Hi Robert,I'll try to answer your second question first... Sure, I've done it lots of times. I install the valve (secured of course) and drill the valve thru the existing drill hole in the tube. No big deal. You may truncate some of the female threads in the tube but that's not an issue... it shouldn't open up any more than if you had used the recommended tap drill (#29)... which is .136" vs. the .125" 1/8" bit.I can't picture the raised bump issue. You shouldn't be able to see where you drilled the valve (from the inside), even if you broke thru, because it should be entirely within the small diameter inlet. My guess is that you have a headspace issue... Is it really a problem?... i.e. poor performance issues?Another way to check if you have headspace issues (at the higher pressures) is with the number of pumps it takes before your piston no longer makes contact with the valve at the end of the stroke... You should be able to feel the contact... btw, that's when I stop the pump stroke... no need to fully close the forearm when both flattop faces are already pressed together. Anyway, for mine, they make noticeable contact for the first 5 or 6 pumps... hth-Wyo
did one shot with the chrony at each level, 5.5" TKO LDC attached, Crosman tuned 18" barrel.5 pumps - 399 / 5.110 pumps - 503 / 8.015 pumps - 550 / 9.620 pumps - 574 / 10.5no residual air at 20 pumps. pumping is smooth and easy all the way up. these are decent, and i got it to just above my 500 FPS goal at 10. not as high as i have seen in similar setups, but decent for what it is with the issue it has. @Wyo... believe it or not i actually understand what the picture you posted above represents. shocking, but yeah... i understand. with Mellon FTP's you have a derlin piston. machining that down, it would be my fear that the seal flange would be to thin and flimsy to hold. there are a few things i can do from that pic... the spring, cutting down the valve threads, shaping, and the dowel pin which i will look up on MMC. how did you get that pin to stick in the poppet? im not ready to scope this gun and wrap it up just yet. i will take a few days to consider what i may have missed, just to be thorough, then decide whether to wrap it up or move towards the things i can do in that pic. i am always grateful when you chime in... you give me new things to learn and consider... thanks!
Hi Robert,I can’t (maybe someone else can) diagnose what, if anything, is wrong with your new project gun. But you wouldn’t be the first to have different performance levels from similar or identical builds.The chrony testing should let you know if there is a problem and to what extent. Until that’s done, who knows.But in the mean time there are some additional things that can improve pump stroke efficiency… 1. The valve return spring is lighter than stock and allows more of the pump stroke into the valve (less differential pressure is required to crack open the check valve). The one shown is McMaster Carr # 1986K83 2. The stainless dowel occupies most of the headspace volume in the inlet and again, more of the pump stroke will go into the valve. McMaster # 98380A419 3. Cutting the flanges to about .020” puts the o-rings closer on the TDC compression stroke so again, less headspace and more of the pump volume goes into the valve. 4. Using 90D o-rings will have less extrusion and less headspace volume in the o-ring glands. Certainly this can be done for the valve o-ring but may give you an unacceptable sliding seal on the piston… I’ve gone both ways 70D and 90D on the piston. 5. Adding more valve volume is a great idea for a long barreled 22 cal. Esp. at higher pumps. Consider that there is a maximum pressure that your pump can obtain regardless of how many times you pump. With more valve volume you get more of each pump stroke into the valve… i.e pump efficiency doesn’t drop off as fast because pressure rises slower.There’s a lot more to it than that (the condensed version above), but no one wants to read 50 pages in one post… or type it for that matter … hth-Wyo
A 1322 with a FT, steel breech and 18" barrel can easily make 550 FPS with 10 pumps.Not into golf, but that's par for the course, 600+ FPS is very doable depending on valve volume etc.So what's holding your gun back?If you want to be a high velocity player and make big power you need to call in the......Heavy Metal.Adjustable full metal FT piston and barrel band, counterbore the valve and barrel, .154" TP.My 1322 Medalist makes 565 FPS with an 18" barrel, steel breech, lightly modified valve, and adjustable cone piston.It'll do over 600 FPS with a highly modified valve.https://www.gatewaytoairguns.org/GTA/index.php?topic=185619.msg156145390#msg156145390This 13xx used all the tricks I could throw at it minus the kitchen sink....LOL.https://www.gatewaytoairguns.org/GTA/index.php?topic=164421.msg155834890#msg155834890
how did you get that pin to stick in the poppet?
Thanks, guysQuotehow did you get that pin to stick in the poppet?I pressed the check valve onto the seat by screwing the valve together with a wooden spacer...Now it's in the sealed configuration so I don't have to worry about tolerance issues. Drill squarely thru the inlet hole with a sharp 1/16" bit about 3/16" deep.The hole will be slightly undersize (normal when drilling thru plastics). Follow with a drop of CA in the hole and press fit the pin.Make sure that the pin is recessed from the face of the valve 1/16' or so as the check valve will extrude slightly under high pressure...you don't want the piston face contacting the pin...Wyo