Hi guys, rebarreling a Columbian Mauser 98 (it has a notch in the back of the receiver ring) originally in 30/06 I believe.
New barrel turns in solidly leaving a 0.001" gap on front of the receiver. The breach end never contacts the inside "C" ring though. It appears the previous barrel never did either. No marks. Ever run into this? I thought maybe the receiver threads might be tapered. If it is a solid connection does it matter? Accuracy might be an issue but is safety. Thanks

It has to contact somewhere.

quote:

Originally posted by Bill Leeper:
It has to contact somewhere.

Agreed. Barrel either contacts the receiver face, the C ring, or both. Making contact 'loads' the thread, creating torque. Interference thread fit is not torque, and theoretically could shoot loose, creating a safety issue. By torquing against a shoulder, with a square shoulder on the barrel, alinement is achieved. I would rather have the threads a bit loose and the receiver face square and barrel shoulder square, than tight threads that need a wrench assist to fully engage. Turn a nice 45 deg chamfer on the breech end and the barrel will most likely meet the receiver ring face. You did 'square' the receiver ring face before barrel work, didn't you?

'98's are designed to contact the inner ring to headspace with secondary contact on the barrel shoulder. Mauser barrel/receiver threads were 55 degree Whitworth form. If your barrel has 60 degree threads there may be inteference. The thread pitch could be a little different too. You could try lapping the threads in with compound until you get contact on the inner ring.

I would suspect that the outside rear corner of the shank is contacting the inside radius of the edge of the C ring

You would have to enlarge the chamfer/step on the rear corner of the shank to clear that radius

J Wisner

Let someone who knows how to fit barrels to Mausers install it for you. Not something to guess about.
What type of barrel vise do you have? As stated, it has to stop somewhere. Did you measure the barrel thread length and the receiver ring face to inner ring length? That will tell you immediately what is going on.

Many Mauser barrels threads are tapered due to how they were thread milled. One could argue this was intentional, but I've never found documentation that points on way or another.

Mr. Wisner's point about the chamfer/clearance is a good point, and something to consider.

Dpcd's point about actually measuring the thread length and C-ring depth is equally important. If this is a Columbian "produced" receiver, it could vary from nominal. Likewise the barrel you have may have already been fit to a receiver. The threads may be shorter than nominal.

I have seen many Mauser C ring bearing surfaces not true to the front face of the receiver.
More so after being re-heat treated.
Many times .001 plus out from each other

I have a lathe set up, and a special boring bar, where I can reach inside and true the inner C ring face, and then the outer receiver face in the same set up

This of course changes those receiver dims slightly, and the new barrel tenon must be machined to match

J Wisner

Mauser receivers very widely in that dimension whcih is why Military barrels do not contact the ring face. I read that the OP's barrel does not contact either the inner, or the outer ring.

Jim Wisner is a pretty precise guy! Just gotta wonder....If the front (outer contact) is perpendicular to the bore and is the primary contact..will the proven accucary be diminished rather than primary inner ring contact?

Anybody?

Definitely Not; you know that other designs do not have the internal ring, and use the reciver face as a barrel contact point. It does not matter where the barrel contacts; just needs to be, ideally, perpendicular to the bolt axis. And we have designs where the barrel does not contact the receiver tightly at all; take downs, ARs, Browning Machine Guns, Tank Cannons, and others. And the HVA, mauser derivative does not have the inner ring anyway.

There's no guarantee that the inner ring is square to the bore and it's much easier to square the face of the receiver. So I've never used the inside ring.

quote:

Originally posted by clowdis:
There's no guarantee that the inner ring is square to the bore and it's much easier to square the face of the receiver. So I've never used the inside ring.

I had a 'drop' of 18mm drill rod in the shop from another job and tried it for fit in 6-8 Mauser '98s. Nice snug fit. Center drilled both ends in the 4 jaw, then cross drilled and tapped for drive plate. I turn a 60deg point on a piece of scrap bar, then drive the bar with action between centers. Face the receiver ring just enough that it's "clean" all 'round. That is my torque surface. I make the tenon so as to not leave any gap. or as little cap as possible, so it doesn't collect fouling. Tenon length effects how much brass is not supported by the chamber, also. I "square" the face of every action I barrel regardless of make. Those that use a "recoil lug" like Rem does, I use a Sunny Hill as they are surface ground. That 18mm bar fits many/most Mauser '98s. I have 'bars' I made on the TC grinder for others. Square shoulders meeting each other can't be wrong. But, I'm nobody. Take my method for what it's worth.

I have set up and machined the face of the receiver and the inner barrel seat so that they are perpendicular to the bore. More or less. I say "more or less" because it is difficult to know whether or not the bore of the receiver is actually straight. A close-fitting mandrel will deflect the receiver enough that it's a bit of a crapshoot. Anyway, after messing with this quite a lot, I decided the only important thing was that the inner seat and the receiver face be parallel. This can be verified by measurement from the face to the seat in four places. If these two faces are not parallel, it is easy enough to make them so with a file and a stone.
For the bolt face, I can set the bolt up in the lathe, indicate the face, and true it if necessary. I fit the barrel to touch the receiver face first, then the inner seat. I figure on .002". I always provide a relief at the start of the barrel threads. This can be a straight relief cut of a bevel; it doesn't matter. Done this way, my Mauser based rifles probably shoot every bit as well as if I had just left them alone and screwed the barrel on! Regards, Bill.

I forgot the issue or question by now, but I fit barrels to all 98 types by cutting the shank so the breech end fits tightly against the inner shoulder and barely touches the receiver ring front. Ain't had one fall off yet and they all shoot fine. This is how they were designed to be fit.

quote:

I would suspect that the outside rear corner of the shank is contacting the inside radius of the edge of the C ring

You would have to enlarge the chamfer/step on the rear corner of the shank to clear that radius

I have encountered the same problem a few times. Apply some dykem blue to the barrel shank and you will find your interference.

It is 0.625" to the shoulder. I extended the barrel tenon to 0.635" and it still wouldn't contact the C ring. I Dykem-ed everything and couldn't spot any contact. As suggested I cut a rebate on the barrel tenon face - 0.875" in diameter and 0.100" deep. It screwed right down to the C ring. After fussing with the headspace the barrel shoulder snug right up the the receiver. I still can't figure out what was holding it up.

Look at the thread relief just forward of the C ring; chances are that there is no relief, or a burr. Relieve your barrel threads at the breech end and it will screw on fully.

quote:

Originally posted by dpcd:
Look at the thread relief just forward of the C ring; chances are that there is no relief, or a burr. Relieve your barrel threads at the breech end and it will screw on fully.

This.

60deg and 55deg interference is likely stopping the full fitment

I BELIEVE all 98 mausers offical torque to the torque flange, either C or H ring

I think that is correct. Additionally, I'd like to see the secondary shoulder interference fit into a counterbore in the front of the receiver ring to add additional rigidity.

quote:

Originally posted by jeffeosso:
60deg and 55deg interference is likely stopping the full fitment

I BELIEVE all 98 mausers offical torque to the torque flange, either C or H ring

Nope. I cut all threads with a carbide insert, 60 degrees. Ain't had one fall off yet. Nor fail to screw in with snug threads.
Come over and I'll show anyone how to do it.
Yes, all Mausers with an inner ring use that for the primary bearing surface. And I have sometimes made them to bear on both the ring face and inner shoulder. Just depends on how I feel that day because it don't make any difference.

Please forgive this ignoramus query: has no one ever sold a tool for squaring the receiver face and/or the inner C/H?

My son has just been replacing bathroom tap washers and found a seat-grind was needed. Looking at the tool used for that I wonder if something analogous might me made for the above tasks, something that would screw into the receiver (assuming the thread itself is likely to be true) perhaps made from an old barrel.

I guess if the inner dimensions of the bridge are tight enough, including an 18mm(?) mandrel would give better longitudinal alignment - but wonder when thinking of the slop in many open Mauser bolts.

quote:

Originally posted by sambarman338:...: has no one ever sold a tool for squaring the receiver face and/or the inner C/H?...

Looks like this tool doesn't hit the face of the ring, but hits everything else. Properly set up barrel does not need that anyway. Of course you are on your own cutting a glass-hard 98 bolt face with a carbide burr, and getting anything as-ordered, and first time, on time from PTG!
Many Good Lucks!!

https://www.pacifictoolandgaug...Mauser_p_116431.html

They are not glass hard and a carbide tool will cut any Mauser.
So, you can get a tool custom ground, for about $500; then what?
You now have both facers true to each other and uniform on every one you build.
Fine, your idea would work, and might be useful if you are mass producing custom Mausers.
I don't want such a tool....

The last one I worked on was, as well as a Siamese. I have no doubt a carbide cutter chucked in a mill will cut a hard bolt. Hand driven burrs not so much.
And I didn't say this "solution for a non existent problem tool" is a must. I was answering the guys question from post 5305. You couldn't run fast enough to give me one of those.
You the only guy that knows anything about Mausers??

To whom are you asking that question? My answers, as always, are not directed toward anyone specific and are only opinions for the general AR membership. They are not for actual implementation, but are based on facts only as I observe them., and are posted only for entertainment purposes. Definitely not for any serious consideration or use by anyone.
Legal disclaimer in case someone is unhappy or confused.
Again, not directed toward anyone in particular so no more hate PMs please.

quote:

Originally posted by sambarman338:
Please forgive this ignoramus query: has no one ever sold a tool for squaring the receiver face and/or the inner C/H?

My son has just been replacing bathroom tap washers and found a seat-grind was needed. Looking at the tool used for that I wonder if something analogous might me made for the above tasks, something that would screw into the receiver (assuming the thread itself is likely to be true) perhaps made from an old barrel.

I guess if the inner dimensions of the bridge are tight enough, the 18mm(?) mandrel would give better longitudinal alignment but wonder when thinking of the slop in many open Mauser bolts.

The exterior of the action on a 98 is cosmetic as compared to centerline and bore. The centerline is broached in the same fixture for the torque flange and the centerline and bolt ways. The face of the action, by design isnt part of it, unlike, say, a Remington. It's NICE that the face aligns with the centerline, but a mistake to assume square with the face means actually square.

Yeah, I'll say it, a 98 that is only aligned education with the face of the receiver that has been somehow squared, has been done incorrectly, regardless of shooting results. That's not how the system was designed to function