Webley Hatsan Patriot Piston Buttoning and Spring Guide

Still working on the Patriot.  Here are a few additional pics of the damaged piston seal.

The face of the seal has actually melted from the adiabatic heating of the piston's compression stroke.

The Maccari replacement seal.   While this seal is listed as fitting the Hatsan 135, it's also correct for the Hatsan manufactured Webley Patriot.

Gonna button the rear of the piston.






























Spotted.



























Drilled three 5/32" holes around the circumference.

Turned down some acetal.

Left the pieces about .002" oversize in diameter. 

A drop of superglue in each hole and then each button was pressed in using a vise.  Overkill, as the press-fit alone was probably more than enough to ensure that they never come out.

The buttons are far too long and can be filed, sanded, carved down to size.

--Or turned down in a lathe.

They're about right when it takes some pressure to seat the piston into the rifle's compression tube.  The "buttons" act as stand-offs, preventing metal-to-metal contact between the rear of the piston and the ID of the compression tube during the firing cycle.  The front end of the piston is held away from the tube by the piston seal.

Now for that longer spring guide.  The stock spring guide is in the center.  Was gonna make a new one from scratch out of acetal, but I found a couple old mountain bike suspension fork spring guides from Rock Shox.  The shock forks are long gone, so this is a good time to re-purpose.   The grey rod on the bottom is about the right length.

First, I drilled a counterbore in the base to fit over the boss on the rifle's end cap.



















Rounded the end, then shaved the diameter down until it just barely fit into the spring.



















Transferred over the nylon and steel washers.


















Thin coat of moly grease on the sides of the piston seal.  The moly on the piston body is really just there to prevent corrosion.

Piston in gun followed by the Spring and guide.  Rifle went back together in the reverse of disassembly.




















Almost forgot.  Didn't like the thick, painted finish on the safety.  Finish was removed by media blasting then the metal was darkened with Birchwood Casey Aluminum Black.

Good news:  The Patriot is putting out 733 fps with H&N .25 cal wadcutters and the firing vibration is gone.

The bad news:  There's a very slight metal "ping" at the end of the shot cycle which I attribute to the front of the piston kissing the face of the compression tube.

This is becoming a semi-trend lately and if you're a regular reader (thank you), you can probably already guess as to the cause(s).  The transfer port on the gun is pretty large.  The bore is also on the loose side.  I can fix the transfer port, so that's up next.

Webley / Hatsan Patriot Tear Down

Picking up where I left off.  Removed the stock from the Patriot and set it aside once again.

A few pics of the trigger components from various angles.  (Just in case I need them)

Wish all the pins had retaining clips.








Three pins secure the end cap into the compression tube.  The front two also hold the trigger housing.  Removed the forward-most pin.







Then the middle pin.  With this middle pin out, only the rear pin holds the the mainspring from firing the end cap into the wall.  Or your skull.  Take heed.

There's another pin to remove before the trigger unit will detach from the compression tube. 

This pin is both a pivot for the upper sear as well as a slide for the trigger block safety.

Trigger unit pulls straight down and it's out.






I realigned the pivot hole in the sear and slipped a drift into place to act as a slave pin.

Another view.

I wouldn't consider taking this gun apart without a mainspring compressor.  There are already picture online of injuries sustained from attempting such.    With the gun secured in the compressor, I knocked out the last pin and backed out the end cap.  Expect to need about 4" of travel in the spring compressor.

Some type of glass-reinforced synthetic. 

Sliding safety is reminiscent of the Feinwerkbau 124/127 series.

Under the lever is a plastic detent ball and small spring.

After the end cap, the main spring pulls out.

The spring is huge.  At 14.5 inches, It's--by far--the largest spring I've ever encountered in an air rifle.  The plastic spring guide looks like it's made from the same material as the end cap.

Removed the barrel pivot locking screw next.

And the pivot bolt.  The barrel assembly now just pulls out of the forks and the cocking lever pops out of the piston.

A nice surprise to find shim washers on the breech block.

Like the mainspring, the piston is also massive.

The seal looks burned.  The lip feels hard and not at all pliable. 

I think this was the main culprit in the harsh firing cycle.

Inside the piston body, there was another piece of synthetic that the end of the mainspring seated against.  Seems to have acted as a rotation washer of sorts.






The heaviest walled piston in the world? 

Ordered up a new piston seal from Jim Maccari at Air Rifle Headquarters.  Should have it in another day or two.  The plan is to replace the piston seal and add some buttons to the rear of the piston skirt.  Also considering a longer, tighter fitting spring guide and perhaps a short front guide, too.  We'll see what shakes out.

More soon.

Toys that Shoot Airgun Show in Findlay, Ohio

The Flag City Toys that Shoot Airgun Show is coming up fast.  Saturday, April 12, 2014. 

Full details HERE.

See you there.