Todays findings are interesting to be sure.

Mod 200 Stevens 6.5X55 24" Shaw barrel.


Mauser Mod 96 6.5 X 55 30" barrel.

Load** 139gr. psp Prvi., 45.3 gr. DP85, PMC case, #34 primer.Oal=3.015", Shaw = 2718fps. avg.
Military = 2714 fps avg.

Load** 139 psp Prvi., 45.9gr. DP85, PMC case, #34 primer OAL=3.015" Shaw = 2720 fps.avg.
2. Military = 2707fps.
Something to be learnt here I'll bet. WAHH. roger

quote:

Originally posted by bartsche:
Todays findings are interesting to be sure.

Mod 200 Stevens 6.5X55 24" Shaw barrel.


Mauser Mod 96 6.5 X 55 30" barrel.

Load** 139gr. psp Prvi., 45.3 gr. DP85, PMC case, #34 primer.Oal=3.015", Shaw = 2718fps. avg.
Military = 2714 fps avg.

Load** 139 psp Prvi., 45.9gr. DP85, PMC case, #34 primer OAL=3.015" Shaw = 2720 fps.avg.
2. Military = 2707fps.
Something to be learnt here I'll bet. WAHH. roger

This means that 0.6 grain of powder difference has adden 2 fps

Seriously though, this is a perfect example of what the reality is between rifle barrels.

Years ago, there was an article in a magazine about the 30-378 Weatherby. And the amazing fact stated by the writer of that articles was that he wantd a specific velocity, and he had to add something like 0.7 of a grain of powder (or something like it) to get his desired velocity.

He seems to have forgotten that large cases like the 30-378 Weatherby hardlu showed any difference in velocity with differences in charges less than 2 grains.

In fact, we have had instances where adding 2 grains has reduced the velocity!!??

Pretty amazing really, and we have no idea why this happens.

May be Dr. Oehler can enlighten us.

quote:

In fact, we have had instances where adding 2 grains has reduced the velocity!!??

OK. Here's a theory. Raising the peak pressure might be increasing the elastic expansion of the bullet due to the accelerating forces acting on the bullet base, resulting in increased bullet to bore friction - which reduces bullet acceleration!
Just a theory.

NOTE BENE!!!
In each case the exspected velocity increase in the longer barrel never happened. Rather substantiates what Fred, Saeed and Ken were pointing out. roger