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Old March 22, 2017, 09:34 PM   #1
4V50 Gary
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So I just tried to headspace a Yugoslav Model 48

in 8mm Mauser. It's the post-war Yugoslavian version of the Mauser 98K. Anyway, the stripped bolt refused to close on the:

Field Gauge. That's a good sign.
No Gauge. That's a good sign.
Go Gauge. That's a sign it needs chambering.

I'd say it's a pretty safe piece as it won't chamber a round.
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Old March 22, 2017, 09:44 PM   #2
Jim Watson
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Will it chamber a cartridge?
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Old March 22, 2017, 09:47 PM   #3
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Any burs at the chamber mouth?

Cosmoline build-up in the chamber?

Debris you missed?


Personally...
I'm a big fan of the Yugos.
The M48 series got a little cheap with some stamped parts, but I think the actions and barrels were of excellent quality.
More often than not, from what I've seen, they usually don't have super-sloppy headspace, either.

I was recently essentially 'gifted' a 1924 Yugo receiver and barrel that I'm going to populate with parts from a 24/47 that I stripped. The receiver and barrel need some cleanup from a Bubba barrel removal; but all signs point to awesomeness (and tight headspace).
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Old March 22, 2017, 09:53 PM   #4
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I didn't try to chamber a cartridge. Didn't see any burrs in the chamber.

At least the commies didn't have to worry about rebellions.
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Old March 22, 2017, 10:04 PM   #5
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As many folks have found out, the Yugo M48 and the earlier Model 24 are not the same as the German Model 98. The receivers are shorter than those of the German rifles and bolts and some other parts will not interchange.

Jim
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Old March 23, 2017, 04:24 AM   #6
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I would try to chamber a dummy round without the extractor. I rarely had good results with American made Headspace gages in foreign military rifles. The CIP specs are usually not even called off the same points and you are splitting a fine hair.
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Old March 23, 2017, 07:52 PM   #7
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At lunch I spoke with a couple of instructors at the gunsmithing school and they came to the same conclusion: ream it.
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Old March 23, 2017, 09:04 PM   #8
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Is it possible somebody tightened the barrel for some reason, therefore shortening the relative chamber depth to the bolt face? Or the bolt is not the original?

Either way, shouldn't take too much reaming to fix.
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Old March 23, 2017, 09:28 PM   #9
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What happens to the sights when you tighten down the barrel? The solution is to remove the barrel, ream it, reattach the barrel to the receiver and check the headspace. Now, if there's a super long reamer (or some way to extend it), the receiver can probably stay on.

BTW, the same guy had a shortened Mauser 95. No decorative crown and the working crown looked like it was filed by hand. Bubba lives!
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Old March 23, 2017, 09:52 PM   #10
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You can get reamer extensions so you can lengthen the chamber in place.
https://www.midwayusa.com/product/77...amer-extension
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Old March 23, 2017, 10:19 PM   #11
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that's neat Jim! Thanks.
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Old March 24, 2017, 02:52 AM   #12
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Quote:
You can get reamer extensions so you can lengthen the chamber in place.
https://www.midwayusa.com/product/77...amer-extension
Yep.
Have one.
Used it on a 6x45mm AR barrel that seemed easier to finish-ream while installed, rather than off the receiver; after fighting with the manufacturer for over a year (3rd [4th?] barrel with short headspace).
Worked just fine.

Keep it well-oiled, or it will rust like a sum-B.

Based on the project rifle lineup, I'll probably need the tool soon to finish a .307 Win chamber, and a 7x57mm chamber, as well. (I really need to stop putting rifles together from left-over parts, free barrels, and 'grab-bags'. )
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Old March 24, 2017, 10:40 AM   #13
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Quote:
in 8mm Mauser. It's the post-war Yugoslavian version of the Mauser 98K. Anyway, the stripped bolt refused to close on the:

Field Gauge. That's a good sign.
No Gauge. That's a good sign.
Go Gauge. That's a sign it needs chambering.


Quote:
Field Gauge. That's a good sign.
And I wonder; If the bolt would not close on the field reject length gage why did you need a no go-gage? Same for the go-gage; a reloaders can determine the length of the chamber with any one of the three gages. I have offered to modify go-gages to 'go to infinity' gages, I no longer make the offer because reloaders are scared because they do not understand.

Before I had a head space gage I made tools that were designed to measure the length of the case from the shoulder to the case head. The same tool also measures the length of a head space gage and fired cases, new/factory cases, fired cases and sized cases. The tool not only measures the length of an 8mm57 case from the datum to the case head, it measure the length of a 30/06 case from the datum to the case head. I know it is confusing but the difference in length between the 8mm57 and 30/06 from the datum to the case head is .127".

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Old March 24, 2017, 01:15 PM   #14
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https://www.midwayusa.com/product/77...amer-extension

$32.00 ? A reloader with a tool box has square drive sockets with extensions to match.

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Old March 24, 2017, 02:07 PM   #15
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Yep. Just chuck the kludge in a cordless drill, and get at it.




There's too much slop in standard socket extensions for hand reaming, in my opinion.
There's no positive feedback through the extension, to indicate that lateral force is being applied. ...And lateral force makes egg-shaped chambers and rough throats.

Plus, if you have the tool, you have a rigid 3/8" drive T-handle.
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Old March 24, 2017, 04:14 PM   #16
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For a few thousandths of an inch I would not use power tools.
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Old March 24, 2017, 06:23 PM   #17
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I was being facetious.
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Old March 24, 2017, 10:35 PM   #18
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You are really "jumping the gun" here. Drawing conclusions from people's ideas (Including me) that have not even looked at this rifle? Going back in with a reamer is hardly a "Fix all" for an undersize chamber. Have you even tried a dummy round or at least a resized case? Who is to say what part of the chamber is undersize? If it is only "A few thousandths". Where at? Reamers have tolerance and are not all the same. You could leave a step in the chamber somewhere. You are about to fix a problem and you do not even know what the problem is. It may not be the chamber at all. Chances are you will muddle your way through it and be OK, but I would lay off the Bubba remarks if I were you.
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Old March 25, 2017, 04:05 PM   #19
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I have a reamer extension/t-handle and have used it working through the receiver- but it's tough to judge very light cuts to .001- and if you eff up, you have to set back the breech and start over which requires a lathe. Yes you can modify a socket extension but it will require work as the head will not fit in the boltway and you need a set screw...I did it once and stopped being a cheap bastage and bought a T-handle designed for the job.

I now use a micrometer reamer stop from PTG for all my chamber reaming- and it's ideal for this situation where you can drop in your gage, set the micrometer for depth of cut desired allowing for thread crush, etc. and it will be spot on every time.

If you cut the chamber deeper with the T-handle go slowly with a good cutting oil. You know the saying...you can always remove more but you can't put it back. Cut too deep...And it's off to the gunsmith anyway.
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Old March 25, 2017, 06:38 PM   #20
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Not being a smart aleck, but are you sure it's the right bolt? Do the serial numbers match the rifle. Numrich sells a replacement bolt, but it has to be modified to work. Is the bolt knob round all the way or is it flat on the bottom?

Pictures would help.

TK
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Old March 25, 2017, 07:28 PM   #21
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^^^^
Now we are thinking. Identify the problem.
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Old March 26, 2017, 09:42 AM   #22
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^^

Post-war, means it's the M48 or M48A- mostly manufactured for commercial export.

It also means it's an intermediate length action like the M24, and a 98K "type" (large ring, large shank) bolt would be roughly 1/4" longer and it would be obvious if the bolt were "incorrect" as to it's compatibility with the action.

Mismatched, likely and could certainly be a cause for the inadequate headspace.

Quote:
What happens to the sights when you tighten down the barrel? The solution is to remove the barrel, ream it, reattach the barrel to the receiver and check the headspace. Now, if there's a super long reamer (or some way to extend it), the receiver can probably stay on.
If you have a barrel vise capable of pulling the barrel this would be preferable IMO. Make sure there are index marks, pull the barrel and clean up the threads, put the "go" gauge in the chamber and snug the barrel up lightly by hand. Feeler gauges between the receiver ring and barrel shoulder will tell you how much deeper the chamber needs to be (again, making the necessary allowances). Because the receiver face will not be true be sure to check several spots.

If you go too deep- the shoulder will need to be set back one full revolution to get the sights clocked, then breech, followed by reaming. Much more work than you'd like to get into.
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Old March 26, 2017, 10:02 AM   #23
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Several years back, these rifles were available for next to nothing from Century Arms U-Fix-it category. Most of these didn't have bolts. There are several intermediate length bolts that will fit the action, but have to be sightly modified to work. Numrich sells these and are in stock.

Numrich also has a replacement barrel with sight bases for $45.

TK

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Old March 26, 2017, 03:16 PM   #24
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Quote:
Post-war, means it's the M48 or M48A- mostly manufactured for commercial export.

It also means it's an intermediate length action like the M24, and a 98K "type" (large ring, large shank) bolt would be roughly 1/4" longer and it would be obvious if the bolt were "incorrect" as to it's compatibility with the action.

Mismatched, likely and could certainly be a cause for the inadequate headspace.
And before that it was suggested a reloader/smith order a bucket of bolts. I made a shop call, seems a builder/resource man was having trouble determining the length of his chamber in a Rock Island 03 period correct 1911. He had 20 head space gages, all of the go-gages allowed the bolt to close and none of the no go-gage would allow the bolt to close. But still he wante4d to know the length of the chamber from the shoulder to the bolt face.

I gave him a choice of 3 different methods; he handed me the box of head space gages so I offered to modify his dies to measure from go to infinity. Anyhow, his chamber was go gage length +.0025" meaning he had .0075" clearance between the bolt face and case head. He wanted less so he wanted to find another bolt. He had no less than 100 03 bolts so I offered to measure each one for their ability to change the length of the chamber. I have 35 new repayment 03A3 bolts; problem I assured him I did not have a bolt that would off set the length of a chamber .0025" and I offered to check all 100 of his bolts. again I told him I doubt if one of them would correct the length of the chamber and he needed a straight handle bolt. He says he found one from John Beard.

And then the question: If the length of the chambers requires shortening, how will grinding/modifying the correct the problem?

And then I offered to form cases for his chamber, I offered to add .005" to the length of the case from the shoulder of the case to the case head. That would give him .0025" clearance. I must have seemed a little eager, he is the only reloader I know that has a hydraulic reloading press, his reloading press has a most interesting story.

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