I have seen many references to allowing for crush when torquing a barrel down. The last I believe was posted by G.Malmborg.

My question is, In a Mauser 98 if both the inner ring and outer shoulder are to make contact does that mean that one should cut the thread shank .002" short of the actual length? For example: the distance from receiver face to inner ring is .625" would I cut the shank to .623"?

Thanks,

Mike

z1r---

No-- It means to make sure the inner ring is eqidistant from the front ring all the way around and then cut the shank to exactly that figure. It's usually .635 or so. Chamber .002 too deep. When the barrel is tightened the chamber will be right.

The barrel shank should be .0005 to .001 LONGER that the actual measurment from the receiver face to the (inner) primary torque shoulder. The receiver face is the secondary torque shoulder.

Thanks Gentlemen!

Now I am absolutely clear on both chambering and threading.

I really appreciate the help!!

-M

Wait a minute. I don't believe it is absolutely necessary to fit to both the inner and outer ring. What the hell is wrong with just fitting to abut the outer ring. This is the way most everyone else, Remington, WInchester, Sako, etc, etc. does it. Why bother trying to fit both. I normally dut the chamber and boss to fit the outer ring and leave about .002 clearance for the inner. I make sure the outer ring is true to the bore and don't worry about it. I do think that Mauser originally fit to the inner and had clearance with the outer.

This is one of those things that seems to reflect how you were taught and not neccesarily what's right.....if anybody knows that!

It was always just plumb facinating to me that the face of the barrel meets the inner ring at the axis of the front tang screw.

I like the idea of the additional vibration dampning of two thrust surfaces.....but it might be my imagination.

We were taught to fit to the outer ring. Mauser did indeed fit only to the inner ring. I like the idea of fitting both. I guess if I was forced to choose only one I'd pick the inner ring. How about you Mr. Belk?

It's like Mr. Belk said, its what you were taught. I've had several instructors and mentors and between them I bet they collectively would agree to about half the methods of building a Mauser. They've all built nice rifles.

-M

The gun gods must have placed that inner ring inside the Mausers for something, if for nothing more than to provide a good place for the barrel to stop. thinking back, some of the old mausers I've worked on, had barrels who's shoulders lacked the meat necessary to provide much in the way of contact with the face of the receiver, if they made contact at all. I had noticed in these instances that the builders used the inner ring for the contact. I don't like walking with a limp so when possible, I machine the barrel to contact both surfaces evenly.

Malm

An I also fit to both rings. Problem is, if the inner and outer are not parallel.... Oh yeah, true the action anyway, even if the customer don't want to pay for it. I usually do. I also usually fit a barrel with a breech boss diameter larger than the original Mauser, usually try for 1.200 or larger.

Hello,
I have found when removing a military bbl from m98 a relief (thin .090 or so in lathe) cut just ahead, of the receiver ring will allow the action to be turned off by hand indicating the bbl just touches the inside surface and the crush is on the receiver sholder,I personally beleive that it is a more rigid assembly if both shoulders touch firmly, especially with target or varmit weight bbls.

Just listening and learning from you guys about this. I have a question though. Doesn't the barrel shank stretch after contact on the reciever face and this keep the barrel tight as it does on any threaded bolt? It seems, if I understand you all correctly, that the shank will actually compress on the inner ring at the same time the shoulder contacts the reciever face or just before contact. Is the friction on the faces and the threads the only thing that keeps things tight? Someday I will have the tools to do these things, I would like to have some knowledge of how and why before that point though. I know a bolts stretch keeps it tight not the friction on the head is why I ask.
Thanks.

Does anyone know?

Brent---

The threads are under thrust load ..

If the face of the action only contacted the shoulder of the barrel the compressional forces would be on the muzzle side of each thread......the same if the butt of the barrel hit the inner ring first. The muzzle side of the threads are the ones that take the force.

On firing, the barrel and the action are trying to be stretched apart.....which also loads the front of the threads. That means there is no slop in the threads for the impulse of firing to work on. It's a solid unit.

Pablo, we were taught to use both inner and outer shoulders for maximum rigidity between action and barrel. Also to cut the thread for a tight fit for the same reason. While most threads are short ( less than one inch )the SSG if I remember has about a two inch thread again for maximum rigidity. Glass bedding also gives max rigidity between action and stock. It sure worked for my M98.

DITTO Jack, you are spot on & this is even more critical in a relatively course 12 TPI of the M98 Mauser as compared to the finer 16 TPI pitch of Remingtons & Winchesters.

[ 12-02-2002, 04:09: Message edited by: Bear Claw ]

Thank you much, my brain was twisted around a little, I was thinking the contact on the inner ring was unloading the threads, you illistration was very clear. Again, thank you.

Mr. Belk, with reference to the .002 too deep chamber comment that you made in the beginning here,

No-- It means to make sure the inner ring is eqidistant from the front ring all the way around and then cut the shank to exactly that figure. It's usually .635 or so. Chamber .002 too deep. When the barrel is tightened the chamber will be right.

I wonder if would please, explain why this is needed? Sorry, probably a stupid question, I just can't see picture the reason.

Brent--

When you tighten the barrel the inner ring will flex and since the shoulder hits at the same time the threaded portion of the receiver is compacted by .002.

Just to pull memory measurements out of the air.

From front to the inner ring lets say is .630.

From the front of the action to the bolt face is .735.

Theoretically the GO gauge should be sticking out .105 from the face of the barrel.

If you cut it that way the bolt won't close on the gauge.

Instead, chamber to a protrution of .103, or .733 from the base of the gauge to the shoulder of the barrel, and it'll will tighten, loosen, and bump tight, just right.

The micro grooves in the machined surfaces will blend together, any small burrs are ironed down, each thread stretches just a schosh, and the headspace gauge ends up .002 further towards the bolt face.

I was thinking the barrel threads/shank may stretch .002" and a .002" shallower cut chamber would be needed, never thought about the reciever threads drawing up and compressing the face by .002".

Is this .002" allowance the same for any other reciever, or does only the inner rings resistance cause this to compress?

Thanks for the lesson.

Brent,

That is the same for all receivers.

Malm

'98 Breeching.
Back in the early '50's Jack O'Connor once mailed me a receiver, bolt and barrel from a "sporterised" WW II K-98. It was a new design of take-down. Owner was a bit surprised because this new feature was added during August getting ready to go hunting target practice. In those years most of the ammo was handloaded from shortened and reformed '06 cases. Jack was still very much influenced by the writings of Col. Jim Crossman who was not what you could call a Mauser enthusiast. Taking the presentation to be an in your face gesture, I went the route on the how comes. You only had to look at the threaded ring as it faced you at chanber end to realise why owner's local experts to a man told him that the steel was crystalised. Matching surface of receiver ring beyond the rather compressed looking breeching face of the re-inforce internal collar. No lug setback, No bulge in the pristine barrel bore, all measurements between max. and min. for receiver. There was the standard gap between the (now) thread collar and over chamber tennon. Breech face to bolt face .1047- the usual for Berlin in 1940. Both lugs good contact and that which should be 90 deg. to bore was. Of interest: The borrowed MASTER waffenamt minimum headspace gage protruded .1075 from chamber.
In the spirit of generosity I'm going to leave this to Jack B to wax eloquently. The 'ol man used to say in other groupings than forums," dammit! Kid! Breast your cards!" Happy ending? Sure, found a V.G. byf with bashed magazine box for $25., Polished and blued those pieces after relocating front sight and heavy duty polishing out of some 50 yards worth of crushed gravel skid marks on the barrel. (that part of the take-down system needed more work. Barrel followed bullet)
And yes, owner got his deer that year- somewhere back in Todd's country.
What do I do about that exterior shoulder?
1, I thread right up to that shoulder, NO relief cut in barrel threads. I put that in the receiver when I face it.
2, I under cut the face down to thread O.D. about .005 more than nominal requirement leaving a thin band about .025 wide for a .002 crush. A step and yes it throws up a fin at tennon O.D. and that comes off in final polishing at assembly just before it goes out the door. There is so much fussy prepping after you know the critical stuff is solved that it all gets polished again.
I do use the modified 55 degree whitworth form thread, I do follow the Mauser procedures- but, If the receiver threads are tapered, -funneled- I match that in barrel threads. If receiver threads are ovaled in diameter I lap them out to insure there is peripheral contact, and, no, I wont't waste my time on a poorly made receiver,all maxed out in dimensions. I have crossed swords with some "instructors" in the past who maintained that there was so little difference in dimensions using a 60 degree thread on barrel to fit a 55 degree thread in receiver that considering the difficulty in grinding a special 55 degree threading tool and the attendant inexperience of the fledgeling that it was better to use the school supplied grind on the top thread form cutter........... My father was a world class expert at profanity ( O'Connor told me that and there was no doubt that he would know) I was an apt student and ate more that my share of yellow laundry soap in the apprentice years, so you can go figure my commentary on 55/60 threading practice.
Tom Burgess