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PostPosted: Sun Apr 18, 2021 9:13 pm 
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Joined: Mon Mar 28, 2016 1:32 pm
Posts: 160
Location: Edmonton
At least... I think it's a lock up issue. Wondering if anybody has had this happen to them and what you did to fix it?

Both HW98 and HW80 would perform fine for like fifty, even a hundred shots or so, but all of a sudden, send a pellet way off expected POI. All deviation is elevation/vertical. No apparent deviation on windage so I'm inclined to say it's the lock up, not the scope. Also, 98 is sub12 while 80 is FAC but happens to both. Something like 3" low at 25m and an estimated 10"+ low at 50m. Sometimes, the following shot would return to expected POI leading me to think I just held inconsistently. At other times, the next few shots would keep the new POI and even group reasonable well. So I re-zero per the new POI. And then, several shots later, the POI would shift up by the same amount! So I re-zero again... I've also tried chronoing the rifles when they do this and get like single digit to less than 15fps spreads on like a 10 to 20 shot string. So I don't think it's the breech seal.

Per what I've read online, I've set the pivot bolt torque so that the rifles, when cocked, would hold the position of their barrels without the influence of the mainspring. I also tried tighter than that on the 98, where it was noticeably harder to slap open, but ended up just galling the area when breech block touches the shims. Must have been tight enough to push all the grease out the side of the shims, hence the galling. I have since replaced the shims and reduced the torque on the pivot bolt to where the barrel just stays in place when cocked. For the 98, also removed the chisel detent and polished it with autosol (also polished the opposite detent on the comp tube side). Also degreased the hole, spring and detent of the factory grease and relubed with high% moly grease. The detent should be able to move back and forth more smoothly now. Still getting random POI shifts on the 98 so didn't bother touching the detent on the 80 as I don't think it'll help.

And again, I'm inclined to lock up issues as I don't have this problem with my fixed barrels.

Could the spring pushing the detent be... too weak? Seems silly but I don't know what else to suspect.

What's going on here? Open to anything.


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PostPosted: Mon Apr 19, 2021 4:20 am 
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Joined: Tue Feb 18, 2014 7:24 pm
Posts: 883
Location: Dowling ,ontario
Here’s the same reply I have on the GTA . Maybe it will help members here. My latest R9 purchase do the same thing. If I let the rifle fall onto the bag when rested my poi would be an inch low at ten meters. I found the hole where the chisel detent is located to be quite rough. I polished it out using some 800 grit Emory cloth ( go slow ) until the chisel was free to move in the hole. The rifle has been consistent since . Also don’t forget to lube it . As for the barrel fork tension I like mine loose, just enough that I don’t have any play side to side.

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PostPosted: Mon Apr 19, 2021 5:33 am 
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Joined: Mon May 06, 2019 4:07 pm
Posts: 430
Maybe you need to oil your gun? Could be your pellets too.
Recoil to much for your scope? Loose stock.screws?
Loose scope mount screws?


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PostPosted: Mon Apr 19, 2021 12:37 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 7675
Location: P.G. B.C.
Hobbyman2007 wrote:
Here’s the same reply I have on the GTA . Maybe it will help members here. My latest R9 purchase do the same thing. If I let the rifle fall onto the bag when rested my poi would be an inch low at ten meters. I found the hole where the chisel detent is located to be quite rough. I polished it out using some 800 grit Emory cloth ( go slow ) until the chisel was free to move in the hole. The rifle has been consistent since . Also don’t forget to lube it . As for the barrel fork tension I like mine loose, just enough that I don’t have any play side to side.


Sounds like that worked well, Hobbyman2007. I noticed with the HW98, every now and then, a pellet would fall out about 2" low at 20 yards, with seemingly no reason. The HW97 does not do this.
I kinda figured it was due to lockup, but have sold the rifle so cannot re-check. Next time I see the fellow, I will mention this to him.

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Daryl


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PostPosted: Mon Apr 19, 2021 1:13 pm 
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Joined: Mon Mar 28, 2016 1:32 pm
Posts: 160
Location: Edmonton
Thanks Denis. Yeah I saw your reply on GTA too. I didn't take sandpaper to the hole yet. Just cleaned it up of any potential factory grit in there. Didn't seem like it needed it. I stuck a Qtip in there then pulled it out to see if anything catches the cotton. Seemed fine. Only the detent was polished, and of course, all parts relubed with high moly grease. One guy in GTA suggested loosening the pivot bolt. Will try that first and if the random low shot still happens, I'll see about smoothing out the hole further. Thanks!


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