I have a 1908 Mannlicher Schoenauer in 8X56MS that after firing a very mild load experiences extremely difficult bolt lift once the bolt handle has reached 1/2 way of its lift.



There was concern that some of these Mannlicher Schoenauer rifles had undersized bores and this might be causing a pressure situation. Although the case exhibited zero signs of pressure, I performed a cerrosafe cast of the barrel and measured a proper bore diameter.

So.........Last night I completely disassembled the bolt.

With no cartridge in the chamber the bolt will easily open. No resistance what so ever. These rifles exhibit a relatively hard bolt lift without anything in the chamber, so removing the firing pin and cocking piece removes all extra resistance to bolt lift.

Using the bolt without the firing pin or the cocking piece I inserted a piece of fired brass. I experienced extreme hard bolt lift once the bolt handle was raised to 1/2 its upward movement.

I full length sized this brass and although the resistance was lessened, it was still very difficult to move the bolt handle past the half way mark.

I measured this piece of brass and confirmed that all dimensions are under the spec I found on the internet for 8X56MS cartridge.
But to be sure I ground a few thou off the rim.....no improvement.

I then ground a few thou off the base of the cartridge....no improvement.

I them took the resized case and cut it 1/2" above the base and using this stub I inserted it into the bolt and pushed the bolt home. I wanted to be sure the resistance was not due to the extractor or the ejector......Bolt opened easily. So the issue is somewhere north of the first 1/2" of the brass.

I then took a piece of once fired brass and in the lathe removed one thou from the middle third of the case. Voila! The bolt handle moved easily!

I then smoked a piece of once fired brass to see if I could observe where it was hitting. The smoked case showed contact with the brass over it's whole length.

My conclusion is that I have a "banana" shaped chamber or an "oval" shaped chamber. Although I can't confirm either of these theories with the measuring equipment I have at my disposal.

I've had this happen with a few rifles in the past. Usually egg shaped chamber resulting from poor chambering jobs (not of my doing) with short cartridges (6BR and 6PPC).
My solution has always been a Cerrosafe cast of the chamber and using the casting attached to a long brass rod with grinding compound and an electric drill to polish the chamber round.

Unless anyone has something else they think I'm missing, I'm moving forward with this process.
Comments and suggestions welcome...........
Thanks


This photo shows the test brass. As you can see on the "smoked" piece, there is extra contact on the middle portion. The piece to the far right shows the turned down rim and the ground base. I also filed some brass off the shoulder to see if this might be the sticking point. And finally the turned center section.


The machining on this 1908 bolt is nothing short of amazing!


The bolt without the firing pin or cocking piece

Hi,

Sorry to hear of your problem. What I am not understanding is how you polish your chamber round using a Cerrosafe casting of the bulged chamber. Would not using the bulged casting with lapping compound applied simply enlarge (polish) the existing "banana" chamber? How do you keep the compound off the shoulder? Seems as though a chamber clean up and barrel set back might be on the menu, maybe not. I would seek out a competent gunsmith to verify findings. I know-that's what your AR query is about, but....

Those are fantastic rifles and the stock on yours is beautiful. Though a pain in the schitzmeier to discover, the "Eureka" moment is satisfying, eh?

Another thought occurred. Is this difficult bolt lift with different brands of brass? Might try changing just to eliminate a variable. Not all brass is created equal or all mfg. runs from the same maker. Ok,Ok, got to quit. Starting to sound like a benchrester.

Please keep us apprised as the results pour in.

Luck,

Stephen

Roy, IMO your analysis seems spot on, and also IMO your correction method seems very promising.

Food for further thought, I've had a number of these rifles in various chamberings and this is what I've found:
8x56 grooves averaged 0.327"-0.328"
8x56 can be rechambered to 8x57 with no other changes
8x56 can be rebored to 9x57 with no other changes
Regards, Joe

quote:

Would not using the bulged casting with lapping compound applied simply enlarge (polish) the existing "banana" chamber?

Yes. Change of plans. I will use a piece of sized brass on the end of a piece of drill rod...Good Call!

I'll just be careful about the shoulder, or I'll end up with a 8X57 Mauser.....

But I'm talking about removing 1/10th of a thou. Just a good polish job I'm hoping will do it.

Stay tuned!

I'd try other brand(s) of brass first to either confirm the same problem or not.
Perhaps the current brass is not tempered properly along it's length and expanding but not then contracting enough after firing for ease of extraction.

That's easier to try than polishing and doesn't change the rifle any in an effort to find the problem.

Beautiful rifle you have. Hope you can solve the problem.
I have a 1908 Model also and find it an accurate and enjoyable rifle to shoot. It sees more use than either my 1903 or 1910's.

quote:

Originally posted by RoyB:

quote:

Would not using the bulged casting with lapping compound applied simply enlarge (polish) the existing "banana" chamber?

Yes. Change of plans. I will use a piece of sized brass on the end of a piece of drill rod...Good Call!

I'll just be careful about the shoulder, or I'll end up with a 8X57 Mauser.....

But I'm talking about removing 1/10th of a thou. Just a good polish job I'm hoping will do it.

Stay tuned!

I hope so. too. Good on you.

Stephen

quote:

Perhaps the current brass is not tempered properly along it's length and expanding but not then contracting enough after firing for ease of extraction.

But it is exhibiting this issue with unfired, virgin brass that has only been through the resizing die.

quote:

Originally posted by RoyB:
I have a 1908 Mannlicher Schoenauer in 8X56MS that after firing a very mild load experiences extremely difficult bolt lift once the bolt handle has reached 1/2 way of its lift.

What kind of brass are you using? Is it original 8X56MS, or is it formed from a "parent" case?

Do you experience the same phenomenon using a normal, rather than a "very mild" load?

Lack of original 9X56MS brass for my Model 1910 has caused all kinds of problems in loading for it, which I had to eliminate one step at a time.
Nothing resembling your problem, but there are always surprises.

After going through a long wait for proper dies to swage .30-'06 case heads to proper MS dimensions, I discovered that Remington factory .35 Whelen brass was already the correct size, by actual measurement, not by specifications.

There is no (or very scarce) 8X56MS brass available. The load is irrelavent as it exhibits this phenomenon with an unloaded, sized piece of brass.

If the gun is fired, the extraction is nearly impossible! An extreme "rap" on the bottom of the bolt handle with a gloved hand is the only way to lift the bolt.

If I remove the extractor from the bolt, chamber a piece of new, resized brass, remove the bolt, leaving the brass in the chamber, it requires a very hard hit with a cleaning rod from the muzzle to dislodge the case.

Strange...........

M-S barrel are not installed very tight.

Send this one to a gunsmith of great reputation.
Have him pull the barrel and polish the back half of the chamber.

I have several 1895 Dutch Steyrs and they have tool marks in the chamber but they extract fine.

Always use hard brass like WW in a rough chamber.

quote:

Send this one to a gunsmith of great reputation.
Have him pull the barrel and polish the back half of the chamber.

I'm well versed with pulling barrels and doing this type of work. But wouldn't want to mess too much with this open top receiver with a 100 years plus barrel attached and a huge chunk of metal removed when someone many years ago installed that front claw mount. This action could twist VERY easily if the barrel threads offered any resistance.

Great job of working this problem through, Roy, I hope the chamber is not too oddly shaped to salvage.

I've just picked up a 1908 myself and have yet to fire it. Old US factory loads chamber in it fine but the breech end of the chamber is a bit tighter than the couple of 1905s I've had and it looks like it might not take cases formed out of current Winchester brass which is the smallest at the head I've found. I have 8x56 cases on order from Quality Cartridge; other brass of theirs that I have used has been pretty good. I like correct headstamps.

And as J.D.Steele noted, the groove diameter of mine slugs just under .328", bore diameter is about .316".

Do you know if the quality cartridges are "real" 8X56MS or just reformed from no headstamped 8X57M and then headstamped?

Maybe I should just go ahead and order some..........

I magnified your photos and I am seeing an hourglass or venturi shaped chamber. Perhaps caused by a re-chamber with a reamer having a different taper. You have an area that is causing a clear ring about at the case midpoint and then scuffing. This would likely be caused by the camming action pulling the rest of the case past the constriction. Hence the hard bolt lift.

I don't believe spinning a fire formed case with lapping compound will fix that. Try taking a fire formed case and measuring the diameter every 2 mm or so to the case shoulder. See if the case is pinched at the scuff marks and ring. That would confirm my theory. Even though the fired case has been pulled past the ring, it will still spring back some and give you a reading. I'm thinking you could construct a chamber lap from a fire formed case cut off before the pinch. Take a couple of thou off the case head so the case can go in a little deeper. Then spin that. You only need to remove .0005 around the circumference to get the .001 you require.

About Quality Cartridge - they do some reforming, but no re-headstamping, and their catalog is pretty good at telling you what you're getting. They manufacture their own for a good number of rounds and those are all correctly headstamped.

The ones I've used most are 8x58R Sauer and they have been excellent; good primer pockets, correctly annealed and the right dimensions.

Their web site is http://qual-cart.com and you can also get it from Midway.

You can get proper 9x56 M-S cases made by Horneber from Huntingtons, as well as a number of other oddballs, but for some reason they don't do 8x56. The Horneber brass is also very good. My second choice for cases would be to neck down the Horneber 9x56 'cause at least the rest of the case is right and they worked great in my 1905s.

I have had the exact same problem with my 1908 in 8x56 M-S. I was using ammo sold to my by a well known custom reloader. Sticky, sticky. I now make my 8x56 brass from NEW Remington or Winchester 8x57 Mauser cases. The problem has gone away.

quote:

Originally posted by RoyB:

quote:

Send this one to a gunsmith of great reputation.
Have him pull the barrel and polish the back half of the chamber.

I'm well versed with pulling barrels and doing this type of work. But wouldn't want to mess too much with this open top receiver with a 100 years plus barrel attached and a huge chunk of metal removed when someone many years ago installed that front claw mount. This action could twist VERY easily if the barrel threads offered any resistance.

If you screw up the chamber you will have to do just that or bore out the barrel shank.

Try some very hard brass or US GI brass reformed. It is very tough and has a good bit if spring back.

Or tweak it VERY slightly with an 8x57 (or custom) reamer, just down at the base area.

BTW a complete conversion to 8x57 does not normally require any magazine mods. I have converted one 8x56 to 9x57 and my friend George the Knifemaker has rechambered his to 8x57, neither required any mag mods for proper feeding.
Regards, Joe

Measure your chamber cast to figure out how bad the egg or banana is.
Then go from there.