How big can these be opened up safely?

I should be more specific.
The Gibbs case is -what?- .635" at the rim?
Can the Mauser boltface be opened this much?
I've seen it opened to Rigby size, and it seemed like a stretch.

[ 05-07-2003, 21:06: Message edited by: Bwana-be ]

C'mon, guys, help a brother out. I know someone among the gurus here has an easy answer for me!
And I'm not asking about the feasability of fitting a Gibbs in a K98. Just the boltface.
Thank you kindly for any input!

Bwanna-Be, From CIP dimensions. .505 Gibbs.
Bolt face Diameter. .642". Diameter of bolt BEHIND nose bevel (it will end up a bevel)around .698". Difference= .056" divide X 2 for wishful thinking will be remainder .028". Enough material? Scant , but workable. But how about the guide prongs? That's the rub. The Gibbs builders decided early on that this ought be re-inforced some how and the various examples of Brit building had an added, stepped projection as a continuation of the slotted left hand lug. The thickness then was re-inforced by roughly 2 m/m addition to the .028. The "C" ring therefor had to have an accommodating clearance for these 2 prongs through a 90 degree sweep on the left side opposite the extractor cut out. This did not hamper the strength by any measurable ammount. The Mauser Werke was not interested in accommodating the requests for this special stepped lug for a number of years so the enterprising builders added these 2 bolstering strips by a variety of means, to include inlaying and pinning in place, dovetailing and staking to prevent sliding back out during use and, best of all Copper brazing these extensions in place and rehardening the entire bolt. The ideal Mag Mauser was one with a box long enough for (and made for) the Rigby and the bolt face was proper distance from the barrel breech face. The mid thirties samples had the stepped lug and Hartmann &Weiss actions seem to be all made with the stepped lug, and instead of bevelling or radiusing the bolt nose rim surround to prevent cutting into receiver ring at entry the Ring "mouth" has an entry bevel as is on the DWM '09 Argentine. H & W followed the Mauser-Werke pattern in this regard. Why .642" dia for bolt face? Planning for eccentricity, of threads,chamber and Ctg as they relate to one another in order that in attempting to open bolt after firing you will be able to do so. All things considered. I viewed a Mag Mauser conversion, where the non pro builder eliminated the surround entirely up to beginning of the lug,depending on the hook form of the extractor and the stabilizing effect of the guide prongs, and in demonstrating to me he tried to gloss past that alteration,but failing, thought I would proceed with ostracising from the worshipful cult of the big bore shooters. He had noticed that the older Mannlichers had a flat (no surround) bolt face and utilised the combination ejector/support guide to accomplish the mission, and well, it worked. Splendidly, because HE TOOK HIS TIME carefully executing the work. Heading off another question, why copper brazing? Melting point is about 150-200 degrees above Carburising temperature. Nuf?

Nuf?
Well, that is a tremendous help.
But I'd sure listen if there was more!
Thank you very much, sir!

As a follow up to Mr Burgess, I have seen two 416 Rigbys, on obendorf magnum actions,that had part of the lip broken out and repaired like Burgess discussed.

Hartmann and Wiess started to make all their 416 Rigby's and above with this extra reinforcement on the lip, about 5 years ago.

When converting P 14's to 505 I have to go through the bolt bodys. Looking for larger diameters and trueness. I only find about half of them that I will open up to 505 Gibbs. I will not open up a P 17 bolt due to its shape, just no metal left where you need it.

I feel that the rigby rim is about as large you can go on the standard mauser bolt head, and not have any problems.