The correct way to tune an unregulated PCP rifle

I will take the barrel off these days and see what diameter the transfer port hole has. But getting the parts might not be so easy I have the feeling. Let's see if I'll get any news from Hatsan these days. But thank you for the support, much appreciated!

Here is a link of the Nova Star´s parts with numbers. Can you point out the parts I need? I´m not familiar with the interns of the gun yet so I´m unsure which on is the right spring on the graphic. 

I´ll take off the barrel these days and have a look on the transfer ports hole diameter. Thanks for the support, much appreciated.

https://hatsanairgunsusa.com/wp-content/uploads/2019/07/NovaStar-and-NovaStar-QE-exploded-view.pdf

Hatsan here lately has been not to good about returning emails/parts requests. With that being said you may want to return the gun. I have had many problems with 2 of them. One got sent back and the replacement I wish I would of sent it back. 
Butch

How old is your Novastar? I wonder if they might have done some improvements on the interns with the later production batches. 

So today I disassembled the Novastar and checked the TP diameters. Both the barrel and block TP do measure 4mm (0,157") in diameter. Is that the standard?

Just about everything that can be done to the NovaStar power wise is the same as the AT44 due to the fact that the platforms are the same. Just google AT44 mods and you will see in great detail what you need to do. 
Butch

Are the parts of an AT44 similar in size? There are plenty of parts available for AT44 but impossible to find for the Novastar. Will a main spring fit?

Hatsan doesnt reply.

I looked at the product diagrams...they all have the same part number. Should work

Yes most parts are the same. 
Butch

I've purchased a Nova Star from Spain and it must have been modified to the legal limit of 18 fpe. Right out of the box it only delivered 16fpe. The highest I can get it to is around 27 fpe with 16gr pellets doing 870fps. That's pretty disappointing. I've watched some videos to help with the disassembling and also to compare the parts. The hammer spring seems to be the original. But the transfer port on mine seems to be smaller. It measures 4mm (.157") aswell as the barrel TP. I'm gonna open everything up to 4,5mm (.177") and hope to get the desired smack out of it. I have ordered a .177 TP for a AT44 Gladius. Part numbers are the same. Other wise I wouldn't know where else Hatsan could've put the breaks on to that rifle. The outer barrel orings have seen better days. That could make a slight difference.
I've also noticed while it was apart that all the parts were bone dry. No lubrication at all. And everything was tightened very roughly. 
Anyways if somebody has an idea please let me know. 

At mine the TP is also 4mm and the barrel
Out of the box was almost 40 fpe

I changed the hammer spring and the spacer with a longer - softer, now i can get 47 fpe and the cocking its much softer

Then there must be something different with the valve. In the video the valve had a black coating...mine is just brass. How is yours?

.

Mine is exactly like yours. 
Butch

And the way they attach the bottle is not good. After a couple thousand shots the 2 grub screws push threw the brass and you blow the larger of the oring in your pic. Ask me how I know this. Lol. 
Butch

Im gonna change every oring once they arrive. There is no leaking though and I doubt that this will do the trick. I dont know what else there is to do.

Really?! And then you have to replace the whole brass thing?

Yes, and still waiting for Hatsan to reply to my parts request. While your in there you mite want to polish the hammer because mine was horribly finish to the point it was gouging the cylinder. Also check your HDD. I had to replace mine. 
Butch

Yea the finish on the hammer is bad. The HDD issue is well known. Im waiting for reply when they are back in stock (AT44 version). I need to call Hatsan and ask them about this mystery. Or is it possible that the valve doesnt let the whole amount of air through? Ive checked the valve...looks ok to me. But I wasnt able to loosen the bottle by hand. Its freakin tight. Dont have a sling device

AT44 HDD same as the one you have now. It is their new version. Lol