Same velocity at different seating depths.... what does that mean?

[russkim04]

So i tried 140 eldm at .007 off the land through .080 off the lands. Velocity with same charge weight ranged approx 50fps. With the shorter jump having more velocity.

NOW the 147 eldm ranged from .050 off the lands through .110 and velocity all fell within approx 50 fps. But more mixing of highs and lows- and typically longer jumps having more velocity.

Thoughts? thank you!

 

[TheOfficeT-Rex]

What was the ES of the load (and number of shots) before you started moving seating depth?

If you’re basing average speed off a 3 shot set for each depth, it’s probably just noise.

ETA just saw they were different bullets at completely different jump ranges. Not exactly a fair comparison.

 

[straightshooter1]

So i tried 140 eldm at .007 off the land through .080 off the lands. Velocity with same charge weight ranged approx 50fps. With the shorter jump having more velocity.

NOW the 147 eldm ranged from .050 off the lands through .110 and velocity all fell within approx 50 fps. But more mixing of highs and lows- and typically longer jumps having more velocity.

Thoughts? thank you!

I've posted this info on another thread, but here it is again (is from a 1965 University of Michigan engineering study) as I feel it should give you a good idea as to what's going on:

 

[straightshooter1]

An "ah ha" moment.

That was the equation.

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