Mannlicher Schoenauer 1950 Barrel Thread - Chamber

spirits

Thought everyone might like to see what the Mannlicher Schoenauer 1950 turned up when the barrel was removed. The plan was to set the barrel back one thread and re-cut the chamber to correct the headspace. The rifle was a shooter grade (i.e., someone butchered it) in 257 Roberts manufactured in 1951. I and the gunsmith agreed the barrel thread-chamber looked too complex to mess with. Need to come up with another plan - any ideas - past experiences?

MIKE WISKEY

you could 'fire-form' brass to your chamber

spirits

Mike Wisky

Fire forming brand new brass and neck sizing only resulted in shorter cases (i.e., head to datum point of the case shoulder got shorter) and I even had one case that started to lean like the Tower of Pizza. Turns out the heavy MS firing pin apparently had enough force to do this. Finally, had to run new cases through a 7mm Mauser FL die first, then a 257R FL die to leave a shoulder bump. After firing these once, I neck-sized only and used a very moderate accurate load. These cases worked out okay 90% of the time with a few still getting shorter. If someone else got this rifle they would probably end up with a head separation and injuries.

Kenneth

v35

After turning the shoulder and reducing it by one thread, the breech end needs to be milled down by the same amount. That triangular section also has to come forward by an equal amount. The trianglular section can most easily be reduced by hand filing.
Following this work, the chamber can be sunk to the correct depth.
I'd suggest you talk to a more experienced gunsmith who is stronger in metalworking and machine tools.
Note MS actions are not drilled through bolt head and action sidewall as are Mausers, Springfields and others to handle gas resulting from blown primers and case separations, so correcting excessive headspace is an intelligent move.

spirits

V35

It is not a simple breech end like a Mauser 98. There's much more complicated machining done at the breech end of the barrel which is not shown in the picture. It is really unbelieveable complex in there. I know I didn't believe the gunsmith when he called and told me.

Kenneth

MIKE WISKEY

if you mave the room in the magazine you could rechamber to .25/06, this would 'clean up' a .257r chamber

spirits

Mike Wisky

That would work fine except I would have to find another MS rotary spool magazine. The MS 1950 rifle was my first 257R and I liked the cartridge so much I went the custom route. I now have a custom Ruger 77 II stainless 257R with Shilen match select barrel, the scalloped stock, and stainless sling loops with which I hunt.

Kenneth

v35

Show us the "other complications" not shown in the first picture. Just the barrel end, not the receiver before you conclude it to be an impossible job.
The 25-06 is a nice cartridge but maybe not for the MS action. Pressure is 53,000 PSI CUP while the standard .257 Roberts is 45,000 PSI CUP.
Your chamber may clean up with an .257 Ackley Improved reamer but you'd have to check on that.
As I mentioned,the MS action does not have the standard safety features of many big bore bolt actions which allows them to pass high pressure gas from ruptured cases or pierced primers.
The difference between a gunsmith having basic lathe skills and a competent model shop or Job Shop machinist is like comparing a framing carpenter with a cabinetmaker or patternmaker.
See another gunsmith.

spirits

V35

Here's the best of three photos
.
It would take at least six separate machinings just to alter the breech face and there is little room to maneuver.
Mr. Steve Cline, a competent gunsmith, could do the required work but I needed to find out if there were alternatives. For example: 1) shim between the bolt body and bolt face (they are separate parts) and/or 2) add metal to the rear of the bolt lugs/lug wells.

Kenneth

v35

Depending on how much headspace needs to be decreased, it looks like
shimming the bolt between bolt face and body may be the easiest way to go.
That amount will be subtracted from striker protrusion.
The striker may need to be altered at the rear end if protrusion is insufficient.

spirits

V35

I measured using three methods: Stoney Point case comparator, Wilson case gauge, and shims using caliper and got 0.011 inches excessive headspace. Probably, be about a month or two before any work on the headspace is done.

Mr. Cline gave me the action so I could more easily inlet the new roughed-out stock I have for it. The "not so original" stock that came with the rifle had cracked and I repaired, glass bedded, free floated the barrel, and reinforced the weaker portions where the stock had been gouged out. It turned out to be surprisely accurately rifle with its light set trigger.

Thank You for All Your Good Advice

Kenneth