Short "action only" model variations?

Howdy;

I'm planning to build a nice .243 Win long range varminter from the action up. As I look at the Browse Models -> Action Only -> Varmint Actions section of the Savage Arms home page, I see the following three variations: (SKU and Model/Load columns only below...)

18539 Standard Bolt Head, 22-250 Box Assembly Right-bolt, right-port

18524 Standard Bolt Head and Box Assembly Right-bolt, right-port

18525 223 Bolt Head and Box Assembly Right-bolt, right-port

This leaves me with a few questions.

1) I understand about the 223 Bolt Head. I'm assuming that accommodates .378" diameter case heads like .223 Rem, .204 Ruger, etc. But, does that also imply a special box assembly for those cartridges? (I'm assuming yes, mostly due to case diameter and taper...) And, having read quite a few threads and various forums I'm still not sure, is the box assembly currently (May 2010) still staggered v.s. center fed? (If so, that implies a different cut out in the base of the receiver on the "223" style action.)

2) Then for the other 2 items, the only difference appears to be "22-250 Box Assembly". I would have guessed that a standard bolt AND box assembly would have accommodated the 22-250. I realize that the 22-250 case tapers a bit more rapidly that some other short action .473" diameter case head cartridges. Is that it? Otherwise, what is special about the "22-250 Box Assembly"?

2a) I guess the real question buried in there ;-) is which .473" diameter case head cartridge chamberings are accommodated by the "22-250 Box Assembly" and which are accommodated by the box assembly which is part of the second line item?

Beyond my just wanting to understand the differences, I'm wondering what might be required to convert between the various actions if price or availability favors one v.s. the others. For example, the 18539 "22-250 Box Assembly" action is in stock at my usual source, but the 18524 standard is not.

Thanks, in advance, for any information....

All the actions are the same.

All of the actions are center feed magazine styles. The 22/250 uses a different magazine box than a 308, do to the taper of the shells. I would say that similar taper cartridges would work in that box such as 250 sav, 6.5x47 lapua, 6x47 Lapua, ETC.

I don't know that the center feed magazines will accommodate the 204 Ruger, (I never tried.) The 204 is longer than the 223, and in the old stagged feed magazine system there was two different boxes. Later production they used the 204 Ruger box on the 223's, but I can not say I have seen a 204 centerfeed. I would imagine that the 223 box would be long enough for the 204, but I don't have any experience with it to tell.

All it takes to convert one to another is the magazine assembly. So if you bought a 22/250 set up, and a 308 box set up all you would have to do is switch one out for the other, and so would be the 223.

There is another option. If you are going to use a detachable magazine you could use a "Fred Sled" and single feed any cartridge you would like. If not you can get a single shot follower from SSS, and then single feed any cartridge you like.