Factory norma ammo over pressure according to quickload?

[Hitzy]

Typical of engineering....hard and fast rules that apply in some cases, but cannot make allowances for the nuances that change the goalposts.
There are so many small factors that are responsible for the rate of erosion in the throat of a rifle barrel. A set formula means little.
I have seen a 220 Swift barrel that had 2500+ rounds through it, and showed erosion that would normally be seen at 8-900 rounds.
On the other hand, I looked at a 6.5x300 Weatherby through the borescope...it was missing the first 5" of rifling from erosion. Round count? <300!!
Why the difference in these two chamberings, both of which are regarded as barrel-burners? Engineering cannot answer this easily.
Regards, Dave.

If it was a factory Weatherby, that's just a "feature".... rifling just slows down the bullet so they need a good 5" of freebore lol.

 

[Dogleg]

This is bread and butter mechanical engineering. In a nutshell, gas mass flow (and velocity) is proportional to load, and erosion potential is proportional to impingement energy (velocity squared). So, by increasing the gas flow by 5% you increase the erosion by 15%.

I refer you to "Combustion" by Joseph Singer P.E., page 23-21. Understandably, this book is not in common circulation, you might find that Marks Standard Mechanical Engineers Handbook offers a similar treatise on erosion.

I'm not an engineer, and not overly smart, but I do know the 5 cubed isn't 15 it's 125. Could you take another swing at explaining it so I can understand it? Type real slow, that might help.

 

[cosmic]

!.05 x 1.05 x 1.05 ~ 1.15

 

[bigedp51]

Its too bad sunray isn't here to come up with a mathematical over pressure answer.