What action mods need to be done to a CZ550 magnum action ( .416 Rigby boltface) to reliably feed 460 WBY cases. I know that folks here have used this action with this case successfully and instead of doping it out myself, I'd like to know what needs to be done.-Rob

Robgunbuilder,
Probably very little is nessecary. Polish the feed ramp and action rails and I bet it will do great. This is a perfect choice for the conversion. The bolt face will do as is.

I always thought the big Weatherbys are Rigby case + ( useless ) belt?

Is there that much clearance there is no opening of the bolt face necessary?

Did You ever think of a .460 G & A? Cooper once wrote about this when he built "Baby". He compared case capacity in 4064 IIRC. Something of 90 grs for .460 G & A and more for the Wby. But no belt and lots of power. Anybody else knows more about this round?

Good shooting! H

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This action is destined to become a 500 A2 for my next trip to Africa. My major concern is how many rounds I can get in the mag box. Some of those MBOGO's appear to need more than one shot. Do you know if I will have to modify the box to get three 500 A2's down? Do the feed rails need to be opened? This action appears to have been designed for the .416 Rigby and I'll bet that I will have to open the rails a bit for the WBY belt. No big deal, just want to know what I'm signing up for. If modification of the box is necessary, what works? Milling or cutting Trianglular sections out like Rem does on their Ultramags?

If you compare the rim diameter of a 460 wby to a 416 rigby, you will find the rigby is a little bigger (although I can't remember exactly how much - the 460 has a .579 rim). I have a cz550 action set up for the 416 rigby and in my opinion the boltface is opened up too much for the 460 wby rim. If I slip a 416 rig cartridge onto the bare bolt, the extractor will hold it, but it will not hold a wby. Consequently I decided that I should start with a cz550 set up for .375 in order to build a 500 A2.

However, if you don't mind the boltface being opened up a bit too much and you use the 416 rigby action, you will find it fits 3 down just fine and they will feed out of the box no problem - no mods to the rails are necessary. If you could just trade that bolt for a .375 bolt and open it up just the right amount...

[This message has been edited by 500grains (edited 09-05-2001).]

The 416 Rigby bolt face will work fine for the 460 Weatherby. You shouldn't need to mess around with the rear portion of the action rails to clear the belt. You may need to open up the front portion ever so slightly however because the 460 Weatherby is an improved and necked up 416 Rigby (with a belt). You will need to feed some cartridges though the rifle to make sure.

This isn't a conversion that you can just say do this and then that and it will be a no brainer. You will need to massage the action rails as required by your individual rifle to ensure good feeding.

I would strongly recommend against using a 375 H&H for the conversion as the rim of the 375 is much thinner than the Rigby/Weatherby/500 A-Square and you will be in for alot of bolt face and extractor work. It is obvious to me that some people on this board do not know what they are talking about.

D

I think JungleJane (Wow what a handle guy!) sounds like he knows what he is talking about, except that for a competent gunsmith it is not that big a deal to open up the 375 H&H bolt face to the 460 Wby on a CZ 550.

I have had Kevin Jenkins convert a 375 H&H to a 378 Wby. No problem. (Sorry, Alf, I know you think the 378 Wby is an abomination, but it is just a cartridge variation to me.)

That one did have some feed work done to get the 378 feeding slickly from the 375 action, but I let Kevin fiddle with those things. I am no gunsmith. I still think the 460 Wby/500A2 might feed well from the 416 action with a minimum of effort. Start with the polishing and then see. After all, some actions "suck against a true Mauser" as Alf says. BTW, my BRNO ZKK 602 started out as a 375 H&H and was converted to "510/460Wby Improved Jenkins and Berry (510 JAB). No problems.

I have also had no problems with the 460 Wby rim working on my as-is 416 Rigby CZ bolt face. Maybe 500 grains has some variant brass or an action that is "suckie" as Alf says.

Does anyone have access to reliable rim diameter and thickness measurements on the 416 Rigby and 460 Wby, or their nominal specs?

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Good huntin' and shootin',
RAB

[This message has been edited by R. A. Berry (edited 09-06-2001).]

Just looked this up in the A-Square manual.

416 Rigby rim diameter .590 x .065 thick

460 Wby .579 x .063

There have been two different rim diameter used for the 460 Weatherby Mag. They are .579" and .603". If memory serves I have listed them old to new. The Rigby is .590" diameter. Teh thicknesses are .063" for the Weatherby and .065" for the Rigby.

As far as the extractor is concerned that amounts to to only .005" (the thickness of a coarse human hair). If your rifle's bolt has been manufactured to any kind of print tolerance you will not have to touch the bolt face or extractor of your CZ550 if you use the 416 Rigby.

I seriously doubt you will need to touch the action rails outside of polishing (this mostly to smooth up the action). Of course like "JungleJane" said every rifle is unique so you will need to check your out to be sure.

I hope this helps.

Todd E

Well- I just ordered a 416 CZ550 from Brownells. I'll get it in a few days, then see exactly what needs to be done to the feed rails. My bet is that the 416 boltface will work just fine for the 500A2. If not, I'm in for some serious reworking of the bolt I'm afraid.

Todd E

The .603 number on the 460 Wby is the diameter at the belt.

Or you could just do the wildcat thing and go 458/416 and it would work wonderfully.

The crux of the issue is this: The extra 0.011" diameter on the CZ550 bolt set up for the 416 Rigby will be a bit loose and sloppy on a 460 Weatherby case head.

David,

You are correct the belt diameter is also .603" as is the rim. The rim and belt have the same diameter on the 460 and 416 Weatherby Mag. The rim is formed by plunging a parting tool into the belt at the appropriate profile position.

Regardless, it is only 0.005" - 0.006" of and inch difference to the extractor claw of the 416 Rigby rifle and that is pretty much within the tolerance range. I seriously doubt any bolt face mods are going to be necessary.

Todd E

Todd E,
That sounds right to me. I am not in a position to measure and verify. I can tell you all that the cases I dealt with had no problems with the 460 Wby case in the 416 Rigby bolt face. There has got to be a little slop involved, especially in a "DGR" where tight tolerances in the bolt face might cause a jam in the heat of the fray.

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Good huntin' and shootin',
RAB