jai_landrover Posted March 2, 2013 Report Share Posted March 2, 2013 (edited) Hey there, I'm playing with my new to me airgun and whilst I'm very happy with it its very down on power circa 6ft/lbs. I ordered and fitted a tuning kit from woodfield which I must say has been excellent. Fitting this kti has turned a very twangy horrible gun into a smooth actiing almost recoiless lovely gun. However its still only producing circa 7ft/lbs. the cylinder is good, the piston seal is ok if i block the transfer port with a thumb and push the piston there seems to hold pressure and after a while no noticable drop in pressure. The breach seal seems perfect the tissue test shows no leaks. I'm getting a bit crazy Ive tested everything I think possible and still have no answers. Any help would be much appreciated i don't want a mega powerful gun just one circa around 11ft/lbs which is nice and smooth. Woodfield have been great I can't say a bad word about them. I just wish I could suss out this low power thing cos its really bugging me!! Atb Jai Edited March 2, 2013 by jai_landrover Quote Link to comment Share on other sites More sharing options...
goodo123 Posted March 3, 2013 Report Share Posted March 3, 2013 Piston seal not mating correctly with cyl or something slowing it down? I presume you changed the spring? So the only things left are piston seal, piston alignment, cyl fit, or o ring? If it's flat it could be leaking? Give the barrel a clean with cleaning pellets it could be fouled up by previous user? Check crown at the end of barrel? Quote Link to comment Share on other sites More sharing options...
malantone Posted March 3, 2013 Report Share Posted March 3, 2013 I put an ox spring in my HW35 about 20 yrs ago and it still kills rabbits at 30yds http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=150832182503&clk_rvr_id=455455559741&item=150832182503&lgeo=1&vectorid=229508 Quote Link to comment Share on other sites More sharing options...
kent Posted March 3, 2013 Report Share Posted March 3, 2013 Hey there, I'm playing with my new to me airgun and whilst I'm very happy with it its very down on power circa 6ft/lbs. I ordered and fitted a tuning kit from woodfield which I must say has been excellent. Fitting this kti has turned a very twangy horrible gun into a smooth actiing almost recoiless lovely gun. However its still only producing circa 7ft/lbs. the cylinder is good, the piston seal is ok if i block the transfer port with a thumb and push the piston there seems to hold pressure and after a while no noticable drop in pressure. The breach seal seems perfect the tissue test shows no leaks. I'm getting a bit crazy Ive tested everything I think possible and still have no answers. Any help would be much appreciated i don't want a mega powerful gun just one circa around 11ft/lbs which is nice and smooth. Woodfield have been great I can't say a bad word about them. I just wish I could suss out this low power thing cos its really bugging me!! Atb Jai never heard of the "tissue test" use French chaulk. Your loosing so much here I feel its a seriously wrong part, I don't trust all tuning kits and fitted with the correct parts from the factory you gun should produce at least 10 ft lb. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted March 3, 2013 Author Report Share Posted March 3, 2013 Cheers for your help I will have another look over it. There is no scors in the cylinder, piston seal looks ok I have heard of pourous brazing which I think is my issue now as everything else seems ok. It was a well regarded kit and the old spring was around the same so I think there is somthing fundamentally wrong with my hw35 to be so low on oomph. I'm not looking to get serious power just getting it back to where it should be. I quite fancy shooting and eating some rabbits but this is really starting to bug me now. Quote Link to comment Share on other sites More sharing options...
Underdog Posted March 3, 2013 Report Share Posted March 3, 2013 Has it the old leather piston seal? They don't like being dry and they don't like years of being soaked in mineral oil and rot. U. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted March 3, 2013 Author Report Share Posted March 3, 2013 Its the later synthetic seal, the cylinder seems smooth and it has good pressure I can only suspect it has a leaking braze joint between the cylinder and breach. Quote Link to comment Share on other sites More sharing options...
Underdog Posted March 3, 2013 Report Share Posted March 3, 2013 I just can not see it being a bad joint, it would be gaping! I am wondering if it is a short stroke version!! Germany has a lower power limit than us! I wonder if the trigger rod off the piston is long on yours! U. Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted March 3, 2013 Author Report Share Posted March 3, 2013 Ow that's something I never thought of. The transfer port seems to be around 4mm which suggests uk spec but I will measure the length between the piston head to the latch on the piston and compare to another one Quote Link to comment Share on other sites More sharing options...
fenboy Posted March 3, 2013 Report Share Posted March 3, 2013 I think the Hw35 only produced around 10 ft/lb when new so 11 may be optimistic. Have you tried adding a little more pre load to the spring Quote Link to comment Share on other sites More sharing options...
Underdog Posted March 3, 2013 Report Share Posted March 3, 2013 (edited) I think the Hw35 only produced around 10 ft/lb when new so 11 may be optimistic. Have you tried adding a little more pre load to the spring Good points but I do know of one years ago that was just over the limit! In the 1980's! Besides that, some guns don't like their port opening! The 35 may just be one!! 4mm seems big, usually less than three on most factory guns ! U. U. Edited March 3, 2013 by Underdog Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted March 4, 2013 Author Report Share Posted March 4, 2013 Apparently years ago you could get him on a fac running upto 15ftlbs I'm not interested in that tbh just getting it up to the legal limit where is should be when new as the internals are in gwo and mostly new Quote Link to comment Share on other sites More sharing options...
fenboy Posted March 4, 2013 Report Share Posted March 4, 2013 As I said try adding a little pre load to the spring one washer at a time see if it starts to go up Quote Link to comment Share on other sites More sharing options...
NIGHT SEARCHER Posted March 4, 2013 Report Share Posted March 4, 2013 (edited) I would try a new spring in it. OX spring. Titen springs are very good. Or put a new HW spring back in. And put a new piston seal in it whilst it`s in bits. Have a look at www.airgunpellet.co.uk for springs top hats tuning bits. Ox Spring on there are £11.00. TITEN Springs are £13.00. Box springs are £13.00. They do piston weight`s. Top hat`s and washers. Edited March 4, 2013 by NIGHT SEARCHER Quote Link to comment Share on other sites More sharing options...
johnbaz Posted March 8, 2013 Report Share Posted March 8, 2013 Hi The first batch of HW35's that were brought in to the country had to go back as they were over the legal limit!! The brazing problems are well known and one or two people have repaired their guns by using some compound similar to liquid metal and then cleaning the excess with an emery cloth tool, power was much beeter afterwards.. If I can find the thread (can't remember which forum it was on!), i'll post a link so that the OP can have a read through.. Cheers, John PS, I have four HW35s and can honestly say, they are among my favourite rifles B) Top- 1976 HW35E Bottom 2002 HW35K 1979 HW35 1972 HW35E stripped and ready for a refurb (it was 'til the missus left it in a cold conservatory through winter,it rusted to hell ) The first three of mine shoot very nicely, dunno about the one in bits as it was in bits when I bought it Cheers, John Quote Link to comment Share on other sites More sharing options...
bruno22rf Posted March 8, 2013 Report Share Posted March 8, 2013 Check that there is nothing in the barrel then cock the rifle and put your finger on the end of the barrel-push down hard and fire the gun-wait a couple of seconds before moving your finger-if you do not get a hiss of air then your breach /piston seal is suspect-replace them both.BTW it is easy to "nick" the o ring as you push the piston into the cylinder. Quote Link to comment Share on other sites More sharing options...
secretagentmole Posted March 9, 2013 Report Share Posted March 9, 2013 (edited) Ox Spring on there are £11.00. TITEN Springs are £13.00. Box springs are £13.00. They do piston weight`s. Top hat`s and washers. Welsh Willy kits are supplied with a Titan spring! His problem does sound like he has a bad brazing on the barrel! Could be worth giving Woodfield Guncare (the home of the aforementioned William who is Welsh) a ring and seeing if he would help, chances are as you bought a kit from him he would do it for very little plus return postage! Edited March 9, 2013 by secretagentmole Quote Link to comment Share on other sites More sharing options...
NIGHT SEARCHER Posted March 9, 2013 Report Share Posted March 9, 2013 Welsh Willy kits are supplied with a Titan spring! His problem does sound like he has a bad brazing on the barrel! Could be worth giving Woodfield Guncare (the home of the aforementioned William who is Welsh) a ring and seeing if he would help, chances are as you bought a kit from him he would do it for very little plus return postage! Yep I have had a look on the web and the Brazing is a very common problem. Loads have the same problem and are all saying they are only doing around 6 ftlb. A lot have used J B Weld to seal the joint. Sounds like a Gunsmiths job to do it right. Or has you say see if Woodfield guncare can sort it out for him. I had never heard of this before but i have never had a HW 35. I have had HW 80s 77s 97s all were very good quality and never give any problems. I must say i am a bit surprised at an HW with such a bad problem. Quote Link to comment Share on other sites More sharing options...
stu nesling Posted March 12, 2013 Report Share Posted March 12, 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 :( Quote Link to comment Share on other sites More sharing options...
darren m Posted March 13, 2013 Report Share Posted March 13, 2013 silly question -- but are you sure your reading the chrono correctly , putting in the correct weight etc Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted May 10, 2013 Author Report Share Posted May 10, 2013 (edited) Long time no read. Yes just re chrono'd it. using 14.5 grain pellets from Pax Guns, I just re fitted a new piston seal and new breech seal. Pre New seals with tuning parts results were: 7.34, 7.32, 7.49,7.93. After New piston seal and Breech seal results: 7.65, 8.02, 7.89, 7.48, 7.44. Obviously I need to give it a good few pellets through it hopefully put a hundred or so tomorrow and see what I get. I hate the thought of chemical metal seems a bodge but hey if it works it works. Guess I'll be heading to screwfix tomorrow for some carb cleaner!! Will keep you updated with results If by some outstanding miracle it turns out to shoot nice at an FAC it wouldn't bother me as I'm currently going through the procedure and could get it added but TBH it would be nice to just get a nice decent grouping nice smooth shooting 10 or 11 ft. I have told Will where I got the tuning kits at woodfield but will try and run a few hundred through tomorrow (although its a busy day tomorrow building Land Rover diffs up) hopefully it increases and stays up but tomorrow I will know. If it doesn't work I may be throwing it in the scrap bin!!! Edited May 10, 2013 by jai_landrover Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 11, 2013 Report Share Posted May 11, 2013 I just don't see how a breech leak or cylinder leak would cause it to be so low without a blatently obvious hole showing! This gun in my opinion is a German market spec; I would love to know how long the cocking rod is in the piston and how long a UK spec one is! 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 I have thought of this also..... but I have no comparison to compare mine to. I do have a serial number tho Quote Link to comment Share on other sites More sharing options...
Underdog Posted May 11, 2013 Report Share Posted May 11, 2013 Can you scale your piston off this image? http://www.airgunspares.com/store/category/64/516/WEIHRAUCH/HW-35/ Has a piston head adapter been fitted? If so could it be robbing volume?? Is the cocking arc of the barrel seem short?? U. How big is the transfer port, the old ones were 4mm! 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) Can you scale your piston off this image? http://www.airgunspares.com/store/category/64/516/WEIHRAUCH/HW-35/ Has a piston head adapter been fitted? If so could it be robbing volume?? Is the cocking arc of the barrel seem short?? U. How big is the transfer port, the old ones were 4mm! U. Piston head looks to be normal later type. I have measured the piston length overall its 150mm and the end of the piston to the end of the cocking pin is 30mm. It looks to be in keeping with the picture tbh. Pulled it apart and sealed up the cylinder holding my finger over the transfer port no leaks apparent this would confirm what I had previously done with the piston holding pressure with no drop. So I assume that its all fine. Now to the transfer port. i said it was 4 mm but only thing to hand is a 3.5mm phono socket without going into the shed and it doesnt fit so its 3mm. Confused now........................... Edited May 11, 2013 by jai_landrover Quote Link to comment Share on other sites More sharing options...
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