DPMS Bolt Carriers, quick question.

[Guest LLArms]

Just want to confirm, these are only case hardened correct?  :o

[Robocop1051]

Depends on who you buy from, and how much you are willing to spend.

• JP's LMOS uses the "QPQ" 416 Stainless steel $$
  
• DPMS uses a 4140 Carbon Steel, either phosphate or chrome coated $
  
• Fulton Armory uses the same as DPMS $
  
• Armalite uses 8620 Steel on the AR10 $
  
• SI-Defense / NEMO Arms uses:
  • a 8620 carrier, heat treated, chrome-lined bore, chrome-lined carrier key $$
    
  • Nib or TiN coated 416 Stainless steel $$$
    

[Guest LLArms]

DPMS factory LR-308 bolt carrier.

[Robocop1051]

I believe they are definitely "heat treated", but I don't know enough about metallurgy to know the difference between that and "case hardened".

[Fröman]

That kind of part is almost always case hard and not through hard. Military M16 BCGs are case hard.