7mm Mauser resizing issue

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7mm Mauser resizing issue

Post by jloader »

I've started work on 7mm Mauser ammo. This is my first rifle ammo reloading experience.

Bought 100 once-fired cases, stamp says "W-W Super 7mm Mauser". Lubricated a few, setup the Lee 7mm Mauser sizing/decapping die to touch shellholder + 1/4 turn - per instructions.
Put first shell in, it goes up, up...and starts to resize the neck and comes to a stop about 0.150" into the neck.
You can see the big compression mark but it would not go any further. My bench bends and poor C-frame press will not go any further.
Mauser-11.jpg
Mauser-12.jpg
You can see that the decap pin fits into the unsized case but will not fit into the partially resized neck.
Tried with the decapping pin removed - stops at the same spot.

The resized portion of the neck is .307 (outside diameter).
The neck size prior to resizing is .324
According to Lyman the case neck at this spot is supposed to be .3207
I have a case of brand new factory ammo and that has neck size of ... .312

What am I doing wrong?
Is it possible that the brass I have is a bit thicker? It is .015". Nope, (outside dia - bullet size) / 2 is (.3207-.284)/2 = .018
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Re: 7mm Mauser resizing issue

Post by Ranch Dog »

Hmmm...

Just my observation, but the cases seem mighty dirty. For testing, why don't you clean a couple with mineral spirits and then lube them? What lube are you using and are you getting some into the neck?

What is the diameter of the neck at the shoulder? That portion of the case looks a bit fat to me, like the rifle that shot these might have a bit of wear. The SAAMI spec at this point is .3243" +.002".

This might be something that Lee is going to need to solve.

As a note, now that SAAMI has allowed public access to their cartridge & chamber drawings, I use them rather than those in the reloading manuals. Much more information. I've downloaded and printed them out for all the cartridges that I reload. Just google SAAMI along with the name of the cartridge. I've attached the pdf for the 7mm Mauser.
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Re: 7mm Mauser resizing issue

Post by jloader »

Diameter at the base of the neck is .328
I used silicon lube, finger spread on case and put some inside the neck with q-tip.
Just sent a note to Lee...
Cannot speak for the rifle it was shot in as I bought these cases online.
I tried to put one of those in my rifle and the neck does not enter all the way so you may be onto something here...
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Re: 7mm Mauser resizing issue

Post by mikld »

Measure! Measure the necks of an unsized case. Compare that measurement to a SAAMI drawing of a 7mm Mauser chamber. Normally is would just be a few thousandths under chamber size. Sounds like you may have bad brass...
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Re: 7mm Mauser resizing issue

Post by Ranch Dog »

I'm glad that those cases are not from your rifle. Look like whatever shot them has a very eroded throat. Can you get a bag of new cases locally?

I've gotten to where I buy Priv Partizan brass if I need it. It is better priced than others, and it is properly annealed. Graf & Sons carries a pretty good supply of it, and they have flat rate shipping; $7.95 an order.
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Re: 7mm Mauser resizing issue

Post by jloader »

Just got a reply from Lee and it's quite comprehensive:

Make sure that you are using a good case resizing lube. I recommend Lee Resizing Lube. Lubricate the out side of the case from just above the case rim to the shoulder of the case. The case shoulder and the outside of the neck need not be lubricated. The inside of the case neck must be lubricated.

When a properly lubricated case is full length sized in a full length sizing die the first 3/4 of the case will enter the die without resistance. After this point resistance begins to build and depending upon the fired dimensions of the case it will take considerable pressure on the press lever to size the case. The case will not have been fully resized until the shell holder makes firm and complete contact with the bottom of the die. If the once fired cases that you have were last fired in a military firearm the fired dimensions of the cases may be larger than normal. Military chambers are purposely bigger to ensure positive chambering of the cartridge in adverse conditions (battle). This results in larger fired dimensions and this makes the case harder to resize.

When the case neck of the case enters the neck area of the sizing die the neck is purposely under sized by the die. Then as the case is pulled from the die the case neck is pulled over the expander on the decapping rod. This opens the inside diameter of the case neck to the proper diameter to seat the bullet. This is a high friction process and is the reason that the inside of the case neck must be lubricated prior to sizing.

If you have the Lee Reloader Press p/n 90045 this press is a little light for sizing rifle cases. I would recommend that you get a Lee Breech Lock challenger or larger press. You will also need to stiffen up your reloading bench.


Soooo...
These cases definitely look more massive than the few new ones that I have so these are most likely military grade/military fired. I purchased a factory box of ammo but this being nearly 100 year old rifle, I don't want to shoot fool factory loads. I could reuse the powder but put only 90% of the original load - that should generally take me from Max to Starting, even not knowing what powder that actually is.

I will take apart a couple of these factory bullets and see how they go thru the dies and will load them with lower charge and lead cast bullet.

I'm going to start by getting shell plate holder for my LoadMaster and Lee case lube and see how that will work - I'd hate to throw away 100 cases, seems to be a better financial decision to get the Lee parts and try on LM.
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Re: 7mm Mauser resizing issue

Post by Ranch Dog »

Yeah, the Load-Master would do it. A shell plate is cheaper than buying the Breech Lock Challenger.
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Re: 7mm Mauser resizing issue

Post by jloader »

This problem is solved!!! On to the next problem.
+guns +guns
So, I got the LoadMaster shellplate, applied the silicone lube, put the shell up into the die... presses... pressed... STOP.
In the same place the ram stops, maybe 1/8 further than on the C-frame press.
So I back it off... try it again... RIP - tore the base of the case!!!
This was followed by a bunch of cuss words... several minutes of removing stuck case from a die... got quite intimate with the die and case and sealed my relationship with those two with my own blood, literally - that brass can be very sharp.

Then I decided to use Lee Case Lube that I bought together with the shellplate (cue the happy music here ...)
The darn thing did the trick!
Went thru 100 cases without any issue using Lee Case Lube.

Lesson learned.

Next issue is loading cast bullets with gas checks into these cases (charged, of course).
I ended up crunching, loading the bullets at angles... and throwing more cuss words...
I cannot figure this out? There is no flaring die so the bullet with copper gas check does not enter the mouth of the case and with pressure applied it is a crap-shoot. The bullet did not want to go in smoothly - it got crushed top, then once there was enough pressure it 'jumped' in at whatever angle it felt like, even leaving a lead beard and bulge on the outside of the case (see pic).
Mauser-13.jpg
Need your advise oh great ones... how to insert the gas checked cast bullets into the cases?

I put the gas checks thru sizer lead first, copper check at the bottom. I've read somewhere some suggesting feeding the bullet into the sizer gas check first (upside down).
Any suggestions?

I actually may have it figured out...
So the cases were originally heavily crimped. Even after resizing, there was a small inward lip on the edge of the neck. That is where the gas check was sitting on without being able to go into the neck. Once I exerted enough pressure, the copper gas check 'jumped' into the neck over that lip/crimp remnant.
So, I took the case back to case prep station and used the inside chamfering bit to smooth it out a bit.
It worked! Now the bullet will enter the case just a tad and stay upright as it is driven into the die. Did 5 or 6 of them with great success.

I think that the original bullets had a deeeep crimp. The cases are a bit on a long side so I could trim them quite a bit removing the original crimp.

And this is why I LOVE reloading - seemingly such a simple process, but so many things need to play together well. Lots of trial and error, corrections, reading, researching trying again. Makes you feel really good when you get it right.
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Last edited by jloader on 16 May 2017 07:08, edited 4 times in total.
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Re: 7mm Mauser resizing issue

Post by akuser47 »

Good to here, glad you will be able to use them. Just be cautious and watch your case necks after you put your bullets in. Be sure to inpect brass to be safe. You never know with surplus or old brass.
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Re: 7mm Mauser resizing issue

Post by jloader »

Thanks for the inspection suggestion. Once I gave them a good cleaning (ultrasonic bath and walnut turmbler) I was able to clearly see the metal. They do look, feel and sound solid. I will be using only light loads in them, considering it is for a 100 year old rifle.
If all goes well I'll shoot some rounds this weekend on the newly restored 1916 Mauser.
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