pressure signs progression chart

One thing to note is that peak pressure occurs just after the bullet has started traveling down the barrel.

  • Handgun cartridges, peak pressure is typically before the bullet has traveled 1/8" to 1/4", magnum a little farther.

  • Typical bottleneck rifle cartridges, 1" to 2"

  • Overbore magnum cartridges, 2" to 4"
So there are MANY factors in the relationship between peak pressure and velocity.
 
Stubble, your observations and experience parallel mine in many ways.
I have a 308 Norma Mag that was built two winters ago by Bill Leeper.
This rifle reaches "expected" max velocities with anywhere from 3-5 grains less powder than is listed as a max in any manual I have.
I know it has a "snug" chamber, due to sizing issues with brass previously fired in another rifle.
It also sports a 26" Custom barrel and that may be a factor, as you observed.
But it would be a bit of a surprise if someone not as cautious as they should be, choosing a max listed load and trying it.
I'm betting the bolt would be plenty tough to open, lol.
I played with the STW quite a bit.
Had one that you could not get enough of one of the recommended powders in to reach proper velocities.
It never did show any signs of pressure.
Another one topped out at 3 grains less than max load listed.
I have a 7mm RUM right now that would be trouble if one loaded a recommended max load of Retumbo behind the 160 and fired it.
The list goes on...so many variables.
A person really needs to be observant so as not to get into trouble.
FWIW, On new brass, I allow up to .0009" expansion of the web area on the initial firing. Any subsequent expansion is taboo, in my books.
Regards, Eagleye.
 
caramel said:
You might have no signs at all but a slight resistance on the extraction, in my book this is the most important sign... JP.
Click to expand...

Some friends and I were out shooting today and couldn't even open the bolt on one rifle . It took about 20 min of yanking on the bolt to get it open.
 
If you see any of these it is a problem (great photo about halfway down the page). .

Absence of these obvious signs does NOT nessecarily mean you are OK, as many have posted, so use your judgment in addition to these warning signs.

h ttp://www.6mmbr.com/laddertest.html
 
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