No experience with the HM2 yet. And on the HMR the estimates seem to vary significantly. Lilja says I should expect 3K accurate shots (assuming you don't get it hot etc.). I had "read" that someone on Rimfire Central still had good accuracy at 30K shots. I didn't put too much stock in that estimate. At today's ammo prices that is over $10,000 of ammo.
Before I left for my shoot, I shot a target with 6 different loads at 100m as I knew I was going to transition from the Hornady 17 gr VMAX I had been shooting in it primarily. Round count on the barrel when I shot this target was around 4600. I wanted to see if POI changed and what the group size was for the other ammo.
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When I finished the partial case of the Hornady, I had added 1440 shots. So now I was just over 6K. I went to the CCI tipped and accuracy was gone with the first shot. I switched to my backup rifle and continued. That night I cleaned the barrel (chemically not mechanically) and shot a test target the next morning. 5 of the 10 shots were sprayed. So I finished the shoot with my backup rifle. I've been cleaning the barrel for evaluation if my issue was fouling or barrel wear. I can't use the 90 degree mirror on my borescope, so it is challenging to evaluate the condition of the barrel. Best I can tell it just looks frosted and I don't see any firecracking. But my view is poor at best.