7.0 gm pellet vs. 9.3 gm pellet, how many clicks upward?

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jipe
Posts: 812
Joined: Wed May 02, 2007 5:50 am

Post by jipe »

tenex wrote:
jipe wrote: The pistol was factory tuned like that, I didn't modify the speed myself.
That's very interesting. Do you know what the difference in capacity is from the same gun?
No, as said its factory tuned like that and was not modified. But the reason to do so is not only the smaller cylinder, it is also the shorter barrel that needs more air to obtain the same velocity => the LP@ light uses more air for this low velocity than the LP10 would use.

The amount of shots with one cylinder is about 100 for the LP@ light while it is about 150 for the LP10 (the 180 of the Steyr user manual is overestimated, Anschutz is more honest and state 150 in the user manual of the normal barrel LP@).
tenex
Posts: 234
Joined: Wed Mar 10, 2004 12:04 am
Location: Connecticut, USA

Post by tenex »

jipe wrote:...
No, as said its factory tuned like that and was not modified. But the reason to do so is not only the smaller cylinder, it is also the shorter barrel that needs more air to obtain the same velocity => the LP@ light uses more air for this low velocity than the LP10 would use.
...
I completely forgot about this. I wrote a short Octave (Matlab) script a while ago to predict the capacity of a typical PCP gun with an arbitrary tank size and fill, and barrel length was a significant factor. The one variable that can be tuned to optimize capacity for a specific fill pressure is the output pressure of the regulator, but I'm pretty sure that for most of the current PCP guns the output pressure is set to the CO2 vapor pressure at room temperature (or a pressure to produce equivalent velocity with air using the same spring tension on the main valve).

Unfortunately, it's not that easy to change the output pressure of the regulator. I'd like to try a higher chamber pressure and less charge volume to archive the same velocity, If my calculations are right, the barrel pressure when the pellet leaves the barrel will be less, and the pellet disturbance and noise should be reduced. Several people have commented that my K2 has a pretty loud bark (but it makes such pretty round holes!).

Steve.
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