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| One of Us |
When cutting the barrel threads, the general consensus is to make the tenon the correct length so the inner C ring and outer leading edge contact their respective surfaces at the same time, maybe a thou or two one way depending on who you speak to. HOWEVER, the barrel I’m wanting to have profiled (original oberndorf model B)is like the military barrels in that their shoulder OD is essentially the same as the thread diameter. Meaning there is no shoulder to seat against. In general, the inner C ring isn’t 100% square (mine is 0.004” out cf the leading edge, which is 0.002” out). It seems unusual for people to lap the inner C ring, but not unheard of. So, what is the standard for installing k98 or model B type barrels that have no shoulder? Do you lap the inner C ring to be 100% square? Do you not worry about 0.002”? Do I try and obtain (or make) a C ring lapping tool? Other option is I could get the shoulder cut say 0.050” - 0.100” wider to give it something to seat against - wouldn’t probably be overly noticeable. Then I could cut the tenon say 0.002” short and have most of the bearing surface on the (easily squared) leading edge)? I won’t be scoping this rifle, will the difference be noticeable? I doubt the inner rings wear, so I assume they wouldn’t have minded the 0.002” discrepancy at the oberndorf factory. | ||
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| one of us |
What you are not taking into account is that the un-threaded portion of the shank will contact the threads because it is the greater thread diameter. Thus it acts as a shoulder. There are jig designs you can use to square the inner ring. My advice is to square this and the breech. Then install the barrel. Contact on the secondary shoulder need not be a heavy crush. It is important the contact on the inner ring is substantial. | |||
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Moderator |
screw it in -- find the depth... headspace is .. just like a remington or ruger.. don't get it hot opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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One of Us |
Fit it like a Military barrel; against the inner shoulder; trust me, you ain't going to be able to tell a .002 out of true inner shoulder anyway once your barrel is tightened. Waste of time even trying to true it. BTW, a K98 is only a Polish small ring 98, only. | |||
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| One of Us |
Thanks - Yeah that’s the most attractive option. I just wasn’t sure how much To worry about 0.002” - I haven’t done a rebarrel myself before. How far out of square would you draw the line at needing new to square the inner C ring? It might be worth noting I won’t be d&timg for a scope. But I will probably Be fitting a receiver peep and with a 28” barrel the sight radius will Be substantial so want reasonable accuracy. And yes my nomenclature is wrong - I was trying to reference the standard German army 98. i am factoring in that the unthreaded portion will will still contact them the receiver. But I also don’t think think it can be relied on Tom take any significant tension due To it’s very small contact area, and the corresponding area on the receiver can’t really Be measured from seeing as it’s a radius at that diameter - before it widens out into the flat edge. Unless I machined a lot of meat back and made it flat down to the threads, but that isn’t how it was designed to work. | |||
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| One of Us |
I never measure the inner rings. Never any issues. The standard German 98 was the Gewehr 98 for WW1, marked GEW98; the small ring carbine is the Karabiner 98, Marked Kar98, and the WW2 German rifle is the Kar98k (the K is for Kurz, sort of a double carbine thing) ; marked Mod 98. Only the Polish small ring is a K98 and only the German small ring carbine is a Kar98. Widely misused. | |||
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| One of Us |
I am curious how the collar is even being measured? Since the front of the receiver where the barrel was never intended to contact may not be true to the receiver bore, the receiver threaded portion for the barrel, the breeching collar or anything else. And probably isn't since this was all done with as separate operations on different machines. | |||
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My concern also Jim Kobe 10841 Oxborough Ave So Bloomington MN 55437 952.884.6031 Professional member American Custom Gunmakers Guild | |||
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one of us |
That's why you true the receiver face first using a tight fitting mandrel through the bolt bore. The inner collars are surprisingly true, especially when you consider the numerous operations. That's how Tom Burgess taught me any way.  Aut vincere aut mori | |||
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| One of Us |
All of which is why I make my barrels fit tightly to the inner collar, and just barely touch the ring. Even though I have trued the ring, it is just there for looks. Just like the Mauser Brothers designed and intended. | |||
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| One of Us |
Yes but it didn't sound like the OP had a snug fitting mantrel or would be turning or fitting the barrel himself. So I am guessing he just measured down from the from untrued face of the receiver. | |||
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| One of Us |
Thanks for the help. I measured the leading edge by screwing in a take off barrel not quite home. I then used feeler gauges between the shoulder and leading edge - 0.018” slipped all the way round, 0.019” moved partially, 0.020” moved less and 0.021” didn’t fit at all. Then I measured back in several places to the inner ring. I did this multiple times to make sure the measurements were repeatable. I am having the barrel made and long chambered, but will be cutting the threads and head spacing it myself. They asked me for a barre profile, and as I’m building a Type B look a like wanted a faithful copy of the barrel profile. It’s taken a while to find. I can true the leading edge easily enough - te mandrel is very simple, and could make an inner ring truing tool but I was just not sure what the majority of ‘smiths fitting barrels with no significant shoulder did. I think I’ll stick with the true profile and decide whether to true the ring when it comes to it. I just want to get the barrel coming along now. I was going to post this on Mauser Central (my login there is wedgetail) but my phone crapped out and my login with it... no shortage of People they know more about Mausers than me here either though! | |||
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| one of us |
I hear you, and was wondering the same thing. More often than not, it is the receiver face being out of true that makes one suspect the inner "C" ring is not. Aut vincere aut mori | |||
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| One of Us |
You are overthinking it. The 98 Mauser didn't get to be so famous for having gross defects in either design, or manufacture, (if you remove the Chinese made ones) Anyway, the way you measured the gap, will be affected by the thread concentricity of the take off barrel you used as a gauge. Forget all this and shoot your new barrel. Mauser Central? There are more guys here who know them. Lots of wannabes there. | |||
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| one of us |
Well if you want no play and given that almost nobody cuts perfectly snug threads, it seems that the larger diameter of the receiver ring would provide better bracing/support than the smaller C ring; as well, you can true the former with little difficulty. So this notion that the receiver ring is not important seems illogical to me. Having said that, we are not talking varmint rifle here so snugging up to an imperfect C ring will kill the enemy just as dead. It's also a lot less tricky than trying to land on two rings at the same time. The people at Zastava in Serbia inherited a lot of the Mauser 98 tooling and machinery after the war; they actually made faithful 98s (complete with thumb cutout) well into this century, even if you don't see them in the USA due to our asinine import restrictions. Anyway, if anyone has the original drawings and other documents they will. With that in mind, I contacted them but so far no response. I see that the "M98" is no longer catalogued so I guess that production has finally ceased. Russ Gould - Whitworth Arms LLC BigfiveHQ.com, Large Calibers and African Safaris Doublegunhq.com, Fine English, American and German Double Rifles and Shotguns VH2Q.com, Varmint Rifles and Gear | |||
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| One of Us |
The Mauser brothers fitted most all barrels to the inner ring; ignoring the receiver face. Many millions of successful rifles made that way. Good enough for me. | |||
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| One of Us |
I don't have too much faith in that method, too many assumptions about what may or may not be true and concentric. Since you have a lathe, I would do as z1r suggested with a mandrel or better yet put it action truing jig, face off the ring and measuring the breeching collar runout with a dial indicator. Or what the heck, just face the collar off, you are there. Might as well chase the threads with a single point too so long as you are on the slippery slope.  | |||
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| one of us |
I suspect the reason lies in the "millions" ... they didn't have time to carefully custom-shank each barrel. I suspect it may have made mass-headspacing easier as well .. the c ring and the lug recesses/bolt face were perhaps machined in the same setup so some consistency in those dimensions. Personally, I hate to see a Mauser type action with a gap between the action ring and the barrel shoulder. It just looks like someone forgot to screw the barrel down. Russ Gould - Whitworth Arms LLC BigfiveHQ.com, Large Calibers and African Safaris Doublegunhq.com, Fine English, American and German Double Rifles and Shotguns VH2Q.com, Varmint Rifles and Gear | |||
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| One of Us |
There must not be visible gap...just not pressure...the arbitrary ".002" gap? would not be visible | |||
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| One of Us |
Exactly; no one leaves a gap; that would be poor workmanship. And the OP can't make his barrel shank fit the ring on the outside; his barrel OD is too small. So he must make the barrel bear on the inner shoulder. Not an issue, in any way, shape, or form. | |||
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| Moderator |
opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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| Moderator |
one can torque off the receiver face or C/H ring.. either works .. and ye olde myth of both .. well, i am not skilled enough for both it all works .. so, you can do it either way opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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| One of Us |
The OP can only do the inner one because his barrel shank is too small to use the receiver ring. Although it is certainly not hard to make them bear equally. If your barrel allows it which any custom barrel will. Another activity that is not rocket surgery but baffles many. It’s simply some careful machining and measurements. No myths involved. | |||
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One of Us |
The old gunsmith that taught me how to barrel Mausers, and he had done several hundreds in his 45 years in the trade, said the same as Duane, .002 clearance from the front ring, looks good, lasts long time. No visible gap. DRSS(We Band of Bubba's Div.) N.R.A (Life) T.S.R.A (Life) D.S.C. | |||
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| One of Us |
I although amateur / shade tree have built and have many very skilled gunsmith friends who have built many mausers agree it doesn't make much difference which method. I always did it using what Frank DeHaas said: tight crush on inner C ring and much lighter contact with front of receiver ring. My one friend who has built match winning (nationally) Benchrest guns only touches the front ring. He trues them up with a mandrel and says that is how Remington and Winchester do it and if that is good enough for them it is good enough fro this mauser. I would point out that he was defeating the gas handling purpose of the design and other reasons they were designed that way. Bottomline it doesn't really matter how you do it as long as you put it on straight! PA Bear Hunter, NRA Benefactor | |||
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| One of Us |
Do you really think gas is prevented from going past the barrel threads and a tightly contacting barrel shoulder by a C collar with a big notch cut out of it? Which rifle designs w/o the collar have a history of gas exiting past the barrel threads and shoulder? | |||
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| one of us |
The .002 clearance is to allow for crush, and will result in some degree of contact. If you want zero contact better use .005 allowance in your measurements. It will certainly be easier to remove the barrel if there is no action ring involvement. You may not be able to see a small gap, but blueing salts will find it. That's a few-million-molecule chasm. And yes we all know the OP's barrel has no shoulder. This discussion has moved past that. Russ Gould - Whitworth Arms LLC BigfiveHQ.com, Large Calibers and African Safaris Doublegunhq.com, Fine English, American and German Double Rifles and Shotguns VH2Q.com, Varmint Rifles and Gear | |||
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| One of Us |
Not sure if there's a question here or a statement..but the extractor on the system 98 does a pretty good job of plugging that gap. I have never seen or heard of gas escaping forward to the juncture of barrel and ( forward )shoulder | |||
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| One of Us |
That is because gas is going to vent where there is the least resistance to doing so, and is sure isn't around a barrel thread whether it abuts the breeching collar or the receiver shoulder. So the latter method doesn't 'defeat the gas handling purpose of the design' as claimed. | |||
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| one of us |
Would be a design improvement to vent gas forward vs. back. A slot milled in the threads after timing the barrel, to line up with a vent in the front ring ... now you've got me thinking ... Mauser 93 ... hmmm ... Russ Gould - Whitworth Arms LLC BigfiveHQ.com, Large Calibers and African Safaris Doublegunhq.com, Fine English, American and German Double Rifles and Shotguns VH2Q.com, Varmint Rifles and Gear | |||
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| Moderator |
BTW, a slimmed down barrel is one of the ways for making a mauser lighter -- i've seen, and maybe did, some pretty sketchy stuff to get weight down on light caliber "stalking" rifles opinions vary band of bubbas and STC hunting Club Information on Ammoguide about the416AR, 458AR, 470AR, 500AR What is an AR round? Case Drawings 416-458-470AR and 500AR. 476AR, http://www.weaponsmith.com | |||
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| One of Us |
A better idea might be a huge hole in the side of it, not those tiny holes like in Springfields; one that will really let gas out. Plug it with a rubber plug like on a pressure cooker. | |||
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| One of Us |
Turns out I had nothing to worry about after all. I turned a mandrel up and squared the leading edge. When I measured off that it was within 0.001”. As I had it all set up I might as well do the others. Turns out they were also spot on! It seems MWO and Brno knew what they were doing, who’d have thought   | |||
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