Underdog Posted May 11, 2013 Report Share Posted May 11, 2013 Later ones IIRC had a 2.8mm port! U. Quote Link to comment Share on other sites More sharing options...
bigman Posted May 11, 2013 Report Share Posted May 11, 2013 be careful with all the tuning parts!! had my old one tuned in the 80's to 11.5 and the barrel shortened. the spring broke in the nineties and i had it replaced in a local shop with what they said was a "good" spring. i used it for years on the sparrows on the house (yrs ago!!) and was wondering why it was turning them inside out.......lent it to a mate who had it chrono'd. damn thing was pushing 28ft lb with eley wasp! no wonder the rabbits were thinning out had to get it signed onto a fac :( You had a springer with short barrel pushing out 28 ftlb ? Was the crony faulty or something Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 11, 2013 Report Share Posted May 11, 2013 http://weihrauchowners.freeforums.org/best-transfer-port-size-for-177-hw-35-t4418.html U. Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 11, 2013 Report Share Posted May 11, 2013 http://www.airgunone.com/forums/showthread.php?t=1813 U. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 11, 2013 Author Report Share Posted May 11, 2013 (edited) On the hunt for a second piston assy. My old man has just tuned up a new piston assy for his B2 thingy its out of Ali and steel saved something like a third of its weight but we had std seals which are expensive and horrible compared to a few o rings. I'm sure I can get way more stroke and use a double o ring instead on a modified piston assy. I cant fault accuracy I just been out putting pellets through it and cut 2 out of 3 dandelions in half only 10 meters but the gun has zero kick to it which is lovely but I fear if im not hitting 10/11ft lbs then rabbits and pigeons will just laugh at it. Edited May 11, 2013 by jai_landrover Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 11, 2013 Author Report Share Posted May 11, 2013 Quote Link to comment Share on other sites More sharing options...
stu nesling Posted May 13, 2013 Report Share Posted May 13, 2013 You had a springer with short barrel pushing out 28 ftlb ? Was the crony faulty or something not faulty at all. was a bit evil on the recoil and even started to deform the hollow recoil stud mounted behind the 1 piece mount.nothing left of an eley wasp when fired at a wall at 15yards except scattered bits! what spring they fitted i dont know. shortening a barrel will if anything increase the fps as the pressure does not die down as much as having the pellet travel a longer barrel. Quote Link to comment Share on other sites More sharing options...
johnbaz Posted May 13, 2013 Report Share Posted May 13, 2013 On the hunt for a second piston assy. My old man has just tuned up a new piston assy for his B2 thingy its out of Ali and steel saved something like a third of its weight but we had std seals which are expensive and horrible compared to a few o rings. I'm sure I can get way more stroke and use a double o ring instead on a modified piston assy. I cant fault accuracy I just been out putting pellets through it and cut 2 out of 3 dandelions in half only 10 meters but the gun has zero kick to it which is lovely but I fear if im not hitting 10/11ft lbs then rabbits and pigeons will just laugh at it. Hello Jai An aluminium piston wouldn't be much good to improve power as weights are added to up the power and can be removed to lower it... I have an 80 that was awful to shoot, the recoil was so bad that it felt like I was getting electric shocks in my hands! When I opened it up an Ox spring had been fitted which had a heck of a lot of preload, I removed all of it and warmed/collapsed the last coil then ground and dressed the end- it turned the rifle from an 'orrible beast into something smoother than a ladies inner thigh Cheers, John Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 13, 2013 Author Report Share Posted May 13, 2013 Cheers John, The Ali steel piston is purely a try out. I have got a second piston although the older leather type will compare to my piston assy. Will then machine off the piston head and make a new head with double O ring and increase its stroke as much as possible. Again as angry out. Have the old mans lathe and milling machine so seems like a bit of fun. I can't find anything fundamentally wrong with the gun cylinder is airtight, piston seal holds good pressure new breech checked or leaks and the max ingot with 14.5 Gr pellets was 9 Lbs feet. Still running the piston in o bed in but has had a hundred through it so will re chrono it later. I think an O ring piston is the way forward. I understand the twangy mess you describe I had that with all the spacers fitted and you can't hit a barn door now it's lovely and accurate with almost zero recoil just a few more lbs ft req before safe quarry kills. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 13, 2013 Author Report Share Posted May 13, 2013 Cheers John, The Ali steel piston is purely a try out. I have got a second piston although the older leather type will compare to my piston assy. Will then machine off the piston head and make a new head with double O ring and increase its stroke as much as possible. Again as angry out. Have the old mans lathe and milling machine so seems like a bit of fun. I can't find anything fundamentally wrong with the gun cylinder is airtight, piston seal holds good pressure new breech checked or leaks and the max ingot with 14.5 Gr pellets was 9 Lbs feet. Still running the piston in o bed in but has had a hundred through it so will re chrono it later. I think an O ring piston is the way forward. I understand the twangy mess you describe I had that with all the spacers fitted and you can't hit a barn door now it's lovely and accurate with almost zero recoil just a few more lbs ft req before safe quarry kills. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 14, 2013 Author Report Share Posted May 14, 2013 Ok more info I got a second hand old type leather piston complete from Ebay. The differences are the piston has a shorter stroke mainly due to the whole assembly being approx 6mm longer. I have just fitted and tried it as std and getting around 4ft lbs. there is also a difference in weight the new type with synthetic seal weighs in at 201g whereas the older leather type weighs in at 229g. Uploaded with ImageShack.us Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 14, 2013 Author Report Share Posted May 14, 2013 (edited) To set my mind at ease my uncle has a PCP and we checked it with the chrono and it was bang on 11.7ft lbs so I know the Chrono is working. I think the next step forward is to use the leather type piston and modify it as its no use to me at 4Ft/lbs. I have a couple of O rings and will machine the end off the leather piston and weld in a new piston head giving maximum stroke and using an O ring. The question i'm now debating in my head is a single O ring or double with a 3mm gap between. The later may mean that I can not get much more cylinder volume. Any ideas or anyone with experience would be appreciated. I may well just make it one for now and see how it goes. still deciding.................... J Edited May 14, 2013 by jai_landrover Quote Link to comment Share on other sites More sharing options...
Capital Bee Posted May 15, 2013 Report Share Posted May 15, 2013 The leather seal adaptor should unscrew from the piston body (it did from mine). You can then make a piston head and screw it into place, maybe trying multiple configurations without having to scrap the piston. Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 15, 2013 Report Share Posted May 15, 2013 Got any plastic to turn? U Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 Yes I have some nylon blocks I turn down but think Ali would be better. As it happens I unscrewed the seal after I posted and will indeed make several piston ends double and single o rings to try I'm in London today so may e able o pick up more material to play with. Lots of people mention limiting stroke to keep within the legal limit and I will not destroy the piston if I can get up close to the limit without having to re work it. Buttoning seems like a cleaver idea one which would be nice eventually the main thing is keeping it nice to shoot while getting 11.5 ft lbs or as close to 12 as possible with my chosen pellets yet to be decided. Been using pax guns own brand and had good results. I have no intention on getting 15 ft lbs and having a twangy mess to try and shoot. On a side note I'm quite happy as I tried rabbit yesterday for the first time all day in the slow cooker with loadsa stew and its just a variation on chicken which means I'm not wasting my time. The idea of getting the gun sorted is for a weekend away Offroad driving and only eating what you catch farmers permission beforehand of course as a kind of survival/green lane driving somewhere remote. Being totally self sufficient except vehicle fuel and water. Next stage is getting the gun up to power and then more practice at the range, eventually a rabbit or two and gutting and skinning. Slow as it might be we're getting there slowly!! J Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 15, 2013 Report Share Posted May 15, 2013 Dont suppose you could try that leather piston head first? Maybe add some washers to the piston as well to up weight. U. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 I have tried it and got 4ft ft lbs no preload pn spring can double that with new type piston assy Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 O ring is desirable due to cost and ease of field repair Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 15, 2013 Report Share Posted May 15, 2013 No preload! I have never come across a wierauch with no preload bwfore! U. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 Best results so fr have been with this at 9 ft lbs its a Titan spring as supplied by welsh willy it's not loose but the spring must not be compressed any more than a mm when assembled. At the lathe now am about to spin up a new piston head see how it goes J Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 Right just got off the lathe we have a double o ring piston I have pics but need to upload then to imageshack first when I get home J Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 (edited) Uploaded with ImageShack.us Edited May 15, 2013 by jai_landrover Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 15, 2013 Author Report Share Posted May 15, 2013 Sorry for the poor pic phone pic not the best Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 16, 2013 Report Share Posted May 16, 2013 Looks like you just more volume Mr ! U. Thats lost some volume sorry. U. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 16, 2013 Author Report Share Posted May 16, 2013 Indeed I can cut the piston down to gain all research suggests that an o ring will be over legal limit start long and cut down as neasasaey Quote Link to comment Share on other sites More sharing options...
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