Bronco- what I mean by the velocity statement is this: the 310 was for a light bullet, at a relatively slow speed, while the heavier bullet in 32-40 is traveling faster (don't have figures in front of me). Now- the bullet doesn't give a spit about "twist rate"- it stabilises with an certain RPM range! So-- a slow twist (310 barrel) will work fine with a heavier than designed for bullet, at a higher velocity, hence putting that bullet into it's preferred RPM range. We need of course to be careful with pressures in getting that velocity, but the small Martini's were tested by, I think, Hunter's Lodge?? some years ago, and are fine in the 30k range. I loaded 14 gr. IMR 4227 and 165 cast, kinda the classic Schuetzen load, and had very good luck.
Now after all that, I sure hope I didn't step in it too bad! Any responses would be appreciated.
             Doug

You are going to have to pull that barrel on that Cadet to rechamber.  That is why I offered the barrel swap.  Thus we save one barrel in .310 for those who would prefer .310 and only modify a barrel that has already been modified.

You will also have to modify the extractor and lower the block by cutting the notch between the horns for the larger case head.