What I understand is that you need a long action, a magnum bolt face, a mag box of the right length, and the rails opened up if it's not a short magnum caliber.
If it's not a long action with a magnum bolt face, you need to
1. lengthen the mag box
2. mill the bolt face and maybe fit a different extractor
3. open up the rails
4. get the feeding right
He recommends a model 70 long action with a magnum bolt, as it is the least work and therefore the least cost.
A Tikka in any Win Mag, or 375 H&H, will also do. A Sako 85 is the best, IMO.
If you take any Tikka short action, it's 1, 2, 3, 4 above.
If you take a Tikka long action in 30-06, for example, then you still have to do 2, 3 and 4 above.
He refers to the mag box, which is the box built into the stock that houses the follower, not external magazines.
If you want external magazines, you need a chassis, or at the very least an action for which there is bottom metal available that can take magnum length cartridges.
Randy is saying that it's an expensive, labor intensive exercise to take a short action, and have all that work done to it to make a 6.5 PRC. The reason why he is describing the process, is to tell how difficult it actually is, because the gun writers are of the opinion the 6.5 PRC is built on a short action.
He is saying it is not.
Consider it a bit like making a VZ24 into a 500 Jeffery. Just because Paul Mauser did it, and it worked, doesn't mean that any gunsmith can put one together and make it work properly.
