Thread: Pressure / barrel speeds?

lets take two bullets of the same type but different weights out of the same rifle.
say 120gr 6.5BT and 140gr 6.5BT
Correct me if I'm wrong but, say 48gr of a 2209 moves the 120gr at 2900.
But as this is well over max it would be dangerous for the 140gr
Is this because the lighter bullet has gone further down the barrel with the same powder charge so the pressure will be less than a heavier bullet that has travelled less distance therefore leaving less empty volume behind the bullet for pressure increase.
Or is that a load of bollocks and it all happens in the chamber in fraction of seconds before the bullet even gets a few mm down the barrel.
Or Something else.

Originally Posted by jakewire

lets take two bullets of the same type but different weights out of the same rifle.
say 120gr 6.5BT and 140gr 6.5BT
Correct me if I'm wrong but, say 48gr of a 2209 moves the 120gr at 2900.
But as this is well over max it would be dangerous for the 140gr
Is this because the lighter bullet has gone further down the barrel with the same powder charge so the pressure will be less than a heavier bullet that has travelled less distance therefore leaving less empty volume behind the bullet for pressure increase.
Or is that a load of bollocks and it all happens in the chamber in fraction of seconds before the bullet even gets a few mm down the barrel.
Or Something else.

Fantastic question i will put mine on option 1