Hatsan Flash is using too much air?

[Jeade]

Hey all, it's been a minute.

I've got a Hatsan Flash in .22 that I had tuned in beautifully. 36 shots per fill with around 25 of them all bang on at 950FPS with my tester CPHPs. There was a fairly quick ramp from 900 to 950 before eventually dropping back down to 900.
Back in February before starting a new job, I had a little time and dove head-first into this cheap little PCP as a new hobby. Rallyshark was very kind to help me with loads of advice.
I started that new job and the rifle sat for a few months, probably half-filled at 2000PSI. When I picked it back up, accuracy was all over the place. I'd routinely been seeing 1/2" groups at 40 yards previously.
Can't remember what the chronograph was reading, but I believe the shot strings on a full tank were starting around 850ish.
After adjusting the hammer spring a bit, I was able to get that back to 900 at the start, but I now had a gradual ramp to 950 where it'd hang out for a few shots before gradually decreasing. Most of the shots were around 925 on average.
Accuracy still wasn't what it had been. I set the gun down and got back to my exciting life in middle-management.

It's been a few months and I figured I'd give myself a reason to pick up the rifle again, so I bought a GX CS-1. Holy cow, that's much nicer than a hand pump!
But, where it'd normally take three magazines (36 shots) to drop the tank pressure from 2800 to 2200, it was now doing so in close to 12 shots.
Accuracy is significantly worse yet, and the chronograph is showing the shot string start at 900, immediately spike to 950, and then steadily decline to 900 over the course of 24 shots.
This is without adjusting the hammer spring. The rifle's been sitting for a couple months.

Any ideas on where I should begin to troubleshoot?

[Back_Roads]

 Good possibility it vibrated out of adjustment during your last shooting sessin.

[kbstingwing]

Question, is the gun stored in a hot or cool climate, (Garage, closet....)
I owned several flash and Flashpups, I found that checking the barrel grub screw tightness is needed, about 15-20 in-lbs, also the shroud barrel nut tightness, "very snug but not so tight it pulls the barrel out".... ,
make sure to loosen the shroud barrel nut and align the barrel to the set screw dimples on the barrel, snug then tighten grub screws, after tightening the barrel grub screws you can tighten the shroud barrel nut, also check your baffles to make sure they're not damaged from pellet clipping, make sure the air cylinder does not have moisture, rust might develop in the main Valve and could clog the poppet area, this would require a complete rebuild of the main valve or replacement, use Dry air only, install moisture filters on air supply, make sure your Hammer is lubed but not over lubed, sometimes grease can be your enemy, too viscus and it will slow the hammer down, light coat with light moly grease or better yet light oil would be better, it sounds like O-rings are ok, you would notice air or the gun getting louder if the barrel or breach o-rings were bad, also try cleaning the barrel, there might be some crud in there.
well that's about it
Good luck

[Keesbo]

If you first fill the gun by means of 's handpump than there can be moist  in the gun and that can give you valve problems.

You did not store the gun with a cocked hamerspring?

Best is to take it apart and check everything. Best is than reseal it to.

[Jeade]

Alright, I've got everything pulled apart for the first time.
From what I can see where the air cylinder meets the receiver, everything is shiny.
The cylinder walls on the other hand, not so much.
What's the cleaning protocol for this? I'm not sure if Hoppes and steel wool would be hazardous if I thoroughly flushed it with brake cleaner and let it evaporate.
I tend to err on the safe side and that concoction makes me nervous. Hopefully, y'all have a better way!


I did notice a damaged o-ring on the valve stem too, so I replaced that with a fresh one of the correct size.

[kbstingwing]

A little Ballistol and a soft bronze wire bottle brush would do the trick, then a good wipe down with a clean rag, light coating of Silicone oil will keep rust from forming, definitely need a Moisture filter in line from your Air source.
one of these would help.

[Jeade]

Thanks, Kevin. I was a little worried about Ballistol in that cylinder because I’ve had it detonate in a springer once. There shouldn’t have been any more than a very light film, but it did pop! Surprised me to say the least.

As for the in-line filter, I was looking at those last night. Actually, that specific one you linked. Do you know if it’s possible to fill those with a desiccant, or are those units which contain a desiccant purpose-built to hold it? I wasn’t sure how much a little cotton filter would actually help, but I suppose it’s better than a rusty HPA pipe bomb. lol

[kbstingwing]

there's a little bit of room in the housing to put desiccant, you would have to shorten the filter a little, I have a large Water separator filter that I filled with desiccant, it works great, but I only use it when it is high humidity, normally I use the small filter in the house with A/C ON and low humidity, works fine.

[uswood]

Did you get your flash working?