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Jim Gillilan's Custom 1322 Carbine

Jim Gillilan's Custom 1322 Carbine w/Custom Stock

Here's one I'm especially proud of and is modded all over, doing 12fpe at 15 pumps.
Stock is Teak from Thailand and super light weight 1322 Carbine!

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A Modest Proposal: I think the recent discussion of pump link length...

April 19 2017 at 10:51 AM

Steve in NC  (Login pneuguy)
Crosman Forum Member
from IP address

...and its effect on pumping effort is very interesting and possibly of importance to optimum pumper design, but variations in design assumptions between different simulations are making the results hard to understand and relate one to another.

So I suggest we standardize assumptions, and start again. Specifically, peak pumping effort numbers are only comparable if we choose in advance...

1. Overall A + B linkage length, because practical pump arm length (and therefore pumping leverage) is related to this sum. Stated differently, because you can theoretically make pumping effort as low as you like if you don't care how long the gun, and therefore the pump lever get, overall length needs to be held constant to make the various results comparable.

2. Total stroke volume. Comparisons of pumping effort are impossible unless the same amount of air is being compressed. Since different B/A ratios result in different stroke lengths, to make comparison of effort meaningful, ratios with shorter strokes should be evaluated against a larger pump bore area to keep volume constant.

3. Full-open pump arm angle. We've seen simulations starting with 90, 120, and 135 degrees. Let's pick one and stick to it.

Any other parameters come to mind? Any preferences for specific design numbers?

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