I picked up a new lower at GunStock, and am now
going through the good-times of deciding what to
make it into...  Ain't these mix & match weapons
fun?  

So I did some calculations and learned that on
an existing chrome-lined bbl I have fired 6,400
rounds (sometimes rapid, sometimes slowly).  And
on an existing bolt, rings, etc. I have over
8,000 rounds fired.

My query is:  Are these parts worn out, or soon
to be worn out?  I have no complaints if they
are, but have no knowledge of how long these
AR parts are designed to last.  Still shoots
flawlessly, and perhaps accurately too.

I have no way to measure throat erosion or such
things.  Just looking for rules-of-thumb, or
the experience of others.  If the bbl and/or
bolt are nearing end-of-life, then it effects
the decision of what to do with the new lower.

Thanks,

DanM

Just keep the vtal spare parts and small parts suceptible to loss and when and if they break change em.I have close to 15000 rounds on my pre ban bushmaster 7000 on a new barrel otherwise all other parts original.I used the old barrel extension and the same bolt is working fine although 5000 rounds ago I switched to a les baer chromed extractor so I changed that after 10000 and it was still runnuing fine.