When things go wrong they really go wrong. In the middle of preping for a ELR woof hunt. I'll take a woof shot at up to 1300 yards maybe longer. Ya can't hit 'em if ya don't shoot. I placed a 1 MOA gong @ what turned out to be 1247 yards. I've been having some problems with bc and velocity. Chrony says 3440 MV but shooter says 3075 to make the drop chart out to 800 yards work. I'm shooting Original Richard Graves 169.5 RBBT bullets out of a 270 AM. The first barrel with a different lot of Original Wildcat bullets (Richard did a special tipping process on them) a bc of 0.74 and a velocity of 3440 put the drops in agreement with Shooter. This batch of bullets does not have the pointer tip. I'm using the same bc of 0.74 but have to drop Shooter's velocity to under 3100 to get things to jibe, so far. Temperature yesterday was between 10 and 15 degrees with a slight wind, at the shooting position, at about 5 mph slightly crossing the line of fire. Mirage however way out there was running hard left to right. Hmmmmm. I cranked in the atmos data and gave 2 MOA left windage additional for the mirage. Shot two shots. The day before yesterday I drug a large cardboard box to the gong and placed it over the target stand to give enough square feet to increase probability of hitting it. The first two shots were high and right with one missing the backer completely. A trudge through the snow shots the two shots landed side by side about 8" apart with very little if any vertical dispersion at 1300 yards. I was pleased with that... While checking the target I noted that for the last 600 yards or so the wind was a little more than 6 MPH and full value. Measured the necessary correction info. By the time ya hoof it 1250 yards and return things are probably gonna change. They did but I blew it off. I cranked the measured correction into the scope and put the reticle on target. Wow, mirage was flowing straight away. Hmmmm, can't make that much difference, eh? Wrong! Two more shots. Another hoof it to the gong. Elevation was spot on but POI was as much to the left as it was to the right with the first two shots. Vertical dispersion was super and horizontal dispersion was on the order of 0.6 MOA. Well good. About an MOA and a half right adjustment and she'd be on target. That would happen today. Wrong! This is where things went to hell in a hand basket. During recording of shooting notes I remembered I was going to change the Leupold rear scope base with the windage screw adjustment. It had shoot loose before I shot those first 1200+ shots. I had one go bad on my 338 RUM and decided they were junk even though I've used them on a 270 Win for more than 40 years. Scope removal is necessary for this operation. Bummer. Now I gotta rezero. I hate rezeroing... The first dumb thing I did was use an inexpensive torque head and stripped the rear base screw. Curse locktite goes here..... Call my neighbor Jim who arrived with a Wheeler gunsmith set of goodies and with the aid of a small hammer (I ran the hammer) we got it loose. The other rear base screw came out with the same effort though unscathed. Second dumb thing I did was, when I found the front base screws loose I ham fisted one with the cheap torque tool and buggered it also. Seeing as how the front base would be unchanged I'd wait till later to remove it. Probably dumb then #3. All is well and good. Not!!! It is when we got the screws from the base container that I was reminded that the mount screw holes were drilled and rethreaded to 8-40. Now were in the heck is a fella gonna get some 8-40s in Blackfoot Idaho. As soon as the stored opened I was there. Fastenal had nothing. Went to the Pawn/gun shop. Low and behold they had them. Saved again! Not!! The heads on these screws were too large for the holes in the mount. Bummer!! What to do? Dipped into my recently acquired machinist skills and very carefully and precisely turned them down to precisely 0.215" which precisely fit the mount holes. Oh yea major proud of self. Got her all together and went to shootin'. Ran out of left windage about 2 MOA short of spot on. Now what to do? About that time neighbor Jim stopped by to see what all the shootin' was about. I gave him my sob story (pun intended?) Jim's the analytical type and measures the ring spacing then doodles on paper w/pencil and says we need 8 more MOA and that the rear of the scope needs to move 20 thou to the right. Hmmmmm. Well heck! Not a problem! My idea was to turn the +10 -10 Burris inserts 1/2 turn in the proper direction (this took way too much discussion to get right) and we'd have the necessary windage adjustment and then some. Darned if it didn't work! Bore sited to get on the paper @ 200 after herding the cattle in the background a safe distance away. Second shot was 3.5 MOA high and spot on windage wise. Cranked her down 3.5 MOA and hit 8 MOA down. What's with that???? Ran out of time plus the cows came back. It shot great with scope tracking spot on, which it always has. . . until I diddled with the mounts. We'll see what tomorrow brings. Will be shooting in subo-zero conditions. That'll be fun. . .