Looking at a .50 Peacekeeper project on a Rem 700 LA and I'm wondering if the bolt face can be modified to accept the big .460 Weatherby cartridge.

The .50 Peacekeeper is appealing to me because of the minimal amount of work necessary to form the new brass. As I'm lead to believe, it is just a .460 Wea. necked up to .510 diameter.

Any thoughts?

Thanks,
Jeff

This ground has been covered many times. In reality the Rem 700 is just too small an action for the 378/460 .590 boltface. The lug strength is minimal at best and most knowledgeable gunsmiths won't do the work because of liability reasons. With that said, People have done it and if you keep the presures low I doubt there would be any trouble. Hot load it and better your head than mine behind that bolt! Given the cost of CZ550's why would you ever consider a Rem 700?-Rob

Jeff,

The problem I see is that the metal left around the counterbore will be so thin you would only need to drop the bolt and be in trouble. A big overload might also expand it.

CRF actions are different because the section protruding from the bolt nose to hold the case against the extractor is not nearly so long as it is for push feeds with counterbored bolt face.

I think as Rob says the CZ is the way to go or pick up a used 300 Wby. Wbys are good in the sense that the action rails are not involved with the feeding. So a 300 Wby fitted with the magazine box and follower for the 378 based guns and you are there. All you need is the small notch cut in the right hand side of the receiver ring which allows a loaded round to be ejected.

Mike

Can it be done? Yes. Is it safe? NO.

Re a 300 Wea MK V, it takes the following to convert to 378/416/460: (I have done several)

Magazine Box, follower, ejector (yes, they are different).

Machining required: Open up the magazine well in the receiver for the larger box. Cut the notch in the receiver ring. Mill the bolt stop groove enough to allow the bolt to come back far enough to pick up rounds from the magazine. (Should use carbide end mills and a good coolant system, other wise you will be buying a lot of HSS end mills.) Open up the bolt face and install the new exractor.

John,

Have you done both US and Jap Wbys.

A mate of mine just recdently changed a 270 Wby (Jap) to 416. Magazine when straight in and only bolt guide slot had to be lengthened. 300 Wbys I have seem are the same bolt guide length as the 378s.

Mike

Thank you for your replies.

I apologize for asking a question that apparently asked many times before. However, please take pity on my poor soul, as I'm new here

I had a feeling that the Rem.LA bolt couldn't handle the .460 Weatherby safely, but I had to ask to make absolutely sure.

Ironically enough, I just sold my .340 Weatherby Accumark 2 weeks ago. Had I known better, I should have kept onto it.

Thanks,
Jeff

Interesting photos & article on this at Dan Lilja's web site. He's not in favor of the idea of shoving .378 Wby size cases into a Rem 700 action.

Robgunbuilder, why are the lugs too weak in the M700? As I recall the lugs and bolt dimensions are very close to a M70 Winchester. I am simply curious as to what the weakness is.

Thanks,
Axel

Axel- I didn't say the Rem 700 lugs were weak I said they were too weak for the 460 WBY. Run the calculations yourself. As john Ricks, Dan Lilja and others have said, doing this mod to the Rem 700 just isn't wise. -Rob

How big are the locking lugs on a CZ 550 as compared to Rem 700.

Mike

After having machined ( from blocks of 4130) a couple of actions myself ( most recently a custom .50BMG), the issue isn't just the size of the locking lugs. It's much more complicated than that as I'm sure you know. Major considerations include the type of steel used and the heat treatment as well as the bolt lug dimensions and receiver locking shoulder thickness and locking contact dimensions. For example, my .50 BMG receiver was made from 4130 treated to R/C 42(tested and certified) and has 1 inch thick receiver locking shoulders and 1 inch thick by .850 wide locking lugs on the bolt ( also tested and certified R/C 42). There is also a bolt handle locking slot ala Rem700 as a final saftey valve. This action was over- designed as a test mule for some of my "way out there projects".
All the calculations are available on Dan Lilja's website. I believe when I ran the numbers on the CZ550 that the action would take in excess of 85,000 psi. That was also pretty conservative.
Finally, when discussing a actions Strength, you have to consider the remaining wall thickness of the barrel with certain cartridges. For example, a Rem 700 uses a barrel shank of 1.060 ( major thread diameter) and a 460/378 at the belt measures .605. This leaves only about .226 inches of metal left. The diameter of the Rem action is 1.356, thus, you only have about .375 inches of steel ( which expands on firing to contain a cartridge which generates 64,000.PSI. The basic rule of thumb is that you should have a total wall thickness of at least .400 for cartridges in the 64,000 PSI class at the weakest point ( i.e the belt).
When you chamber a CZ550 for a 460 WBY for example, it will result in a total wall thickness of .411 which just meets the above criteria. Now for cartridges which deliver lower pressures or for less than max loads, the above dimensions in the Rem 700 will be adequate.
I personally consider making a 30/378/378 or 460 WBY on a Rem 700 action just too marginal although as I have said, I have seen this done and even with heavy loads they have held together. at least so far. I would not like to speculate on what would happen in an overload situation or wheter the receiver lugs will set back over time.
Doing the math on the .600 Overkill for example indicates that with a CZ550 1.100 inch shank and a cartridge which mikes .681 at the belt, and a CZ outside receiver diameter of 1.427, that you again have only about .378 inches of steel to contain the cartridge. However in this case, you are dealing with only 52,000 PSI and it's probably not possible to get any more powder into the case so an overload is not possible. This is a great advantage of the larger bores. Finally, we will be using 3 groove barrels on the .600 overkills so that even lower pressures can be obtained. As I've said, I think the .600 Overkill is the "mostest" you can squeeze out of a CZ 550. I hope this diatribe helps.-Rob

Rob,

What are you views on the Wby Mark V which has (I think) the same barrel thread and receiver diameter as the Rem 700.

Mike

Babs2...if you are looking for a Rem 700-type action take a look at the McMillan MCRT as you can order it with the big bolt face...this is the action that Lazzeroni uses and they are hell-for-stout. Not cheap but a solid foundation for a powerful custom rifle.

Robgunbuilder,

I have measured the locking lugs on a M70, CZ550 Magnum, M700, and M77. The M77 has the smallest effective lug contact area; therefore the greatest stresses! The CZ has the greatest contact area and the M700 and M70 are very close.

These rifles were:
M70 300 Winchester magnum
CZ550 416 Rigby
M700 7mm Remington magnum
M77 375 H&H magnum

I cannot comment on the materials, but stresses do not depend upon material. It seems to me that from an lug strength point of view the M77 is the weakest. It seems the biggest problem with converting a M700 to a Rigby sized case would be converting the extractor to a Sako type. Is that a problem, I do not think so?

Axel

Axel- Converting a M700 extractor to a sako is the least of the problems I'd be concerned about. As I've said, I'd be concerned about a M700 converted to a 460 WBY sending the bolt through the back of your head and bouncing off into the parking lot with a stiff load. There are people on this board who have hit 2700fps with 500 gr bullets in 460 WBY's despite obvious overpressure signs like enlarged primer pockets,buldged belts and clear ejector marks. I'd love to see what would happen to a M700 with such a load. The conversion is trivial, the safety concern isn't.
Mike375- I know you like Weatherby's and I will admit to owning a 460 WBY myself, however, I'm not a fan. As you know Weatherby's multiple locking lug system will handle the 64,000 PSI forces quite well. I think there is also about .400 of metal also around the belt. It is definately a strong action. I've not done the calculations on the lug strength, but I'm sure it's greater than the CZ-550's and sure as hell more than a M700.
I don't like the feeding of the 460 nor the mag capacity of two down. The other thing I have against WBY is that I have had WBY's with flawed barrels. Their service here in the states is a joke and they seem to have no competent gunsmiths available anymore. One WBY I owned a 30-378 had its muzzel brake installed so off center that the bullet actually made contact with the end of the brake. It would be a cold day in hell before I'd reccomend one for a big bore project. I'm sure it can be done, but not when there still is better starting material around.
I will admit that the WBY single stack mag is an interesting option, but it's just too crude IMHO.-Rob

Robgunbuilder, how much additional thrust force is generated by a 64,000 psi 460 Weatherby load as opposed to a 65000 psi 338 Ultra magnum load?
I think you just do not like M700 for anything outside the realm of varmit rifles. As I stated earlier the Ruger is the highest stressed. It also uses a cast receiver so it is very probably the weakest material as well. There are guys converting the Rugers to 416 & 460 Weatherby, 500 A-Square, 505 Gibbs, Etc. All of these are high thrusting cartridges I believe although I do not hear of anyone having bolts flying our of their guns.

Are you aware of the fact that CZ only specs their actions to 53500 psi! You are saying it is ok to chamber a CZ550 in 460 Weatherby magnum. That cartridge generates pressures over 10500 psi greater than the action is proofed for. I do not know you from Adam so I do not know if you are what you say you are, but I know what my CZ550 has stamped into the side of it's action!

Axel

Axel- Are you for real? Think about it a bit more. Do you know what the differences in force are between the .530 boltface of a .338 ultramag and a .590 boltface of a .460 WBY. Do you see Ruger chambering the M77 in 460 WBY or Remington either? Guess why not!
I could care less if you build a T-rex on a M700.
From this and other posts it's clear to me you don't have a clue about what your talking about nor the experience to do so. Please do us both a favor and don't reply to my posts in the future and I'll do the same.-Rob

Robgunbuilder, I think the more appropriate question is; are you for real? Thrust force does not depend upon the bolt face diameter. Thrust force depends upon the internal surface area of the base of the case.

You also ignored my statement regarding the CZ's safe maximum load pressure. By safe I merely mean the maximum pressure the manufacturer specifies the action to.

For your information, the thrust force difference between a 460 Weatherby and a 338 Ultra both load to 64000 psi is 1500 lbs. According to my calculations, based upon measured firearms, the contact stresses on the various actions when subjected to the 460 Weatherby would be:
M700 - 115000 psi
Ruger M77 - 128000 psi
CZ 550 - 100000 psi.
So there you have it. As I said earlier I do not know for sure what the mechanical properties are for the receiver / bolts of these firearms, but stresses don't care about that.

Axel

Robgunbuilder

I am not really a big fan of the Mark V. Although until the CZ in 416 Rigby came out I always thought it was the nice and east way to a big banger. I do however like the easy convesion from one caliber to another and the long magazine and that it takes Rem 700 mounts.

The vertical stack in my opinion produces the most control feed of all but compared to a nice staggered feed it is probably like having and injection of alcohol as compared to getting drunk on Krug champagne

I have seen a 378 loaded with what would have been 110 grains of Varget and 270 Hornady. The powder measure had been set for 108 grains of IMR 4350 at the range and then the rifle was going to be switched back to lighter loads with Varget but the measute was not changed.

Obviously a ramrod down the barrel with someone else on the bolt handle. The action appeared to set back about .001" or so. That was based on rechambering previously fired cases. Chamber seemed fine. Maybe all 9 lugs were bearing in after that load

Mike

Mike375 -I'm impressed that the WBY took that load and only set back .001. Thats amazing! I guess those nine locking lugs are good for something other than collecting grease or dirt. In my 460 about 113 grs of IMR4350 is max. At that point case expansion at the belt is .002 and stable. I've gone as high as 117 grs to see what it would do, but I saw significantly more belt expansion and extractor marks so I quit. I could not get better than 2640fps out of mine with Hornady solids. Since then I've come to learn that the 460WBY is probably best at 2500 fps at the muzzel so that you are in the 2400's when used on Buff and the like. This frankly seems like the best approach to essentially slightly improve on the 458 Lott/watt/ Ackleys.
As far as the single stack is concerned, mine is just cheap sheet metal and the lips continuously get out of whack so that I have to adjust them from time to time. This and the two round down limitation made me think twice about taking it to Africa. It's got great accuracy, It just doesn't seem reliable enough to me.-Rob

Rob,

That 110 grains would be about 15 grains over max for a 270 grain bullet. The person who shot the rifle did not know it had happened until the bolt was to be opened. I was the shooter.

I have owned two Japanese 460s and both were very accurate with 500 Hornadies and 115 grains of IMR 4350 which did right on 2500 f/s. I found with 4350 that slight ejector mark started at a bit over 2600. I have never had any problem with the vertical stack, however, probably 99% of the shots I have fired on 378 based rifles have been single shot.

The lips have all been stiff on the ones I have owned and they have all been Japanese. To stiff to be able to get a cartridge dopwn threough the top without a lot of effort.

The biggest difficulty with the 460 is working up mid range loads with lighter bullets. The huge freebore makes hangfires the order of the day. With 85 grains of 4064 and 500 Hornady I use to get just over 2000 f/s and full accuracy. I have nebver really done much with the 2 378s I have owned with mida range loads and light bullets but they also huge freebore. However the smaller bore would help with the hangfire problem.

Being in Australia I prefer the 378 case to the Rigby case because the Wby agents always have plenty of brass and if you were really stuck they would be bound to always have at least 2 of the calibers on the 378 case in stock. To me Wbys and big calibers are a bit like Rem 700s and accuracy rifles. I am not in love with either but they are an easy way to go. While it is probably only a problem in my mind I am not keen on any action like the CZ that has the integral scope mounts. The other thing I like about Wbys is that because they are basically a piece of shit and also because of the actions appearance, they remove all temptation to go down the road of quarter ribs and other dollar eating exercises

Mike

Mike375, are you saying that you accidently fired off a 110 grain Varget load in your Weatherby? That is somewhat scary. I have seen published load data for the 475 A&M Magnum which was 110 gr of IMR3031. That would be in the same class as your accident. Although your accidental firing would be at a somewhat higher pressure since you were shooting a 378, but then Varget is a slower powder.

Robgunbuilder, I see you are now ignoring me. That is typical of someone who knows they are wrong. I still do not understand your attack on me. I asked you to explain your comments on action strengths and you could not. The reason is relatively clear. All of the mauser derived actions are similar in stress level. In other words they are all stressed to about the same level and for the matter made of the same stuff. Please grow up and recognize that we are all entitled to our opinions, but facts are facts. The facts are the M700 action is almost certainly strong enough, but it is not an action you would build on. They are not used for heavy magnum target guns do to action stiffness concerns not "strength". The M700 is the least stiff of all the popular hunting rifle bolt actions, with the exception of the Savage which is similar to the M700. But then again as you said I know nothing ie am an idiot. Again GROW UP.

Axel

[ 09-21-2002, 03:50: Message edited by: Axel ]