Mauser Actions with Lug Abutment Setback

[AkleyFan]

A few years ago I purchased 4 stripped Argentine Mauser actions from Sarco - each has a degree of lug setback. I have 3 semi-custom Mausers that I built myself that shoot 1/2 moa or better wearing McGowen and X-Caliber barrels - I did not pay any attention to lug setback when I screwed them together, but I assume there is some as they're all military actions.

Does anyone here have experience correcting lug setback on these actions or able to recommend someone I can discuss this with? I've read D'Arcy Echols' posts and an article that describes the process including annealing the action to remove/relieve the hardening before the machining takes place then re-hardening afterwards. Doesn't sound like an inexpensive process, but I'm going to go down this rabbit hole. Your assistance is greatly appreciated.

 

[shortgrass]

Can you post a link where the Echols' post/article can be found?

 

[tobnpr]

There's acceptable "wear", which shouldn't be more than .002- and actual setback which would indicate that the case hardening has been worn through.

Lugs are lapped into acceptable contact, assuming your stripped actions came with their bolts apply some Dykem to the lug and abutment surfaces of each to see what you're starting with. If you're dealing with minor wear and can lap into acceptable contact with both lugs without needing to remove a lot of material you should be gtg. If you've got actual setback, lugs are lapped in as above- but you need to send out for heat treat as you stated.

If a smith is going to do the work, he would true both the primary and secondary (receiver ring) torque shoulders as well, prior to heat treat. Contact Blanchard's Metal Processing for this:

Metal processing - Salt Lake City, UT - Blanchard Metals Processing Company

Blanchard Metals Processing Company does metal processing in Salt Lake City, UT. Call today 801-972-5590

www.bmproc.com

 

[shortgrass]

Case hardening requires a quench. Upon quenching, those 'trued ' torque shoulders will be "wopperjawed".

 

[AkleyFan]

Can you post a link where the Echols' post/article can be found?

Mauser Heat Treatment

The key words here are Rockwell hardness. Rockwell testing is great for metal that is heat treated and is hard all the way through. As discussed, Mausers are case hardened which is better measured by other methods, Schorr(sp?) for one. Unfortunately, to get an idea about the true case dept...

www.24hourcampfire.com

Butch Lambert posted this on the Campfire in 2016. There's more on the 'net, I'll look for my references

 

[Hugnot]

My personal opinion would be to retire any Mauser action vs heat treatment.

 

[shortgrass]

My personal opinion would be to retire any Mauser action vs heat treatment.

Why? They make beautiful classic style hunting rifles. They do have their limits, so use common sense (which isn't so 'common' anymore).

 

[shortgrass]

Sending all 4 of those 1909s will get you the 'batch price' from Blanchards. A big savings over sending 1 at a time. I believe Blanchards requires their Mauser re-carburizing business be conducted FFL to FFL, meaning they don't except this work from an unlicensed individual. Call 'um for pricing and other info. I had an even dozen done last spring, that should last me for the rest of my life. My 32+yr experience with Mauser '98s is, 1908s and 1909s are soft. Any I use will get re-carburized. The 'lure' of the 1909 is the hinged floor plate bottom metal, not the action itself. The Brno, Czechs seem to be the toughest followed by the Yugos. While I was a gunsmith school student I did work for the local pawnshop. Over that 2yrs I saw at least 4 military Mauser '98s with set-back lug abutments (the pawnshop did a huge business in firearms). Those were 1908s and 1909s made by DWM, that were used 'as is', with no re-carburizing having been done to them,,,, and barreled up to some belted magnum or hot-rod wildcat. That's what I know , that'll fit in a thimble.....

 

[shortgrass]

We need to know, to the thousandth, how much set-back there is to give any reasonable answer to your question. Hopefully, you have a snug to tight fitting mandrel that you can run between centers with the action mounted on it to square the face of the front ring. Accurate measurement with a depth mic from there.

 

[AkleyFan]

We need to know, to the thousandth, how much set-back there is to give any reasonable answer to your question. Hopefully, you have a snug to tight fitting mandrel that you can run between centers with the action mounted on it to square the face of the front ring. Accurate measurement with a depth mic from there.

Merry Christmas All.

I have a mandrel and handtools from Kiff and Manson that I can use to square up the face of the receiver, but nothing in the tool box that I can use to get past the C-Ring and measure the depth of the setback. I would estimate .002" - .007" between the lot of 'em.

I'm no machinist, just a hobbyist with space constraints and a shooting habit.

 

[shortgrass]

I think I'd try to lap 'um smooth, not smooth by appearance, smooth by feel. Use a bolt that'll get re-carburized or will be "sacrificial", but Mauser '98 bolts are getting more expensive every day. If you decide to cut it out, in a lathe set-up, you'll need to come up with a cutting tool to reach the lug abutments, and preferably set the action up in a 'truing fixture', so it's straight. Either way, lapping or cutting, they'll need to be re-carburized. I don't send bolts, just the action when I send 'um to Blanchards. Good Mauser '98 actions (as are Springfields, P14s and M1917s) are getting hard to find. A 'good' rifle is too valuable to dis-assemble , just for the action.

 

[AkleyFan]

OK - I'm feeling like the setback is less a concern if you are - ultimately - going to re-carburize the action. I appreciate your point regarding lapping. Partial lapping to smooth the surfaces with a "sacrificial" or single purpose bolt prior to re-carburizing seems like a worthwhile practice as I can then final lap with the bolt I'm go to finish the build with, and not worry too much about over lapping the engagement surfaces of each. I have a few bolts in the parts drawer that I could use for this operation.

Side Note: 3 years ago now I built a .308 Win on a VZ-24 action. I was curious to know if the recommendation of lug lapping to approx. 80% engagement contributed to accuracy - nothing else, so I decided to conduct a simple test. My test consisted of 1 military, 3 Interams and 1 Parker Hale bolt that were not lapped to the action and had varying degrees of lug engagement, some as low as 40%.

Each bolt headspaced properly and all loads were the same - my go-to California hunting load of Hornady cases filled with 45gr of RL15 and a 150gr TSX @ 2.810" (I correct bullet runout to .002" or less) - it shoots sub-MOA in the 7 rifles that I load for.

The results of the test: there was no change in bullet impact @ 100 yards among any of the bolts I used. I found that very interesting. I can see where lapping the lug surfaces is beneficial in other areas, so not looking to stir the pot, just to share this observation.

 

[shortgrass]

With the set-back you describe, that is the only reason I'd lap a Mauser. When I barrel one, I square the action face and I may square the bolt face. I have my own methods of doing this. I don't believe I've ever lapped the locking lugs, other than to smooth-up some slight set-back before re-carburizing. With a quality made barrel, properly fit, chambered and crowned, and not just crammed into any old stock, they very easily shoot 1/2" or less @100yds.

 

[tobnpr]

Partial lapping to smooth the surfaces with a "sacrificial" or single purpose bolt prior to re-carburizing seems like a worthwhile practice as I can then final lap with the bolt I'm go to finish the build with, and not worry too much about over lapping the engagement surfaces of each. I have a few bolts in the parts drawer that I could use for this operation.

Makes zero sense to lap with any bolt other than the one actually to be used.
Consider this-
Your "sacrificial" bolt has full contact on the top abutment, and very little on the bottom.
Your "real" bolt has the opposite.

You'd end up lapping the bejeezus out of the top lug abutment- only to need to do the opposite when you stick the real bolt in.
Don't do it.