What to do with Mark V

I would definitely build a big 338 on it. I have been working with a accumark 338-378 at long range and it will match what I could do with my customs.It is a excellent action to work with.A guy that holds some word records at 1000 yards has a Lapua improved on a Mark V action and it has shot unreal to even past 2000 yards.Guys that bad mouth the Mark V action don't know what they are talking about... It is a very capable action and is very strong. It would be tough to beat a 338-378 or Lapu AI

You are wrong on at least 2 counts. First is, I have had conversations with some very experienced smiths regarding the Mark V actions and I know a little something about them.

Second is, I am not at all "bad mouthing" the Mark V. It is a fine factory action. that said, It was not 'designed for a Lapua class case, although you can certainly build a Lapua on one.

As for strength, I think you'll find that is not significantly any more strong than a 700, M70 or Howa. It does have some good features like a beefy integral recoil lug and one piece bolt. My biggest beef with the Mark V is the 9 locking recoil lugs. While that allows for a short bolt lift, you will almost never be able to get them all to contact their mated surfaces which defeats the strength design theory and results in uneven contact.

The Lapua has a a .589 bolt face which is larger than the standard magnumum bolt face the the Mark V was designed for. The larger bolt face results in greater bolt trust which the Mark V was not designed for. That said, 338 Lapua's have been built on the Mark V.

If and when I do build a 338 Lapua class rifle, it will be on an action that was designed for it like a TRG or Custum. You do as you wish and please be careful not to misrepresent what I say.

Thanks

Deviant Action « Defiance Machine
 
Mark, not arguing, but the .378 Wby cases have a larger bolt face than the standard .513 magnum bolt face that the .300 Wby and smaller cartridges have.

Also, if it wasn't designed for the larger magnums, why does it work so well for everything up to a 460 Wby?

Seriously, not arguing, just wondering about those comments.
 
Mark, not arguing, but the .378 Wby cases have a larger bolt face than the standard .513 magnum bolt face that the .300 Wby and smaller cartridges have.

Also, if it wasn't designed for the larger magnums, why does it work so well for everything up to a 460 Wby?

Seriously, not arguing, just wondering about those comments.

Mud,

Actually the 300 WBY has a .511 (or .513 depending on your source) base diameter and the standard .532 bolt face/rim diameter that the other 375 H&H belted prodigy have. That said, you are correct that the 378 variants have a larger .579 bolt face which is about .010 smaller than the Lapua which I just learned by looking it up :) So that is really not that big a diff. That said, i would still go with a custom action. Some things just bug me, and the 9 little lugs on the Mark V's bug me. I was actually considering using them for some of the builds I just did as well as a 339 LM Imp and after a chat with Kirby, i decided against it. Now let me make this very clear since I have used Kirby's name... He did not say the Mark v was a bad action or that it could not be used for a Lapua build... he did say the 9 lugs were an issue as far as getting them all perfectly lapped and also said a beefy custom action was better or more suited for chambering a Lapua. My current smith also agreed about the 9 lug issue and tells anyone who wants to use a Mark V for a build, that he only guarantees 1 lug of of the 3 in line will fully contact the receiver. Maybe more but only guarantees 1.

Last, If I were to ever design and build my own actions, I would use the Mark V as the model. The only thing I would do different is to change the 9 itty bitty lugs to 3 beefy lugs like my Sako 85 and use the same CRF design. Everything else would be identical to the Mark V, except that I would also offer a longer version for longer cartridges like the RUMs
 
Have a Weatherby Mark V action. Was used on a .30-378WM Accumark. Now just have to decide on what kind of build to use it for. Considering a .338-378. Would like to be able to shoot 1200+ with it. Under 15lbs. Whats a good custom gun maker that could help with the build and supply good ideas. Lets be creative...
gun)
See if Trunbill Restorations in N.Y. has done any of that kind of build.

 
Mud,

Actually the 300 WBY has a .511 (or .513 depending on your source) base diameter and the standard .532 bolt face/rim diameter that the other 375 H&H belted prodigy have. That said, you are correct that the 378 variants have a larger .579 bolt face which is about .010 smaller than the Lapua which I just learned by looking it up :) So that is really not that big a diff. That said, i would still go with a custom action. Some things just bug me, and the 9 little lugs on the Mark V's bug me. I was actually considering using them for some of the builds I just did as well as a 339 LM Imp and after a chat with Kirby, i decided against it. Now let me make this very clear since I have used Kirby's name... He did not say the Mark v was a bad action or that it could not be used for a Lapua build... he did say the 9 lugs were an issue as far as getting them all perfectly lapped and also said a beefy custom action was better or more suited for chambering a Lapua. My current smith also agreed about the 9 lug issue and tells anyone who wants to use a Mark V for a build, that he only guarantees 1 lug of of the 3 in line will fully contact the receiver. Maybe more but only guarantees 1.

Last, If I were to ever design and build my own actions, I would use the Mark V as the model. The only thing I would do different is to change the 9 itty bitty lugs to 3 beefy lugs like my Sako 85 and use the same CRF design. Everything else would be identical to the Mark V, except that I would also offer a longer version for longer cartridges like the RUMs
Can't really tell frop pic but visual sure shows more than 1 making contact.
 

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I'm a big fan of the .30-378 however I already have a 7RUM, .300 RUM and 7.82 Warbird that shoot great. So I figure since I have the action I minus well go with a .338. More than anything I want the build to be done right the first time and have confidence with it. I know it will be topped with a NFX so I'm good there. With so many options in a build like this it could get really fun. I've tried emailing Kirby Allen but yet to get a response ( I'm sure he is building or hunting so I understand). But I'm open minded to any good maker though.
gun)
I think the 338-378 is one of the great rounds that doesn't get a lot of attention due to brass
Really think it's the kind of factory 338's and even with Norma brass… just can't get as many reloads. Waiting if rcc brass I've good thing with some big high pressure rounds so may be able to more of the round with it
 
See if Trunbill Restorations in N.Y. has done any of that kind of build.

Considering this question was posed in August of 2013, I hope your answer is a really good one! Maybe the OP has been just waiting for this! 🤣🤣🤣
 

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