Hatsan Galatian .177 (yes, .177!)

[sactargetshooter]

Well, I have received and played with this .177 Galatian for a few weeks. Don't ask me how I got time to do this because I should not!

First I plugged all but the exhaust port facing up with epoxy putty. Standard trick with most Hatsan guns. Then I turned the hammer spring adjustment all the way clockwise to use the least tension.

I fit a HUMA regulator in it and the velocity spread was impressive, we are talking about less than 5 fps at an average of 850 fps shooting JSB Beast 16.2gr. However, shot count was not so good. Wtih the regulator set to 130 bars, I am getting about 24 consistent shots from one fill.

I have a strong suspicion that one of the reasons is hammer bounce. Although the AT44 platform has a hammer debounce mechanism, I examined the Galatian schematic (exploded diagram) and could not identify a similar debounce mechanism. The factory valve spring is very soft. It is a bit softer than the tension from the hammer itself, making it impossible to fill the gun when the reservoir is empty. I am suspecting that when regulated, it takes time for pressure to build up in the plenum and air is just wasted in this duration. I installed a stronger valve spring and the difference is minor. It may need a much stronger valve spring to shut off quickly.

Mechanically, with the plugged holes on the valve, stronger valve spring and hammer spring tension dialed back all the way, the rifle should be shooting more efficiently compared to factory configuration.

Just yesterday, I decided to uninstall the regulator and guess what? I got 34 (instead of 24) shots, the average was 910 fps. The velocity standard deviation was about 7 fps. The shot string started at about 900 fps, climbed a little to 920, then back to 900. Not bad for an unregulated gun. Reservoir pressure dropped from 200 bars to about 120 bars.

I will test for accuracy next. Regulated, the gun is capable of sub-dime groups at 37 yards if I do my part. This air rifle is a little more challenging to shoot than, say, a Daystate Airwolf. There is a bit more mechanical drama, and the trigger is not exactly in the league of an electronic one! I am hoping the accuracy remains the same now that it is back to unregulated. I still need to practice more to get the most of this rifle!

910 fps with a 16.2 gr pellet is close to 30 FPE, pretty good for a .177 gun I think. The reported BC of these JSB Beasts ranges from 0.036 to 0.042, and that is pretty good even for .22 or even .25 pellets. I understand a .22 rifle probably can get more FPE and even shot counts, but I doubt I will be getting the same velocity with the same BC and still have the same shot count.

[Rallyshark]

If you have the hammer leaning on the valve a little as you say, then the best next move to improve your shot count would be with the hammer spring.  A shorter/slightly stiffer spring that allows you to make that power without the hammer leaning on the valve should be a big help in the air waste department  

[sactargetshooter]

If you have the hammer leaning on the valve a little as you say, then the best next move to improve your shot count would be with the hammer spring.  A shorter/slightly stiffer spring that allows you to make that power without the hammer leaning on the valve should be a big help in the air waste department

That makes perfect sense! I will investigate this once I got some other business finished. Thanks for the suggestion!

[KnifeMaker]

Most likely the reason for the low shot count on the reg. is that one, the reg is set too high. That is very high for a .177. Also, the hammer spring is too strong.

To fill from empty, to cure your problem, simply fill with the ag cocked. it will take the pressure off the valve and allow it to close.
Knife

[sactargetshooter]

Well, I got the gun disassembled.

It is pretty typical of Hatsan, well engineered, but production/manufacturing can be improved. The trigger group housing is plastic, but all metal where it counts. I can see some polishing attempts, but there are rough edges. Interestingly, the debounce/anti-bounce mechanism is right in the trigger group. It consists of a metal blade that is spring loaded. As the trigger is pulled, there is force exerted on the blade to go up against the hammer, but the spring just makes the blade brush along the hammer until the hammer is free. Then the spring pushes the blade up. When the hammer bounces back, it hits the extended blade and that stops the hammer from going any further. I could see how the blade is getting a good beating from stopping the hammer bouncing back. It is a surprising that the plastic trigger group housing can withstand that kind of impact without breaking.

The hammer spring uses .051" wire with an OD of 0.32", uncompressed length is 2.25" with about 19 coils. I measured the position of the hammer where it rests on the valve, and the spring would be compressed to 1.875" or so. This means there is a 0.375" preload even with the HST dialed all the way back.

The HST set screw has about 6.5 turns, amounting to about 0.35" of travel. There is no mechanism to lock the HST set screw in place, however.

By comparison, the factory valve spring is a whimpy one. 1.2" uncompressed, OD of  0.325", coil diameter of 0.035". There are about 8 coils. The compressed length is about 0.98". With a regulator, once the plenum is emptied out, this spring will take a long time to close the valve. Even with a slightly stronger valve spring, I am suspecting the amount of time to close the valve is too long, ending up wasting air.

I have a whole bunch of springs being shipped right now. I may go the regulated route by strengthening the valve spring further, or go unregulated with a shorter hammer spring. Lots of experiments coming up!

[Hobbyman2007]

As Knife mentioned th regulatory pressure is a little on the high side. I would drop to 110 bar and cut a couple of coils from the hammer spring so there is no preload . I get more shots at 40 FPE in .25 cal it’s the same airtube. If that doesn’t get you closer , you might want to look at reducing hammer weight , somewhere near 20 grams should work .YMMV

[sactargetshooter]

I received all the springs only to find out that I didn't need any!

As it turned out, the factory hammer spring is of the right length. However, when the hammer is all the way out without the airtube valve to limit its position, there is enough play for the hammer spring to slip out of the rear stop. This must have happened before so there was significant pretension to begin with.

I did replace the valve spring with a stronger one, and replaced the lost safety detent spring that went flying when the trigger group was removed.

I also lowered the regulator pressure to 125 bars. Now the gun is shooting 16.2 grain Beasts at 800 FPS. Shot count is significantly improved. The gun is also much more mild mannered now. The trigger is smoother after some minor deburr and polish, and muzzle report is toned down a lot.

I will test for accuracy some time next week. I am hoping all this is helping with accuracy as well.

More updates to come!