GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: Hobbyman2007 on October 18, 2015, 06:06:42 PM
-
I'm in the middle of a .357 build and have run into an issue with hammer strike . I'm using an AR79 with custom tube and bottle regulated to 2200 psi. On the first outing with the gun put together I was able to get 700fps with 81 gr jsb for a total of 15 shots from 3000 to 2200 psi. I replaced original hammer spring and did the cock on open mod and my results were at coil bind on the hammer spring. So here is the question, if I increase the hammer throw (.25 ") will I see an increase in either valve lift or dwell? The reason I ask is the only way that I see possible to increase the hammer throw is to move the trigger /sear assembly on the tube ,which will have me inlet the stock to match . I know I can get a custom hammer made that wold produce the same results but I'm trying to save a couple of bucks for a slayer purchase once available to us in the great white north. I'm trying to reach mid 900 fps with the jsb pellets to start.
-
Increasing the hammer throw by 1/4" will increase the hammer energy by the same proportion as the change in travel, if you keep the average spring force the same.... That will increase both lift and dwell, as well as allowing you to knock the valve open easier at 3000 psi.... all things you need to achieve your goal.... You don't mention what you are using for a poppet, but I assume it is not the stock, soft one as it won't live at 3000 psi, and would be VERY hard to unseat, sucking up most of the hammer energy to do so.... Either a Delrin poppet, or even one made from PEEK, will unseat much easier, leaving more of the hammer energy to produce lift and dwell....
Bob
-
Thanks Bob. That's exactly the info I wanted. The popet is delrin I got made by Jexz. I would be happy if I could get the jsb 81gr. up the 950fps . I'll get a heavier hammer on order now and hopefully a bag of assorted BBT's as well .