G'day,
I have an old - 30+ years - Anschuetz 1532 in .222 Rem. with an ATN 4K Pro NV sight. Notwithstanding some pitting in the bore it is very accurate. It is bedded. I have been hitting hares and foxes shooting off quad sticks out to 280 yards at night.
Late last year it lost accuracy. I checked with my bore scope and found a high copper build up so cleaned it thoroughly. It returned to accuracy after about 25 shots. In fact it shot a three-shot clover leaf off my bench early in the year. Soon after the firing pin broke while I was hunting. The local gunsmith repaired the firing pin and test fired the rifle.
Two weeks ago, I re-attached the NV scope and set up to zero the rifle. First shot was high and wide as I expected. After adjusting the reticle, I fired three shots. Two shots [at 100 yards] hit in my aim point, a 30mm black dot on white paper. The next two shots were 100mm low, 40mm right but spaced at 20 mm apart. All shots were taken 1-2 minutes apart at least with rifle left to cool with bolt open in a strong breeze. There was about 12 minutes between groups. I quit at that point being somewhat confused and wondered about temperature.
Yesterday I attempted to zero the rifle again, but with different ammunition - Fiocchi. First three shots at 100 yards gave a 15 mm group 60mm high and 30mm left. [I expected to be off target with different ammunition.] I adjusted the reticle, and the first two shots [of three] were inside my 30mm aim point. The third was 110mm low, 25mm left. As before I left a couple of minutes between each shot and there was about 12-15 minutes between groups. I shot one last three shot group without changing scope settings. The centre of last the group was about 110mmm low, left 25mm. Curiously three of the four last shots formed a group of about 22mm! The worst shot was 150mm low.
I have checked the action screws, the scope and ring mounts. They are all tight. Clearly the rifle is accurate but is not consistent.
I tried to allow for temperature given the rifle has a lightweight barrel. The only other thing that comes to mind is the settings within the NV scope. I keep record of what they are. What else can cause such POI changes?
Jim