Does a larger bolt face size have any practical real-world advantages?

My CZ 505 has a very thin metal rim on the bolt face (I've borrowed RIP's picture from another thread to show this):



Would a larger bolt face (eg on the new MPH action) have any real-world beneficial effects in comparison?

Peter

Good question. It doesn't change the bolt thrust, everything depends on the lugs holding.

Which brings up a related question. Weatherbys are noted for their locking strength but they are push feeds. Why don't we have mauser-type actions with more lug-face? You might think that the big CZ action could develop a super magnum action for rounds in the 8000 ftlb range and up? Our brass can handle 60000psi these days, why not our magnum actions for Gibbs caseheads?

Which brings up a perennial point of mine. If someone is going to build a cartridge beyond the Rigby size, by all means use the friggin' capacity to do what the Rigby case can't do. Otherwise, we already have the 416Rigby (Mbogo) case and its belted sister in 460Weatherby (A2-Wells). Both can produce 8000 ftlb cartridges.

Good question as tanzan says and I'm sure it crosses the minds of all gibbs/nyati/overkill CZ550 owners at least once.

I guess going only off the fact no one has seen a CZ bolt fail yet there is no solid necessity for a bigger boltface(unless of course you are running a 577 Trex, 700AHR, 700 Hubel etc which literally won't fit on the CZ550 bolt)

One advatange is the bolt may be tougher outside the gun with the MRC PH size. eg if bolt is physically dropped onto a hard surface.That little sliver of metal left on the CZ550 may not like it.

quote:

Originally posted by Karl:
That little sliver of metal left on the CZ550 may not like it.

Regarding the MRC PH bolt diameter of about .805" instead of .700" with the CZ 550 Magnum or Mauser Magnum M98, or Ruger RSM, used to build a .505 Gibbs:

quote:

Originally posted by Karl:
One advatange is the bolt may be tougher outside the gun with the MRC PH size. eg if bolt is physically dropped onto a hard surface.That little sliver of metal left on the CZ550 may not like it.

Yes that is the main advantage of the MRC PH.
I am not a-feared o' bolt thrust.

I can imagine if the thin metal rim were to be damaged, then loading may become a problem, or metal may shear off into the action mechanism.

Presumably this thin metal rim doesn't have a big role in extracting a stuck round. Would it be better to have a completely flat, no-rim bolt face?

On mine with .700" diabolts and my 585HE I don't leave
thin edge. All guns so far have lug forward opposite extractor
and with curve in that lug extension and compound curve
of extractor, the case can't slip out the top once it
is under the extractor. If you have feeding issues where
the case won't go under extractor in CRF gun that little
thin edge on top half won't help or matter. Ed

The purpose of that thin rim is to control the cartridge so it doesn't slip off the extractor.No you better not remove that rim. M 1914 bolts compensate for this with metal left on the opposite bolt lug. This controls the cartridge quite well as ED has pointed out. Despite all the great concern about this which we all thought would be fixed by the Montana PH action with its 0.8 diameter, however, no one we know of has had a bolt rim fail or break off of a opened up CZ550 bolt. So in my opinion, this issue is much ado about nothing!

A CRF extractor if fitted properly to the cartridge case size should hold a loaded round to the bolt face when the bolt is held in the horizontal position.
A loaded cartridge when feed up from the magazine should be clipped tightly in position by the extractor with the crescent shape of the extractor claw sitting in the case extractor groove and stopping the case sliding further up the face of the bolt i.e. the thin rim of metal left after opening up a bolt face should not be needed to position or hold the case on the bolt face. Of course an empty case will extract out of the chamber in a straight line, again held tightly to the bolt face and be ejected from the action, again not needing any protruding metal on the bolt face to accomplish this.

If it was felt that thin rim of metal could become damaged on a hunt, say if the bolt was dropped, I would get rid of it before this could happen..

All .700" bolt actions I have 585 in have
left lug out front oposite extractor
so any thin edge above that across the top
I get rid off. Saves work and makes sure I
have extractor good and tight.Wew are talking
5 Enfields 2 Rugers , 2 Savages, a BBK,
a Mossberg,

On 2 big bolt MRCs left metal edge on top.Ed

quote:

Originally posted by eagle27:
If it was felt that thin rim of metal could become damaged on a hunt, say if the bolt was dropped, I would get rid of it ...

That was exactly my worry! Hmmm, may flatten the bolt face, if only for peace of mind

quote:

If it was felt that thin rim of metal could become damaged on a hunt, say if the bolt was dropped, I would get rid of it before this could happen..

Or just dont drop your bolt on a rock-----

quote:

Originally posted by Cross L:
Or just dont drop your bolt on a rock-----

Peter

No amount of extractor tension will make up for not having a rim to control the cartridge. With that said I repeat, NO One has ever damaged the thin rim left on a bolt. You are obsessing over a non- existent problem. I have 10 rifles built like this and have hunted all over the world and probably have fired my guns more than any 10 of you guys. For get about it!a-Rob

quote:

Originally posted by Robgunbuilder:
No amount of extractor tension will make up for not having a rim to control the cartridge. With that said I repeat, NO One has ever damaged the thin rim left on a bolt. You are obsessing over a non- existent problem. I have 10 rifles built like this and have hunted all over the world and probably have fired my guns more than any 10 of you guys. For get about it!a-Rob

My my there's a couple of big statements here Rob.

One of the greatest battle rifles ever made and used extensively throughout the world in battle and also for sporting use where it has probably accounted for more head of two legged and four legged game in the world than any other rifle, the venerable Lee Enfield in 303 British, has a flat bolt face not needing any rim to control the cartridge as it is fed from the magazine under the extractor and into the chamber.

I don't have any particular interest whether PD999 keeps the thin rim of metal or not and it will be perfectly fine as long as it does not get damaged but Murphy's law sometimes bites us just when we least expect it.

MY MY Eagle27, thats because I know what I'm talking about! Tell you what, why don't you grind off that little rim from a CZ550 bolt then try and TWEAK your extractor enough to hold the case in place. Let us know how it works out for you. Prove me wrong! You won't and You'll then understand why that little rim is so important. It doesn't magically break off either, but I assume your a magician with a Dreemel tool!
As for your beloved P14 bolt, now carefully inspect the extention on the bolt locking lug ,you know the one OPPOSITE the extractor and try and figure out what it does. Wow !controls the cartridge just like the rim on a CZ550 bolt does! Amazing stuff huh! Now you know why some people who BUILD Big Bores use P14 bolts in 1917 Enfield actions.

quote:

Originally posted by Robgunbuilder:
MY MY Eagle27, thats because I know what I'm talking about! Tell you what, why don't you grind off that little rim from a CZ550 bolt then try and TWEAK your extractor enough to hold the case in place. Let us know how it works out for you. Prove me wrong! You won't and You'll then understand why that little rim is so important. It doesn't magically break off either, but I assume your a magician with a Dreemel tool!
As for your beloved P14 bolt, now carefully inspect the extention on the bolt locking lug ,you know the one OPPOSITE the extractor and try and figure out what it does. Wow !controls the cartridge just like the rim on a CZ550 bolt does! Amazing stuff huh! Now you know why some people who BUILD Big Bores use P14 bolts in 1917 Enfield actions.

I wonder if you do know what you are talking about, who mentioned "beloved P14 bolt"? The Lee Enfield or SMLE battle rifle has nothing to do with a P14, different rifle different bolt!

Eagle27- you embarrass yourself! Pathetic. Your dismissed!

quote:

Originally posted by Robgunbuilder:
Eagle27- you embarrass yourself! Pathetic. Your dismissed!

Whatever flicks your switch Robogunbuilder, by the way I quite like your little signature line, autobiographical is it?