A month ago I went to our range with my magnitospeed to re check our 3 rifles because I had switched from dry media tumbling to wet. I discovered that for some reason, although I have my own theory, all 3 rifles slowed down around 25 fps.
Also I noticed that my 260 had some pretty bad consistencies. I was asked if I annealed and if I had checked it with tempilaq. I have not ever checked it only gone by the dark room technique.

Robinhood sent me a bottle of tempilaq and I discovered that indeed I had the speed of the machine set pretty close. The main problem with that was I had the flame way to close and wasnt getting even heating over the whole neck and shoulder.

Ill try and make a long story as short as possible.

The High SD's really bothered me so I decided to check and re check every measurement. Good thing I did. Honestly I had been on auto pilot for months and hadnt pulled out calipers to check anything. Well I did and here is what I discovered. I use the Redding type S full lenth sizing die with their piece of crap ring on it. Apparently they all loosened, which they did regularly, and slipped and were no longer bumping the shoulder back at all. I replaced them all with Forester rings. Now as for the slow down with the stainless media. My theory was they were super clean and now the bullet was slightly more loose in the neck. So I dropped all three down one bushing size to counter that effect and all the numbers came right back up. Now that everything is re set and re measured I went to the range to see what the "final" MV was of all this change.

Here is where im getting to my question. Ill use my rifle only as an example.
Magnetospeed average MV 2800 SD 8.3 over 10 rounds fired.
Ok great. I punch all that into my calculator and get set to shoot 300 yrd target. Only Im 3" high. I think I recall Litz saying to true the MV inside the transonic and the BC at the transonic so I measure what the drop should be to be on target and true the MV. It bumped it up to 2900 ish. I reluctantly chose "use this velocity". Now I drop down to shoot 500 yrds at an 8" target. HIGH. So I adjusted to hit center and trued the velocity once again. The actual vs measured and now the mv is like 2974. REALLY?

What is up with that? I confirmed that at that mv I hit dead center at 508 yrds. I had 1.5" group at that distance 1 inch to the right of center. But is the calculator wrong. Is the magnetospeed wrong? I am using the g7 BC that 140 gr berger hybrid says to use.

what is going on? Why are the numbers that far appart?