It could easily be done if the design was similar to the AR upper and lower receiver
Donald
This has already been done by the Webley Tomahawk which uses two different pistons to achieve different outputs from the same platform. Admittedly the top power was between 18 and 22 foot pounds and the lower was 12 foot pounds, the difference being a stroke of 3 and 4 inches, so a stroke of 2 to 2.5 inches might well deliver 6 foot pounds of energy.
All in all it could be done but not at 30 foot pounds output.
I'm saying, if you look at the ICS M4 airsoft rifle, it's obviously an AR platform... the bottom half has the motor, trigger, gearbox, and the upper half holds the spring, piston and compression tube all in a handy clamshell package. The rifle splits open same as an AR, but the upper gearbox as they call it, comes out and can be swapped over with ones containing heavier springs, larger bores etc.
As for why isn't it done? Simple. Because nobody has done it yet
It's a bit of a crude drawing, but I'm thinking something like this
https://i.imgur.com/VgnWjmg.jpg
Last edited by thisisdonald; 17-11-2018 at 09:58 PM.
Donald
Ahh, got you, not quite AR but anyway. Thing is, as I believe someone pointed out already - it's not at all necessary to go down that route with an underlever. (Engineering wise, needing to make everything super stiff would mean the sketched design would be ludicrously heavy and bulky) Everything is already modular today, no changes needed. You can swap out a compression tube and piston of the TX/HW type with one with thicker walls and shorter/longer latch rod. Voila, reduced bore / stroke or vice versa.
**WANTED**: WEBLEY PATRIOT MUZZLE END; Any Diana/Original mod.50 parts, especially OPEN SIGHTS