New entry. Date shot Sept 8, 2022, at 8PM.
WIND: Zero wind. Flags were dead, the ribbons not fluttering. This is a rare opportunity at my local range to shoot with zero wind.
Temperature about 24C.
Ammo: SK Biathlon Sport. (This is my favourite training grade target ammo. My Anschutz and CZ's like this ammo, lot to lot. Never had a bad lot....but it is not without bad fliers as all ammo has, see results below).
Shooting style: Free recoil. My only contact with rifle was trigger finger pull and thumb on back of grip for resistance for the trigger pull. The 2-stage trigger 2nd stage is on its factory set at 125g (4.4 oz).
Gear:
Rifle: Anschutz 1907
Scope: Sighton 45 x 45 (target dot reticle), with bubble level
Front rest: Caldwell Rock BR, with Protektor 3 inch flat bag. On left side, not visible is a 3/4 inch spacer block that helps to make the forearm fit snug side to side.
Rear bag: Protektor, in riser box for extra height (this range shoots downhill).
Caldwell elbow rest bag.
HOLD of target dot: All dead on in the center of the "X" character, except for target #3 (see below for details). The 45 power Sightron target dot reticle is so fine that it can be placed on it precisely. (Its so good its almost cheating!.....but mirage can be bad some days, but not today).
Results: The best overall average 10-shot groups me and my rifle ever shot for this challenge, but 1 bizarre flier ruined the average!
Target 1 = 1.798
Target 2 = 0.938
Target 3 = 0.855
Average = 1.197
The largest group was target #1 top left. You can see the one bizarre flier high right, totally away from the rest of the 9-shot group that is about 1 inch. I am fairly confident this was a bad round from the box, not the rifle, not the rest and bags, not me. Recoil was perfect.
For those viewers who have never shot with a scope of this magnification power like the Sightron 45x45, the tiny target dot can easily be placed on the center of the X on this target, the very thin cross hairs provide perfect spatial context before and after the shot, and the view through the lens is basically what you see on this screen. You can see the recoil track, and often see the flight of the bullet for the last few dozen meters, especially the fliers which show more trace because they diverge from the center line of sight, i.e., you get to see some of the diverging side of the flier's bullet trace as it curves away from the line of sight. So with this resolution in a zero wind condition, you
usually know when it was a shooter error poor recoil management shot vs an errant flier that was bad ammo. I say "usually" because even with free recoil style, the shooter can do something wrong, something happens in the bags to change the recoil, or there can be a subtle gust of wind out of nowhere that can move a round's trajectory.
Largest group. (fricken flier!)
Interpretation:
Sighters: Prior to shooting this target with the SK Biathlon Sport, the rifle had about 40-50 rounds through it from a clean barrel of a different brand (Eley Biathlon Club, which is whole other story). The first shots with the SK Biathlon were low and left. Clicking the turrets I walked them into a new zero for this ammo.
For Newbies reading this, it is common that different rimfire ammo shoots different points of impact, so re-zeroing is often required when switching ammo brands.
Target 1: Excellent 9-shot group with a defective flier round, (see comment above).
Target 2: Excellent group, but note that the group is migrating upwards from target 1. I have found that POI migration happens with every ammo brand after several dozen rounds, and my guess is that as the fouling increases, the internal ballistics are changing. The migration is not always upwards, it can be anywhere, but it does inevitably happen.
Target 3: The first shot was in the X ring. But shots 2 and 3 migrated upwards forming a worrisome triangle. I decided the migration upwards was happening, so I held the target dot at the bottom of the X ring for the next 7 shots, and amazingly the next 7 rounds shot high as predicted and made a bug hole above the point of aim. This hold change saved my group, or at least kept all hits internal to the triangle I had formed in the first 3 shots.
Hypothesis: Although I am in the "clean the rifle after every session" camp, this almost looks like the barrel after about 80 rounds was settling into a groove and now likes the internal barrel conditions. Maybe I should not clean it and see what it does for the next 100 rounds?.....or that is fantasy and Target 3 is a random effect, and the very next round could be a devastating flier and all the next groups will open up because too much crud is in the barrel! (such is the mystery of rimfire).
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