Thinking about a ".25 Auto Long Rifle" Case and Cartridge of around .930" case length, made from swaged down "5.7x28mm" once fired Brass.
The Metric Size would be "6,35x23.622mmSR" if Done as exactly .930 Case length.
Rounding to "6,35x23,6mmSR" would be about .929" case length.
Other Possible sizes are "6,35x23mmSR" at .905"-.906" case length or "6,35x24mmSR" at .944"-.945" case Length.
This Idea is An Intermediate Length Between the .25ACP, at .620 (-.010) Case Length, and My other "Wildcat" lengths of 1.024"-1.056", or 1.125".
It is Slightly shorter than the .22WRF case Length of .960" or 24.384mm.
If made from the 5.7 brass it would be capable of supporting about 50,000psi MAP rating. The Case walls will Be thicker than Normal so should give a Long Reloading Life, even at Maximum MAP loading.
Bullets would again be .250"-.251" diameter like the .25ACP and .25 Stevens Cartridges.
50 grain FMJ are readily Available and, with Resizing, 60 grain Soft Flat Nose Half Jacketed (Hornady #2510), or even heavier ones are possible. For Even Lighter ones there are the 35 Grain JHP ones made for .25ACP use.
Barrel Blanks are available at 1 turn in 9.8" Twist rate and Barrel Liners Are Available in 1 turn in 14" twist rate. so the heavier bullets can be stable in use.
This size Would give a Definite Improvement in Velocity and Muzzle Energy over the .25ACP; but not be a Magnum Type Cartridge with their Earsplitting Muzzle blasts.
Case and Cartridge Lengths in the range of the .22WRF would mean many rifles could be converted To this cartridge Relatively easily.
Any Rifle or Pistol/Revolver that Could Handle the .22WMR (Magnum) Cartridge would be capable of handling this cartridge also after conversion.
What are the reader's Thoughts on this Idea?
Best Regards,
Chev. William