91 Mauser chambering problem

After reforming a bunch of 30-06 brass, I loaded up and went to my club to fire-form the cases for my 7.65 Mauser.
Closing the bolt was tight but extracting the empty was easy. Empty cases chambered easily, but after full length sizing
it was again an effort to close the bolt [on the same empty case]
Case length was fine after sizing, so the question is: are the chamber dimensions different on a 91 compared with an 09 which Lyman
probably made their dies for ?
I've checked Olsen's book and everything else that I have but I can't find any info.
I guess the obvious answer is to neck size only in future, but it's an interesting mystery.

You have described the symptoms of a full-length sizer not adjusted to compensate for press flex, leaving a visible gap between die and shell holder when actually sizing a case. While this may not be the source of your problem, it's a very common error.

https://www.milsurps.com/images/impo...espring2-1.jpg

This condition displaces the shoulder forward as the die reduces body diameter. The result is insufficient "headspace" - the sized case's head-shoulder dimension is now greater than the space available in the chamber.

Most die makers are careful to warn about this in their instructions -

• RCBS - When setting up the full length sizer die, screw the die down until it touches the shell holder at the top of the press stroke. Then lower the shell holder and screw the die down about 1/8 to 1/4 turn. You will feel a slight thump as the leverage system cams over center. Size the case and again check it in the chamber. Size a couple more cases and check in the chamber. If these cases chamber, go ahead and size and load the rest of the cases.
• Lee - When using our full length sizing dies for rifle cartridges, the die should be turned in to touch the shell holder and then enough more that there is no daylight between the top of the shell holder and the bottom of the die during the sizing process. This is the preferred method because the act of sizing sometimes results in flex that prevents the shell holder from touching the bottom of the die. . . If you note that your Lee Die doesn't appear to push the shoulder of your case back, ensure that you are adjusting the die so that there is no daylight between the top of the shell holder and the bottom of the die during the sizing process. If you see daylight at the top of the stroke, readjust the die downward and repeat sizing until it disappears.

Many handloaders apparently miss the part about the added adjustment, stop when they merely have contact under a no-load condition, and never bother to check for contact during sizing. While this often works OK for rifles with generous chambers, it isn't good enough for those with precise workmanship and tight tolerances.

My woods "carry" rifle is a very light, very short 91 Mauser sporter with peep sights. It has a super short barrel, Timney trigger, and Williams sights on a drawfiled barrel. It is very accurate with 130 spitzers. We call her "Master Blaster".

The 7.65 round can be handloaded to a wide variety of circumstances. One can make those 130 grainers rock and roll. My 12 year old grandson loves it.

I use Norma 7.65 cases, but 30-06 brass can easily be adapted as you know. It is a fun little rifle to shoot, and the 7.65 is one of my favorite rounds. I also have an Engineer's Carbine, but it stays in the safe. Good luck with yoursm as I think the advice you have been given will solve your problem.

Jim

I wish you were right Parashooter, then the problem would be solved.
However, my die is set correctly and is camming over.
I've been reloading for 30 years, so I'm pretty good at it, but the results you describe from a badly set die seem to fit pretty well even though, as I said, my die is set correctly.
I'm going to have to fire form all my cases again and then neck size only.

Sounds like a tack driver you've got there Jim. You're bringing the boy up right.

Thanks all.

Sounds like you may have a tight chamber. I know of no difference between 7.65 mm round dimensions from year to year or model to model.

How does the rifle handle military or commercial 7.65 rounds?

Jim

Get a PrecisionMic headspace gauge from RCBS and compare the as-fired headspace vs the as-resized headpace. Then you have the info for some follow-on decisions.
Real Guns

Depending on what you find, realize that even necksizing-only results in gradual lengthening of the case -- especially with a conventional reloading die. So after you find out how much you need to "bump" the as-resized headspace down, consider machining/belt sanding the shellholder face down a few thousands to compensate**
-- OR --
Get a Redding shellholder set that compensates for any number of out-of-spec conditions
shellholders.html

**(Make sure you tag it/keep it separate)

If the die is adjusted for full shellholder contact under load but the sized cases still won't chamber easily, you have several choices of remedy -

1. Return the die and several fired cases to the manufacturer for replacement or re-working. Most will not charge for this unless the fired cases show that the chamber is grossly out of spec.
2. Face off the mouth of the sizer die enough so it sizes sufficiently to fit your chamber.
3. Face off the top of a spare shellholder until sized cases fit. Mark this shellholder distinctively and reserve for use with this rifle. (I believe it's better to remove stock from a cartridge-specific sizer die than from a shellholder that could be used in error for another cartridge of the same head configuration.)
4. Ream the chamber deeper.

Before trying any of these remedies, check to see if new 7.65 cases or factory ammo will chamber easily. If they do, you have a handloading problem. If not, you have a rifle problem and you'll need headspace gauges and a 7.65 Mauser chamber reamer to correct it precisely.

The RCBS "Precision Mic" does not appear to be offered in 7.65 Mauser. With a good caliper and an empty 9mm pistol case, you can perform relative measurements of head-shoulder dimension to compare fired and sized cases - and at significantly less cost. This will enable you to determine how much, if any, adjustment is required for your sizer or shellholder.

https://www.milsurps.com/images/impo...mmcasega-1.jpg

The Redding competition shellholder set is a series of incrementally thicker shellholders. They will not be useful if what you need is a thinner one.

I like it. :)

I like it.** :)

Actually, the Redding Competition shellholders have a constant thickness, but the case-head relief cut in the base gets deeper by 0.002" for each size. They start off ~0.002" deeper than a "standard" shellholder and end up 0.010" deeper by the fifth shellholder. (I went down and measured my `06 Redding holders just now.) Ordinarily this allows you to precisely adjust a "minimum headpace" FL resizing die all the way up & down from GO to NO-GO to fit a particular chamber.

But with an FL die which *appears* already to be too long for the chamber, you are correct. That wouldn't work. `Ya then need to remove a few thousands from the shellholder surface until things chamber, then paint the shellholder some gawdawful color (`ceptin' top & bottom sufaces).

BREAK BREAK.....

While searching around, I came across this citation:
> You may have a problem with your "7.65 BM" dies. I've found over the
> years that the Belgian Mauser has about .01" more headspace than
> the 7.65 Argentine. Thus many 7.65 Belgian dies will not size (set back
> the shoulder) enough for cases to chamber in many M91 Argentines.
> If you run into this problem you can take a small amount off the bottom
> of the FL die so the sized cases will chamber. If you have a stone
> point (Hornady now) cartridge headsapce gauge you can easily measure
> the difference between a fired case and a formed case and shorten
> the die that much.
>
> Another option is the Lee 7.65 Argentine dies, they are made correctly
> now for the Argentines.
Argentine Mauser followed me home, now what? - Cast Boolits

Does this sound familiar ? :beerchug:

After much frustration and head scratching, I think I've figured it out.
I noticed that a few cases would chamber easily, some were tight, and many would not chamber at all.
It finaly dawned on me to check head stamps. The Lake City brass, of which
I have only about 12 chambered easily. The Remington, of which I have 100 formed + 50 unformed is the sticky stuff.
It's that damn Murphy again.

Great info from you guys. Thanks.
Anybody want 50 Rem once fired 30-06 for postage

You're sure that you don't have Belgian (vice Argentine) Mauser dies? I can't think of any reason that different headstamp brass should put you that far out of spec so as to be completely out of headspace-forming range.

I don't know the answer to that. My Arg dies are Lyman. I always assumed that all the 7.65s would be the same. What reason would Mauser have to alter things
and make their supplying of ammo problematic ? They supplied Belgium, Turkey Spain and many South American countries with at least their initial ammo supply.
As for Remington brass, I do know that many people don't like it too much, for various reasons. I choose Winchester when there's a choice.

You can correct similar sizing problems by running the brass though the zier then rectracting enough to spin it 180° and resize again very slowly.
This type of problem is influenced by the amount of lube on the brass, how fast you size it, the temper of the brass and the size of the previous chamber the brass was fired in.

There's one more indication that the problem is press flex and a need to screw the sizer down a bit more to compensate. Different makes (and lots) of brass have different mass and temper. It appears your Remington cases are somewhat more resistant to sizing than your LC. As a result, the press and sizer are probably flexing more with the stiffer cases and not receiving the same degree of reduction in head/shoulder length.

Before you decide to scrap those cases, try sizing them again after screwing the die down about 1/8 turn (.009") beyond where you had it set before. Then see how they chamber. You might be pleasantly surprised.

There is no sense in tossing any brass. Just size it until it works.

I will comments that the 7.65 Mauser has the most messed up set of sizing die standards on the market.
I have 4 brands of dies for the caliber and only one sizer the RCBS is correct.
I ran into a rusty orphan RCBS sizer at a guns show and it too is correct.
Most of the other dies give grossly excessive headspace in the rifles that I own.

I checked my handloaded ammo, Norma factory and Prvi Partizan against a L E Wilson case gauge and they all agree with the case gauge.
None of the cases sized in the non-RCBS sizer dies matched up to the Wilson gauge.

Maybe I should start a collection of case defects.
I have some cases of almost every brand that have horrible birth defects.
I have one case that has a big fault line running down the inside that is not visible on the outside. It is only noticeable because it is a straight wall rifle case that you can see into.

Well, tomorrow is my shooting day {Wed] so when I'm done I'll have 50 or so cases to experiment with. I'll try a little more cam on the die, turning 180 etc.
However, if ireload is correct about the dies all being out of whack except the RCBS - well, we'll see. I'll probably end up just neck sizing + my 311 M die.
I've noticed one thing - extra hard bolt closing does not help accuracy.
I'll be back

Turning the die 180 degrees (1/2 turn) would probably be way too much. With the 14 TPI thread, that much rotation would lower the die 1"/14/2=.036" - far more than typical press flex. Somewhere around 1/8 to 1/4 (.009"-.017") turn beyond no-load contact is usually enough.

Forget about the "cam over" advice. It's much too subjective and doesn't apply to all press designs (some stop at TDC with no "camming" action). Just be sure to look where the die meets the shellholder. If there's a gap, you aren't using the sizer fully. Holding white paper on the far side can help visibility.

https://www.milsurps.com/images/impo...espring2-1.jpg

I think Ireland2 meant turn the case (not the die) a 1/2-turn and run it up again for a repeat sizing step. That might help just from the double-tap invoked.

I would, however, use the calipers/.38 case measurement technique shown by Matt in an earlier post, to check the *relative* headspace of your resized cases. I just tried it out tonight w/ a half-dozen fired 30-06 cases as compared to an RCBS Precision Mic and the (relative) results were dead-on within a thousandth.

As I said before, "neat idea."

>>>use the calipers/.38 case measurement technique shown by Matt in an earlier post,<<<
It is an excellent idea especially since it can be a free tool.
I use the Stoney point tool that works the same way but I had to pay for mine.
The 9mm case should be excellent especially when comparing a sized case to a well fomed case fired in the same rifle.