I shouldnt say this but I have had no problems with the blowback pistols I have bought new.
They tend to get light use which may be the answer.

I have had plenty of problems with second hand and collectable Co2 guns of all types

But older guns can be fixed if you are lucky enough to have frienda like Baz.

I think we have to accept that the new guns are disposable.

Factory testing for the 600 was unprecedented and guns were placed on rigs for hundreds of thousands of shots.

I think the Umarex Peacemakers were tested at 5000 shots and they are one of the best modern offerings, and no blowback.

I would guess a blowback pistol would fail at over 1000 shots?