Seem to remember that someone here uses a .338/.416 Rigby Ackley Improved?
This made me wonder if there are any limitations on which cartridges can be Improved upon? I guess shapes like those of the H&Hs arent really conducive, but how about, lets say, 7mm RemMag, 300 WinMag, or 308 Norma Mag?
Anyone know where I could get reamers, if its doable?
Nope, any cartridge can be changed or "improved". Just the amount and actual benefits for your trouble will vary.
If working with a case that has a lot of taper, improving will be beneficial. Most modern cartridges are already improved so little benefit is seen.
Where an improvement can be made is in moving the shoulders forward and shortening the necks. The Gibbs family is a prime example on the 30-06 case. Excellent results but extra work is needed in the case forming.
Again, most modern cartridge designs take that into account and shortening these necks may lead to not enough to hold the bullet.
Any reamer company (JGS, Clymer, Dave Manson, Pacific Tool Company, etc) will make a reamer to your specs. They usually have lots of different versions already in their files. not much new in this game.
Guess that all makes sense, especially that not all cartridges will gain much from Improving. From just looking at the case shapes it looks as though both 300 WM and 308 NM have steeper shoulder angles than the 30-06, for example.
Might be more hassle than its worth, in other words....