Just got a new upper and have (extra) used bolt carrier and bolt. (From old upper i sold) …if i use my “GO” gauge and it closes…i should be fine or do you recommend a brand new bolt…and do you recommend checking new bolt for headspace also since its new…
This has been covered a Krillion times. Just run the bolts. No need to headspace unless it’s some piece of crap Olympic Arms or LWRCi garbage.
Well the upper i got is a dsa zm4 carbine upper…and the bolt/carrier is a bushmaster…barely used…
As mentioned, just run it.
There multiple threads about headspace including a recent one in the Technical area. Read them and do what you think is smart.