Yeah you’ll want to neck down a 6.5x47 to .257 and put 38-39gr of H4350 behind it…
Jokes aside, my 257AI is very similar in capacity to your 25-284. N165 with a starting charge will be the ticket. Low-Mid 2800s and very manageable recoil impulse.
Agree!! Even the man that experiment, designed, and tested various wildcats from rimmed, semi rimmed, rimless, and magnum cartridges! The College Professor that intentionally blew up rifles in a lab on a college campus!!!! He taught Gunmaking and Metallurgy!!! He was a very successful Gunsmith!!!! His rifle barrels were highly praised and sought after!!
That man is Parker O. Ackley (P. O. Ackley)!!! Of all his designs and testing, the 257 Roberts AI was his best design rimless cartridge with a high Added Velocity to Added Powder Ratio!!! The BOB AI is the optimum case capacity (velocity vs barrel life) for the quarter inchers!!! But, his favorite rifle was chambered in 26-06!!! He did no like the 25-06 AI!!! Way Over Bore Condition Cartridges have to much thrust (exit gas pressure) which adds to the bullet recoil and short barrel life without the benefit of added powder capacity and less velocity gain!!!
He himself, stated that there is something magical about those long case to caliber cartridges!!! I have a 25-06 custom (built in 1986) that has taken several trophy whitetail!! One at 574 yards!!! One shot kill through the heart!!! Several Wiley Coyotes at over 700!!! And, that 117 SBT SGK is quit accurate at 600!! Most of the Sierra Gameking Spitzer Boattail Bullets increase in BC as the velocity decreases down range!! While their target bullets decrease in BC as the velocity drops!!! Some times, I wonder if BC is a sales gimmick!!! BC IS NOT A CONSTANT AND IS BASED ON MODELS!! WHY IS THE RELOADING WORLD NOT GIVEN THE ACTUAL DRAG COEFFICIENTS (CONSTANTS @ STD (Standard Temperature and Pressure))????? I'VE STUDIED COEFFICIENTS IN PHYSICS AND MATHEMATICS AND USED THEM IN MY ENGINEERING LIFE!!! And, how much gain is there in increasing the velocity and extending the range slightly for ethical lethality on game animals!!! LONG RANGE TARGET IS A DIFFERENT STORY!!!
There is nothing wrong with a long action unless your purpose is rapid cycling of the bolt!!! I will be rechambered my 700 VLS 22-250 to the 6-250 AI!! It was developed long before the 6XC!!! I want to extend my varmint shooting range without sacrificing the barrel life of my 25-06!!! If the barrel goes out on the 25-06, a new barrel is going back on that 03A3 action, chambered in 6.5-06 Improved (extending the lethality well past 600 with 140 SBT, where the 117 SBT is just shy of 600, while gaining longer barrel life)!! The AI version is once again Overbore!!!
JEFFREY!!! I CAN NOT WAIT TO SEE THE RESULTS OF THESE 2 SHORT ACTION RIFLE BUILDS!!! I'M SURE THEY WILL MATCH, OR POSSIBLY EXCEED THE VERY OLD 1/4" KING (25-06)!!! Also know as the .25 Neidner (the 1st and oldest 30-06 wildcat)!!! I believe you are going to truly enjoy you new quarter horse (25-284)!!! It has about the same case capacity as the 25-06, which I have thoroughly enjoyed in almost 40 years!!!