These are all estimates based on what we have seen from customers, including trainers, law enforcement and more.
The lifespan can be impacted by so many variables- suppressor use, full-auto/mag dumps, maintenance, etc.

MK1 in .223- We estimate 15,000 to 20,000 rounds on average. We have heard up to 50,000 rounds through a barrel before needing rebarreled or opening up on accuracy.
MK2 in .308- We estimate around 8,000-10,000 rounds.
MK2 in 6.5 Creedmoor- We estimate around 2,500-4,000.
If your firearm does need rebarreled at any point due to it wearing out/from normal use, we charge $200.00-$350.00 (depending on firearm make/model) which includes all labor, QC checks, test fire and shipment of the item back to the owner.