Home Forums Hunting & Shooting Hunter's Campfire Reloading... Reading pressure signs

The same phemenon can be observed when swithing from cup and core spitzer boat tails to the Nosler Partition if using the same powder charge


The partition yields higher pressures coupled with higher velocities.

Increased bearing surface of a bullet will tend to do that.

That's not an absolute. Generally speaking, load manuals list loads at a given, industry standard pressure.

Power Pistol is only two positions below Unique on the powder burn rate chart. Yet Power Pistol gives quite a bit more velocity that can be achieved with Unique in many handgun chamberings despite the fact that they're very close in burn rate.

When the seems upset and says "everything's fine" when asked.

Absolutely correct. But according to your criteria. It is still not a guage, as you have no idea what pressure was required to expand the primer pockets of this particular piece of brass.

Proper use of a Chrony could have warned of excessive pressure/velocity, before you ruined your brass.

And yes, I have ruined my share of brass. I have managed, while experimenting, to expand brass enough that it would not fit into the shell holder on my press.

Wife

Burn rates change, and even trade places depending on chamber pressure.

While a powder A might be 1% slower than powder B at 18,000 PSI. The difference might be much more significant at 25,000 PSI.

I'd keep adding more powder until the correct brass headstamp showed-up on the bolt face.

In and of itself, then no.

But the implicit assumption is an appropriate powder is being used. If I'm using 4064 in that example and I'm getting higher velocities than other sources show for similar charge weights and barrel lengths, then it's a good bet I have higher pressures and not one of those magical "fast barrels" we sometimes hear about.

Burn rate, powder charge, case capacity, chamber geometry, bullet geometry, bullet mass, etc drive pressure. Propellant gas force, friction, and barrel length drive muzzle velocity.

Muzzle velocity is very highly correlated with peak pressure for any given powder, and so can be an excellent indicator.

As mentioned, I swelled the primer pockets out of some .243 brass using a load that was listed as below maximum. I didn't check velocity. But I doubt if the velocity was excessive. The pressure in the cartridge was high because the long bearing surface of that particular bullet was creating much higher than typical drag as it passed down the barrel.

That excessive drag could very well have caused velocities to be lower even though it pushed pressures higher.

Chronographs don't measure pressure.

That's it.

That's all.

LOL... ya got me.

Worked with a guy in the mid 80's who took a 25-06 Ruger 77V tanger & a 308 77R tanger to the shooting bench for a sight in session. Him & the son were arguing....as usual, not paying attention, he fired a 308 round out of the 25-06. I saw it happen. The flame came out of the receiver vent hole like he was shooting a flintlock. Cracked the stock behind the tang & behind the trigger guard. Took a wooden 2x4 block & hammer to get the bolt to lift. He used the same block to pound the bolt rearward but sheared the rim off of the case. Used a hydraulic press & steel rod to push the empty casing from the chamber. Looked like a straight walled case. He sent it back to Ruger, they replaced the barrel, bolt, & stock (free of charge) but reused the receiver as the serial number was the same, which I thought was odd that they would trust it to be reusable. He also got a long written letter on what a bone headed mistake he made and how lucky he was.

Wouldn't be surprised if the bullet from that .308 round didn't hit dead center - inherent accuracy, you know.

Sorry B. It don't work that way. Area under the pressure curve is directly related to bullet energy, thus velocity. The two can not be separated.

Buy a pressure trace and see for yourself if you refuse to believe those who have done the research.

Yes, it is a matter of faith. have some!

That load could work well for some of the posters on the fire.

If you were using the proper burn rate powder, your velocity was higher as well

Pretty cool trick. When a FC brass stamps "HORNADY".

This is like the thread where a guy posted pictures of another mans buck and claims it as his.. Only more obvious. Kind of like the idiots that start at the max book loads and work up from there to "find pressure and rock on". Those guys are known for starting there and then adjusting seating depth to find accuracy too. Carry on though, is all I can say..

I have been banned from more gun forums for posting my overload work ups... than I have blown up guns.

~15 years ago there was a guy on Accurate Reloading forum that could calculate von mises stress in brass case heads.
https://en.wikipedia.org/wiki/Von_Mises_yield_criterion
His name was "a$$ clown".

When I overload a 308 case until extractor groove growth [mauser case head] Quickload would say ~72 kpsi
That agreed with his prediction, as did 223 at a higher pressure.