Why is it that AR-15s are gauged with expected lifespans of about 10,000-30,000 rounds (heavy barrels, non-stainless steel) while pistols like Glocks supposedly maintain accuracy to at least 100,000 rounds and that 30,000 rounds is just breaking in the Glock?

A lot of Glock "experts" proclaim that springs need to be changed every 1,000 to 5,000 rounds whereas I have never heard of such nonsense with AR-15s (changing springs every x # of rounds, or every 3-5 years, whichever comes first).

life can mean different things to different people.  a precision rifle might last 8000-10000 rounds before the group opens up to a spec the shooter is not willing to accept.  he will then change his barrel to get his accuracy back to where it was.  the old barrel will still shoot fine, just not to his standards.  there are plenty of rifles around that have 50,000 rounds or more through them.  their groups aren't as good as they were, but they still function.

The life of the rifle as a whole, lower, trigger, upper, and barrel, can last many lifetimes as long as it is properly taken care of.  Barrels, and small parts that break are really the only things that you could consider to have a round count life expectancy...

IMO, of course...

Normal noncromed barrels should last at least 30000-50000 rounds Crome lined barrels much longer than that

More propellent, higher velocities lead to faster bore and throat erosion.  Hence the shorter life expectancy of an AR barrel.

Upper and lower receivers may last indefinitely...well, probably longer than you or I have the patience to test.

Stainless is not bad.  Rust gets a lot of guns.  I have had good life out of stainless.

Good precision on a pistol is bad precision on a rifle. Different standards.

Quoted: Why is it that AR-15s are gauged with expected lifespans of about 10,000-30,000 rounds (heavy barrels, non-stainless steel) while pistols like Glocks supposedly maintain accuracy to at least 100,000 rounds and that 30,000 rounds is just breaking in the Glock? A lot of Glock "experts" proclaim that springs need to be changed every 1,000 to 5,000 rounds whereas I have never heard of such nonsense with AR-15s (changing springs every x # of rounds, or every 3-5 years, whichever comes first).

It's a great question.  The answers vary greatly.  Thus, lacking confidence in the responses, I decided to eliminate the issue m by owning "very numerous" of them.

It is a vast underground conspiracy perpetuated by the ARFCOM vendors to get us to buy more stuff.

I swear it.....................

Quoted: It is a vast underground conspiracy perpetuated by the ARFCOM vendors to get us to buy more stuff. I swear it.....................

Could be true.  That said, besides the money, I'm having a very good time being victimized.

Quoted: Good precision on a pistol is bad precision on a rifle. Different standards.

Im not following. You can still get .5moa out of a pistol at 50 yards.. Accuracy is almost the same in that regard. Its more a value of type of metallurgy isn't it??