Re: 168 AMax or 178 AMax?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Guess the Oehler 35 and actually shooting it at distance and having the data run true to the ballistic data must be wrong. Guess you wont believe it no matter what I say so we will just have to agree to disagree. </div></div>
O.K. so you have an Oehler 35 I have a PVM21. There is no magic involved in designing chronographs these days as they are pretty simple clock systems.
<span style="font-weight: bold">Would you agree that if you could send a 178g bullet at 2,700+fps you can send a 168g bullet a whole lot faster at the same chamber pressure? If you can agree to this then it is really all a matter of ballistics. </span>
As for getting 2,700+fps with a 178g pill out of your 20" barrel I didn't say it can't be done I said I doubt it. Next time you are in L.A. look me up and show me I'll even bring the PVM21 out to ASR for you to shoot over.
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No, I don't agree. On an exceptionally crude, low level basis, you are correct. If there was a "perfect" powder for every bullet, case, primer, chamber and barrel combination - I'd agree...but there isn't.
While we are blessed with many good choices for powder, we are still quute limited. Max pressure does not equal velocity, but rather, the integral of pressure times change of volume (PdV), which is the mathematical expression fir the work done by a piston/cylinder arrangement.
Case in point:
In my Savage 10FP, 45.5gr Varget is MAX SAFE for a 175smk. That load goes between 2655 and 2675 depending on weather/temperature. Meanwhile, 46gr is MAX SAFE for the 178bthp, which is good for 2745fps @ 45°F ambient.
Why?
The dynamics of bullet/bore friction, pressure rise time, volume of the cylinder at Pmax etc etc etc conspire to do do MIRE WORK on the 178hpbt than with the 175smk. Perhaps a faster powder would perform better with the 175? Maybe, but Varget has an excellent reputation for that bullet, so...
Bottom line is that theoretically, the lighter bullet can always go faster. In the real world, however, with less than ideal powders for any given application, lighter bullets will NOT always go faster.