Sorry for the long post however, I am experiencing an odd issue with my CZ 452 which I bought SH around 3 years ago. Having been away from shooting for roughly a year due to working overseas, my fellow PW member and I popped out for some social distanced Rabbit shooting on Monday. After a quick check of the Zero at 100m everything seemed to fine however out in the field things started to deteriorate.
I was head shooting rabbits at around 50-80m no problem, then the next 3 shots completely missed the target, back to headshots, next 2 shots completely miss the target this continued sporadically throughout the night.
Having discussed it at length it was noted that I had never cleaned the bore of the rifle as that was the advice from the previous owner and a number of other people WRT .17HMR. The rifle was purchased from an ex PW member and had apparently only seen a couple of boxes of ammo from new and was in VGC aesthetically ( I am new to firearms!)
I then spent the best part of 8 hours trying to clean the barrel, starting with KG2 bore polish, patching, soaking, brass brush on a rotating rod (only one way from breech to barrel) and patching dry, this process was completed over 20 times and the patches would still come out looking like the below pics.
I then found and old unopened bottle of Tetra Gun Copper solvent and repeated the process above. When this didn't have the desired effect i poured some of the solution down the barrel, left to soak for 30 mins and repeated the patching process.
This was repeated another 6 times in total in my quest for a clean patch!
I have now used over 250 patches and scrubbed the barrel over 200 strokes and the patches are still fouled! At this point I stopped, cleaned the barrel a couple of times with KG2 and put a couple of lightly oiled patches through the barrel.
Last night we went out into the field to check the rifle again. To start with we ran a couple of patches of Bore Eliminator through and scrubbed as above. The patches were slightly improved but still showing some deposits.
The first couple of rounds (Hornady V-Max) were used as fouling shots and then the targets were set at 50m. All shooting was prone using a Harris BiPod and shooting bags.
Initially the groupings seemed good, under a thumbnail size for around 15 shots, we had the occasional odd shot but that was put down to me laying on the ground.
We moved to 100m and again, a couple of odd shots but the majority were within an inch for the first 10 shots. the rifle was zeroed and then it all started going wrong, 3 shots on top of another, 2 shots inches apart and so it continued.
We changed Ammo to Winchester, it got worse. We changed to Remington and suddenly 4 bulls eyes. Then the next magazine goes back to un grouped shots. We tried a new pack on Hornady - all over the place. Back to the original V-Max and three shots in a tight group, 2 slightly off.
Changed to Winchester, all shots on top of each other, next magazine all over the place within a 3in group.
And so this continued!
Things tested in short as im waffling!
1. All scope fittings checked MTC Mamba 4-16
2. Moderator swapped for new
3. Moderator removed Mod is in good condition with the exception of a bit of clipping / blast damage to the very middle holes?
4. Different Ammo
5. no visible damage to barrel, crown looks in VGC No signs of rust or deposits
The only feedback on the internals from my shooting buddy is that the rifling looks rounded where as on a CZ he would expect it to be squared off?
We are both baffled 😞
Any suggestions welcomed!!!!!!