Hatsan AT44S-10 Long in .25 cal

[Rallyshark]

I think you still have stuff all out of whack there.  There's no way that reg should need to be at 180 bar.  It should be around 130-140 tops I would think.  Something isn't right, if you have to set it at 180bar to get 35fpe out of a .25?  I would mark the cylinder, so you know where the opened hole on the valve is, and make SURE it is pointing straight up when the cylinder is in the gun.  Also, make sure you aren't getting any leaks at the probe or barrel o-rings.  Better yet, take the reg out, and see what the max power of the gun is.  If you can't get it in 50+fpe range without the reg, something isn't right(assuming all of the mods are correct and lined up).  One more thing... Is this an AT44 short or long, and is it a QE/have an LDC?  The loud report tells me it likely isn't tuned correctly(too much HS).  For example: Bob's mods done to an AT44 long will do 35fpe in .22 with a reg setting of 130bar(Huma). 

The good thing about the Huma regs is that they are marked, so you have a pretty good idea of where they are set.  They also come with a different plenum for .25 vs .22/.177.  I still say to put that big o-ring back on the valve and see what the gun is doing without the reg.  That will take the reg out of the mix, and give you a good idea if the gun is working like it should otherwise.

[8upwithairguns]

Hey Rallyshark..i just ran a 18 shot chrony on regulated gun. Average 748. SD 4.84. Spread 21. I prefer my SD in the 2s but it's still the best so far on that gun. Thought about taking reg out and running chrony but I think im just gonna leave it alone. 18 shots is ok from what I've read. Also..i did dry fire sound test indoors with a phone app and it's at 72 dec. My Flash is at 74 and i always considered it too be pretty quiet for a .25. I think I may just be spoiled to my AT44 .22 and Gauntlet .22s noise. Also when I chrony I'm shooting into a big oak tree at 10 feet so that may be causing perceived loudness. Anyway thanks for all ur great advise. I bought some more 6-32 allens and plan to do Bobs mod on my AT44 .22 next. Not that I need more power but for shot count. Planning on porting all to 11/64". Guns currently a paintball buster at 50 yds.

[8upwithairguns]

P S. Actually on that 18th shot I think I may have fell off reg. It was 737. So my SD and Spread were much better. 125 bar left when done.

[Rallyshark]

P S. Actually on that 18th shot I think I may have fell off reg. It was 737. So my SD and Spread were much better. 125 bar left when done.

As long as you're happy, that's all the matters   You never answered if it was a long or a short AT44?  If it is a long, then I still say something definitely isn't right.  You're running 10-12 shots shy of what you should be getting in a long fwiw.  Either way, happy shooting, and feel free to PM me if you have questions.

[8upwithairguns]

Short QE.

[Rallyshark]

Short QE.

In that case, I don't feel as bad about it,lol!  The down side is, I would have told you to take the reg out from the start had I known it was a short .25.  As a side note, you can get a very good 20 shot string without a reg in that gun at significantly higher power.  You can easily get a great string over 40fpe.  Now that you've opened everything up, it will be a beast without that reg.  It will probably be quieter as well.  I say relocate that reg to a .22 or .177

[8upwithairguns]

Yeah I thought about that as well..hatsan usa has had a great deal on a refurb AT44 .177 pump for $199. But like I really need a third gun this year. I may try that and see how she chronys.

[Rallyshark]

Yeah I thought about that as well..hatsan usa has had a great deal on a refurb AT44 .177 pump for $199. But like I really need a third gun this year. I may try that and see how she chronys.

It should be quite the thumper without that reg in it

[8upwithairguns]

Hey Rallyshark, I should probably just message u direct instead of overextending this thread but here goes. I finally got a chance to try to sight in my AT44 .25 today at 27 and 40 yards. First off, it's shotgunning something aweful. All over the paper. Still louder than i like, but it does seem to hit pretty hard.  Well, i noticed that when i shot it I felt air coming from the magazine. I then confirmed this by taping some TP over magazine and sure enough it's a blowing out the magazine. I think they call that the breach? Am i correct? Anyway, I wonder if one or both of the 2 barrel oring's surrounding barrel port are scalped. As a matter of remembrance, 2 years ago when i was pretty new to airgunning and just received this gun, I was trying to clean barrel and ended up getting cleaning cloths somehow jammed in barrel. I ended up pulling off barrel and didn't really know what i was doing at the time, I either scalped something or possibly left off or lost something. All i know is that after i put it back together, it started being loud and has been loud ever since. Last week when i removed barrel to do the 3/16" drilling i checked the orings but didn't see anything overly obvious. Anyway, your thoughts are very appreciated. Maybe i can end up getting this gun to shoot right eventually. If airs blowing out magazine something soiunds wonky!!

[Rallyshark]

You can replace the two o-rings on the outside of the barrel for good measure, but your problem is likely the one o-ring inside the barrel that seals the probe.  If you got the gun new, there is probably one in the little kit of o-rings that came with it.  Either one will lead to lower velocities, which means that gun should be making more power   Yes, feel free to message me directly.  Also, a little know fact is that the end of the barrel is a cap that screws off, making that o-ring much easier to replace(probe/breech o-ring).  That cap is hard to get off on some guns, fyi. 

[8upwithairguns]

How do u get that cap off without scratching barrel?

[8upwithairguns]

I dont think mine comes off.. just used electrical taped vise grips to attempt. Scratched it bad. Hope it dont leak worse now

[Rallyshark]

I dont think mine comes off.. just used electrical taped vise grips to attempt. Scratched it bad. Hope it dont leak worse now

Like I said, some are very hard to get off, and are glued on.  Scratching that part won't hurt anything.  Just use a spring hook or something to fish the o-ring out, if you can't get the cap off.  I've even used a staple bent into a little hook to get the o-ring out before.  A small paper clip can be made into a little hook too.  Like you said, let's move this to PM, to avoid running off with Mr. Sterne's awesome post  

[8upwithairguns]

Ok, so this is my last post on this thread. I feel that i have abused it enough..sorry Bob. Last night i managed to resurrect a 2 year old sleeping AT44 .25. For the last 2 years, unbeknownst to me it had no breach oring. Air was just blowing out the magazine. After Bob's mod completion, it was still shooting terrible. and very loud. After managing to replace breech oring and other 2 barrel orings, it is a whole new gun. This morning i readjusted the hammer and regulator and managed a very satisfying 27 shot chrony string with 27.8 gr Benjamin's with 745 fps average, 2.51 SD!!, and spread of 10! That's not too shabby in my book. Gun is crazy quiet for a .25 especially since adding 10 stage baffles off Ebay. Also, since replacing breech oring, the magazine cycles so much easier. It was jamming something aweful before. Gotta give a shout out to Rallyshark who has been much help and encouragement through this long process. I'm now planning on doing Bob's mod on my .22 AT44.

[Rallyshark]

That is great!  Bob deserves all the credit for most of us Hatsan tinkerers  waking up our AT44s and other Hatsans.  If not for his exhaustive testing AND documenting the process in this thread, many of us would still be a few shots and fpe behind the curve  

[Jzizzle]

I apologize in advance for bumping such an old thread. 

I want to give a shout out to rsterne for sharing his wisdom on these modification detailed out in this thread.

I performed these mods to my Bullboss in .25 cal and wanted to share my results.
After much testing I am right where I want to be in terms of fps and am surprised how consistent this has become.  This is unregulated! 

JSB 25.39

01. 928
02. 931
03. 930
04. 933
05. 932
06. 932
07. 938
08. 940
09. 936
10. 918
11. 935
12. 935
13. 933
14. 931
15. 932
16. 930
17. 931
18. 930

[GoneShootn]

I apologize in advance for bumping such an old thread. 

I want to give a shout out to rsterne for sharing his wisdom on these modification detailed out in this thread.

I performed these mods to my Bullboss in .25 cal and wanted to share my results.
After much testing I am right where I want to be in terms of fps and am surprised how consistent this has become.  This is unregulated! 

JSB 25.39

01. 928
02. 931
03. 930
04. 933
05. 932
06. 932
07. 938
08. 940
09. 936
10. 918
11. 935
12. 935
13. 933
14. 931
15. 932
16. 930
17. 931
18. 930

That would be a really nice string if regulated. Unregulated, it is amazing! Good work. What does a 50 yd target look like?

[Jzizzle]

Accuracy tests will be another day.  I want to try the Hades too.

[GoneShootn]

Accuracy tests will be another day.  I want to try the Hades too.

I'll be looking forward to them! Good luck.

[Jzizzle]

Happy to report accuracy is spot on with JSB 25gr.  Pretty darn close to hole in hole at 50 yards. 

The JSB heavys both mk1 and mk2 open up at 50 yards which is unfortunate.  Although I haven't adjusted the current tune geared for the 25gr.  This same tune slings the heavys avg 802 fps for 18 shots.  They stacked at 22 yards sight in though.  Perhaps if i give more preload they might group better. 

I have Hades on order as well as some various slugs to try out.   I will likely re-tune for the slugs.  28gr and 30gr on the way.