Brake Man, First welcome aboard. There are 2 different .25 cal. rounds based on the .243 case that I know of. The .257 Durham Jet has a case capacity of 52.66 gr. of H2O and the 25 Souper has a capacity of 56 gr. of H2O. The .257 Roberts has a case capacity of 52.43 grs. of H2O and the 257 imp has a case capacity of 59.35 gr. of H2O. Both are far more popular than any 25 wildcat on the 243 case, and neather of them are big sellers. If you build a wildcat like you want it will cost you extra to have the barrel chemberd as these reamer are harder to come by. You dies for reloading will run $ 100 and if you ever go to sell the gun the market will be very small. I would recomand eather the .257 R or the 257 imp, and do have a 257 imp at present that would really be just the round your looking for. Dies can be had for under $ 70. To form cases you just fire 257 R ammo in the imp chamber, and if you ever try to sell it it would be easier to sell. I play with alot of different wildcats from .17 cal to.411 cal. as you might guess from my handle, Ackleyimp, and figure the first rule is to never build a rifle on a wildcat round that there is a factory that it dupclates. I will buy rifle in these rounds as you can pick them up for little more than the price of the action with the dies included. That means the guy that built the rifle paid a high price to play with it. I on the other hand can play with it then rebarrel the action and still get most of my money back. If your wanting something different you also might consider the a 25 cal on the .222 case, known as the .25 Copperhead. That would get you about 3,000 fps with a 100 gr. bullet. Or, the 25 on the .222 mag case would do even better. I have a 6 x 47 which is the 222 mag. case neck up to 6 mm which is a real sweet round, and the 25 cal should be real nice also. Anyway, just my thoughts.If you have any specif question that I maybe able to answer feel free to pm me.
