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ffwd

ffwd

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First ever locked bolt. Had to hit it with something to get it out. Then the primer fell out. Chose not to fire the other 2 with the same powder charge. 70 gr. H4831 with a Matrix Ballistics 175 gr. bonded bullet. I may have measured the powder wrong as 69.7 gr. had no noticeable over pressure signs.
 
Seems like a hot load to begin with, perhaps the bullet slipped forward due to recoil ( if it was in the magazine ) a bit too deep or the neck was a bit thicker to push the pressure way above the other load.
 
Hogdon does recommend 67.5 not 69.7gr. as max.
What manual did you get that data from?
2.2 grains is a hell of a difference in a magnum class cartridge.

The evidence on that case, is not from a minor change in pressure, (3 tenths as you suggest) it's a major one. A big pressure jump.
Be sure you were looking at the right cartridge in the manual.
 
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Yeah, I started my load work up at 68.5 gr. as My best load was 70.3 with 168 gr bullets.

From 68.5 to 69.7 there were NO pressure signs.

Wait....are you telling me everyone takes the numbers in the manuals as gospel?
 
ffwd said:
Yeah, I started my load work up at 68.5 gr. as My best load was 70.3 with 168 gr bullets.

From 68.5 to 69.7 there were NO pressure signs.

Wait....are you telling me everyone takes the numbers in the manuals as gospel?
Click to expand...

I think you made a measuring error. It takes more than 0.3 grain increase to do that to a case.

Sometimes there's room to go with a higher max load than a manual recommends, but starting above the maximum and working up even higher isn't exactly the recommended way to develop a load.
 
I've seen this happen in other rifles. You are going along, pushing the edge of the envelope, nothing is happening and then everything is happening. You don't always get a gradual warning curve. Another thing to watch out for in Weatherby cartridges in particular, is when the data was written, and how much freebore your particular rifle has. Wby has changed that spec at least 3 times that I know of, and some custom makers have changed it even more. More freebore means you get away with larger powder charges before bad things start to happen. FWIW - dan
 
65,000 psi is just right, 70,000 is too much. Once you cross the threshold, funny things start to happen in a hurry. If you're pushing the envelope, you really need to keep a close eye on everything. Some things can be done safely, others you can get away with for a long time, until Kaboom. Somethings will just KB right off the bat, but just because something doesn't blow you up, doesn't necessarily make it safe either.
My biggest fudge up, was making some 45 acp rounds with 2grs too much powder, fortunately I caught my mistake before I put those grenades in my gun. Quickload told me those rounds were roughly 50,000 psi, in a round designed for 26,000.
 
At least it extracted when you opened it with a hammer, much better than ripping off part of the rim. What is the small circle from? I know nothing about weatherbys....
 
Well, I pulled the bullets out of the other two cartridges and verified what I thought was the problem. I had worked my way up the balance beam, to 69.7 gr. And then moved the ball bearing into the 70 gr. location, failing to reset the slider to 0. Then I measured out "70" gr. Which was actually 80 gr. When I took the cartridges out of the box, I should have noticed that I could hear no powder in them, as 80 gr. In a 7 mm Magnum cartridge is a compressed load.

I will be more careful. That was about the 400th cartridge I had loaded, first big mistake, lucky I didn't get hurt.
 
What velocity?

That was a big Oooops, good to see there was no permanent damage.
Just out of curiosity how fast was that 175 gr. bullet going with that extra 10 grains of powder. I don't have the "load from a disk" or any other programs to predict velocities. If anyone out there has the resources could you plug in the data and guess the final velocity?

270 totheend
 
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