8 MM Mauser load question

[wallenba]

I've had a problem with my choice of mold for my K98. I'm using the Saeco #081, 190 RN. The only load data I have found for this boolit is in the Lyman 4th edition Cast bullet handbook. It gives a C.O.A.L. of 3.010". At that length the entire lube groove is exposed (which is OK), but I can't chamber it. Checking with a Hornady over all length gage, I find my maximum length is 2.963.
Using IMR 3031, I chose the minimum charge of 34 grains, max is 41 grains, a difference of 7 grains. I don't normally stray very far from published data, but I seated these deeper, down to 2.957". I reasoned that the difference in seating depth being 0.053" is much less intrusion into the case volume space than the additional 7 grains would be, that it should be OK pressure-wise.
Is my logic flawed in some way I'm not aware of?

I have a 170 grain FN RCBS mold on order, but can't find any 8MM Mauser loads for that at all.

[Ben]

So many reloaders think the the Cartridge Overall Length given in loading manuals is the " Gospel.".

WELL , IT ISN'T THE GOSPEL ! !

Different chamber reamers are used by gunsmiths and different manufacturers of center fire rifles. It isn't unusual to see differences in the COL from rifle to rifle, in the same caliber.

If you'd like to establish the correct COL for your current cast bullet and rifle combination , here is the procedure :

(1)

For safety reasons, take an empty F/L sized case ( no primer, no powder ) that chambers smoothly with no bolt closure resistance in your rifle.

(2)

Now.....seat your cast bullet out much farther than you think is needed in this " dummy round " that you are making.

(3)

Most likely this " long seated dummy round " won't chamber smoothly in your rifle.

You may now take your bullet seating die and begin turning the seating stem about a 1/4 th of a turn at a time downward and then try again to see if the bolt will close on your rifle. By trial and error continue this process checking the round in the chamber of rifle to see if the bolt will close. ( DO NOT FORCE THE BOLT CLOSED, stop and remove the dummy round if you feel ANY resistance on the bolt handle when you are trying to close the bolt )

(4)

When the bolt is just about to close, change the 1/4 turn downward to 1/8th of a turn downward on the seating stem of your bullet seating die.

(5)

When the bolt closes with little or no resistance, you have the CARTRIDGE OVERALL LENGTH for your particular rifle and your own particular cast bullet style. You now have minimum " bullet jump " into the rifling of your rifle , a condition that many cast bullet rifle shooters find desirable.

You can set this " dummy " aside for future reference when you are trying to establish the COL for your rifle and that bullet on another day . Many reloaders write or type the caliber of the rifle , the make of the weapon, The model of the weapon and the cast bullet style of the bullet along with the COL on a label and tape it to the dummy round that you have just finished making.

(6)

Any other ( different ) cast bullet style will require you to do each of the steps above a 2nd time and obviously you'd end up with a different COL for that cast bullet style.

Ben

[Skunkworks]

To further up what was written in the above reply, let me show you this:

http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Small%20Ring%20Mauser/R0011566_zps1cac2c19.jpg (http://s295.photobucket.com/user/Chickenthief/media/Skydning/Small%20Ring%20Mauser/R0011566_zps1cac2c19.jpg.html)

These two cartridges will chamber in the same rifle.
It is a Mauser chambered in 8.15x46R that has a chamber wich has no throat. It continues at neck diameter for @.6" from the original chambering.
The short cartridge is the true 8.15x46R at 46mm with a stopring boolit that has a .317" nose that stands at the rifling.
The long one (resized 30-30) at 51.85mm has a stopring boolit that is a borerider.

It shows that there is no set rule.
Some rifles might be affected by the length of the magazine before the boolit reaches the rifling.
On the other hand the Swiss Schmidt-Rubin rifles are notorius for having next to no throat, so way shorter than max cartridge length is the rule with cast.

[wallenba]

Ben, the Hornady tool checks and establishes the col. My only concern is with the pressure, and it will be higher. But how much? When they say, minimum aol, I figure there must be a reason for that. Their test rifles include a K98, And I'm aware that they differ.

[wallenba]

To further up what was written in the above reply, let me show you this:

http://i295.photobucket.com/albums/mm153/Chickenthief/Skydning/Small%20Ring%20Mauser/R0011566_zps1cac2c19.jpg (http://s295.photobucket.com/user/Chickenthief/media/Skydning/Small%20Ring%20Mauser/R0011566_zps1cac2c19.jpg.html)

These two cartridges will chamber in the same rifle.
It is a Mauser chambered in 8.15x46R that has a chamber wich has no throat. It continues at neck diameter for @.6" from the original chambering.
The short cartridge is the true 8.15x46R at 46mm with a stopring boolit that has a .317" nose that stands at the rifling.
The long one (resized 30-30) at 51.85mm has a stopring boolit that is a borerider.

It shows that there is no set rule.
Some rifles might be affected by the length of the magazine before the boolit reaches the rifling.
On the other hand the Swiss Schmidt-Rubin rifles are notorius for having next to no throat, so way shorter than max cartridge length is the rule with cast.

Cartridge length over all is my problem, I can't close the bolt on their published minimum. I have a Steyr M95 that can handle long necks, If I can get them (not). I have a 6.5 Swedish Mauser with such a long leade I can crimp them literally on the gas check if I wanted to. I routinely trim rifle brass below the minimum trim length just to make them all the same and square them up. And my K31, forget it. The gas check and lube grooves are down in the fire. Not been a problem, because the load data used has been tested.

[Maven]

wallenba, There's a simpler solution for the OAL v. IMR 3031 pressure issue: Seat the Saeco CB so that it will easily chamber in your rifle, then start with 29grs. 3031 regardless of Hornady's recommendation. I used to use 3031 with 195gr. CB's in my .30-06 (with the CB jammed into the rifling). 29grs. was a fairly stout load, but it never created excess pressure. It won't create excess pressure in the 8 x 57mm Mau. case either. (Don't ask how I know this.)

[UBER7MM]

wallenba,

The published OAL off a cartridge and what you can chamber and what will fit in your magazine will vary from gun to gun. My Lyman 48th manual states 3.250" for a maximum OAL of J-word spitzers. The ogive is the major factor. Bore riding boolit designs, would in theory, allow for more of an OAL.

Ben's method is the same way I establish OAL for a boolit/bullet for a particular chamber. Boolits can touch the rifling with the action closing without binding. (Ejecting a live round shouldn't leave the boolit in the rifling, or a mangled ogive.) I keep my dummy test rounds as gauges if I ever need to reset my dies.

Lyman's 323470 is spec'd to 160-165 grains. As far as the 170 grain FN RCBS mold, the minimum loads for the Lyman should be an acceptable starting point. Look in Lyman's manuals. Sorry, no help with IMR-3031 in the 48th edition. Older manuals tend to have a larger selection of powders.



I hope this helps,

[WILCO]

I have a 170 grain FN RCBS mold on order, but can't find any 8MM Mauser loads for that at all.

You can use the load data for the LEE #C324-175-1R that's listed on the same page in the Lymann 4th edition manual, as it's a heavier bullet than your 170gr. FN RCBS.

As for your min. O.A.L. question, I think it's a non issue.

[wallenba]

I'm confident the MINIMUM load is fine at the seated depth I had to go to (2.957). I don't feel I should try to work this load up any further. I think it's wiser to wait for my new mold which is 20 grains lighter and should be shorter. This Saeco mold had to be Beagled to get it large enough to size for my Mauser, and that created other issues as well. The bore ride is larger and could be contributing to the problem. But the real PITA is Beagling enlarged the gas check shank too. About 1 in 20 go through the lubrisizer and come out with the check crimped crooked.

[Larry Gibson]

34 gr 3031is a little stout under a 190 gr cast bullet, especially as the starting load. I suggest, based on my own loading of 190 cast in the 8x57, that you start with 25 gr as a starting load and work up to 32gr as a max load. I also suggest the use of a 1/2 -3/4 gr dacron filler with the loads.

Larry Gibson

[Prospector Howard]

Yep, Ben hits it on the head. I'm kinda new around these parts, but I've noticed he has alot of knowledge to pay attention to. The lack of choice of 8mm Mauser molds out there is a real bummer as far as I'm concerned. I didn't buy the Saeco mold because of the way it was designed. I settled on the Lee 175 gr as the least bad option (I thinks it's too light though). I've decided to make a tumble lube mold a little heavier than the 175 gr, and see if I can do better than what's available. As far as loads go for my K98, I've had good luck with 2400 powder and the Lee 175 gr. 19 gr for when the weather is hot and 20 gr for when the weather is cool. Uses much less powder and you don't need dacron filler either.
So many reloaders think the the Cartridge Overall Length given in loading manuals is the " Gospel.".

WELL , IT ISN'T THE GOSPEL ! !

Different chamber reamers are used by gunsmiths and different manufacturers of center fire rifles. It isn't unusual to see differences in the COL from rifle to rifle, in the same caliber.

If you'd like to establish the correct COL for your current cast bullet and rifle combination , here is the procedure :

(1)

For safety reasons, take an empty F/L sized case ( no primer, no powder ) that chambers smoothly with no bolt closure resistance in your rifle.

(2)

Now.....seat your cast bullet out much farther than you think is needed in this " dummy round " that you are making.

(3)

Most likely this " long seated dummy round " won't chamber smoothly in your rifle.

You may now take your bullet seating die and begin turning the seating stem about a 1/4 th of a turn at a time downward and then try again to see if the bolt will close on your rifle. By trial and error continue this process checking the round in the chamber of rifle to see if the bolt will close. ( DO NOT FORCE THE BOLT CLOSED, stop and remove the dummy round if you feel ANY resistance on the bolt handle when you are trying to close the bolt )

(4)

When the bolt is just about to close, change the 1/4 turn downward to 1/8th of a turn downward on the seating stem of your bullet seating die.

(5)

When the bolt closes with little or no resistance, you have the CARTRIDGE OVERALL LENGTH for your particular rifle and your own particular cast bullet style. You now have minimum " bullet jump " into the rifling of your rifle , a condition that many cast bullet rifle shooters find desirable.

You can set this " dummy " aside for future reference when you are trying to establish the COL for your rifle and that bullet on another day . Many reloaders write or type the caliber of the rifle , the make of the weapon, The model of the weapon and the cast bullet style of the bullet along with the COL on a label and tape it to the dummy round that you have just finished making.

(6)

Any other ( different ) cast bullet style will require you to do each of the steps above a 2nd time and obviously you'd end up with a different COL for that cast bullet style.

Ben