GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: UCChris on October 01, 2017, 05:02:25 PM
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Hey all. Wanted to share my build of my 1720T half shroud.
Disclaimer: I am aware of the forum rules discussing LDC's/shrouds. I hope this post doesn't break any of those rules.
I wanted to try a two chamber design, so I started by moving the rear shroud mount. The tolerances on the rear shroud mount are loose and use the front face of the breech to stabilize and keep the mount from cocking off center. Point is, a shim was used between the rear shroud mount and barrel.
(https://i.imgur.com/YUJTpX1.jpg)
Here is the factory shroud cut down to size for the inner chamber.
(https://i.imgur.com/wBNme5M.jpg)
(https://i.imgur.com/ZTHMNDe.jpg)
Now drilling holes for the rear chamber venting. Filed the holes down smooth, didn't bother making them look nice, since this chamber will be completely hidden inside the half shroud.
(https://i.imgur.com/RJnrH4Q.jpg)
Two delrin bushings create the inside chamber after a 1.75" diameter carbon fiber tube is press fitted over the bushings.
(https://i.imgur.com/EhnF6Ej.jpg)
(https://i.imgur.com/YPCP6DL.jpg)
(https://i.imgur.com/86fCGuB.jpg)
Insert some baffles and press fit the end cap and it's all finished!
(https://i.imgur.com/ETwa77w.jpg)
(https://i.imgur.com/LA9RrEn.jpg)
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Looks like you had fun making that gizmo.
I bought mine from TKO:
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Looks like you had fun making that gizmo.
I bought mine from TKO:
TKO makes some quality stuff. Since I'm going with a bottle adapter, I have the room to make a laughably huge pickle thingy.
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Interesting work, and will like to know how effective it is. How hot do you or plan on running the 1720T? I run mine at 15FPE with 10.3 AA/JSB. Most available LDCs and even my grafted on Mrod shroud section, seem to work well at that power level. I assume you are targeting something higher, maybe 18-20FPE? At those levels, the 12" barrel will not be very efficient and would make more noise.
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I like it. Large hushemuppers are cool with me.
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Interesting work, and will like to know how effective it is. How hot do you or plan on running the 1720T? I run mine at 15FPE with 10.3 AA/JSB. Most available LDCs and even my grafted on Mrod shroud section, seem to work well at that power level. I assume you are targeting something higher, maybe 18-20FPE? At those levels, the 12" barrel will not be very efficient and would make more noise.
See, that's the silly thing. I'm only going to be running it around 11.5-12 fpe.
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Consider this constructive criticism .....
You would be better served in NOT having the sound pulse traveling down a small diameter tube as this (https://i.imgur.com/YPCP6DL.jpg)
The amplitude of the pressure wave is so fast it dang near blows right by the venting holes therefor not losing much energy due to expansion ending up not damped much & nearer LDC's exit.
Ideally you want the pressure pulse to find AREA unobstructed, then reduce area and expand it again, constrict & expand again etc ...
Hope I stayed within the rules too ???
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Thank you for the advice! I will fiddle with it.