Do barrels "get faster"?

Read MY post again. I did not apply any powder limitation to the 240 Weatherby.

MAYBE you can find "a" load that fast.....AND AT THAT PRESSURE, but you'll have to scrounge.

I've doubts you can find a LOAD DATA for the 240 Weatherby at ANY pressure that fast.

Again........this is all MOOT as LOAD DATA is guesstimations and is not, cannot be "maximum" for ALL rifles.

Still in all, this isnt the only comparison I have seen that even the load data doesn't work that way.

It's a GUESS and as accurate as throwing rocks at a black cat running across the yard on a moonless night.
You MIGHT get close, but without definitive PROOF your load is XYZ's pure speculation.

Use if you wish. No harm no foul.......but it's still no more accurate than just guessing without calculations.

Use 3.5 percent, 4.5 percent, 5 percent.........see HOW CLOSE they are to the "4 percent rule". You wish to go out on a limb and say the 4-1 has THAT small a standard of deviation?
Go for's don't , won't , ALMOST can't.

It's speculation using numbers that are dreamed up going by load estimates.......estimates. I have YET in 50 years found a load data that gave me anything near the velocity stated ......with their load, and therefore the pressure also is not the same.
Using THOSE for calculations for ALL RIFLES?

God Bless