Hatsan Mod 25 Super Tact QE .177

[Robert 5mm]

I just bought a Midway USA Birthday discount

Hatsan Mod 25 Super Tact QE .177 Steel Spring version for $155 delivered for a plinker and to tinker with.

.177 CPHP 7.9 gr chrono at 390-400 FPS - something is wrong. Expecting 600 FPS.

I cleaned the barrel, lock tighted the stock threads and put a little Tune-in-a-Tube grease on spring - so now shooting it.

I have a Gas-Ram Piston Striker .25 ( gas ram went limp ) and I repaired it with a Crosman NP2 ram. The only Hatsan I have ever had.

So I thought to try a spring Hatsan.

With the Low FPS of 400 I figure it is the spring, piston seal or breech seal.

Tissue test - breech seal OK, the spring does not look broken viewed through cocking slot below trigger.

So the piston seal is suspect - 27mm same as the Striker I have, so already have one.

But I think I am going to shoot it for a while since I just thread locked the stock screws and to see if it gets better.

ANY advice from the Hatsan users will be appreciated on what to do. Thanks, Robert

[splitbeing]

That's lower than I used to get with my supertact .177, but it was a gas ram.

Shoot it some more.  If it stays low then check the piston seal makes sense to me.  You'll also get a better view of the spring.

Sometimes a really dirty barrel will slow things down, but not that much.

[Robert 5mm]

I put a few drops of 100% silicon oil into air camber through air exit port to lube piston seal and let sit cocked for 1/4 hour.

Shot it a few times and then checked chrono - it is now at 600 +/- FPS.

Must have been a very dry seal and piston chamber walls.

[splitbeing]

Wow!  That super tact had been sitting super long in a warehouse iikely!