Argentine Mauser from 30-06

[CoRifleman]

Rifle is an 1891 Engineers carbine.

Used an old Pacific die set to form some 7.65x53 from Win 30-06 brass. Annealed before forming, reamed necks to thin them after forming. Easy chambering and extraction. I'm aware the Pacific die is among the shorter ones, so I raised the die to ensure shoulder dimension was in the 1.816 range (vs screwed down with shell holder touching die is ~1.789 iirc). Loading was a breeze. Imr3031 40-42gr, 150gr hornady. Shot well.

BUT.... after firing, I'm getting a sharp line at the shoulder.

In the pics, the row of cases are all fired except the far right; the far right case is as-formed.

It's not necessarily 'sharp' but I would imagine this will become an issue, if not now, then if I try to fire these again.

What gives?

Closest thing I found online is this...
https://www.carolinashootersclub.com/threads/ring-around-223-brass-shoulder.223978/


Here are my pics
https://uploads.tapatalk-cdn.com/20211203/c36c8a3133c601906b54c52437fbd500.jpghttps://uploads.tapatalk-cdn.com/20211203/d4e93fa8a98e78e2f5fff9d651ce99b1.jpg

[725]

I would suspect a sharp anomaly within the chamber. With care, I'd prepare a device that mirrors the proper cartridge and use it to polish down the interior of the chamber. got any good bore scope or something to look in there? If this occurred before firing, I'd think it to be something about the dies, but after firing, ..............?

[Jim22]

Take a piece of spring wire, sharpen a point on one end, bend that end into a 90 degree angle so it will fit in the neck and touch the inside of the case. Put it into the case mouth and feel to see if the ring is on the inside as well. If t is the case is about to separate at that line. If not there is less concern. We used to do that when there was a similar ring near the base to see if we were about to have a head separation.

Jim

[CoRifleman]

Take a piece of spring wire, sharpen a point on one end, bend that end into a 90 degree angle so it will fit in the neck and touch the inside of the case. Put it into the case mouth and feel to see if the ring is on the inside as well. If t is the case is about to separate at that line. If not there is less concern. We used to do that when there was a similar ring near the base to see if we were about to have a head separation.

JimDoesn't seem to be a ring inside the cartridge that I can feel. I'm going to measure the fired shoulder dimension tonight.

[CoRifleman]

I would suspect a sharp anomaly within the chamber. With care, I'd prepare a device that mirrors the proper cartridge and use it to polish down the interior of the chamber. got any good bore scope or something to look in there? If this occurred before firing, I'd think it to be something about the dies, but after firing, ..............?A borescope would help here, I may run down a gunsmith for this one if it's a chamber issue.

[Texas by God]

Try some true 7.65 brass and see if the ring appears on the fired cases. If not, and your reformed 06 cases work normally; no worries in my opinion.

Sent from my SM-A716U using Tapatalk

[CoRifleman]

Try some true 7.65 brass and see if the ring appears on the fired cases. If not, and your reformed 06 cases work normally; no worries in my opinion.

Sent from my SM-A716U using TapatalkI've got some hornady factory loaded I'll try. I guess I'm hoping it IS the chamber and then I can find a course of action.

[ulav8r]

LOOKS like the shoulder may have been set back too far and the brass was not annealed in the shoulder area. Just one possibility, there are others.

A chamber cast or borescope inspection should show if it is a chamber issue. Definitely try the factory loads, one or two shots should be enough to show a defective chamber.

[skeettx]

Looking on with interest
I see no current safety issues
Neck size, load again and see if anything changes
Mike

[smithnframe]

Have you checked the headspace?

[toot]

I have made 100ths, of them out of your parent brass and never seen or had this occur. strange!

[AntiqueSledMan]

Hello CoRifleman,

Is there something in your chamber causing the defect?

I've not seen anything like that when I formed them.
But I did turn the necks. The left case has been fired,
the right case is just formed with neck turned.
The shoulder does sharpen up after firing.

AntiqueSledMan.

[CoRifleman]

Took some measurements of the fired cartridges today.

I have not yet fired the hornady factory ammo in it, but based on measurements I'm not sure I need to...

I ran a sharpened spring wire in chamber edge, could feel no obvious lip, but don't have a boroscope to verify.

I think it may be a headspace issue, or just and overly large chamber...

A thread for reference... https://www.gunboards.com/threads/7-65x53-mauser-miscellany.393661/

My measurements were eye-opening and perhaps definitive.

Ok, using the .375 bushing here are my readings...

Unfired Hornady frontier brass cartridge loaded by hornady, #80489 :::
1.8125, 1.8130, 1.8140

Formed by Pacific die raised to lessen shoulder bump per previous research here and gunboards threads :::
1.8165, 1.8170

Formed by Pacific die while touching shellholder :::
1.789, 1.790

Drum roll... Fired WW 30-06 converted cases with detented ring at shoulder area :::
1.8255, 1.8250, 1.8240
Note: these cases will all chamber without effort after firing!

Now, if I put a piece of scotch tape on the base of the fired cartridge, the measurement changes to 1.827 and it chambers with mild difficulty.

I'm pretty green here. I'm assuming this thing has a monstrous chamber. Can I simple re-anneal these past the shoulder to soften them and fire them again to "fireform" them and then reset my die to only slightly move the shoulder back (to 1.825ish) for ease of chambering and record all data to load this rifle specifically? (The bolt is matching, with no obvious flaws or galling.)

I've put a lot of time into bringing this rifle back to life, and she was a pleasure to shoot.

Thank you all.

[CoRifleman]

50yd iron sights. The carbine sight rear notch is smaller than the long rifle by a considerable amount, if you can believe that.

Hornady 150gr SP interlock
40-42gr imr3031https://uploads.tapatalk-cdn.com/20211204/1ba1380c091b0e85ea668919a848919a.jpg

[wyowillys46]

This thread has plenty of blueprints and information for the 7.65 cartridge.

https://www.gunboards.com/threads/mauser-7-65-cartridge-history-and-specifications-speed-sheehan-webster.1096545/

As for headspace gauges:

https://mansonreamers.files.wordpress.com/2015/06/argentine-headspacing-information.pdf

[CoRifleman]

Willy thank you, I found the same headspace document as I was searching. I guess what I'm trying to determine now... Is a case that I've sized to the .375 datum line at 1.8250, which chambers freely and is 2 thou below a case that chambers with resistance (1.8270), an acceptable solution for an old rifle that has a large chamber and 'safe' with normal loads? Can I assume the gun just had a large chamber from the get? The barrel is original and is beautiful inside.

I'm tempted to scrap the "ringed" brass under the assumption that stretching to fit the long chamber caused the ring, form a new batch of five or so cartridges to the 1.8250 shoulder spec and give her a whirl with a 41-42gr charge of i3031.

I'm looking for the community feel on this plan.

[CoRifleman]

LOOKS like the shoulder may have been set back too far and the brass was not annealed in the shoulder area. Just one possibility, there are others.

A chamber cast or borescope inspection should show if it is a chamber issue. Definitely try the factory loads, one or two shots should be enough to show a defective chamber.Yes, see my measurements above, although not set too far back according to a couple sources (although the Arg chamber seems to be a moving target), but simply set too far back according to my specific chamber on this rifle.

Looking on with interest
I see no current safety issues
Neck size, load again and see if anything changes
MikeForming new brass to 1.8250 is the same essentially as necksizing these fired cases, so am weighing this approach. New brass is simple enough to make. Thank you.
Have you checked the headspace?See above, measuring the fired cases is as close as I can get to a true headspace at this point, with the addition of the single scotch tape layer. Bush, I know :-( thank you.

[405grain]

I'd be leery of shooting that ringed brass again without a broken case extractor handy. There is the possibility that a subsequent firing might cause the case neck/shoulder to separate and lodge in the chamber. This probably won't injure you or the rifle, but will be a hassle to remove. Here's my recommendation: Toss out the ringed brass. When you reform new cases load them with your boolits seated long. You want the boolit to engage the rifling so that it will prevent any forward movement of the cartridge during firing. Use a charge of powder appropriate for case forming. If the boolit is slightly pushed back into the case during chambering that should still be OK as the intent is to fire form the case to your chamber, and the goal is to hold the case with it's base against the face of the bolt. Upon firing the case should expand to match the contours of the chamber. After that you can reload either by neck sizing or just barely bumping the shoulder, and the cartridge should headspace in your chamber.
Note: Those cases will match to that rifle. If you own more than one gun in 7.65x53 you need to keep these round separate and only use them in the rifle that you formed them for.

[Mk42gunner]

It has been a long time since I had a 7.65x53 that I formed brass from .30-06 for. You did ream the necks before loading, that is a good thing; in my experience either reaming or outside turning is required.

What I would do is form some new cases with the rifle there to try them in. Form until there is a slight resistance when closing the bolt. This way you don't have to try to load a projectile out to jam into the lands for headspace control.

Robert

[skeettx]

The fired cases have been fire-formed
Neck size and load
Shoot
Have fun
Mike

[ulav8r]

It has been a long time since I had a 7.65x53 that I formed brass from .30-06 for. You did ream the necks before loading, that is a good thing; in my experience either reaming or outside turning is required.

What I would do is form some new cases with the rifle there to try them in. Form until there is a slight resistance when closing the bolt. This way you don't have to try to load a projectile out to jam into the lands for headspace control.

Robert

Agree with Robert.

Robert

[AntiqueSledMan]

Hello CoRifleman,

I had a hunch, have some cartridges marked 7.65x54 SF 76.
Thought there might be a difference, but they seam to measure very close.
Mine are about (I say about because it's very hard to read the shoulder).
OAL 2.100", Base to Shoulder 1.775", Base to Neck is 1.870"
This is close to what I have for dimensions listed,
OAL = 2.100", Base to Shoulder 1.778", Base to Neck = 1.876"
The only issue I encountered was they were hard to chamber,
but after I started turning the necks, that issue disappeared.

AntiqueSledMan.

[CoRifleman]

Thank you all for the help here.

Yes I've got some of that sk75 ammo. That stuff is rough,like they had sand in the dies ha. Some corrosion, so I pulled the bullets (talk about a heavy crimp!) And dumped them.

I also have a 1909 carbine and a 1891 long rifle, so I think the "short" 1.8160 to datum cases I made with the die set will go in either of the other two, I just am going to get 50 cases made up for this oddball and then move onto the others.

If I had access to a lathe, I'd buy three of the lee sizers and just have one for each, knowing they're so long, I could trim them to length at press full contact. Maybe someday. I hate the idea of the time spent getting this die just right at 1.8250 in a lock ring and then spin it away for other rifles.

[CoRifleman]

Today's update...

Made 5 cases up to more closely fit the chamber...

3@41.5g, 2@42g.

Figured out true neck length, made these cases .020 short of contact, trim length ended up being 2.150. Lyman trim-to spec is 2.100.

1.8245/1.8250 shoulder measurement, which is 2ish thou back from contact.

For cartridge OAL I set the hornady cannelure to crimp correct, which put my ogive about .012 from the lands (much closer to the lands than spec 2.100 trim length and my previous 2.900 oal). New oal to tip is in the 2.950 range.

Cases chambered and fired well.

After firing, the 41.5 charge cases actually shrunk in length to 2.1490, the 42gr remained the same at 2.150 or grew to 2.1505. Shoulder measurements were in the 1.8250 range still.

Velocity was a smidge down to yesterday, which jives with a bit larger case volume.

But... The slight ring at the shoulder on fired cases is still there.

[15meter]

I load for an 8x50R in a double rifle, the neck comes out very similarly after fire forming 7.62x54R or 8x56R in the rifle. Being a double rifle it is easy to look inside the chamber. You can't see a visible problem but the necks come out looking quite similar. I've got some of the brass with probably a dozen firings with no problems. As a guess, every 5th loading the necks get annealed. Haven't lost any yet to neck splits or other maladies.

[CoRifleman]

Thank you 15. I also spoke to a local gunsmith, and he reiterated what many of you said.

A chip hung on the reamer, a broken reamer, re-reaming with a slightly smaller reamer will all produce this slight shelf. He said it's no big deal, AND it'd be all but impossible to fix without rebarreling. Just watch the brass and keep this brass only for this rifle.

You guys are a great help.

[jdsingleshot]

Looks like the chamber has a ring in the shoulder area caused by a nicked reamer at the Mauser Werk. If so, there is steel left sticking UP in the chamber as a ring. Touch the shoulder with a good reamer and the problem will disappear.

[Baltimoreed]

Cut a few weird cases lengthwise to inspect the interior, and a true sideview of the case, borrow a borescope to look in the chamber. Could also do a chamber cast with cerrosafe.

[gliebegott]

Anyone interested in some actual rounds of this caliber?

They would be free.

PM me

[CoRifleman]

anyone interested in some actual rounds of this caliber?

They would be free.

Pm me

yes!

[paul edward]

The best way to discover whether there is a chamber defect is to do a chamber cast. Alloy is available from Brownell's and instructions are available online.

Look for PM

[sse]

I have had a couple of rifles in the past 60 years that had fired cases that looked like that.
You can take 1 case and see how many times you can load it before it fails. I have saved time by doing that on rifles that I wondered about.
After 10 or so loadings I figured there was nothing to worry about.

[Hick]

The fired cases have been fire-formed
Neck size and load
Shoot
Have fun
Mike

This really important-- note Mike is saying "neck size." Regardless of any oddity of the chamber, if you have fireformed and then do not push back the shoulder-- only neck sizing, your brass is now custom fitted to the chamber and will work just fine. So do not push the shoulder back. There is no reason to expect the brass to separate here. (Not impossible but very, very unlikely). My 1909 Argentine carbine also has a slightly odd chamber, and the brass lasts for many, many firings, but neck sizing only.

Brass separation at the base is a completely different problem. It happens because the brass flows toward the neck in full length sizing, then it stretches again the next firing, then gets full length sized and the brass flows forward again, then streches again when fired-- until eventually it thins too much at the base and separates. Neck sizing prevents this because after the first firing it never grows.

[Reg]

Thank you 15. I also spoke to a local gunsmith, and he reiterated what many of you said.

A chip hung on the reamer, a broken reamer, re-reaming with a slightly smaller reamer will all produce this slight shelf. He said it's no big deal, AND it'd be all but impossible to fix without rebarreling. Just watch the brass and keep this brass only for this rifle.

You guys are a great help.

I would agree with your local gunsmith. I think he is spot on. Neck sizing and keep the brass for this rifle separate and a good neck annealing from time to time are all good ideas. One thing I question is the neck turning or reaming. Since about 1962 I have made thousands and thousands of these cases from 30-06 and even 270 cases and have used them in at least 20 or more different rifles and never once have had any apparent problems. No chambering problems, no signs of pressure, nothing. I am sure it makes no difference in brass life but it might save you a step.

[Hick]

I would agree with your local gunsmith. I think he is spot on. Neck sizing and keep the brass for this rifle separate and a good neck annealing from time to time are all good ideas. One thing I question is the neck turning or reaming. Since about 1962 I have made thousands and thousands of these cases from 30-06 and even 270 cases and have used them in at least 20 or more different rifles and never once have had any apparent problems. No chambering problems, no signs of pressure, nothing. I am sure it makes no difference in brass life but it might save you a step.

I'm with Reg on this. I make my 7.65 cases from 30-06 and 270 brass and have never turned or reamed the necks and had no chambering or other problems.

[leadman]

The original 1891 cartridges, along with some commercial cartridges made on worn out Argentine equipment was marked 7.65X54. Later when the bullet was changed to a Spitzer from a roundness the neck was shortened 1mm.
Some say there were 2 different cases with different headspace but I don't believe this was true. I think what was the case is that the extra barrels that Argentine bought (3 per rifle) had short headspace so they could be fitted and headspaced when a barrel replacement was needed. I have bought 5 or 6 of these replacement barrels and on the first couple I installed I just trimmed a shellholder to get the cases to fit. Now I have the reamer and headspace gauge and have adjusted the headspace on my six 1891s so they are all the same. I have a couple of these NOS barrels waiting for a couple more guns in need of them. There is a very long leade in front of the neck designed into the chamber so it is not not possible with some jacketed bullets to touch the rifling.
Graf & Sons normally has new PPU brass if needed. I wish they still sold the 150gr Hornady SST as it is very accurate.
I do not ream or turn reformed brass as the chamber dimensions are generous and this is not normally needed. I think it is an advantage to not turn or ream as far as accuracy goes.

[Uncle Grinch]

I'm with Reg on this. I make my 7.65 cases from 30-06 and 270 brass and have never turned or reamed the necks and had no chambering or other problems.

I’ve been forming 7.65 Argentine from R-P 30-06 brass for many years (20+) with a forming die and never have annealed or reamed the necks. I use R-P brass just so it is different from my HXP or Winchester. No issues with cast or jacketed bullets in either my 91 or 09.

[376Steyr]

"Some say there were 2 different cases with different headspace but I don't believe this was true. I think what was the case is that the extra barrels that Argentine bought (3 per rifle) had short headspace so they could be fitted and headspaced when a barrel replacement was needed."

That could explain how the ridge got cut in the chamber. Somewhere along the line, the rifle was re-barreled, and somebody used an under-sized reamer to hog out the chamber. It was probably "close enough for Government work and now let's go to the cantina and get some cerveza!"

[GONRA]

GONRA sez - don't worry about it! !!

[Larry Gibson]

I've been forming cases using 30-06 military for the 7.65 Argentine for many years. Back when available picked up several hundred R-P 8x57s that just need sizing in 7.65 FL die and a bit of trimming. With the 8x57 and LC M72 match '06 cases I don't turn or anneal the case necks. I have annealed when formed out of M2 cases though. I also have 100+ Argentine SF 85 cases I have converted to use SR primers in.

I currently have three M91s and a M1909 rifle. They all have a bit different head space so I keep the cases separate for each and just NS. I use a Redding 308W bushing die to NS so necks give .002 - .003 neck tension. I have also thinned a 1/2" nut to slip over the case to NS using a Lee .308W collet die.

Never really found that much difference in the Headspace on Argentine Mausers. I have always found them to be as much as .010 shorter in headspace than the 7.65 Belgian Mausers. The cartridges, both Argentine and Belgian, have the same cartridge head space though. That was the problem with Lee's early 7.65 Belgian dies. They seemed to size the cases be headspaced for the Belgian chambers and were too long to chamber in many Argentine rifles. Appears Lee has corrected that.

[WRideout]

I'm with Reg on this. I make my 7.65 cases from 30-06 and 270 brass and have never turned or reamed the necks and had no chambering or other problems.

In the dark ages when my only rifle was a sporterized argy, i made cases from 30-06. i did have trouble initially with overpressure loads, but i had not acounted for the possibly thick brass reducing the internal case volume, or the certainly thick neck wall that i did not ream or thin.

Wayne

note- sorry for the grammar, but my shift key for some reason is not working.

[Texas by God]

I recently aquired my first 1891 Mauser.
I don’t have 7.65 Mauser dies yet, but long ago I shortened a 7.7 Japanese FL die so that I could load 7.65(neck size) for a 1909 Peruvian that I had at the time.
I used 30-06 brass at first, moving the shoulder of a trimmed case back until the bolt will close.
For grins, I also converted some 7x57 brass that had previously been converted from 6mm Remington brass…..
The shoulder needed to move forward a bit on these, so with 3 grs of AA#2, paper, corn cob tumbling media, and old orphan primers- I fireformed them in vertical position.
Thank You, Push Feed Mauser!
I’ll post some pics later on.


Sent from my iPhone using Tapatalkhttps://uploads.tapatalk-cdn.com/20230810/29a458c1243cdce1c539b1feb873b889.jpg
Here are the formed cases next to a surplus case.
When my proper dies arrive, I’ll just use 30-06 brass since I have quite a bit of it.

[405grain]

I really like the 7.65x53 Mauser. I built a sporting rifle with a 1908 Brazilian Mauser action and a new/old stock military barrel off a 1909 Argentine. The rifle looks kind of goofy with that 29" stepped barrel, but when it shot the first 15 rounds that I fired through it into a group that you could cover with a quarter at 50 yards I decided that this dorky looking rifle was beautiful. I like the 7.65x 53 so much that I'm planning to build a second one on a 1895 Chilean action. In the beginning I did form some cases from 30-06. I used Lake City brass and had to turn the case necks. Not long after that I chanced on a treasure trove of new Norma brass that had sat on the shelf at a Mom & Pop gun shop for so many years that they had it for sale at give away prices (I bought all they had). I won't need to be forming brass again for a while.
As a side note, I've had some really good accuracy using the Lyman #311284 powder coated and sized to .3125" I have been using a charge of 24 grains of Shooters World Buffalo Rifle (almost the same as 5744). This load has been amazing in my rifle, and shoots better than I can aim. I was wondering if anyone has tried the RCBS 30-180-FN in 7.65x53? Powder coated and sized to .3125" I'm guessing that this might be a good bullet in this caliber, but it will be a while before I can get some range time to find out. Just wanted to know if anyone's tried it?

[jdsingleshot]

Haven't shot mine enough to get to know it. I do form cases from .30-06 brass. I use a course disk sander to shorten the case almost back to the shoulder, run it through the die, then trim to length. Works well.