Home Forums Hunting & Shooting Ask The Gunwriters Metallurgy of Older Firearms

Yeah, Kuhnhausen says re-heat treat. Seems to come down to process control particularly during wartime production - did case depth meet the specification. Reading between the lines I think Kuhnhausen's point is do you really want to take a chance on lug setback after putting all that time/effort/money into a custom rifle. Re-work would not be cheap. And you remove some of that possibly minimal case depth fitting the bolt lugs.

With all due respect to idahoguy101, if I felt the need to re-heat treat a receiver before I could trust it, I wouldn't use it.

No, no, no, there's nothing wrong with military Mauser receivers. They were made of mid-carbon molybdenum steel that everybody used at the time and the particular alloy could vary by quite a lot using today's standards. The receivers were case hardened to increase their resistance to lug setback, which is forcing carbon into the surface of the receiver to form a layer of high carbon steel.

I don't have the specification as to the depth of the case hardening before me, the thickness of the high carbon layer, but if that specification is met the receiver is fine for any normal use. The problem is that process control to get the specified depth of case was, at the time, as much art as science. And as you would expect the rush of wartime production lead to shortcuts that made process control worse. You might get case depth just good enough, within the specification, or deeper than the specification. And customizing machining operations such as lug lapping can't help but remove some of that case.

Re-heat treating is simply a way to be absolutely sure that the receiver meets specifications to start with.

I don't know for certain that they were or were not reheat treated before I bought them. Remember that DWM in Berlin produced these prior to WWI. I had the gunsmiths check them over for safety before hand. One is a 7x57, and the other a 30/06. I've has no problems with either rifle. Ive had the 30/06 for twenty hunting seasons. Supposedly the 1909 action is the "cream of the crop" for actions of their era.

Read an article in , G&A, I believe, years ago. Author got to tour the Norma factory. They used model 95's for most all their pressure test guns. Used them over and over and over again. Some VERY good metal has been made before the turn of the last centry that still gives great service.

And there is always the Samurai swords, which going back 4-500 years were known for having very fine steel.

Samurai swords using a composite process soft steel on the mune or back of the blade and then five different types of steel to a very high tensile carbon steel used for the edge that has been modified by differential tempering. Much of the more complex manufacture comes from a group of Korean Emigrees about 900 AD. Japanese had steel swords before this but nothing that the masters developed from this time on.

Some of these early blades could cut through stone lanterns or even rifle barrels without damage.

The Japanese steel process used laminations that weren't to heterogenous and weren't to homogeneous as well. The different composite steels were balanced with a close to exact number of folds that allowed for flexibility yet also hardness.

Sincerely,
Thomas

Case hardening can not prevent "set back". Mausers were made
many different places using different metals. There is an
argument if their total number was 25 or 50 million.
The point is there is a lot of room for variables so
make positive statement at your own risk.

As I understand metallurgy in Mauser actions "set back" was an intended safety feature. This was preferable to an action fragmenting and possibly killing who ever shot the rifle. The first thousands of US Army M1903 Springfield rifles produced by the Army's Rock Island Arsenal were found to be brittle. Some of these rifle actions literally exploded. So all those early Springfield action had to be scrapped. You can see why "set back" is preferable to your rifle action exploding into shrapnel!

However, the Army retained the Bolts from you early Rock Island service rifles and reused them in WWII in new Model 1903A3 Springfield rifles. If you check a M1903A3 bolt don't be surprised to see the initial RI stamped on the bolt.

Since the age of 14 I have shot a DWM Mauser stamped 1897 on the receiver. It was rebarreled in 308 Win before it came to me. I imagine it would originally have been a 7x57.

I have probably shot at least 8000 rounds through it since then. Probably about 2000 of those were factory loads. The balance were handloads, mostly on the mild side - ie around 2650fps with 150g bullets.

More recently I have loaded them even milder - about 2575fps with 150g bullets. This is in deference to the age of the receiver. There appears to be no sign whatsoever that the firearm has suffered any sort of stress over having shot warmish handloads in the modern cartridge.

I am pretty confident it will see me out. These days it is mostly a spare rifle or one to loan to mates when they want to come for a hunt with me. My kids will get it before I die with luck.

When it comes time to rebarrel it I will probably go with the original 7x57 as the mag length is specific to that case. The 308 is just a little short looking in the mag though it feeds fine.

It appears that not only Mausers, but other rifles as well were designed to withstand much higher pressures than would be used on a day to day basis. This would be a built in safety feature.

If a rifle was engineered to, for example, take 50K PSI continually, but would fail at 55K PSI, a constant diet of 50K loads would probably cause failure before too long.

In Hatcher's Notebook, I have read that a few 03 Springfields were testfired, IIRC, with proof loads over 100K, with no failures. This would be the Double Heat treated and 03A3 actions. This would be a lot of built in safety factor, which, in my opinion, would be a good thing.

One thing I don't understand, however, with the way the case head is supported in the 03, is how the brass withstood this much pressure, but there is no mention of case head failure.

The older, black powder era rifles and pistols, such as the 73 Winchester and the Colt Revolver could probably withstand much heavier loads than was considered a normal load.

I don't know how much pressure you could get by deliberately overloading a black powder cartridge, but I am satisfied these older pistols and rifles would safely handle the normal, day to day loads, over and over. And I know for a fact that some of these guns have been used with later smokeless loads.

Regarding the layering of Japanese "Samurai" swords, the structural layering itself wasn't the key, it was the fact that the folding process exposed fresh iron to the air so more impurities could burn off. What the swordmiths had learned through trial-and-error was how to use the folding to produce a relatively uniform steel containing roughly that magic 1% carbon (even though they didn't have a clue what the hell carbon was).

The method of construction evolved, too, the earliest ones being made from a single (relatively) homogeneous block of iron. They achieved differential hardness by painting the backbone with a solution of clay before the final heat treating. The clay-coated areas were insulated a bit, which slowed the speed of the quench, limiting the hardening of the sword's spine but leaving it tougher and more resilient. With no such insulation, the cutting edge quenched to maximum hardness. The differential rate of cooling also was responsible for the sword's iconic curvature.

In time, they began using steels of slightly different compositions for different regions of the sword. The swordsmith smelted iron sands gathered from riverbeds in a clay furnace fired with charcoal, which produced lumps of steel. Different lumps would have different carbon concentrations and the swordsmith could tell by examining them which lumps would be best suited for which part of the sword. Masamune, widely regarded as Japan's greatest swordsmith, used three different "blends" of steel divided into seven separate layers to produce a sword that could be as sharp as a scalpel but nearly indestructible.

"1234567", For testing the ultimate strength of a firearm, extremely high pressure test loads use steel cases as brass starts to "flow" around 75,000 psi and will fail before reaching 100,000 psi. Black powder and smokeless powder have almost nothing in common when it come to pressure. Black powder proofing not only used extra powder, but extra projectiles to put more strain on the barrel and action, as powder alone wouldn't do it. All black powder burns very fast regardless of "F" grade and lead bullets offer little resistance to get moving. Actual pressures vary little regardless of caliber or gauge with black powder. When a black powder gun failed, it was usually a defect in the manufacturing process and not excessive pressure.

Several years ago a guy ran some pressure tests on Black Powder.
He was able to get 100,000 psi. So Black powder isn't pressure
limited.