What actions were originally used for the likes of the 505 Gibbs?
That is a fat, long monster, and I can't imagine Enfields or Mausers handling it.
(And there are others.)

The 505 Gibbs was originally built on magnum length mauser actions.

The 505 can be done on a Enfield with a
little work.It has large action diameter that
helps with putting in bigger barrels for
fat cases...Ed

Brevex magnum mauser actions and 1917 Enfields/model 30's-Rob

What are your thoughts, with regard to the reboring and rechambering of M77 MkII Magnum Rugers to the 505 Gibbs? There is a company in Tennessee, Bowen Custom Arms, performing this conversion. They advertise it on their website.

The enfield is large enough.. it's a frickin huge action. The larger magnum actions are very expensive, except the coming attractions of the MRC PH.

it's very possible to build a 50 cal HUNTING rifle on a cz 550, if you are not dead set on a 505.

for the most part, get a 550 in 416 rigby, do a barrel swap for a 500 asquare, a 510 wells, or a 500 jeffery. They are all on the same casehead diamater, which is the same as teh 416 rigby.

You would need to do A LITTLE feed work as all three of those rounds are slightly larger diameter, by body and rebatted rim, or case belt, than the 416 rigby.

If i knew THEN what I know NOW about the 500 jeffe, I would have built a wells. The brass is abotu 1/3 the price, you can get it from midway, it's not dogturd soft bertram, and all the rest is right there.....

Of course, I would have loaded it at 500 jeffery ballistics, not the higher wells/a2.

All in all, your real choices, today, are in terms of increasing price of the action, as related to the 505.

p14/m17 100-200 action
rem mod 30 200-400 action
cz 550 650, deliveried, every day
MRC PH (when it comes out) ???
<other mag mauser sized actions> 1500-4000

jeffe

I mus' ha' bin asleep when it were discussed. Who is dis MRC PH and where dey gonna cum frum?

opps, forgot one...
olympic arms bbk?
jeffe

You can build a .505 on a Ruger M77 Magnum action. Bowen Classic Arms does the conversions.

The issue with the M98 isn't the action ring diameter( literally all bolt actions are nearly the same in that dimension). It's in the amount of metal in the ramp/lower locking lug area as well as in the bolt throw distance. To build a 505 Gibbs on an enfield you have to seriously recut the ramp and cut way back into the receiver. Been there and done that! To do so on a M98 will take you right into the lower locking lug. you can't go back as far! That is bad! The practical limit of what can be done on a M98 is probably a .416 Rigby! You can ( although it's not easy) build a 505 Gibbs on a 1917 enfield ( with a fair safety margin) and probably hundreds have been done. I want to see one done on a M98. One shot -Kaboom!-Rob

Re-barreling a Ruger m-77 in 416 Rigby would work just fine and I hear Bowen does a fine job...

Personally I would use a M-98 Mauser or a Winchester pre 64 M-70, both with a Blackburn drop box, straight bolt handle... and go with the 500 Jefferys...It will outperform the 505 and do it all in a std. length action.