Friday, June 6, 2008

Hy-Score/Hammerli Air Rifle Part 2

Continuing the disassembly...

This piston seal is leather, with a nylon washer. The piston had no lube at all.

The seal unit.

I removed the screw, thinking it retained the rear sight, but it just adjusts for elevation. Since the rifle seemed fine for windage I decided not to drift out the rear sight from the dovetails.

The screw and sight element.

The metal sticker on the loading tap knob was removed carefully. It was glued on. Then the screw was removed, and the knob taken off.

Tiny ball...there's always one.

And a tiny spring...I didn't lose either one.

The loading tap. There is no seal or provision for a seal, which might account for the rather low velocity.

I used this deburring tool, and some files, to remove some of the burrs in the slots. That slot may be for the anti-beartrap mechanism, as nothing was there, but there are tapped holes...curious.

I soaked the seal in silicone oil overnight and reassembled.

I sparingly lubed the piston with moly.

The piston was pushed back in.

Again, a sparing amount of Maccari heavy tar on the spring.

I used some double sided tape on the loading port label. Cut out to a circle and pressed on.

Taped back on.

So the gun was lubed all over (no need to show pics of dabs of grease). I didn't really see any change in performance.

Before the tune, I got 481 on average with Crosman .22 wadcutters (14.3 grain), afterwards I averaged 470 or so. So slightly slower, but not significantly so. Probably due to the drag of the lube, although I need to check and see if I'm getting any blowby in the loading port. The numbers seem pretty slow, possibly the spring is tired as well. Only after I reassembled it did I wonder if the tap bore was tapered...I need to check that. Performance aside it is much smoother to shoot and cock now that everything is lubed, which is good. I hope someone will definitively identify the model of the gun and let me know how fast it's supposed to be shooting.

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