Inner torque shoulder out of square

[mcassill]

Working on building a 6.5x55 sporter on a K Kale Turk action. Did some measuring after getting the outer torque shoulder squared to the receiver ring threads, and found that the inner shoulder is about .009" out of square with everything else. Way I'm looking at it I have a couple of options for dealing with this. One would be to build a tool to cut the inner shoulder square to everything else; the other would be to just leave the barrel shank a couple thou short so that it doesn't contact the off-kilter inner shoulder. Any thoughts on which would be the better (or easier) way to go here? Thanks in advance.

Mark

[z1r]

How do you know it is the inner ring that is not square? It could be true while the threads are really out and thus your front ring would be too since you relied on the thread to be square.

 

 

[flaco]

mcassill-

 

If you go to Steve Wagner's Site

 

and rummage around, you'll find instructions on making a tool to lap the inner torque shoulder.

 

I'd then lap the lugs, and then the bolt face.

 

It seems to me that everything should line up pretty well then.

 

Still, .009 seems like a lot, and in general the advice is not to lap the lugs too much, for obvious reasons, or the bolt face too much, because of potential feeding/extraction problems

 

Now--at risk of yelps of protest--I'll suggest that opinions vary on whether to torque the barrel to the inner torque shoulder, both shoulders, or the receiver face.

 

A couple of weeks ago I spoke to a smith who builds top grade Palma rifles: He advises torquing to the receiver face, as it's impossible to torque to both faces, and the outer torque face has a larger diameter, and is therefore more stable.

 

I'll be curious to read responses here, as this is by no means my area of expertise; I've only built two rifles, and the inner torque shoulder was parallel on both (judging by depth micrometer) after truing the front.

 

flaco

[z1r]

Steve's lapping fixture would work in theory IF and only IF the threads are square to the bolt bore. If, in fact the threads are cocked, then so too will be the inner shoulder. That's why you MUST first determine what is square relative to what.

 

Consider this: If you lap using Steve's fixture and the threads not perpendicular to the bolt bore, then you will have the barrel abutting a surface that is perpendicular to the threads but the bolt will be cocked compared to that. Sure, you can lap the bolt face, but it will only be square when the bolt is locked. When you try to open or close it the bolt face will try to cam against the case head.

 

Sure, you can fit the barrel up to the receiver face but again, if the bolt bore is not perpendicular to the threads you essentially have the same problem as above.

[Doble Troble]

Excellent explaination of receiver truing concerns. Thanks Z!

[flaco]

This beggars a couple of questions, Z.

 

I know that one cannot use a mandrel to ascertain if the bolt is square to the threads.

 

Is there any way to tell if the bolt is square to the threads?

 

And if truing the receiver face, and all the subsequent processes, are based on the act of faith that the threads are square to the bolt, why does virtually every gunsmith offer a Mauser accurizing service that begins with squaring the receiver face. Using a mandrel.

 

Is this just a rip off?

 

Is it more often than not an improvement to the action?

 

Thanks.

 

Your loyal disciple,

 

flaco

 

You may call me "Grasshopper."

[Doble Troble]

one cannot use a mandrel to ascertain if the bolt is square to the threads

 

Yes one can. This is about the only way to do it.

 

Unless you mean bolt face, and then if you're going to go to the trouble of measuring you might as well lap it true. A bit of Dykem and the lap will tell you how far off it is.

 

There aren't any mysteries here.

[flaco]

DT-

 

See z1r's post here.

 

I believe he is correct.

 

Your loyal disciple,

 

flaco

[Doble Troble]

Um, thanks for the link...but I don't see anything about a mandrel not telling you about a bolt/receiver misalignment.

 

The only convenient way I can think of to measure bolt alignment is with a properly fitting mandrel...and it ain't going to both go through a cockeyed bolt race and screw into the receiver (I've tried, and learned that receiver wrenches are important tools).

 

I hope I'm being clear. Maybe you need to define the word "mandrel". To me it is this.

 

From your link it seems that you're concerned with determining the extent to which the receiver ring and inner rings are parallel. I agree with Z that careful measurement is the solution. If your question is what to do if you find that the inner and receiver rings aren't true - this is a tough one. If a mandrel indicated that bolt race and receiver threads were true, I'd use a Steve Wagner inner ring lapping tool, hit the bolt face, and call it good.

[z1r]

DT,

 

It's true that enough slop exists that you can easily put the screw-in mandrel through a receiver with cocked threads. Not only is the bolt bore oversized, especially in the bridge, but think of the loose thread fit necessary to ensure functoning with the myriad mausers out there. The type used to recut threads on rem 700 receivers as sold by Dave Manson use bushings to ensure a tight fit in the bolt bore.

[Doble Troble]

Well, damn. I'm wrong again. I hate that!

 

Possibly in my defense the mandrels I've made fit pretty tight. Also in my defense, I'm a Bubba.

[z1r]

Everyone, Including myself buys/bought into the notion that those mandrels work.

 

Even with tight threads though, just measure the actual diameter of the rear bore under the bridge. They will often measure .710" or more, the front bore is tighter.. The bolt is a nominal .700". Thus, it is impossible to cut a mandrel that screws in from the front with diameters large enough to accomodate both the bore sizes.

 

You need a special mandrel(s) cut to fit both bores approriately. This requires MANY mandrels to fit the many variations you will encounter. These are a pain to make and even harder to describe how to make them so I won't even try. Seriously, it took near half a year for me to decipher this mystery.

 

Take solace however in knowing that for most people's needs the screw in type is usually close enough. Especially if you use a good receiver. Defining good is a whole new thread.

 

Where the shortcomings of the screw in mandrel are readily apparent is when using one to surface grind a receiver then machining a set of custom made rings.

[mcassill]

Very interesting. Thanks much for the info, fellas. I know from measuring that I do have a bolt face parallel with the outer shoulder; I guess the decision comes down to whether torquing to both shoulders (vs. just the outer one) would give a benefit worth the considerable trouble involved in making it happen.

Mark

[albertashooter]

Very interesting.  Thanks much for the info, fellas.  I know from measuring that I do have a bolt face parallel with the outer shoulder; I guess the decision comes down to whether torquing to both shoulders (vs. just the outer one) would give a benefit worth the considerable trouble involved in making it happen.

Mark

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.009 out of square is a lot. That would cock the receiver out of line with the barrell about .081 in its 83/4 lenghth, I would think that is a visible amount . If you have the original barrel I would true up the shouder on the barrel, make sure it did not contact the inner ring and screw it on snug. Line it up visually and see if it is straight. I have heard that running a fine tight string from the top of the muzzle to the rear tang screw can help spot a out of line condition. If it is straight the outer shoulder should be true and you can go from there.Personally, I would try to find a way to true the inner c-ring in that case. however if ithe receiver is cocked the threads are out of line and to make things right you would have to find a way to recut the threads straight and then retrue the receiver from there. In both these conditions, is a turk worth the time and labour to you?

[z1r]

Ask Rembo on 24Hr CF how he proposes you "set it up" and cut both shoulders?

 

Ask him how he indicates it in so he knows it's running true?

[albertashooter]

What is 24hr CF. Out of curiousity, I would love to know the answers to those questions . I am aware that the proposed method I put forward is a attempt to get a general idea if the receiver shoulder is kinda square and not a precise method of squaring the action . Probably all the effort a turk is worth.however to get a really accurate and proper job is a very different kettle of fish.The only way I can think to mount the receiver to get acccess to the threads and c-ring is a cathead sized to fit.As far as indicating, that one has me stumped except for maybe building a mandrel for that specific receiver that extends far enough out of the receiver to be able to indicate near the receiver and also perhaps 8 inch in front of it. Seems kinda dicey to me. I do not think a Turk is worth this kind of investment unless as a learning and practice piece.

[z1r]

Albertashooter,

 

That reply was for mcassill.

 

24 hour campfire where he also posted this question. A poster there sugested it would be easy. Like you said, not worth the effort for a $50 Turk.

 

Again though, before you can true anything you must first determine which surface is REALLY out of kilter.

[albertashooter]

Thanks Z1R

 

I read the post and all made sense. For a while I was under the impression the someone out there somewhere had the answer that I just could not see. I know there are a great many people out there( on places like this board) that know considerably more than me and it is always great to pick up a little of that wisdom.

[carzngunz]

The first K Kale rifle I bought had this same problem. The inner ring looked like crap in addition to being out of square. After I got it cleaned up and trued up I had a whole new problem. The extractor extended past the inner ring by .020". That means having to cut an extactor clearance slot in the barrel. This was all before I found this great place with all the knowledgeable people that hang out here. I never have used the receiver but have a Remington 30-06 barrel already threaded for it. So after all this just know that the receiver is salvageable but it may take more work (or money depending on your abilities) than it is worth. Personally the knowlege I gained truing up that receiver was worth more to me than it cost anyway. Good luck with your project.

[Doble Troble]

the knowlege I gained truing up that receiver was worth more to me than it cost

 

This is mostly what it's about for me too. Having a rifle that shoots in the end is the cherry on top.

[mcassill]

Ask Rembo on 24Hr CF how he proposes you "set it up" and cut both shoulders?

 

Ask him how he indicates it in so he knows it's running true?

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Sorry for the delay here; the last week has been nuts, and it looks like I may have to put off the whole project for quite a while. Anyway, I did ask him about that by PM there; his explanation makes all kinds of sense.

Mark