Quote:My version of Quickload , which is 3.9 and has the October 2023 update installed, defaults to 37.50 for the case capacity on the 6.5 Grendel. I would like to know if this is the correct default case capacity and why you upped it from 35.99. Could you please clarify this for me.

Quote:Apparently there are different Lapua cases around.

Quote:Powder burning rate anomalies related to case design, size and insufficient
ignition:
This anomaly has only proven to produce QuickLOAD calculations indicating
higher than actual pressure and velocity.

In certain small-caliber cartridges, those types with relatively small
combustion chambers and in some big-bore cartridges, those types with almost
cylindrical cases (which often require the same types of propellant),
QuickLOAD often significantly deviates from suggested published reloading
data.

For such cartridges, it can be meaningful to adapt an existing propellant
data file. The resulting powder data file is applicable only to the
specifically verified cartridges. Store this data record with a special name.

(Candidate cartridges include the following and similar chamberings:
45-70 Government, .458 Win Mag, .22 Hornet, .30 Carbine, .416 Rem Mag, and
all the old Nitro Express cartridges.) For example, propellants in the
.458 Win Mag, .416 Rem Mag and .22 Hornet demonstrate a somewhat better
efficiency than QuickLOAD's standard calculation suggests. This results in
QuickLOAD predicting increased pressure and velocity, when compared to
published data or chronograph results.

To correct predictions is possible to enter a somewhat bigger cartridge case
volume, compared to what actually exists. This causes a corrective effect.
For example, in the .416 Rem Mag, misrepresenting case capacity about
+7% often results in good correspondence with published loading data.

This method limits the effects of input data alteration to the specific
cartridge, which seems better than creating an imaginary powder data file
that will only be useful and appropriate with a specific cartridge or
possibly a small class of cartridges.

The only problem with this approach is that it prevents direct assessment of
powder loading ratio. That can be secondarily derived by temporarily
reverting to the actual case capacity.

Lot-to-lot dependent adaptations:
When the user notes differences between the properties of a reference powder
lot (which is stored in the program file) and a new propellant lot, an
adaptation of the propellant data is necessary. Such differences will occur
with practically each new powder lot. Sometimes these differences can be
significant. For example: with many manufacturers, when the nominal Heat of
Explosion is 4000 J/g, accepted lot-to-lot variation is between 3900 to 4100
J/g.

So long as no new values for the Heat of explosion are admitted by the
manufacturer the old Qex values are retained and only the Ratio of specific
Heats cp/cv and linear burning rate Ba are changed, as necessary.

When calculated velocity (and pressure) are too high, the value for cp/cv is
reduced. cp/cv-1 is approximately 0.25 and corresponds to the 'efficiency' of
the transformation of the Heat of Explosion into propellant gases, which
produce chamber pressure. (A propellant with cp/cv = 1 generates no gases,
cp/cv = 2 signifies, that 100% of the available energy is converted into
pressure.) Carefully change this value in 0.001-steps to correctly accomplish
this adaptation. Increasing cp/cv increases both velocity and pressure
(and vice versa).

To adapt pressure together with this (lowering cp/cv), change the burning
rate coefficient Ba. An increase of Ba increases pressure, a decrease reduces
pressure. With this adjustment, velocity also changes. Change cp/cv and Ba
until sufficient approximation to test result is achieved.

When completely new propellant properties are available, the user can also
change other properties.

Scrape hunter Wrote:Jasper after seeing how much crap,you have been through with this computer simulation .Ain't no way in hell I'd ever trust the figures coming from it way to many variables for this cat .

Quote:(I don't have a conflict of interest where QL is concerned but the bashing it gets from people who are not prepared to enter precise data is revealing. If you think the program is too complex then by all means rely on manufacturer tables, but don't bash what you don't understand).(I don't have a conflict of interest where QL is concerned but the bashing it gets from people who are not prepared to enter precise data is revealing. If you think the program is too complex then by all means rely on manufacturer tables, but don't bash what you don't understand).