Home Forums Hunting & Shooting Long Range Hunting 7mm Mashburn VS the 7mm Weatherby

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"We're on a mission from Gawd!"....

Can we dance wif yo' dates??........ooops, sorry, wrong Belushi flick.......

I did a little research overnight and thought the crowd might be interested. My oldest loading books are a 1978 Speer and a 1979 Hornady. Both show the 7 Rem max load with a 175 at about 2850. Both show the max loads for the 7 MM Roy at about 2900 with the 175. The slowest powders listed were Norma MRP and H870.

Fast forward to my last Hornady book and the 7 Roy max load show 3100 with Retumbo or RL-25.

Over the intervening years we had slower powders become available and also better pressure equipment. Did either or both of those affect the manual publishers willingness to raise the Roy pressure/velocity?

This relates to the Mashburn issue in that Prof. Page achieved 3050 from his H4831/175 gr. load and I believe that current published Roy loads make safe max loads in the Mashburn. From what I can tell neither the Mashburn nor Roy seem to suffer from the occasional erratic pressure problems that plague the 7 Rem.

I've read the theory about rough throats causing erratic pressure spikes. Why does this seem to be more of a 7mm RM problem than a 7mm Wby or Mashburn problem? Don't the latter two expose their throats to very similar heat and metal erosion?

This sounds like a specific case geometry phenomenon, not fully understood or explained.

DF

There is a cart. called a 7 MM Hart which is a 7 Rem AI that the Hart barrel people shoot. They seem to not experience pressure spikes with it either. I am with you on the geometry guess.

Doc,

I agree with your assessment and the question(s) you raise. It definitely hasn't been answered to my satisfaction and I shoot a 7mm Rem Mag. With all the high tech ballistic technology out there, you would think someone would figure this out.

DF

I have been shooting 7 Mags since 1978, have about 4 currently, all rem 700's. These pressure spikes must certainly happen with Winchesters, not Remingtons! Hee Hee!

Another thought. If these pressure spikes are seen in the ballistics labs where the test barrel is shot a bunch, I wonder if other 7mm's, like the Wby. and the Mashburn, see the number of rounds that the more common 7mm Rem Mag sees? And the same thing with the .243 Win, reportedly another round prone to pressure spikes. Do they shoot their 6mm Rem. barrels an equal number of rounds?

DF