Problem with HW97K

Discussion in 'Hunter (HFT) & Field Target (FT)' started by Alex, Apr 15, 2013.

  1. Alex

    Alex New Member

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    Hi all,
    I have a problem with my HW97 and I'm running out of ideas what might be the reason.
    My setup: HW97K left hand factory sporter stock, .177, 12ft/lbs, V-Glide bought 07/2012, Steve Pope trigger, softer spring in the cocking lever latch, aluminium handle on the cocking lever.
    Machined aluminium 11mm to weaver rail with 0.3 ° drop comparable to the Steyr rail, low B-Square mounts, Bushnell Elite 8-32x40 with Bushnell custom shop Mil-Dot reticle.
    The V-Glide has some dampening material in the front of the piston, acc. to S.P. this was newly introduced around the time I bought my kit.
    After fitting the V-Glide in 08/2012 and a short run-in the HW performed flawlessly and with constant velocity and superb accuracy with my testet lot of JSB 8,44gr 4,53. The rifle is capable of 20mm groups at 47m at ideal conditions, probably better, but I'm the limiting factor. I use dots and I didn't remove the caps on the turrets of my bushnell for about 3 months, perfect. The HW shot time after time spot on. End of october with temperatures dropping below 10 ° I began to realize shifts in the POI. First from one training to the next, then during one training from one shot to the next. The shift is vertically and to compensate I have to make about 20 clicks up or down. Its always this shift, not more or less, not a process of several shots and small shifts. Always one shift, about 35mm off at 40m. The V0 is still constant and OK. The ballistic curve is not effected. After clicking and zeroing in again all my holding points work as usual. Until the next shift...
    I've tried the following to find the cause, I've disassembled the rifle and inspected everything, at this time I had about 8000 shots on the V-Glide and everything looked like the day I first put it in the HW. Absolutly no visible wear. I've stored the HW cold so there's no temperature difference from storing to the range. I replaced the Bushnell with a brand new one. I loosend and tightened the bolts on mounts and rail on the range before shooting. I moved the rail forward on the prism so that the rear clamping of the rail reaches over both trigger block and main system tube. I've moved the mounts on the weaver rail from furthest apart to closest. I bought a new one piece Diana mount with 1mm drop. Today finally we had a nice spring day with temperatures up at about 18 °, same problem, after it happened, I tapped the back of the system using a piece of wood and a hammer. No change, tried the same from the muzzle side. No change. My last idea was that there might be a shift between system and stock which might affect the tension on the trigger housing. After tapping today without anything happening I guess this is not the problem either.
    Please help! A bit desperate here, I find myself thinking about a TX200...
    Regards Alex
     
  2. Brian.Samson

    Brian.Samson Allowed in Sales Staff Member

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    Hi Alex, welcome to stb

    Just a quick question, when you get the variation have you tried testing the output over a chrono?
     
  3. Alex

    Alex New Member

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    Yes, no change. And as stated above, the ballastic curve is identical once I adapted with the turret.
     
  4. skires

    skires Well-Known Member

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    Alex

    I feel for you fella I really do. This is virtually exactly like the problem I've had over Winter.

    I hate posting about it as no one wants to hear excuses ... me included but this is driving me crazy.

    My case ... HW77k with V Mach kit fitted ... in a Paul Wilson style FT stock ... but I'm shooting HFT.

    I could go down the range and zero and practice at 35 yards and put AA Field 4.52 8.4gr on top of each other on a decent still day. I've had c-t-c of 6mm. At my max of 45 yards it's done 12mm. Then suddenly the poi will move ... always vertically ... by a good inch. It's over 20 clicks on my scop but that is 1/8th and at 9.5x.

    Once I've rezero'd the poi's are all the same for all my aim points. The whole thing just moves up or down. When I've turned up at shoots and the zero has held ... and then held for the 30 shots through the course I've shot several over 55 / 60 scores ( I'm not saying I'd get that all the time ... these have been on days with sensible wind ). I've also had courses where I'm 22 out of 30 targets through the course and I've scored 43 out of 44 at that point ( so missed 1 target ) ... and then just cant hit a target ( and I mean a 40mm kill at 35 yards ) on the next 8 and I've ended up with say 52 / 60 ( 7 misses out of the last 8 ). Go back to zero range and check and yup ... the zero has moved 25mm or more vertically. I've scored 58 / 60 one day and the very next shoot in very mild wind I've scored 42 / 60 on a similar course and virtually all my misses are vertical by quite some way.

    I thought it was the scope ... so changed that. Mounts ... changed that. Pellets ... changed them but went back to AA Field. I then noticed that the profiles of the AA Fields changed depending on batch and I was convinced it was that. So I made sure I bought the same batch and then measured them in a Bic tube. Still this vetical leap occurred.

    I was then convinced that it just had to be me. So I made sure I was holding the rifle exactly the same and releasing the shots exactly the same. I will put pellet after pellet in a tight group at 35 yards ... and then just suddenly ... poi has jumped over an inch ... and then I'm putting pellet after pellet in that new group.

    Just to totally fry my brain ... when the temps dropped to freezing I noticed that the power went up ... from about 780fps to 815fps. So I stripped the gun and tuned it down to 765 warm and 800 freezing. However the vertical jump kept happening, even if I took the gun to the woods and left it in the freezing cold for half an hour and then zero'd. I would zero in the cold and then the gun would shoot accurately but then it seemed as if after a number of pellets ... say 20 or so ... the poi would jump back down ... so I was convinced that the gun was getting cold and the fps going up ( and the poi going up ) and then after so many shots the gun had 'warmed up ' internally and the fps coming back down and the poi coming back down. I must admit that I've not taken the chrono to the range and tested this out on the chrono. To confuse this ... I took the gun to the range a few days after I'd shot the World's and had a disaster on the 2nd day. The temps were much warmer in the woods back home that day ... say 8 degrees instead of freezing. My first 5 pellets went through the bull at 35 yards and all inside 10mm. So I presumed it may have been the temp at the World's ( ie the freezing temps in the early start on day 2 had sent the gun high and the poi had gone high ... all my misses were high ... even at 40 yards plus where the poi should be below the cross hairs, I was missing above the cross hairs. I was too cold to mess about on the zero range that day and virtually went straight on the course. On day 1 I'd put about 60 pellets through the gun on the zero range waiting to shoot the afternoon. So wondered if the gun had 'warmed up' as I'd seen at home, as my misses on day 1 were all sideways due to mis reading wind and I was happy with a 52/60. On day 2 ... straight on the course ... I dropped 16 points in the first half of the course and just 4 on the second half and I shot all the 2nd half kneeling. So I wondered if the gun had 'warmed up ' after those first 15 pellets and had then returned to zero ? ). However, after shooting for a while in the woods at 8 degrees the damn jump came again and my pellets started hitting over an inch high. So was it the cold ... or is the cold just adding another variable ... ie there is the original jump and also something happening with the temp? Brilliant.:D

    I'm not the greatest shot but I'm not bad with a springer but I feel I've wasted most of winter driving around the Midlands not knowing whether I'm missing because of me or whether the gun has thrown another wobbler. I'm seriously considering giving up on the springer and using one of my pcp's.

    So what am I going to try now? Well, like you, I've thought that this may be an issue with the action moving in the stock ( like you I've been checking all bolts all winter ... I even thought at one point it may be the Venom silencer/end catch or the cocking aid on the underlever ... so I got them off ... cleaned them up and loctited them all back on with new grub screws ). When I take the action out of the stock the large hole where the front trigger pin lug sits ( the lug that screws in to the end block through the main tube and the anti bear trap sits under ) is not perfectly round. It looks quite rough. So I'm thinking it may be slight movement there ( I haven't tried hitting with wood like you yet ). So Paul James advised me to wrap the lug in clingfilm and put some car filler in the stock hole and push the lug in, so that the fit there will be tight. So I will try that. My other option to see if it is this stock is to just use one of my other HW77 stocks for a while and see if it goes away.

    I'll tell you what is in the back of my mind ( I'm sorry this has turned into a mammoth post but this seriously has fried my brain this Winter ) ... when I stripped the gun to tweak the power down ... the rear guide on this V-Mach kit is black plastic ( delrin ? ) with a metal rear end stop. The guide is tight when I push it in the spring. When I used to tune 77's myself and used to get a local guy to make the guides I had them made a 'slide' fit but not tight. I just can't help thinking this is too tight and that the spring may be catching on it at times and then at other times it's fine. I've not actually taken the chrono to the woods and shot a few shots and noted the poi and the fps ... and then tested the fps again as soon as the poi moves. I should do that to see if the change in poi is related to change in fps ... but you have said that yours doesn't seem related and like yours ... the poi curve through the range stays the same ... the whole lot just moves vertically.

    I've not really helped you there fella I'm afraid ... but at least you know that you are not alone.:D

    Good luck

    Col
     
    Last edited: Apr 15, 2013
  5. Alex

    Alex New Member

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    OK Col,
    I feel a little better now... :D
    At least somebody can judge that I haven't gone completely nuts.
    What you discribe, is exactly what I'm experiencing.
    After the move my rifle riflle will put pellet on pellet again, I just can't predict when the next jump will happen. And as it happened yesterday at 18-20 °C, I was afraid it was only coincedence that the problem first started beginning of winter. If it were the springguides, I think we'd have bad overall precision or V0, but our rifles perform well, just hard to tell where to pellet goes. :rolleyes:
    Regards
    Alex
     
  6. poison dwarf

    poison dwarf BANNED

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    common denominator here would seem to be the v-mach kit. Home or factory fitted?
     
  7. Alex

    Alex New Member

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    Home fitted V-Glide. But the V-Glide comes completely preassembled and prelubed.
    I've grown up with HW springers and did a few strips and tune ups. Before I went with the V-Glide I shot the rifle with the V-Mach in 7.5J for 1 year. Never a problem. I guess I give Steve a call.
     
  8. IvanM

    IvanM Member

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    Picking up from your last line. I have a TX 200 that does exactly the same thing. Its taken me over a year and four scopes before I've gotten around to considering the gun as being at fault. As an addition to other things that have been touched on in the thread; I have also swapped the spring guide from (relatively) loose fitting metal to tight fitting delrin and back again and also a looser fit delrin, changed the spring and piston seal and for good measure the breach seal. I've ruled out the bad lock up/seal issue and loose barrel too. I have also swapped the piston out of my Prosport for the one in the TX both being short stroke alloy jobs: made no difference. My TX is in a Ginb and that is now the main suspect.

    Low temperature seems to be involved in my case too and although I also get a power increase, its nothing like enough to give the POI shift involved. Mine also moves fairly precisely between two zeros. I have recently witnessed the shift occurring, once with my Burris on, once with my Nikko on. In both cases it made the shift to the other zero in something around 20 shots, then stabalised. It usually moves back within a few days. I have always associated this with low temperature but I now have a thermometer on the gun and it has shifted when temperatures have been fairly stable at around 9 - 11C. This was one of the ones that occurred while I was on the zero range. I have only one incidence of this though and although it shifted after I'd been shooting for 20 minutes or so, the gun had been in the car boot overnight so temperature could still be playing a part. Whatever the cause is, in my case it has started happening a lot more often recently.

    I recently spoke to Nick Murphy about this and he is familiar with the problem but doesn't know what the cause is but barrel or stock are what he puts in the frame. I was also relieved to know it wasn't me going off me trolley :) . Though if NM doesn't know the answer, I doubt if I'm ever going to find it. :eek:o Amusingly, I'm now desperately trying to get my V-glided HW77 in an FT stock and ready for the first GP :D The TX is now with a mate who also has TX's including an ally piston modded one. I'm hoping that maybe a fresh pair of eyes will see something I have overlooked.

    Springers eh? I love em but they don't always love me back!

    Sorry this is of no actual help Alex and worse, I seem to have put your TX escape route in doubt.

    ATB

    Ivan
     
    Last edited: Apr 15, 2013
  9. skires

    skires Well-Known Member

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    Mine is a V-Mach stage 1 kit ... home fitted but again it comes all pre lubed and I just dropped it in.

    Just to add that I've tried to replicate this to see if it is me. I've tried tensing up to see if that does it ... I've tried snatching the trigger. Holding the rifle really tight and all other sorts of weird stuff. All of these make my groups poor but there is no way I can replicate the groups being very good but moving a precise amount vertically and then moving a precise amount back again. So I'm convinced it's something on the rifle/stock.

    On my FT style stock there is only one pin at the trigger end. A large bolt that goes through the stock and fixes in that lug. No rear trigger pin as there is no trigger guard ... it's built in the stock. I used to have this very same action in a self made custom thumbhole stock but that stock had a trigger guard and two trigger pins. I used the gun in that stock for about 2 Winters and I can't remember it ever losing it's zero. I just turned up week after week and the zero would be good. So maybe that is suggesting that it's something to do with this Ft stock ... However, since taking it out of that thumbhole stock the action has had this more recent V-Mach kit fitted. So that's telling me it's either this FT stock or the V-Mach kit? Or it could be some 3rd option.:D

    I suppose it's logical to put it in that old thumbhole stock to see if that eliminates the problem as that will prove it's something to do with that FT stock.

    Col
     
  10. IvanM

    IvanM Member

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    Interesting that. My Ginb stock has the same arrangement, bolt and trigger guard wise and NM mentioned to me that he knew of one instance where putting the action back in a standard stock cured the problem. The holes for the front bolts on the Ginb are also misaligned as apparently many are. I've tried shimming the metal yoke to compensate but this, as Paul L (Platitude on here) as pointed out, is not a good solution as it puts another stress into the system. He has suggested just fixing the one bolt (temporarily) that is correctly aligned and seeing in there's any difference. Another mate has also loaned me a stock that mounts with the two bolts through the trigger guard to try so we're on a similar track there.
     
  11. Conor

    Conor Never been banned from sales Staff Member

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    Burn, melt, crush, destroy, eliminate and deactivate all spring guns! :p

    The work of satan himself :eek:
     
  12. wyn

    wyn New Member

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    Would the aluminium handle on the cocking lever be causing things to shift about a bit at different temps.
     
  13. skires

    skires Well-Known Member

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    Ivan

    You've got me thinking now. The front pins on this FT stock must be slightly misaligned. If I take all the pins out I can set the action in the stock bang on centre and square. I can put in all the pins ... 2 front and the 1 at the rear and screw them up so far and it remains all central and square. When I really tighten the front ones the action twists slightly and is then slightly off centre and square. So I have to make sure I line up the scope ret with the action and not the stock.

    I think this is going in that other stock to see if this goes away. Shame as I love this FT stock as it makes sure my head is in the same place every shot.

    Col
     
  14. Alex

    Alex New Member

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    True! :D But I like the damn thing nonetheless.

    As all other thing have been replaced my suspicion is also the stock or the barrel. What else?
    The original triggerguard is also deformed. The rear attachment of the system in the stock with the zinc die-cast trigger guard is a weak spot in my opinion. I'm thinking about a Rowan brass triggerguard. I don't know how the FT stocks without the rear trigger pin can produce good groups. If I don't set that small bolt at the right tension, not completely tightened and secured with Loctite, the grouping is horrible. And there is little air around the front bolt. I thought this was the reason, but something should have happened when I tapped the system yesterday.
    About the barrel, how is the TX200 barrel fixed?
    I also thought about the 2 welding spots that fix the barrel block in the system!?

    Anybody tried a 77/97 system in an alu-match stock? Some friends suggested so, but I'm afraid if I put a steel system in an alloy shaft it'll make things even worse with the 2 metals expanding differently in changing temperatures.
    Alex
     
  15. paul4be

    paul4be Why do I bother????????

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    Might it be worth trying to get hold of/ borrow an original synthetic 97 stock to try the action in??
     
  16. Adam

    Adam Active Member

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    Very interesting. I had a complete 'mare at the York NEFTA Hunter shoot on Sunday, with my old lazaglided 77K. I took the trigger unit out last week to fix a jammed safety catch, and had trouble lining up the front two stock screws. This stock is a CS800 with an extra deep forend, so a semi FT type, but it does have the single bolt through the lug, and no screw in the rear of the trigger guard. Now I got one bolt properly aligned but couldn't get the second one. It was ok before the strip. So on Sunday, after taking the rifle strait from the zero range to the course I noticed that bolt had come a little loose. Tried to tighten it but it would just have stripped the thread if I did it any more. I started off pretty well, knocking down quite a few, but then the wheels came off big style. But the wind was so bad I didn't even think about that screw. I bet it was that, as the latter half of the course I was convinced most of my shots were going very high.

    My other main springer, a 97K with a regular V-Mach kit, in a GinB stock, had a zero shift issue on the practice range the other week before the springer championship at Anston. That time I simply tightened up all 3 screws, a quarter of a turn, and it was back, bang on zero. They weren't loose, but I'm sure that little extra tightening did the trick. The GinB stock however seems to have spot on holes. It's the CS ones in my experience that are a bit off.

    Both the above stocks have no screw into the rear of the trigger guard but I can't for the life of me see why the lack of a screw into the trigger block is going to affect anything, IF the action is securely fixed in the stock by the other bolts.
     
  17. IvanM

    IvanM Member

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    The TX200 barrel is held on with a great big nut (17mm I think it is) and that's thread locked. It should apply even pressure assuming everything's true. The barrel shroud is a bit more of a mystery though as that is spaced and I think glued. I know my nuts tight (insert own gag here :)) but there's no way of checking the internals that hold the shroud and apparently its an absolute bugger to disassemble.

    I agree with Adam that on the TX or the HW's its hard to see what the lack of the small bolt itself will do. However, in both cases the trigger guard does act as a spreader when it is secured with that bolt, balancing and directing the load. Whereas the one bolt system puts all the stress in one spot and may also have a less predictable and repeatable fit, as its fairly intuitive when to stop tightening against the metal trigger guard, less so the one bolt into the wood system.
     
  18. plattitude

    plattitude Active Member

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    Meeting Ivan at the club this evening for a play with his rifle, had it shooting at home today but can only get 18 yards but 30 shot can be covered with a 5p, this is with one front screw fixed and the other removed, also did around 30 shots through the crono inbetween the ones at my card so 60 shots in total, I am sure Ivan will give it some hammer between now and the weekend (GP1) and post his findings.

    Paul
     
  19. skires

    skires Well-Known Member

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    Looking at this again last night ...

    There is room around this lug in the cut out in the stock. When the stock is fitted there is also a small gap between the back of the end of the action and the flat back of the stock ... so there is the possibility for the action to move. The only thing that is stopping it from moving rearwards is the downwards pressure of the round maintube on the round machined out stock.

    So it does seem sensible to do as Paul suggested and fill the gaps around that lug and also at the back.

    Do I really need that lug? I don't have the anti bear trap fitted.

    I have another 77 that is an old Venom Tyrolean walnut sock. On that stock there is no cut out for the lug and it uses a HW80 style long pin that goes straight through the stock and into the end block where the lug normally screws.

    So can I not just fill that entire rough lug hole in this FT 77 stock and then drill straight through the filler with the same size as the pin hole ( so just extending the existing pin hole )? I can then use a longer pin that goes straight through the stock ( and new filler ) and into the rear end block.

    I then put some filler at the stock flat back end to make up that gap.

    Col
     
    Last edited: Apr 18, 2013
  20. Alex

    Alex New Member

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    As mentioned before I tapped the action with a block of wood and a hammer. Back and front and nothing changed. Still I'm suspicious about the stock.
    Col, I think that's a good idea you have there, I also removed the bear trap.
    Next I will bed the action in epoxy. I need the rifle 27-28. of april for 2 Tourneys, I'm afraid a Rowan trigger guard won't make it in time to Germany?

    Cheers
    Alex
     

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