Not saying anything's wrong with that data but if the exact same bullet is used energy and velocity will bleed off at similar amounts which would lead one to think the spread would remain uniform throughout not shrink.
I noticed this about two weeks ago with the Wby chart. If you check the Wby velocity over 100 yard increments it goes like this:
3570 3312 3079 2840 2396 2203
Notice between 300-400 yards how much velocity drops as opposed to any other yardage range?
I'll break it down another way. This way is broken down by speed loss
0(Muzzle)258 233 239
444 193
One of these things is not like the other...
I took it one step further using the velocity and B.C. from the Wby numbers and plugged it into a ballistic calculator. Here's the numbers from it...
3570 3305 3062 2831
2613 2406 2209
25-06 Federal:
3210 2966 2740 2527 2324 2131 1948If you notice I went out an extra 100 yards, on purpose, because if you omit the blue number, it's essentially the same as Wby's published numbers. My guess is the data was flubbed up and they skipped their 400 yrd velocity and shifted their 500 yd over. But I digress...