I accidentally posted this in another thread and meant to post it here...
I never go to "ranges" but while here in Wyoming for the next 2-3 weeks I went to a local, very quiet and not hardly used gun range.
I swapped my Tikka .223 into a Rokstock and wanted to practice some field position shooting and also check zero on the gun after the stock swap. I've swapped many stocks, and have sometimes seen little to no POI shift to my 100 yard zero. I've also swapped stocks and have sometimes seen minor to moderate POI shifts to my 100 yard zero. I don't claim to be any kind of expert on why or how, I just shoot, observe, and correct when needed.
Lately, with loctiting and torqueing actions screws on my Tikkas and Sakos to 65" lbs I have not seen very much in the way of POI shifts to zero when swapping. This morning, I did see a shift that needed correcting.
I setup on the concrete table and bench, with front and rear bags eliminating as many errors as possible. This Tikka .223 with factory 20" 8 twist barrel and factory Black Hills 77 TMK ammo is a little hammer of a gun. My first shot aimed at the bottom left 1" square showed a POI shift to the right (see orange circled shot). Using
@Formidilosus sight in method, I used the Maven RS1.2 MIL reticle as a ruler and made the correction to the horizontal turret. The next shot is the bullet hole you can see in the center of the 1" red square, bottom left target.
I proceeded to then get setup OFF the bench and shot in 3 different shooting positions from the concrete floor. My plan was to shoot 4 full magazines (16 shots) in each position for 48 shots. I did not take time in between shots and spotted all impacts... Only time taken was re-loading a new magazine and rebuilding the shooting position (less than 6 seconds timed average); and then obviously time taken to setup the next complete shooting position (less than 18 seconds timed).
I also setup my Garmin to track muzzle velocity which was last checked in 80 degree weather in Arizona at 1,500 feet of elevation. It was 55 degrees and 4,000 feet of elevation at the range this morning. My MV used when creating my laminated dope cards prior to showing up in Wyoming was set at 2820 for this rifle and ammo. See the photo below for the average of 48 shots this morning. Worrying about adjusting your muzzle velocity and 100 yard "zero" for things like elevation, temperature, barrel temperature, etc. is not something to fuss over.
All shots were at 100 yards. Tikka .223, Rokstok, Maven RS1.2 Scope, UM Tikka Rings, High Desert Bottom Metal, factory trigger, factory 20" barrel.
Position 1: Bottom Left Target
I shot in the prone position with my pack supporting the front of the rifle. For the rear of the rifle I used my bino harness as a rear rest. This is an ideal and often times common hunting shot for me depending on the hunt and terrain.
Position 2: Top Left Target
I shot seated with a long Spartan bipod, with my backpack and bino harness as a rear support. I bear hug the pack and wrap my quads around it. Off hand goes on top of the the bino harness which is sitting on the pack, supporting the rear of the stock. This can be done from the ground like I did this morning or from a glassing stool/chair. This position is probably the most common used for me currently in Arizona for big game hunting.
Position 3: Bottom Right Target
I shot seated with a long Spartan bipod, with nothing as a rear rest. I use my quads, calves, and off hand arm/hand to support the rear of the gun. Probably the most common general hunting shot I take inside of 300ish yards. Used mainly on coyotes and rabbits, but big game as well when rushed to get a kill.
The 100 Yard Target:
The Chronograph Results:
