IMHO... a lot of the answer depends on the diet of ammo.... and the gas length system, or if it is overgassed / cycling much faster then needed.
And the rate of fire... giving even a general round count is kind of tough.

So...I will try to answer in a round about way.

if you are looking to maximize part life... plan on a adj. GB to help slow down cyclic speed.

I still tend to believe chrome lined CHF barrels are the way achieve long barrel life.... IE, over nitrated

Purchase a high quality bolt if longevity is a concern.

Another way to plan for future NOS parts storage would be buy numerous moderately priced barrels and BCG's ... or buy high quality first and moderate priced for back up parts.

Lol... no numbers yet... hell, I haven't even shot out a barrel yet !

So, I was just trying to hedge the bet.

I can add.... my PSA .308's have seen about 2K on 2 of the PSA / DC Machine barrels and PSA BCG's... ( with my slower cycling recoil parts ) and no signs of bad wear.
The Criterion barreled PSA... has been "ignored" while I have been working with the 6.5CM PSA uppers and misc. barreled configurations and barrel brands...

The .308 / 6.5CM PSA's have been flawless after the same tinkering I have posted in the PSA Industry forums. ( IE slowing the cyclic rate, with Adj. GB and heavier recoil systems. IMHO, very important to keep part stress levels down... as well as much easier on the brass )

Soooo... no broken parts or crap from the PSA barreled and BCG's with about 3.5k of ammo fired total ( between all of them, 5  )

I have full confidence in all the PSA's when I take them to the range.

They just keep on ticking... just like they should.

The 6.5CM Criterion 22" barrel is a tack driver.... the FN 20" CHF CL .308 barrel is surprisingly very accurate / consistent with group sizes / and a variety of ammo brands. I need to get to the range to see how the 6.5CM DSG Arms / BA 22" Heavy contour does... ( Damned adulthood gets in the way )

Frankly... I have seen more issues with the dozens of various ammo's fired... Eagle Eye ammo pierced primers ( .308 ) , and Fed. 7.62x51 130 Grain SOST MK319 OTM T762TNB1 pierced primers... while none of the other .308 ammos did... ( 50ish + different brands and styles fired for accuracy and function )

6.5CM ammo's have been GTG as well... except for this last batch of Fed. AE 140gr ... one pierced primer as well from one chamber. I put that batch off to the side for later testing in more chambers...

Basically... having to many large frame AR's shooting rifles "in the fire"... has not allowed me to fire any one, to the point of any full on conclusions.

Again.. I want to say the PSA's have proven to be a helluva bargain. Especially considering the precision to cost factor. The PSA's don't shoot everything ammo accurately, but they sure as heck do like certain ammo's a lot. With enough variety to be a great choice.

And the PSA / large frame AR's are MUCH easier to keep shooting accurately over my M21 ... that lovely rifle needs cleaning every 150-200 rds to keep its precision.. especially the gas piston. The M21 has shot numerous very respectable sub MOA groups... but not over 8-9 hr days at the range.

Grudgingly, and while I would never get rid of the M21 ... the large frame AR's a vast improvement, over the older M1A M21... most certainly gunsmithing wise... far easier to change a barrel, to disassemble for cleaning.. etc.

The large frame AR will fire a much larger assortment of reloaded ammo weights and powders than the M21..

Lol...brother... I could ramble on for hours...