Happy Easter:The Snow is falling and the ground is almost covered again. Minimum barrel length but long enough to efficiently burn a case capacity efficient load built for accuracy and heavier bullets for deer hunting.
My 2 caliber choices for this project are 257 AI & 7x57 AI. Bearing in mind I am a Left Handed shooter who already have the Following � 22-250 Ruger # 1; LH Sako 264 Win Mg 27 ��; LH Rem 788 7mm R Br built for sub-sonic; 7 STW Ruger #1 26�; LH 300 WBY 26�; LH Rem 8mm R Mg 24�; LH Sako 375 H&H 26�. It is time to build a lighter shorter practicable rifle as I can foresee the day that where I will appreciate carrying a lighter rifle with less recoil. I have dies for both 257 AI & 7x57 AI but am leaning towards the 257 AI. Loaded with 100 � 120 g bullets & I would assume this case will prefer slower powders to utilize case capacity what is the shortest barrel length that will efficiently burn this combination, 18�, 20� or 22�. If the 7x57 AI where to be used a 150g bullet would be my choice.

257 Roberts Improved(??)/ 115 gr. Nosler Part./ 55 gr Reloder-25

18in/2765fps 20in/2861fps 22in/2944fps 24in/3018fps

7x57 AI /150 gr. Nosler Part. / 52.7 gr. H4350

18in/2694fps 20in./2774fps 22in/2844fps 24in/2905fps

Just for comparison. The powders were chosen to be among the best for the 24 inch barrel in each case.

Don

Sorry about the snow (unless you like it, of course). When does spring officially arrive there, anyway? Do you have summer?
I have a .257AI and, until recently, a 7x57AI, both with 22" barrels, and my chrony data is about exactly as Don shows it to be. I've also had good luck with H4831SC in the 257AI (at about 3 or 4 grains less than R25). The 7x57I definitely preferred H4350.
The 24" barrel obviously makes a difference; whether you want to lug it around or not is another thing.
Don - Did you actually chronograph this data, or, do you have a program that calculates it?
Good luck,
R-WEST