I am new to this board. I have a very clean Polish Radom small ring large thread Mauser. It is chambered in 7x57 with a 19" stepped barrel. The barrel is an unfired DWM. I plan to build a light weight mannlicher stocked rifle in the Mauser commercial style. I will be shooting 140gr. factory ammo, occasionaly. I've read somewhere on this board that these guns are unsafe. Is this true? I certainly don't want to spend a lot of time and $$ on this rifle if it is unsafe. I will be turning the steps out of the barrel.

Thanks

A large thread in a small ring action doesn't leave a lot of metal. If it was me, I'd leave the steps in the barrel.

Pete M., The less than desirable features of many small ring, large thread mausers are attributable to the method of manufacture at the Prussian Govt Arsenals. Around 1916 the steel used for these was supposed to be at the higher end of the carbon content range, at least past 30 points and they were to be more carefully "pasted-up" in the pack hardening process to insure hardening of the ring outside as well as inside in the business area. By 1917 this seems to have been accomplished most of the time. This did not fulfill the mission.
There is a clearance cut, A groove at the rear end of the receiver thread for the barrel at the juncture of "C" ring breech face, which at that time, was considerably deeper than needed to simply clear the very end of the barrel thread without interference. This was done so that a separate milling machine cut would not be required at the end of the lug/extractor slot on the right hand side of the receiver where this slot meets the threads. The slotting cutter pushed the chips forward and clearance had to be provided for them to break cleanly. This overdeep machining met the need. It also made the thread collar thickness very thin from one side of the recoil lug over the top and down to the other side. Somewhere in 1918 this got changed and No relief cut was made at the rear end of thread,(or very little). The barrels were altered in production by removing more than one full thread at the rear. A separate milling cut was made where the extractor slot goes through the "C" ring. Subsequent to this, scrunching in the barrel to seat against the "C" ring did not overstress it as had been capable of happening prior to the various modification print changes.
When found, these receivers after re carburizing, would be as servicable as a G or VZ-33, though not as desirable because of the stigma attached to all of them.
A bargain hunter who assumed he had found the "Mother Load" came in all smiles with 10 F.B actions made at Radom, all like new and as you describe yours to be. Every one of these made during the alleged 3 years of F.B. manufacture were machined as the very last of the Prussian arsenal production had been but Much tighter and much more finely machined, but still tainted in the eyes of the buying public. And still needing additional carburising.

The thing to keep in mind is that the bottom lug seats in the same ammount of metal support as does the large ring. The small ring is thinner in wall thickness all the way around. That infamous cut I described results in a wall thiskness of somewhere near 3/32 " and as the critics say, Hell, a water pipe coupling is thicker than that!
This section of your F.B. more than likely is about 5/32" in cross section, though less than that at the bottom of the thread grooves. This is nearly the same thickness as the G33 types inside the receiver where the lugs seat to the exterior surface. The Europeans did not seem to get much bent out of shape about this inasmuch as the lug which turned in at the top during firing was slotted for the ejector and did not provide (in practice) as much support as the bottom lug did anyway.
What usually happened to the militaries was, at first the barrels got loose because the thread "collar" section had stretched, increasing the headspace, Then when there was sufficient case head protruding from end of barrel during firing this let go allowing lots of gas into the bolt head area. This tended to distort and undo a lot of careful machining of the receiver. The stretching was first noticed in military training school weapons, and once a theory was developed and firing to prove the theory advanced the changes were mandated. Firing a rifle with excess headspace did two things. It pounded lug seat sockets in the receiver and also further stretched an already stressed area just ahead of the "C" ring face. Repeated headspace gaging caught many of the probem receivers but not all.
This is still how you can determine what'shappening
To be concise you must also be clear and not equivocal if you wish to communicate properly. I sincerely hope that I have accomplished that in this post without pounding the subject into the ground because this wasn't just for you,Pete.

Mr. Burgess, Not to be thick headed, but would you use this barreled action as is, after head spacing, for occasional shooting w/ factory 7x57 ammo or would you have it heat treated? Thanks.

Pete, You did say you planned to turn out the steps on the barrel. Your post suggested that the barrel was unfired. This further suggests that the barrel has not been screwed into the receiver and that the lug seats are visible to you. You can rather easily see if the receiver lug seats have been pocketed. It wouldn't hurt to have the receiver checked for Rockwell hardness by measuring off the flat underside. If the reading is around R c30 you can get away with using it as is. At one time my cut -off point was R c26. With todays powders and enthusiasms to match I've run it up to R c34-36. You can examine the thread to "C" ring junction for what I described in the previous posting. If it is undercut as described in the posting , I'd pass up using the receiver.
When you are an army you can send the crew around each month to check headspace and the records and withdraw the stretched from service. You can be your own Army of One and check it with your own headspace gages as the spirit moves provided you know how to use the gages properly. Most of us simply get a go gage and use a shim or pack of shims to see what we have going. Onion skin typewriter paper is about .001" thick. Go figure and have fun. You put a drop of oil on the bolt face and attach a scissor cut sort of round disc or stack of them on the bolt face and run the stripped bolt into the receiver where it will contact the gage already in the chamber and measure. If repeated firing allows more stacks of discs, something is moving or giving way albeit slightly. When installing the barrel you set the headspace on just feeling the gage, then test fire it with the loads. It takes at least 2 to tell the difference (if any) and after 5 shots with no apparent difference visually then measure the headspace again. You would do well to fire without the extractor on the bolt and if necessary remove the case by means of a rod, simply removing the fire-pin assy. to check the after reading. You could get all carried away and use a stock, or, use a 2x4 piece of lumber inletted to clear the trigger mechanism and the bolt handle when down ready to fire, the recoil lug and front screw used to attach the receiver with barrel assembly epoxy bedded with a steel cross piece, all of this to use an old tire casing for firing using a long string. You drill a hole through the tread for the string, insert the rear end of the 2X between the edges of the casing with barrel laying across the side wall and proceed to fire away. If you expect company during all of this you could of course stain and varnish the launching platform before the big day. This tends to add an aura of professionalism to the event eliminating most of the smart ass commentary from the Kibitzers. It works better if the wider part of the 2X4 is vertical. I'd be far less concerned with the F.B. Radom than with the
wartime Prussian arsenal actions. You may properly assume that I suggested the 2 X 4 to have some parts left over if she blows. That way most everything but the receiver survives.

Thank you very much.

System98

What incredibly detailed and valuable descriptions. thanks

Red