Receiver Opinions Please

[Slamfire]

Slamfire, I'm interested to know if you plan to follow the "recommendations" on the Sarco webpage for these receivers. As in, square the receiver and bolt face, etc...

I have already checked out the lug engagement with Prussian blue. One of the split lugs is not bearing so some lapping needs to bring that into contact. Bearing was adequate on the lower lug.

Talked to the gunsmith, he is more concerned about even bearing on the inner collar than truing the receiver face. I asked him his opinion on truing the bolt face, he hemmed and hawed, he does not do it for himself, he trues bolt faces because everyone else asks for it. This guy is an active across the course and long range shooter. He has won the Long Range Matches at Camp Perry, he still shoots with a pre WW2 M70 that he did nothing to the action besides adding a new barrel and sight bases. (of course the trigger , stock, etc, have been changed to a target configuration) If he does not bother with this stuff target shooting, and is one of the top XTC and Long Range shooters in the US, I doubt it will make much of a difference on a hunting rifle. I will ask the gunsmith to check, but unless it is horribly off, I don’t want anything done. It is too easy for these guys to remove some of the bolt face shoulder when truing the bolt face. I do want all lugs to bear. The Mauser has split lugs on the left, if only one bears that might overstrain the bearing lug. Lug contact around 60% is fine, for me, on a new rifle. I am not a fan of lapping or grinding as there may be a case hardened surface and I don’t want it removed, and don’t like it being reduced in thickness. I am of the opinion that lapping, truing lugs, grinding, is something that is mandatory for major out of tolerance situations, but otherwise, as little as possible.

This M14 rifle bolt, it is on its third match barrel, all cases lubricated with Johnson paste wax, maybe it had 60-70% engagement when it was new. It has settled in nicely and the lug engagement has increased over time. I doubt I will ever get to a fourth barrel as I hardly ever shoot the thing anymore.



On my match Mauser, with a military receiver, I only asked for receiver face/inner collar truing, I have no idea how much the lugs bear in the receiver, but I shot hese 20 round groups, prone with a sling, with irons, in competition, with the thing, so I am not convinced that all that bench rest machining adds all that much in a hand held rifle.

 

[Slamfire]

At least of my 100+ Mausers I have worked on and over load tested, I never sent a Mauser to the heat treat shop.

If you heated the thing up to the point that you annealed the receiver, than you either heat treat or toss, because it would be too soft. But re heat treating an old receiver has its risks, it could crack.

What a terrible book!

Anything else in the book not correspond to your experience?

 

[Gunplummer]

I pay attention to what Clark says because he is a guy like me. Instead of reading a book and taking it as Gospel, he will check it out. Can someone tell us just what type of material most mausers were made of? It sure was not 4140. Very few modern rifle receivers were made of 4140. The terms "4140" and "Chrome Molly" are used as comparisons by advertisers because so many people have heard them in advertising over the years that they have become a standard for buyers that do no metal working. Someone mentioned the '03 and had it backwards. The '03 had problems BECAUSE it's core was not soft. Most mausers are case hardened and have junk metal as a core. When heat treating O-1 or A-2, I doubt that a hard shell with a softer core can be attained. Maybe with newer, modern heat treating, but I doubt it. It is drawn back somewhat like 4140, with the complete section attaining the same RC hardness. I have made many claw extractors from 4140 and O-1 just by drawing the material back to "Spring". I prefered O-1 over A-2 only because of the limited furnace I was using. I had a harder time controlling warpage with A-2. You will probably have the same physical properties as 4140 using A-2. Much tougher, but softer without the hard wearing outer surface.

 

[Bart B.]

Slamfire, a 'smith who barreled many Win. 70's for folks winning matches and setting records in high power matches told me that about 1 in 20 or so had a receiver face square with its barrel tenon threads. Every once in a while, one he'd set up for facing would clean up all the way around on the first .0002" of tool cut into the metal on the receiver's face. That may well have been the case with the competitor you mentioned.

On the other hand, one old early '50's Win 70 receiver got passed around among several top ranked shooters and 'smiths but none could get it to shoot well after truing up everything they could think of the first time. Finally, the 'smith mentioned above checked it out. He found its tenon thread axis was so cockeyed and out of alignment with the boltway, it never held epoxy bedding very well nor shot worth loading ammo for. On a mandrel between centers on a lathe and it threaded onto it, the boltway's back end spun near 1/4" off center. How Winchester let that one get out of their plant remains a mystery.

 

[Slamfire]

Can someone tell us just what type of material most mausers were made of

I sure you can answer that one yourself. You can find this with a web search and the information is in several books on Mausers.

Very few modern rifle receivers were made of 4140.

Being a bookworm, I found, from books, that the pre 64 M70 was made from 4140, the M1 carbine receiver was made from 4140, and I recall reading the Ruger M77 was made of 4140. Now that leaves a lot of commercial receivers that I don’t have material specifications. Not extractors, but the structural stuff: bolts and receivers. Commercial manufacturers have no particular reason to educate the public by telling us what materials they use, so there is very little good information on this topic.

Being a practical man, not a bookworm, how about telling us something that will add to human knowledge? To your best extent possible, how about telling just what commercial receivers/bolts are made out of what steels?

 

[Slamfire]

On the other hand, one old early '50's Win 70 receiver got passed around among several top ranked shooters and 'smiths but none could get it to shoot well after truing up everything they could think of the first time. Finally, the 'smith mentioned above checked it out. He found its tenon thread axis was so cockeyed and out of alignment with the boltway, it never held epoxy bedding very well nor shot worth loading ammo for. On a mandrel between centers on a lathe and it threaded onto it, the boltway's back end spun near 1/4" off center. How Winchester let that one get out of their plant remains a mystery.

I have heard similiar horror stories about factory fresh M52D's. Based on what I have read, Winchester never really recovered from WW2. They wore out their production equipment and they had an illogical, complicated, process control. Of course at the time, it was a game between production and quality control, if production could sneak garbage out the door, they won. Even today, Quality is always subordinated to profits. Corporations view their customers as easily manipulated morons. A classic story is Schlitz beer. I got to talk to a gentlemen who worked for thirty years in the beer industry, and he was around and worked with former Schlitz employees. Schlitz changed the process and the taste in the quest to maximize profits. From the gentleman I talked to, Beer companies view their customers as inebriated rubes , people with no taste or intelligence, and they thought therefore, customers would not notice, in their drunken stupors, that Schlitz beer tasted different. They were wrong: Schlitz almost disappeared. http://www.beerconnoisseur.com/the-fall-of-schlitzI . While Beer companies still view their customers as rubes, they are very careful about maintaining taste consistency. I recently heard some horror stories from a gunsmith on recently made M700's. This guy claimed that the barrel threads and receivers threads were so off, so loose, that Remington was using some gunky thread sealant to keep the barrel and receiver together. I had one of those cheap M700's and nothing I did brought the groups down. I did not take the barrel off, but a loose joint there would explain the loosey goosey groups.

 

[Dixie Gunsmithing]

Gunplummer,

I am not quite sure what steel was used on receivers back then, but when you calculate the longitudinal force that the cartridge applies to the bolt, it does not take much to hold it to be honest, and as I mentioned earlier, a lot of as-annealed steels will hold it without a drop of hardening. They may have used something like 1040 or 1045, which have a decent yield strength, around 60,000 psi for 1040, and around 45,000 psi for 1045. The 41xx series, I think, came about around or maybe just before WWII. I think they use that as a sales pitch any more.

 

[James K]

Everyone thinks of rifle pressures in the 45,000-65,000 psi range. But that is pounds per square inch inside the case. The actual thrust on the bolt (or on the bullet) is a lot less because the areas under pressure are only a fraction of a square inch. The thrust on the bolt face is that on the inside rear of the cartridge case, which is around .1 square inch. So for a 50,000 psi cartridge, the thrust on the bolt is about 5000 pounds. A .30 bullet has a base of about .07 square inch, so the pressure on it is about 3500 pounds.

Those are not insignificant pressures, but far from the usual "50k psi pushing on the bolt" we usually hear. So where does all that 50k psi go? Most of it is wasted trying to push out the chamber walls.

Jim

 

[Dixie Gunsmithing]

Jim, you hit the nail square on the head. From what I have found, especially on large frame guns, is that receivers hardly ever have any heat treatment that I can find. One can easily see this when drilling and tapping one for rings, etc. The only places that they might spot harden would be the major wear areas, where a bolt, etc., does a lot of sliding, but I doubt they do that much, especially if they use the right steel. If they didn't wear out, they wouldn't be able to sell a new one. When you get into pumps and semi-autos, you really start seeing wear.

Now, like you said, on barrels, there is a very big outward pressure difference. I was shown how they developed those, and then tested them. They calculate the barrel, especially around the chamber for minimum outside diameter at proof pressure, and they make a test barrel, in the form of a bull barrel, so they can drill into the bore about every two to three inches, and tap the holes. They install pressure transducers into these holes, all the way down to within maybe two inches of the muzzle, and connect them to a recording x-y graph, and fire a round in the barrel fixed in a jig. They record the peak pressures all the way down the bore, and use the dropping pressures to calculate or check the needed taper.

 

[Clark]

Thank you Cowtowner for starting this thread.
Thank you Slamfire for the pics.
Thank you William for reminding me My 49 year Mauser addiction has been a money pit.
Thank you tobnpr for coming through with the stock and bolt handle.
Thank you Gunplumber for the kind words.
Thank you Bart for 22 years of great posts.
Thank you Waffenfabrik for sending me the pdf of your FFL.
I ordered a quantity of these actions today. They will probably arrive while I am gone hunting ~ a week. But maybe I will get to see them before hunting.

 

[CowTowner]

For my part Clark, you are most welcome.

 

[Jim Watson]

I looked and looked but could not find another integral scope dovetail like the one shown here.

You might contact Conetrol, they make a number of Daptar bases for different integral bases and they never throw away a blueprint.

Of course you could just screw a Weaver down on top of them since they considerately provide the screw holes, but that would not be as classy.

 

[Clark]

To:acammermans@dumoulin-herstal.com

Hi,
I just ordered a quantity of Dumoulin Mauser Actions from Sarco:
http://www.e-sarcoinc.com/dumoulin-mauser-action.aspx

What do you call that type of scope base?
Where can I buy rings?
What do you call the rings?

from: Alexandre Cammermans <acammermans@dumoulin-herstal.com>
Hello
You can order the adapted mounts with APEL in Germany; ref. 300-05165, model Fortress for A2000.
Best regards,

A Google search finds:
http://www.eaw.de/assets/files/09_SM_Ring30.pdf

And
http://www.rivolier.com/mont-eaw-o-30-dumoulin-a-2000.html

and
http://www.acp-waffen.de/downloads/produktinformationen/EAW/EAW Kataloge/EAW-Katalog-2004.pdf

 

[CowTowner]

Awesome work, Clark. Boy do they make some pretty rings/mounts.
I don't suppose there are any U.S. based sources for the mounts?

 

[Gunplummer]

I have never worked on a Mauser that did not have a heat treated receiver. P.O. Ackley had Mauser receivers checked by a lab and they are in the 1018-1020 range. Most military actions are case hardened. The exceptions I have seen are the Arisaka and MAS 36. The Arisaka is proven to be 4140 or very close and is heat treated accordingly. I never heat treated an MAS 36, but it machines the same as an Arisaka. I have a section of a '99 Savage receiver(Somewhere) and have been meaning to heat it up to test it. I suspect it also is in the 4140 range. The difference between trueing up a receiver that is case hardened and one that is a constant hardness through the section is understandable. You can true up the 4140 or tool steel receiver and nothing will change in regards to strength unless you really start removing metal. The cased receivers are weakened when you remove only a few thousandths of material. I have seen the result of underloading and overloading and the "Setback" caused by it. I have heard about some people sending a receiver out to be heat treated after truing up. Sounds like a waste of time. The receiver will warp again.

 

[CowTowner]

My Google-Fu must be getting weak. I'm unable to find those European made mounts here (U.S.) anywhere. Does anyone know of a source?

 

[Dixie Gunsmithing]

Gunplummer,

That's the whole thing about heat treating, in that is warps the part. Generally, the piece is made slightly over-size, hardened, and then ground, or sometimes machined, but grinding is the best. I've tried turning hardened pump parts, and it isn't any fun.

Case Hardening can warp one, too, and you have to brace the piece to try to hold its dimensions when doing it. However, they have to be very close to final dimensions, as if you remove the surface, its soft again. Generally, a little stoning is all that can be done, to smooth a working surface.

Spot hardening, that they do now by using RF coils and immediately hitting the spot with oil or water, is about the best they have, and is what they use on gear and sprocket teeth, along with other parts. Of course, the old rifles would not have had this done.

Most all modern guns, even bolt actions I have noticed, when drilling and tapping, are easily done, and those are the front holes at the bolt lugs and barrel threads. However, they have access to a lot better steel now, that wasn't available when some of the old bolt actions were in military service. I am like you on case hardening and not thru-hardening on them, or not hardening at all.

What I've read about the 4xxx steels, is that they first appeared around the end of WWI, and it was invented for thin walled structural tubing, in Germany, for use in aircraft, and it later became popular here for landing gear, etc, then engines. That was more, though, at WWII, and after our bolt actions were falling from military favor.

When you calculate the locking pressures, like Jim and I mentioned, and multiply that to 1.5 to 2 times, it is still way under the yield of modern steels. Here, they can make the parts the same thickness as the old ones, but they are strong enough, that no case hardening, or thru-hardening is necessary, and that saves some big money. If you order the steel with a little lead, or resulphurized, it machines easily.

 

[Clark]

I picked up the receivers at the FFL.

The holes seem to be on 0.86" centers in the front and 0.504" in the rear, or close to those old Weaver standards for centers. They are flat. The closest flat bases would be #29 Weaver in the rear .504" center 0.292" thick, and #61 or #161 in the front .860" centers .361" thick.

If it is 4" between bases a difference of .069" in thickness would be

inverse tan .069/4" = .98 degrees = 60 moa in the wrong direction [pointing the barrel low].

I can't get 6-40 nor 6-48 to fit. It takes a .121" pin gauge as minor diameter of the holes.
It might be an M3.5x.5 or M3.5x.6 metric thread.
Or maybe I need to try harder with the 6-48.

I made a drawing of the dovetails. The look like 16mm in the front and 14mm in the rear.

 

[Dixie Gunsmithing]

Clark,

That screw size sounds like an M4 x 0.7, as 0.121" for a tap drill does not show up on my inch chart for a #6 screw, but it's close to a 3.3mm drill or a #31 drill 0.120". The tap drill for a #6 screw is a #33 at 0.113". The tap drill for a M4 x 0.7 is a #30 in the inch chart, or 0.1285". A #31 bit might work for a M4, but it would be a tight fit.

 

[Clark]

Whoops!
The Brownells stainless replacement pack 6-48 screw did not go in easily late last night, but the Weaver supplied Chrome moly screw 6-48 just went it

The point is, the scope base holes are standard American 6-48 threads.

I am going hunting and will not work on these for a while.