What's the caliber?
Hatsan springers are IMHO good entry level bargain air rifles. They typically DON'T have the finest finishes and tolerances at their price point. However, the breech face on your rifle appears to be one of the roughest I've ever seen. Also, the transfer port insert appears to be damaged. While that damage should NOT significantly affect the performance it is disappointing to see such crude work on one of my favorite brand of air rifles.
Simple round hole on unrestricted muzzle energy US rifles. Yours look like a threaded insert was added to restrict airflow/muzzle energy for your country or a restricted muzzle energy country near yours.Edit: will try to measure one of mine and post results.
I believe that this topic belongs in this part of the forum and if it is proven that they made a big mistake, it should be posted on the bulletin board!I recently got a nearly new Hatsan 125 5.5mm to install an optic on, of course I did a velocity measurement first and found it to be around 22J. I also noticed that unusual transfer port that I hadn't seen before, but at first I thought it was a piston seal problem because the rifle was all full of factory grease and oil.When I disassembled the rifle, I first noticed that the shorter spring 43 coil 41 was active and removed the piston, but the seal was not damaged from dieseling, but had minor damage during factory assembly. I was interested in that insert in the TP and I twisted it and it was stuck with something. The threads on it correspond to a standard M7 screw, and it is drilled with a 4mm drill bit, about 7 mm long, the transfer port on the cylinder is 3.9 mm and about 5 mm long, so the total length of the TP is 12-13 mm, that insert, when twisted, passes into the cylinder about 0.7 mm, the four slots are about 2x2 mm for the screw driver.I put that insert back again and put Loctite 241 got a bigger original spring 48 coils carefully installed a new piston seal properly applied Feinwerkbau special grease and tried the speed and then I found that I didn't get any power, the speeds even fluctuated a lot for a spring gun. I contacted the Hatsan factory and got no answer, the supplier is totally ignorant and justifies that the warranty is lost because he did not service that classic rifle. My only fault is that when they made that insert, they didn't make it from M8 or M10 (M7 is hard to find) with an O-ring holder, then people would have made it easier with stainless steel screws and two holes so that it can be unscrewed and screwed in.What do you think about this because I was thinking of making a 3.5 mm wide insert. Please join this discussion as all new Hatsans come with this insert*. here are the pictureshttps://www.gatewaytoairguns.org/GTA/index.php?topic=210458.0