7mm Mauser pressure signs
Marcus Sgro
In the Hogdon rifle reloading manual, it says words to the effect of:
"older military rounds which have been tradtionally underloaded, like
the 7X57 Mauser, a maximum load has been reached when the extractor
groove expands by 0.002 inches", whereas modern rounds can have up to
0.005 inches of expansion prior to calling it quits.
I can understand if the rifle is a Golden Member of the Spanish Army
Veterans Association, but in a modern action? Especially when they
make no similar recommendation about the .257 Roberts?
I asked around about this, and the reason I was given was that the
7mm's case design is not capable of taking high levels of pressure
since it was an early mauser design.
Anyway, I'm curious if anyone has any ideas on what's behind this
story. I don't see any point in pushing maximum loads in this round,
but I'm still curious about this.
Thanks!
Thanks!
-------------------------------------------------------------------
Learn about rec.guns at http://doubletap.cs.umd.edu/rec.guns
Ken Marsh
Marcus Sgro <sg...@gwu.edu> wrote:
#In the Hogdon rifle reloading manual, it says words to the effect of:
#"older military rounds which have been tradtionally underloaded, like
#the 7X57 Mauser, a maximum load has been reached when the extractor
#groove expands by 0.002 inches", whereas modern rounds can have up to
#0.005 inches of expansion prior to calling it quits.
Case head expansion is a relative measure of pressure, assuming one uses
new cases and has good measuring technique. You can't set a pressure
value on a measurement, though. The only thing you can do is measure
several of one load, several of another, and say that one is a higher
(or longer sustained pressure) than the other.
#I can understand if the rifle is a Golden Member of the Spanish Army
#Veterans Association, but in a modern action? Especially when they
#make no similar recommendation about the .257 Roberts?
Some do make a similar recommendation about the 257 Roberts. The
existance of '93 Mausers for both cartridges, plus the historical oddity
of the Roberts artificially low pressure standard, coupled with the
reluctance of manufacturers to make modern loads for these cartridges,
mean only handloaders and Europeans get decent performance out of these
excellent cartridges.
Only Hornady seems willing to push the envelope, but even then not
too much. The 7mm-08 Light Magnum loads are slightly faster
than the Eurospec 7x57 loads. I can understand them not loading 7x57
to 7mm08 levels, but it should handily beat the 7mm-08 if loaded
to .30-06 pressures, which apparently it is not.
Look at Sierra's loads for the 7x57 to see what .30-06 pressure
performance in a handloaded 7x57 is like.
#I asked around about this, and the reason I was given was that the
#7mm's case design is not capable of taking high levels of pressure
#since it was an early mauser design.
If you are reloading 109 year old cases, maybe. There is nothing wrong
at all with modern US made 7x57 cases. Cut a few open with a dremel
and see for yourself.
#Anyway, I'm curious if anyone has any ideas on what's behind this
#story. I don't see any point in pushing maximum loads in this round,
#but I'm still curious about this.
What is behind this is, SAAMI has a low pressure spec for the 7x57
and Hogdgon is not about to go over it. Sierra and Nosler will.
That's all.
You can make up your own mind. I would go by the strength of my action
and brass. For example, '93 Mauser use lowest loads, '98 something more,
a Rem M700 Classic, any reputable load, worked-up in all cases, of
course.
Ken.
--
-------------------------------------------------------------------------
Don't call your civil war | Mail: kmarsh at charm dot net
our War on Terrorism. | WWW: http://www.charm.net/~kmarsh
-------------------------------------------------------------------------
Bterr
expansion, etc.) often do not appear until a load is about 10,000 psi. OVER the
maximum average chamber pressure for a cartridge. Therefore, it is very unwise
to ever exceed the lowest maximum load listed for a cartridge in any loading
manual.
FBC3
Not sure what's meant by "extractor groove." The great Ken Waters mikes the
pressure ring (the case OD just above the web) of a fired factory round. He
then compares this to the same area on a fired handload. He tends to allow up
to .0010 greater expansion with a handload; more than that may indicate
excessive pressure. See his "Pet Loads" for details. F.B., Denver
Thomas Vincent
I just finished setting back the barrel on a Spanish 7 x 57mm Mauser. I
have seen several soft receivers of this model. After carefully looking at
the receiver, I noticed that, this is the third time. The receiver
apparently was not properly case hardened. The bolt lugs, were pounding on
the receiver locking lugs, creating excessive headspace. You way want to
use a file on the bottom of the receiver, to see how head the receiver is.
If you have a good case hard receiver, no problem.
Tom
"Marcus Sgro" <sg...@gwu.edu> wrote in message
news:abqohq$ei5$1...@grapevine.wam.umd.edu...
> ...
Donald Merritt
I have been loading the 7mm Mauser for over 40 years.
Most of the "cautions" about reloading this round revolve around loading
for earlier and older Model 95 mauser, you know, the ones with only the
two front locking lugs and no rear locking lugs.
I don't have my load tables handy, but I got very satisfactory results
with really good velocities with 150 grain speer bullets with a
sporterized (me and a gunsmith friend did it ove 25 years ago) persian
carbine. Groups were within 3 inches at 150 yards and I used it with
iron Redfield Receiv er sights on pigs.
Sincerely
Don Merritt
Marcus Sgro wrote:
> ...
--
Donald Merritt
--
dmerit at quiknet dot com
(replace 'at' with @ and 'dot' with . to send me mail)