03-14-2022, 01:28 PM
In terms of an "accurate" estimate, and since you don't know your actual starting pressure, and it's primarily a theoretical issue anyway... and it will depend upon, among other things, which powder/bullet/case/primer combo you use, what your actual chamber sizing is, which increment of 0.005" you are doing (ie, how close you are to compression), etc etc etc for - idk - maybe 20-30 other parameters... o yeah and how warm your chamber is...
The answer as to a "formula" is either QL or GRT, both of which are mathematical models that depend heavily on all the input parameters (many input parameters) and on how much you trust their results...
One prediction from GRT with a 100 gr nosler BT and xbr that I have modeled... if you were "only" at 99.6% fill the pressure increase is ~200-300 psi. But if you were at 100.6% capacity the pressure goes up 2000 psi.
These are only mathematical estimates and have not been validated in any way by real pressure testing, but there you go. As always, ym WILL v.
Now the question here is, are you at 99.6% full or 100.6% full? That's another factor I don't think we've been able to measure precisely at the bench.
Both of those models, QL and GRT, are relatively complex models.
Most guys use an MV ladder and study the results to see what their loads are doing for them.
The answer as to a "formula" is either QL or GRT, both of which are mathematical models that depend heavily on all the input parameters (many input parameters) and on how much you trust their results...
One prediction from GRT with a 100 gr nosler BT and xbr that I have modeled... if you were "only" at 99.6% fill the pressure increase is ~200-300 psi. But if you were at 100.6% capacity the pressure goes up 2000 psi.
These are only mathematical estimates and have not been validated in any way by real pressure testing, but there you go. As always, ym WILL v.
Now the question here is, are you at 99.6% full or 100.6% full? That's another factor I don't think we've been able to measure precisely at the bench.
Both of those models, QL and GRT, are relatively complex models.
Most guys use an MV ladder and study the results to see what their loads are doing for them.
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