I believe that I have discovered exactly why your rifle is as it is, with the oddball chambers. Since I have never owned a .318 WR, though I have handled cartridges a few times, and have seen a few double rifles in this caliber, including one extremely nice WR, cased, I decided to do a little research on the cartridge and on the double rifles chambered for it, something everyone should do, if they are contemplating the possible purchasing of such a rifle, or who have already done so, but are not all that familiar with the cartridges used in such. The cartridge was designed, of course, for bolt action rifles, but a few double rifles have obviously been chambered in it, same as was done with the .416 Ribgy cartridge, though not a good idea, as the extraction/ejection isn't as positive acting, and the breech pressures should be kept as low as possible for double rifles too. Anyway, the .318 WR bullet dia. is .330", 250 gr. bullet at 2400 fps velocity. I am sure that you already knew all that, but I next read that West. Rich. had done some experimental work on the cartridge, designing a more square shouldered version of the cartridge, TO IMPROVE HEAD SPACE CONTROL. At that point, I said "BINGO," that explains why you have a DR for that version of the cartridge. Reading more, it said that this more square shouldered version DID NOT LAST, thus we have the more common version we now are more familiar with. Seems to me that you have to choose between two choices: 1. Get custom made, special order, handloading dies, and load for the rifle as is, OR 2. Have a good well experienced gunsmith ream out the chambers for the more common version of the cartridge, so you can easily shoot the more common cartridges for the caliber.