The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

I have increased powder libraries for the online internal ballistics simulator at

http://www.bbt.scot/ballistics/pressure.htm

There are now powders from Alliant, Chemie-Swiss, IMR, Lovex, Norma, Vectan and Vihtavouri

Geoffrey Kolbe

I just ran my 6BR load through QL and BBT.........BBT predicted an MV of 2798fps, QL predicted 2881fps.

Labradar said I got 2890fps... (an average of 10 shots fired on a comfortably warm day)

Pete

Thanks for that Pete
Out of interest, what the load, usable case capacity and barrel length?

Correction: I entered my TOTAL case capacity with the BBT s/ware, not my usable, hence the low MV prediction.
Entering the usable case capacity given by Quickload for my cartridge length with the 105grain Scenar, the BBT predicted MV is 2917fps.
Thanks Borbal for drawing that to my attention.
The barrel is a Lothar 760mm 8-twist, and the usable case capacity is 2.28 cm3

Pete

Pete wrote:Correction: I entered my TOTAL case capacity with the BBT s/ware, not my usable, hence the low MV prediction.
Pete

Easily done. I have tried to think of ways to make it clearer that it should be the usable case capacity that is used, not the total capacity to overflowing, but a simple way to do that has escaped me.

It is actually quite easy to measure usable case capacity, as I show in this little movie

https://www.youtube.com/watch?v=o3eJxKXqmn8

Now why didn't I think of that??

Pete