I read pretty much only good reports on the Primary Machine barrels, and that is great. There has got to be variations in the P-09 barrels and lock up from the factory. So, in my opinion, the value of the Primary Arms barrel is pretty much dependent on how good or bad your original barrel/slide is. If you have a CZ barrel that is at the loose end of the tolerance stack, an aftermarket barrel might show a good result. If you are lucky, like me, and already have really good barrel/slide fits, I think even Primary Machine would suggest spending your money on more ammo and practice.
Similar to the CGW 10x bushing question--how much smaller will my groups be? I had a very sloppy factory bushing in a 9mm 75B slide, so the 10x bushing was the best money I ever spent on it. Most people don't have a factory bushing that is as sloppy as mine was, so they see less improvement.
I have shot several sub 4" groups at a 100 yards with the factory barrels/slides now in the polymer models. I don't think any aftermarket barrel would improve on that. If the factory pistol was spreading out the group to one or two feet at 100 yards (over 3" at 25), I would try a Primary Arms barrel or sell the gun. The OEM barrel in the example on the PA website would certainly be a candidate. None of my polymer CZ's are candidates. My opinion is that the CZ barrel/slides are very good on average, but I only have a very small sample to go by. Good to have a source for a potentially better barrel if you have a poor shooter.
My opinion is that the accuracy of the pistol is much more dependent on the lock up tightness to the slide than it is to bore finishing, assuming the crown is good and that the machining is uniform in the barrel, even if not smooth. Humans love smooth shiny mirror finished bores, a rough bullet just sees a hole that is too small that it is going to be forced through very quickly.
