Suppressor Interface
Blue Print for Upper Receiver Modification
None of these build kits come with the upper receiver included. It would need to be purchased separately.