Looking for opinions and comments on an idea I have been kicking around. As I stated in a post I am having a 577 bulit. The barrel coming off the action is now a 458 win mag(not a bad caliber),I have an Interarms Mark X action(375H&H) length. Here is what I am thinking, have the barrel rethreaded to fit the Interarms action,But what caliber? 458 Lott,450 Ackley or 458 Ultra? All comments welcome,good and bad

A 460 A-Square (460 Weatherby Short) would be real cool for this project. Good luck.

Go with the 458 Lott. I,m no expert but its what I want. 458 brass can be used for lighter loads and then use the 458 Lott for full power loads. I,m told the 458 Lott feeds better than some other shouldered cases, Is this true?

The Lott or the Ackley would be a great choice. I prefer the Ackley myself but either would be good. My buddies 450 Ackley feeds like silk. When you close the bolt it's hard to tell if it actually fed a cartridge. Either cartridge will take any game on the planet with good bullet placement and the recoil can be managed with a little practice.
470 Mbogo

I would go with a .458 lott and thats what I would opt for myself. Especially now it has been chambered in a factory rifle.

DD,
no reason to rethread, it's std large ring mauser threads.. and since you'll probably ahve to rechamber, the lott is a great idea on a std mauser. Even if you can't get a big enough mag box, you can single feed lotts over 458 winiie
jeffe

Switching gears on this project. Got to thinking about practicality of putting the #1 bbl on a mauser action,yes it is doable,but I am thinking I will go with a CZ 550,458 WM,have it rechambered to the Lott. Next question, is the magazine long enough for the Lott cartridge? I am thinking this will give me the most recoil for my dollar!

Diesel-Dude- The 500A2 is a snap to do on a 416 Rigby CZ550. That's a big step up from a 458win and a big step up from the 458 Lott/450 Ackley. The 500 A2 will require a new barrel, but the performance is way better. Believe me way better! If your into 45's then take a close look at the 450 Ackley. In a CZ t'is 5 or 6 down and more power than the Lott.-Rob

RGB, Other than the rebarrel for the 500A2,what other modifications have to be made to the action?

Diesel-Dude. The extractor works fine as is. If it was from a .416 Rigby it will be a little loose, but will eject just fine. Open the rails a little to feed the belt and grind the wings on the ramp away and contour the ramp face till a 570 gr woodleigh softpoint feeds smoothly. Sometimes the follower may be too loose on the left side and may require welding a small stub on to better control the feeding. Last time I did one I'd say about 45 minutes worth of work.

In a mk-10 or Whitworth, one must remember that those 375 actions are standard Mausers that have been opened up COMPLETELY in front, so I would not remove much metal from the feed ramp as you are about out of metal in that area...

They have gotten away with that due to the use of very good steel I assume....It will probably work for the Lott as metal removal is not significant..but a 577 could be a real problem I would think...?????????

Pretty much scrapped the idea of using the whitworth action. Sounds like a better idea to use the CZ action.
Ray, the 577 is being built on a #1 action!!

diesel_dude,

Go for the .450 Ackley. You can use full lenght .375 H&H brass. If you have money to change the barel the .470 Capstic could be an option nearly same as the .450 Ackley but with .470 bullet diameter.

DD or RGB,

Can the CZ 550 416 Rigby be rebarreled to 460 Weatherby without extensive modifications?

A460 WBy on A CZ550 is basically only a new barrel and maybe some minor rail/ramp work. Probably 15 minutes worth. Definately a good idea as you will get three down. Alot better than a wby 460 at 1/2 the price..-Rob

[ 02-08-2003, 08:00: Message edited by: Robgunbuilder ]

Rob:
Could you make a 460 WBY out of a 458 CZ, with out having to rebarrel?
Can you run the WBy at 2400 with a 500 grain slug, and, if so, how's the recoil, and pressure?

DR S

[ 02-10-2003, 11:12: Message edited by: Socrates ]

Scocrates- The boltface has to be opened and perhaps a larger mag box, but maybe not. The barrel still has to come off for the rechamber and that introduces the problem of timing the sights etc.-Rob

The .460 Weatherby and .450 Dakota both can achieve up to 2500fps with a 500gr pill. Not much fun to shoot. There is not much need to push beyond 2400fps unless you just want your clock reset ever time you pull the trigger.

Rob:
Do the 375,416, and 458 all use the same size threads?
In other words, is pretty much all you have to do to change caliber screw on another barrel?

In short, instead of selling my 375, could I just rebarrel to 458 or 460 WBY?

GS

Socrates,
I will jump in here, as I have done just what you are talking about, via the services of good gunsmiths, and have a couple of more projects in mind .

The CZ 550 Safari Magnum action has metric threads, and all the different caliber barrels are, of course, threaded the same. 2mm thread pitch, 28 mm thread outside diameter, V-shaped threads, designated: M28x2sp3. They currently chamber barrels with these threads to 7mm RemMag, 300 WinMag, .375 H&H, .416 Rigby, .458 WinMag.

The CZ 550 Medium of 30-06 length, however, has 26 mm O.D. threads of the same pitch, hence is: M26x2sp3.

A .375 H&H CZ 550 Safari Magnum may be converted to .375 RUM by simply rechambering. It can be turned into a 378 Wby by rechambering and opening up the bolt face and some feed work. My smiths have not had any difficulty timing/aligning the factory sights on simple rechambering conversions.

The factory barrels are tough to get off, may require heating the action and using extensions on the action wrench, and some good fixtures to hold the barrel in lead blocks in the vise, etc.

CZ seems to almost swage the barrels in, they put them on so tight. I have never had a smith do any significant damage to himself or the rifle in getting the barrels off however.

Gee thanks guys...now you got me wanting a CZ in .460!

Gotta get my Lott first, though...my dealer can get on in in a few days too! Yippie!! Now just gotta find a smith to bed the stock/ream the chamber...

best of both worlds... get a 416 cz, and a takeoff 458 barrel... then go 460 weatherby?

will be rather light, but you could also do a 500 a2 barrel, and have a 416, 460, and 500 on the same action.
jeffe

Thanks Daggaron.
I would much rather have the gun double bolted, and rechambered to 460 WBY, and load 300-500 grain bullets, at minimum 2400 fps, then have to fight the high pressure blues
with the 458 lott, to get 2400 fps, with 400-470 monos. However, the lott/ackley have the advantage of shooting the 458 win mag, in a pinch.
My 375 chambered to 460 would be ideal, with a new, 26 inch, or longer barrel, to wring the last bit of velocity out of the 460, but with low pressure. Figure when reloading, and past the initial cost, I should be able to load for a long time...at little cost.

If I want a light rifle, I can focus on buying that darn browning, in 458, and loading it with 300-400 grain bullets for plinking...

GS

FWIW-The only advantage I can see for a 458 lott in a CZ550 is cartridge capacity. you can hold more rounds( 5 maybe six) and I suppose if a Buff hunt goes badly this is the only situation I can imagine where more than three rounds in a gun will be of any value other than adding weight! I will add, that I met a guy in Africa last year who rechambered his cz550 with a hand reamer to 458 lott and successfully hunted elephant with it. This isn't proper gunsmithing in my book, but there is no doubt it can be done.!
The best mod of a CZ550 IMHO is the conversion to a 500 A2. This is best done starting with a .375 or .416 Rigby. Trying to salvage the original barrel for a 460 wby rechamber will be tricky and not worth the effort in my opinion. As Dagga Ron says, they are a bear to get off the action and getting a correct re-time may be very complicated. All Mauser type actions require that the primary and secondary torque shoulders mate exactly, doing this and getting the sights at TDC is a job for a really competent machinist not a gunsmith ( unless he has real experience as a machinist). Why bother anyway? The 500A2 is such a major step up in power, that it's worth the cost of the barrel.-Rob

[ 02-13-2003, 10:00: Message edited by: Robgunbuilder ]

Diesel Dude. ., I use a 450 Ackley. At the moment I have two. One on a Ruger No 1 and the other on a brno 602. {CZ}. I use Barnes X projectiles in the single shot and Woodlieghs in the crank handle. Over the years I have had a number of odd 45s including a 500 jeffreys necked down to 458. The acley seems to do everything I need.
Have fun. Jhon