GTA
Airguns by Make and Model => Hatsan Airguns => Topic started by: SpiralGroove on February 11, 2015, 04:02:10 PM
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Hey Guys,
Made a minor change (I thought) to my Hatsan 95 (.177 cal.) and now it's all over the place and loosing power? :o
What I changed:
- Tightened the Pivot Bolt on the barrel so it would stay in horizontal (in place) after cocking, for loading. Before, the barrel was loose and could flop easily up/down after cocking. After tightening, the barrel is very firm/solid and cocking is a little more difficult because of the increased friction (not bad at all though).
Went to shoot and noticed the poi was considerably higher? Started messing with my scope to adjust down (went about 60 clicks) until I decided to remove scope from 1 piece mount and remove any shimming. Removed (2) rear shims. Shot again and the gun shot much lower (even after adjusting the scope back up about 45 clicks). The gun still was relatively inconsistent though. This had previously been my most accurate springer. ???
Went to crony it and noticed it was shooting CPM (7.9 gr.) at 641 fps, shot CPUM at 560 fps? The gun previously had been shooting the CPM at over 1000+ fps and the CPUM about 950ish fps. Next, I put more pipe tape below the breech seal thinking the adjustment to the pivot bolt must have changed the barrel fit to the transfer port. Then reshot and notice a marginal increase in power, but nothing close to normal.
Sounds like I have a bad piston seal or mainspring causing a large ES and POI changes, and was just a coincidence with the pivot bolt change? Lastly, I had been also trying my Son's Air Force pellet seat-er on this gun because the bore is very tight. Unseated pellets shoot about 50 fps faster -> do to increased friction?
Didn't expect this can of worms and just trying to get any other thoughts before I open her up :P If I need to, this will give me an opportunity to add a Nylon Top Hat to the spring inside the piston ;)
Kirk
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Have you checked the breech seal?
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Assuming the breach seal is still good, maybe try loosening it back to where it was? Perhaps tightening it shifted the left/right alignment of the barrel to the cylinder orifice?
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..................... Tightened the Pivot Bolt on the barrel so it would stay in horizontal (in place) after cocking, for loading. Before, the barrel was loose and could flop easily up/down after cocking ................
oh my goodness , you don't hold the cocked barrel with your freehand while loading with the other ?!!
Rick would be disappointed . :(
hehe
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Maybe loosen it back to the same position and add a shim to one side ? !
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1) BenjiHunter, after cronying, the first thing I did was double check the breech seal ;)
2) packard8, Yes -> I will look into that before pulling out the spring compressor :D
3) ??? Oh Well .....
4) Pappy, I'll look into that too.
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piston seal
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It sounds like you might be having the same issue I do. On mine there is slop between the pivot bolt and the hole in the barrel. You can move the barrel up, down, in, and out just a fraction of an inch. Depending on the position it locks up in you could have a good breach seal but not be getting a good seal. Another Problem with tightening the snot out of it is that the washer will crush/pancake and you will end up with a loose barrel again. I'm new to break barrels but this is what I found with my 95.
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I had my 95 .25 apart to check for play in the barrel pivot and detent lock, pivot ok on mine but has play in the lock allowing very slight up and down movement. the gun had been grouping a ragged hole @ 10 meters, afterwards it would not group at all. one problem is the rear stock mount screw is a bad design for a consistent attachment. remounted the stock and let the barrel loosen and its back to shooting 1 ragged hole. another project for me now is to make a pillar/post for the rear stock mount.
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I guess it makes since that you anchor the action solid first before the fore stock!
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Hey Guys,
I'm still not sure what the issue is? I don't think it has to do with the rear stock screw (kept very tight at all times) or tightening the snot out of the Pivot Bolt (which I did), but don't have the answer either :o.
Before I do anything, will replace batteries in my crony and the HF lights that allow it to work in my crawl space. The F-1 has given me some false readings in the past -> so I want to rule that out first. Thanks all for your input, I will report back what I find.
I've tried to buy some barrel shims from Hatsan USA, but they're not communicating we me anymore, after my somewhat unflattering review of the Galatian on the GTA or something?
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check your piston seal.
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Thank Blackfocal..............will do ;)
If the crony says anythig less than 850 fps w/CPM (7.9) it has to be the piston seal or mainspring :P
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Thank Blackfocal..............will do ;)
If the crony says anythig less than 850 fps w/CPM (7.9) it has to be the piston seal or mainspring :P
could be that junk from northwoods... ::)
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Hey Boomer,
That NW purchase was a pretty sweet deal; (2) Hatsan 95's for $60 each ;)
Looking at this as a minor bump in the Hatsan road giving me a chance to experiment with more mods & understand the gun better :D.
Kirk