A few weeks ago I took my new-to-me Smoke frame R51 out to the range. It was shooting 6" low at 35 feet. @%^#&*$@%!!! This was strange because my black R51 is spot on.
Then I lent it to a friend. As I was demonstrating it, I loaded a laser training cartridge into it and it was hitting dead-nuts. Huh?
Eventually, I realized that I was using the laser training cartridge with my street glasses. Tri-focals. And I was looking at them through the proper lens. When I was shooting at the range, I was using my safety glasses, with mono-focal corrective lenses. It's supposed to be the same focal point as the same lens I was using with my laser cartridge.
So I went back to the range and checked my bio-mechanics. I found that I was tilting my head down a little, in a sort of more aggressive body position. This aligned my eyesight through the top 1/3 of my lenses. Remember, they're mono-focal. Supposed to be the same focus no matter what part of the lens I'm looking through. but changing the point I was looking through the lens very subtly added a bit of unexpected parallax. It wasn't much but it changed my POI.
When I moved my head up to a more erect posture, my groups moved to the exact right spot.
Lesson learned.
Peace favor your sword,
Kirk
Very interesting. I'll have to try different head positions next time I'm at the range, even though I wear my bifocals when shooting.