8mm Mauser seating depth

[Worn_Holster]

I bought some 8mm 175gr RN GC from Bill Benny of Burnham, PA who advertises cast bullets on Gunbroker sometimes. I would like to know an overall case length to which I should seat this bullet. I am loading the Harris load of 17gr 2400 into new 8mm Mauser Winchester cases for my 41 Obendorf RC K98 Mauser.

[HangFireW8]

It gets down to three things:

1. What feeds (if you care about feeding from the magazine)
2. What fits (in the chamber, also known as Boolit Jam Length),
3. What shoots best.

Seating to just touch the rifling often shoots best, or at least well, but that may have nothing to do with whether it feeds from the magazine or not.

You may find some who won't seat a GC boolit deeper than the neck. On the 8mm Mauser that is a severly limiting proposition! I don't use the old slip-on gas checks, I use the modern crimp-on kind, crimp them on well, and don't worry about it.

HF

[Hardcast416taylor]

As a rule of thumb, don`t seat them any deeper into the case than the base of the neck. You can seat them out as far as is possible since I doubt you will come near the rifling with the bullet nose for engraving.Robert

[462]

With my K98k, I seat the boolit to touch the rifling. I single-round load, so overall length is not a concern.

If you have some Unique, give it a try, too.

[Wolfer]

My Turk seem to work just fine with the base at the bottom of the neck or crimped in the crimp groove or ran out as far as it will chamber. I seat to bottom of the neck just because I think that's proper but in reality 17 grs 2400 behind the lee 175 gr seems to work no matter where it's at.

[UBER7MM]

OAL depends on your gun's throat and the ogive of the projectile in question. Magazines are also a consideration, however, 98 Mauser are pretty long so it probably isn't going to be a problem for a 8x57 cartridge. They were designed to hold long sharp spitzer bullets.

I like to have my boolits touch the rifling, and my "J" words backed off 30 thousandths. To do this I make a dummy cartridge without a crimp starting the OAL too long. Then I attempt gently close the bolt to chamber the round in the bolt action. If the bolt won't close, move the seatjng plug down a 1/4 turn and re-seat the boolit in the dummy cartridge. Then attempt to chamber again. Repeat this step until you can close the bolt on the dummy cartridge. To complete the seating die set up, adjust the crimp on your seating die to your liking. Then re-adjust the seating plug with the dummy cartridge in the die as a template. Your done. I save the dummy as templates for quicker retooling.

I hope this helps.

Uber7mm

[largom]

OAL depends on your gun's throat and the ogive of the projectile in question. Magazines are also a consideration, however, 98 Mauser are pretty long so it probably isn't going to be a problem for a 8x57 cartridge. They were designed to hold long sharp spitzer bullets.

I like to have my boolits touch the rifling, and my "J" words backed off 30 thousandths. To do this I make a dummy cartridge without a crimp starting the OAL too long. Then I attempt gently close the bolt to chamber the round in the bolt action. If the bolt won't close, move the seatjng plug down a 1/4 turn and re-seat the boolit in the dummy cartridge. Then attempt to chamber again. Repeat this step until you can close the bolt on the dummy cartridge. To complete the seating die set up, adjust the crimp on your seating die to your liking. Then re-adjust the seating plug with the dummy cartridge in the die as a template. Your done. I save the dummy as templates for quicker retooling.

I hope this helps.

Uber7mm


+1 Your throat and ogive diameter will probably be the determining factor. I highly suggest you slug your throat and buy or cast boolits to fit.


Larry

[runfiverun]

i get them out as far as i can.
whether that's determined by the magazine or the throat....
if it chambers and dechambers without pulling the boolit also changes things.

[adrians]

make a dummy round with empty brass , hand seat your boolit of choice ,carefully put it on the follower and close the bolt to finish seating the boolit , again carefully open the bolt ( so boolit won't stick in the throat ) ,take the seated round out measure and go from there.
milsurp rifles are all very differant so i do this with every 8mm i have and all seat at differant lenghts. :evil::coffee::twisted:

[Worn_Holster]

I shot my Harris loads on Friday and the 17gr loads of 2400 burned clean and were pleasantly accurate for the windy day that is was. I seated the boolits so the crimping groove on the boolit matched the crimp on the case, which was not as far out as the boolits could have been seated. The cartridges fed just fine. They grouped about 1 1/2 to 2 inches at 100 yds with a few shots touching each other. The trigger on the old Mauser is nothing to write home about either, so I'm sure there is room for improvement.