9.3davison
Active Member
I have a Sako A5 action that has had the bolt face opened up to accommodate a 7 mm Dakota. Would it be too big now to use for the Nosler/ultra mag/wsm family family of cartridges?
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Dakota bolt face compatibility
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J E Custom
Well-Known Member
The bolt face of the Dakota is for the 404 Jefferies and the Ultra Mags, Even though they are based on the Jefferies case the case heads have been turned down to the standard Magnum case head, (.532 ) and the Jefferies/Dakota is .545.
So with the bolt face opened up to handle the Dakota it will be somewhere around .546 to .548 and there will be to much clearance for the RUM in my opinion and will/can result in extraction problems. (It may not hold the case tight enough against the extractor.
There is however a solution, Just buy 404 Jeffers brass (with the larger case head) and size them in a set of RUM dies. "OR" buy a new bolt with the .534 bolt face.
J E CUSTOM
So with the bolt face opened up to handle the Dakota it will be somewhere around .546 to .548 and there will be to much clearance for the RUM in my opinion and will/can result in extraction problems. (It may not hold the case tight enough against the extractor.
There is however a solution, Just buy 404 Jeffers brass (with the larger case head) and size them in a set of RUM dies. "OR" buy a new bolt with the .534 bolt face.
J E CUSTOM
Roeder
Active Member
In the real world, no manufacturer that I know of actually uses a different size bolt face for the Dakota case and the RUM, Not even Dakota. Straight from my calipers on actual 7mm Dakota cases and 7mm RUM cases, the actual case head diameter is .540 for the Dakota and .534 for the RUM. I can't imagine that you would have any problem with extraction and even if you did, a little work to fit a new extractor would surely correct any issue.
J E Custom
Well-Known Member
When Remington designed the RUM, they decided to use the Jefferies case (The same as the Dakota) but rather than change all the bolt face diameters to fit it they simply changed the rim diameter of the 404 case to fit all of their bolts. The Dakota will/should not fit in a standard magnum (RUM) bolt face.
In order to extract well, the bolt face must have .002 minimum to .005 thousandths maximum clearance more than the case head. any more clearance, and the case head will/can move away from the extractor and disengage while still in the action.
If your Dakota cases are .540, the bolt face is at least .542 or larger
and would give you .010 or more case head clearance with the RUM Case. This would be to much for normal function.
The Dakota is bigger unfortunately and will never perform proper extraction with RUM cases. Sorry, but It is what it is.
PS: I once tried a different size case in a bolt to see if it would function, that had less than .007 thousandths clearance, and as soon as the case backed out of the chamber just a little, the extractor released it (Every time) and it dropped into action and had to be cleared to operate the bolt.
J E CUSTOM
Roeder
Active Member
Be that as it may, Remington has also offered the 700 in a variety of similar but not identical case head diameters and custom action makers use a .480 bolt face with both the .440 diameter PPC and .470 diameter .308 based cases in what they call a "Universal bolt face" which has a Sako extractor with a little extra claw length. In this case the actual difference between actual cases is .006 and if it does not work as is, a little extractor and possible ejector adjustment will absolutely make it work.
shortgrass
Well-Known Member
I'd suggest a simple test, take a magnum cartridge case and see how it fits the existing bolt face.......... I know,,, that would be too easy!
J E Custom
Well-Known Member
Sorry I couldn't help you.
There are many other problems associated with poor tolerances, and Most people don't want to deal with them.
Precision means everything in this game and we work within 10/ths
of a thousandths and stay within the maximums and minimums to eliminate any problems.
Making it correct is called Gunsmithing. Making it work, or "OK"
is not in many peoples vocabulary when it comes to firearms, especially one used for long range hunting/shooting.
Not criticizing, just trying to answer your question.
J E CUSTOM
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9.3davison
Active Member
9.3davison
Active Member
Thanks for all the help. I have decided to go another route.
Roeder
Active Member
My life's work is machining military aircraft parts to tolerances of tenths or less. This is just a case of differing opinions. I think there are a lot of gunsmiths out there that would not have an issue with this.
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J E Custom
Well-Known Member
Once again, In an effort to help someone stay out of trouble and keep them from spending lots of money to solve a problem, I get slammed.
You don't know me, and I don't know you so My post and recommendations are based on My experiences and If someone disagrees, so be it. Normally when a person ask a question on this web site, It is because they don't know or need/want a second opinion.
I'm sure you are a better machinist than I am if it's your life's work
and I cant say how good of a Gunsmith you are, so if you disagree with me or any other person on this site, that fine. And my website was/is there to help others with questions and solutions to problems not to boost My ego. I also did not know that I had a big internet presents because I have learned more from listening to many of the fine gunsmiths on this site that don't mind sharing their secrets and recommendations.
I will continue to try and help those that ask for help, And try not to offend anyone in the process but if I do, it is not intentional.
J E CUSTOM
Roeder
Active Member
Unfortunately, once the post button is pushed, the post is out there. I have looked over your website and I think you offer nicely designed brakes and people seem to think highly of your work. I do see the point of view of trying to help someone stay out of trouble. If the OP had asked about the advisability of his project I might have advised against it for other reasons.
I don't come to this forum every day and I don't post often. I would hope we can politely and respectfully disagree. I regret the wording of my last post and I will edit it to reflect.
J E Custom
Well-Known Member
It's not necessary. But thanks !!!
Also, I don't make brakes to sell, I just occasionally make a custom brake for a member that wants one custom tuned for their rifle to get the most recoil reduction from it.
I to hope we can respectfully agree to disagree on future post.
J E CUSTOM
D
Deleted member 46119
Guest
Your un-edited post was very inflammatory in it's form. I hope that was because you were having a bad day.
First sentence is completely a condescending slight on someone you know nothing about. Beyond "respectfully disagree" a full face apology is warranted. (My opinion)
Second sentence. Any gunsmith who uses a Datota bolt face for a "normal" magnum bolt face cartridge is dangerous. (MY opinion). As someone who claims to be a machinist to tenths, I am at a loss to understand how you could condone .010 of slop in a fitment.
Sorry, escaping errors is not as easy as editing. I've been on both sides of this kind of thing. I full face apologized.
