Pressure Velocity and Load Data

[357cyrus]

I'm curious to see what other people's views on the load data found in any number of reloading books is, and how you apply it? For instance, when I started reloading, I looked into my Lee Modern Reloading book and got the impression that I should start low (but not too low!) and never go beyond a maximum charge listed, I should look for signs of pressure in my brass and primers, and that if I get to a max charge without seeing those signs, my velocity should be what is listed.
The more books I pick up, the more I see how different they all are in terms of load data (especially now that I've used a chronograph for a few years). My latest understanding is that velocity is a direct result of pressure. I feel that as long as I use a chronograph AND watch my brass/primers for signs of pressure, I can use any book's min/max charges as an ESTIMATE of what my rifle will need to produce a maximum velocity listed.
For instance, with my 223 I loaded up brass with what I determined to be a moderate dose of powder. The velocity over my chronograph, due probably to a number of variables, was near max with the book I took info from. So I went no further. My 25-06 on the other hand, took 2 grains more powder than Nosler's book did to get their max velocity. Neither my 223 or 25-06 seemed to show any signs of pressure in the brass or primers.

[Ranch Dog]

I've always fallen into this school of thought: Don't exceed the listed charge or velocity, which ever occurs first. In other words as you work through your load increments, if one of the increments produces a velocity near the max, you have reached a load limit.

[62chevy]

Just been doing book loads and not exceeding them. A crony would help in that development but don't have one yet, maybe after a bottom pour pot then maybe before. Decisions, decisions, lol.

[357cyrus]

Have you ever had signs of pressure before you reached a listed max VELOCITY from a book? (other than detonation from being well below suggested minimums) I have not, but that doesn't mean it can't, just means I haven't experienced or read enough. That would flush my theory down the toilet. I'm probably going to buy QuickLoad soon, as it seems you can fill in those variables I mentioned, and seems to have earned quite a bit of trust among those that have used it

[Ranch Dog]

I have seen, with pressure trace equipment, where I'm increasing the charge to get to a target velocity but the velocity is no longer moving in relationship with the pressure. I'm having to add a lot of pressure to get any change in velocity. With an increase in the powder charge near max, I have see velocity stagnate or slightly abate. The one thing I always see with an increase in the powder charge is an increase in pressure.

Look at it this way. The pressure is the result of the explosion or combustion of powder. Add to it and it is something greater. Velocity is the result of a lot of the boom but there are a bunch of other factors influencing the outcome. These factors would include the bullet, barrel, and the environment (elevation, temperature, humidity, and barometric pressure). Velocity is the sum of a lot of stuff where pressure is pretty much at the boom.

[62chevy]

See if this is right, the bullet will go slower at 10 deg than it will at 70 deg. Also if the pressure is low the bullet will go faster than when pressure is high. Or is it a little more complicated than that.

[mr surveyor]

you're referring to air temp and barometric pressure?

[Ranch Dog]

See if this is right, the bullet will go slower at 10 deg than it will at 70 deg. Also if the pressure is low the bullet will go faster than when pressure is high. Or is it a little more complicated than that.

That is correct.

you're referring to air temp and barometric pressure?

Yes. What it really boils down to is the density of the air in which the bullet must pass.

[62chevy]

Thanks RD I'm learning.

[357cyrus]

That's it!!!! I've said "If only I had Quick Load" too many darn times! A copy is finally in the mail with my name on it.