I believe I already know the answer to this one, but is it advisable to heat treat an action, if it has been drilled and tapped through the locking lug recesses and/or lug abutment ? From what I gather, it can compromise the integrity of load bearing surface. I suppose you can attempt to regain the hardness. But, essentially, you cannot TRULY repair the structure of the area that has been compromised. Am I correct...?

Someone thoughtfully drilled the scope base holea right through the top locking lug abutment. And it is an Arg 1909...
Like that generous chamfering; you only lose two threads by doing that.

To be honest I don't really think the screw holes will compromise anything. After all many Mauser actions have the receiver ring scalloped at the top lug abutment by smiths opening up an action for longer cartridges and by the Mauser factory to give clearance in some of their actions for cartridges like the 30-06 etc with longer bullets.

I note some go on about losing action strength when cutting away some of the feed ramp/bottom lug abutment area when opening actions for longer cartridges but ignore and accept scalloping of the top of the receiver ring/top lug abutment area.

The Winchester factory worked both areas fairly aggressively on the receiver rings of their pre-64 M70s when opening up the actions for the 300 and 375H&H cartridges and nobody questions their strength or lack of it.

Chuck hardened scope base screws in that Argy and it'll likely be better than new

Drill out the threads and press fit a plug.
Then re-drill in the proper place.

it hasn't bothered the rear lug of a g.33/40 in 7/57 that I have shot many times

Consider that the Model 70 is made from 4140 steel, and the Arg 1909 is made from low carbon steel, and many were not case hardened much; the 7.65 cartridge is relatively low pressure. 1909s with set back receivers are not uncommon even without the hole through the ring.
Also, the 33/40 is Czech; all of which were heat treated properly and never set back the lugs; Unlike the 1909, which, do.
And the military Mauser with the scalloped rings, are FN in cal 30, again, properly heat treated.
Let me get this clear; you are going to plug that hole, and drill two more for the scope base, now having 4 holes in the ring?

So, comparisons to a Winchesr M70, and a 33-40, might be comparing different animals.
Of course it is his decision on whether or not to use it.
It will probably be fine. Maybe.

I have had a few drilled like that. Most were 8x57, 30-06, or 257 Roberts with no issues. Another thing is the top recoil lug on the top is split to allow the ejector to pass through, so the hole is lined up with the split. But of all the Mausers I had or knew of with lug setback were all M1909's, approx 5 in all.

quote:

Let me get this clear; you are going to plug that hole, and drill two more for the scope base, now having 4 holes in the ring?

Make sense? Not to me...

quote:

Originally posted by airgun1:
the top recoil lug on the top is split to allow the ejector to pass through, so the hole is lined up with the split.

I wonder if that potentially could cause a few issues? If the recoil lugs on the action absorb the force of the cartridge during fire, wouldn't drilling a hole through the "split" compromise the strength of the lug? After all, the split in the top lug is already a point of "reduced" material...

quote:

Originally posted by airgun1:
I have had a few drilled like that. Most were 8x57, 30-06, or 257 Roberts with no issues. Another thing is the top recoil lug on the top is split to allow the ejector to pass through, so the hole is lined up with the split. But of all the Mausers I had or knew of with lug setback were all M1909's, approx 5 in all.

The 1909s with setback, DWM or FMAP?

Both makers.

You aren't drilling through the split, they were drilling on the lug in the receiver; the bolt's top lug is split.

ETA: All of those setbacks were sporterized with unknown history. They may have seen hot loads or over lapped trying to get full / even contact I don't think any M1909's were in combat or even shot much. We used to say shot little and cleaned less.

Most K98k were battle worn firing potent 8x57 loads and I never came across one with lug setback, just something to think about.

There are two different things being discussed here. One is lug setback where the hardened bolt lugs 'squash' back into the softer top and bottom lug abutments, a known issue with Argy 1909 actions. The other issue is grinding or scalloping away on the lower and upper abutments in the receiver potentially weakening these where they could shear off allowing the bolt to blow rearwards out of the receiver.
As I related, plenty of rifles have had this modification done to enable longer cartridges to be accommodated in shorter actions, with no ill effects. Mauser and Winchester themselves have undertaken these modifications so presumably find safety margins not compromised.

The OP was questioning whether screw holes through the top locking lug recess or abutment would compromise the integrity of the load bearing surface.
A screw hole through the receiver ring into the lug recess won't compromise anything as this is where screw hole should go anyway.
A screw hole through the lug abutment wouldn't compromise the abutment in terms of shear strength and due to the split through the bolt lug itself bearing on the abutment wouldn't increase any set back that was not already there. Having a hardened screw, either holding a scope base on or just a blind screw to fill the screw hole in the top abutment is basically returning the abutment to it's full strength.
Pretty simple engineering really although some engineers don't always think in simple terms, hence bridges, buildings and carriageways collapse that have all been designed and built by qualified designers and engineers

Ok… interesting thread. So is the 1909 Argentine lug set back due to the quality of the metal or the lack of proper tempering? Can this issue be resolved with proper tempering/ heat treating?

Some facts;
1. It was the heat treatment (case hardening), on pre ww1 receivers that was adequate for the 7.65 cartridge but is too thin for modern 55K psi plus cartridges. The steel is fine; like 1018 or so.
2. Comparing the Kar98k to the Arg 09 is invalid; 30 plus years later they made the receivers to take any pressure.
3. Model 70s and FN commercial receivers do NOT have holes drilled through the lug abutments! They are forward of that.
4. Yes, two issue, albeit intertwined.
A. Low strength due to heat treatment. Potentially.
B. Potentially compounded by the hole.
Just facts. As to whether that receiver will work on a 55K psi cartridge; it might. Or might not. .5 probability.
I think we should do a test.

In cases like this, we always hear a lot of, "I've seen a lot of them like that, and they seemed fine." Or, other actions are opened up and weakened more than that hole will. They seem fine"
These things may well be true, but the fact of the matter is, it is WRONG! The scope mount holes should not be drill behind the lug abutment nor into the face of the lug abutment. It is not proper practice. A person can justify improper work all they want but it is still wrong. Regards, Bill

dcpd, According to the official Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (CIP) rulings the 7.65×53mm Argentine can handle up to 390.00 MPa (56,565 psi) Pmax piezo pressure. In CIP member countries every rifle cartridge combination has to be proofed at 125% of this maximum pressure to certify fit for sale to consumers. This means that 7.65×53mm Argentine chambered arms in CIP regulated countries are currently (2013) proof tested at 487.50 MPa (70,706 psi) PE piezo pressure.[2] I don't exactly call that low pressure. I've shot a lot of the Argentive military cartridges with the 170 some grain spitzer bullets and it is some pretty hot stuff.

Wait for it.

This, while true after CIP got involved, has nothing to do with rifles and ammo from pre WW1; the 1891 Argentine, and the 1909, were not made for the current high pressure ammo. Ammo of the period was loaded at 42K PSI.
Go ahead and shoot the CIP ammo in pre WW1 rifles; report back.
Many reports of set back 1909s validate this. And definitely do not shoot 55K psi in an 1891.
CIP gives the shooter more credit for good judgement than we do in the US. And rightly so.

quote:

Originally posted by Bill Leeper:
In cases like this, we always hear a lot of, "I've seen a lot of them like that, and they seemed fine." Or, other actions are opened up and weakened more than that hole will. They seem fine"
These things may well be true, but the fact of the matter is, it is WRONG! The scope mount holes should not be drill behind the lug abutment nor into the face of the lug abutment. It is not proper practice. A person can justify improper work all they want but it is still wrong. Regards, Bill

Bill I don't think anyone is suggesting it is correct to drill scope base holes into the top locking lug abutment or for that matter the front screw hole going through the receiver, threaded barrel tenon and into the chamber as I have seen two examples of. For the screw holes for a two hole forward scope base, the rear hole should be drilled forward of the lug abutment and front hole through the receiver to touch the treaded tenon. That will provide the maximum thread strength for the screws which I always epoxy in along with the base.

My post was responding to the fact that screw holes have already been drilled in the action dpcd has provided an image of. Yes both screw holes should have been drilled forward of those positions and as dpcd points out, not chamfered like they have been. Not all is lost with that action though.

As to what is right and what is wrong, all depends I suppose. Take a look at these two images below and give us your thoughts, pre-64 M70 standard action as it came from the Win factory opened up for the 375H&H. Not a lot left of the bottom lug abutment and a fairly radical scallop of the receiver ring behind the top abutment. Right or wrong? Scope base holes would be okay though

quote:

Originally posted by dpcd:
This, while true after CIP got involved, has nothing to do with rifles and ammo from pre WW1; the 1891 Argentine, and the 1909, were not made for the current high pressure ammo. Ammo of the period was loaded at 42K PSI.
Go ahead and shoot the CIP ammo in pre WW1 rifles; report back.
Many reports of set back 1909s validate this. And definitely do not shoot 55K psi in an 1891.
CIP gives the shooter more credit for good judgement than we do in the US. And rightly so.

According to Websters book the 1891 ammunition ran at 48496 psi and the 1909 slightly less at 47761 psi.
Muzzle velocity for the 180gn bullet was well over 2700 fps.

We've got a K98k receiver in the shop drilled similar to this one, but the front hole is into the internal ring. The rear hole is blind and only 4 threads deep.

I've seen pics of 4 Mauser receiver blowups and all started at the extractor cut and peeled the ring up to the upper lug abutment. One might speculate that a hole in front of the abutment weakens the ring more than one in the abutment. the steel is relatively thin there. I'm not an engineer and don't know.

quote:

Originally posted by dpcd:
Someone thoughtfully drilled the scope base holea right through the top locking lug abutment. And it is an Arg 1909...
Like that generous chamfering; you only lose two threads by doing that.

You have a Kar98k; totally different heat treatment than the pre WW1 made ones like the 09 Argentine.
Every make of bolt action puts the rear hole, in front of the abutment. So I wouldn't worry about all those; now going on 400 million of them.
But steel and heat treatment matter more; hence the origin of this discussion; double whammy; hole in the top in the wrong place, and suspect heat treatment common to all Arg 09s.
if it was anything else, we would not even be talking about it. We would be shooting it.

First and foremost, most of you need to go to my website and purchase a copy of my "Heat Treat in Brief" which addresses most of the mis conceptions posted here. I would post a link, but were not allowed to do that, so you'll have to search for it.

quote:

Originally posted by Bobster:
I've seen pics of 4 Mauser receiver blowups and all started at the extractor cut and peeled the ring up to the upper lug abutment. One might speculate that a hole in front of the abutment weakens the ring more than one in the abutment. the steel is relatively thin there. I'm not an engineer and don't know.

Can you post or send these pictures? I've blown up several Mausers, including one with several 90k and 100k PSI loads and never had a ring separate.

quote:

Originally posted by eagle27:
A screw hole through the receiver ring into the lug recess won't compromise anything as this is where screw hole should go anyway.
A screw hole through the lug abutment wouldn't compromise the abutment in terms of shear strength and due to the split through the bolt lug itself bearing on the abutment wouldn't increase any set back that was not already there. Having a hardened screw, either holding a scope base on or just a blind screw to fill the screw hole in the top abutment is basically returning the abutment to it's full strength.

This is correct. There is a far cry between what works and what is "best". We have rolling wrecks that shouldn't be on the road, they may not be "best", but they get the job done.

quote:

Originally posted by dpcd:
This, while true after CIP got involved, has nothing to do with rifles and ammo from pre WW1; the 1891 Argentine, and the 1909, were not made for the current high pressure ammo. Ammo of the period was loaded at 42K PSI.
Go ahead and shoot the CIP ammo in pre WW1 rifles; report back.
Many reports of set back 1909s validate this. And definitely do not shoot 55K psi in an 1891.
CIP gives the shooter more credit for good judgement than we do in the US. And rightly so.

1891's handle 55k just fine, as do 1909's. There's something about their lug setback you don't know.

quote:

Originally posted by metal:
According to Websters book the 1891 ammunition ran at 48496 psi and the 1909 slightly less at 47761 psi.
Muzzle velocity for the 180gn bullet was well over 2700 fps.

And most were proofed (depending on year) at 4000 ATM, which for those of you who need doughnuts per bald eagle is 58783.8 PSI.

Don't have time for any more, but that should be enough kicking to get the hive riled up for a few days.

Take care!

When gun smiting was cheap and there were thousands of cheap actions out there if no 100's of thousands.

It mad sense to use these old actions.

Now with modern steels, modern actions.

The cost of turning such actions into "modern rifles" makes no sense what so ever.

quote:

Originally posted by p dog shooter:
When gun smiting was cheap and there were thousands of cheap actions out there if no 100's of thousands.

It mad sense to use these old actions.

Now with modern steels, modern actions.

The cost of turning such actions into "modern rifles" makes no sense what so ever.

If cost is the only factor, then you are correct. Fortunately most people who commision custom rifles evaluate much more than just the final dollar amount.

quote:

If cost is the only factor, then you are correct.

Unfortunately for us on the lower income.

Cost is a huge factor. That is why lower cost firearms sell my the hundreds of thousands

Then full customs sell by the dozens

I have no problem with how one spends ones money.

NM, I do want you to tell me/us about lug setback, because the only Mausers I have ever seen with it were 1909s converted (rechambered) to 30-06. Also, are you recommending using 1891s for modern cartridges at 55K PSI?
I have about 8 of them sitting here.
This is all new to me.

Pay attention, you might learn something.

Why don't you just tell me and save me time waiting?

Because I don't have all the answers.

quote:

Not all is lost with that action though.

There are people who are far more versed in this particular area than me. I have decided to scrap this receiver and use it as a fishing weight. It will come in handy next time I head to the surf and go fish for blacktip shark.

quote:

Originally posted by dpcd:
NM, I do want you to tell me/us about lug setback, because the only Mausers I have ever seen with it were 1909s converted (rechambered) to 30-06. Also, are you recommending using 1891s for modern cartridges at 55K PSI?
I have about 8 of them sitting here.
This is all new to me.

I have seen lug setback in nearly every make and model. Only two come to mind that I have not seen lug setback, Czech vz-24's and Argentine 1891's.

I haven't finished my testing, but based on what I have found, ammunition was a large contributing factor to the lug setback seen in Mauser rifles. It also caused many of the somewhat commonly seen "bulged" barrels. You've probably seen one, a slight ring, or maybe even a moderate ring, somewhere in the last 6" of the barrel.

In my little pamphlet I cover the metallurgy of an 1891, they are great little guns. Metallurgically and heat treatment they are as good as any Mauser. Engineering is a different discussion. I prefer to put a 96 3 position safety on my 1891 builds.

I've got 3 or 4 junk 1891 receivers that will get tested to destruction this fall. What pressure do you think they will handle?

quote:

Originally posted by Sabretooth:

quote:

Not all is lost with that action though.

There are people who are far more versed in this particular area than me. I have decided to scrap this receiver and use it as a fishing weight. It will come in handy next time I head to the surf and go fish for blacktip shark.

Send it to me. I'll run progressively higher pressure loads through it until something fails. When brass gets liquid in the 80-90k PSI range there will start to be issues. I would bet it will "fail" just like all the other Mauser 98's I have tested. At 110k psi you'll get severe lug setback, the bolt will crack the standoffs, and you'd need a pack of wet wipes and a new pair of shorts. But you'd be alive. Once it's been thoroughly mangled, I'll send it back to you, so that you have not just a paper weight, but a conversation starter.

I suspect that when I am done with it, you can all go. Damn... it was functional. Not "correct", certainly not "best" practice, but functional. Safer than the 76 Chevette I used to ride to school in.

The 91s are my favorite Mausers, but I only put 35 Remington and 450 Bushmaster on them.
Leaving them 7.65 would be boring.
There is another facet to this; sustained impact on the 09s, which is why we see so many 09s with lug area setback; it is not the one time extreme high pressure that is concerning; the ones I have seen with set back were not due to high pressure; but sustained commercial 30-06 pressure over a few hundred rounds. They still fired fine; just hard to open.
That is the concern; not total failure. I am sure the OP's receiver would handle any pressure for a few rounds.
To me that is.
The OP is going to use his receiver for something less intense; no need to blow it up; that will prove nothing you don't already know. It just can't be barreled for anything in the 55+K psi range.

Anecdote on 09 Argentines; my first job was in a Basic Training company at Ft Knox. When we went to the M60 range, I would take a 1909 Argentine carbine and me and the drill sergeants would shoot 7.62 Nato out of it, by the hundreds.
Brass came out with a very short neck. Of course, the pressure was reduced due to the increased "case" capacity.

So, if one were to install the M96 fire control, weld on a bolt to notch into the receiver for a safety lug, mill a gas vent notch in the side rail, drill a gas vent hole in the receiver ring and a couple of holes in the bolt body, would the M91 be a safer action? I'd think so. I'll pile on and suggest milling back the left locking lug to a '98 configuration and use a rebated breech on the barrel like an Arisaka. Oh heck, why not weld on one of those FN '98 bolt handles with the cocking cam like the Belgians did and fully 98-ize it!

[QUOTE]Originally posted by Fal Grunt:

I have seen lug setback in nearly every make and model. Only two come to mind that I have not seen lug setback, Czech vz-24's and Argentine 1891's.

I haven't finished my testing, but based on what I have found, ammunition was a large contributing factor to the lug setback seen in Mauser rifles. It also caused many of the somewhat commonly seen "bulged" barrels. You've probably seen one, a slight ring, or maybe even a moderate ring, somewhere in the last 6" of the barrel.

In my little pamphlet I cover the metallurgy of an 1891, they are great little guns. Metallurgically and heat treatment they are as good as any Mauser. Engineering is a different discussion. I prefer to put a 96 3 position safety on my 1891 builds.

I've got 3 or 4 junk 1891 receivers that will get tested to destruction this fall. What pressure do you think they will handle? [QUOTE]