Haenel 303-Super Tear Down Part 3

Still operating on the assumption that the transfer port is too large in diameter. The easiest solution is to sleeve the port down to a smaller size. 1/8" was the size Cardew favored from his research and I'm in no position to argue.

Some brass tubing from the scrap box. The ID of the tube is 0.125".

Test fit. The port is drilled at an angle. I'll assume that the angle at the breech face is identical to the angle of the inside face of the compression tube. I filed the brass tube to match the outside angle, turned it around and turned it over. An index line scribed on the tube made this easier than it sounds.

Because this can't be quick and easy, the tube is too loose in the transfer port bore. Knurling the tube will expand the OD a few thou.

It'll also give the epoxy something to grab.



Was pretty liberal with the JB Weld. If it doesn't work, the brass will easily drill out and Cardew and I will have something to talk about.

A 3/4"rod held vertically in the vise acts as a stop inside the compression tube for the blind end of the brass tube.

Cleaned up the excess JB Weld from the breech face before it hardened.

Cut the tube off flush with a jeweler's saw.

Finished the breech end.

Back to that too short spring guide. Found some likely replacements in the scrap box by test fitting them to the ID of the mainspring. A piece of o.500" cold rolled tubing and a spare Weihrauch spring guide made the final cut, but the HW won by virtue of a better fit to the spring. For what it's worth, the HW guide is 0.514" in OD.

Punched out the stock sheet metal tube. This was easier said than done. I expected it to pop right out, but no, Haenel had reduced the diameter of the tube, inserted it from the front, then rolled that rear flange. Tip of the hat to them for permanence, but I'm scratching my head that they put so much effort into fastening what's no more than a piece of too short, too small diameter, sheet metal. Uh, way to go guys?

Cut the tabs off the HW spring guide then through drilled it so the Haenel piston rod would clear.

Of course, the OD of the HW tube is too big to fit into the bore of the plug. Reducing the plug end of the HW tube will leave the wall thickness on the thin side.

So rather than thin the tube, I drilled the plug out to 0.500".

Then used a boring bar to open the hole to 0.512".

Set everything in the vise jaws and heated the plug with a torch. Used the vise to press the tube into the bore while it was hot.

Took a substantial amount of force to seat the new tube. Given how hard it was to remove that original guide, this one is even tighter. I think the guys at Haenel would approve.

I was getting ready to reassemble the rifle when I remembered that metal cap--or button whatever you want to call it--that keeps tension on the cocking lever. It was all scarred up.

Just a thin stamping. Almost looks like a bottle cap.

More scrounging in the metal box gave up a piece of tool steel--most likely W-1.

Turned an end down to 0.640" OD.

Then hogged out the end until the coil spring fit inside. Cleaned up the interior with a boring bar...

and parted it off.

Sanded the top flat on a granite surface plate.

Took it to 400 grit. I'll harden, then polish it so it doesn't wear out like the original.

I'll be back with more in a few days.

Haenel 303-Super Tear Down Part 2

Finally back to the Haenel 303 after a brief hiatus.

Removed the pivot bolt locking screw.

The pivot bolt head has 4 cut outs around it's circumference. The pivot bolt is snugged up to the desired tension then the locking screw is installed. The head fills into one of the radii and locks the bolt in place.

The locking screw is really tiny. I believe it's an M3x 0.5mm.

Before I remove the barrel/breech block from the compression tube, I wanted to take a look at the barrel latch. On many guns, the barrel latch itself is spring loaded and fits into a precision recess. And on many guns, that latch is pulled forward toward the muzzle to unlock the action.

Not so on the 303.

The Haenel has a spring loaded chisel shaped detent.

The latch is pushed toward the rear where it bears directly against the detent. It's a bit awkward in practice, but you get used to it.

As you push the latch rearward, it shoves the detent into the compression tube and unlocks the action.

No pressure on the latch, the detent sticks out under force from a small spring, locking the barrel in place.

Latch pushed in, pushes the detent in.

Here's a better pic of the detent with the barrel opened.

Removed the main pivot bolt and the breech/barrel unit.

A small screw secures the detent mechanism.



The chisel and the spring.

And the latch itself. Polished then reblued the sides that fit against the breech block.

Thought that the trigger could use some help. It's supposed to be a target gun after all.

There are two adjustment screws in the trigger unit. The front screw sets the amount of first stage travel.

I removed the screw and polished the end that bears on the bottom of the sear.

The rearmost screw (not well shown here) adjusts the amount of sear contact. On a target trigger, less is helpful--it shortens the amount of trigger travel in the second stage to fire the gun. Too little contact though will make the gun fire unexpectedly--like when the barrel is opened for loading. That's bad. So, I'll err on the side of caution. When the gun gets reassembled, I'll cock the gun and give it a "bump" test to see if I can make the sear slip and fire. There's no shade of gray here--it's pass or fail. Increase sear contact until it's absolutely, positively safe--then add just a tiny bit more overlap.

Trigger at rest with a ton of first stage travel. (forward screw backed out)

About that much travel. Too much for my preference. I'll screw the front adjustment in a bit further and shorten this up.

Click on this pic (or any for that matter) to enlarge it and see the circled sear contact point. This is the one spot where the trigger really should be lubed.

I used a 60% moly grease and set the trigger unit aside.

The piston got a quick polish on the front and rear.

Can really see the colors from the hardening on the body. Deburred the slot in the piston body since I was working on it.

Here's the inside of the compression tube. The transfer port hole looks awfully large.

For a target gun, the 303 is quite harsh firing and I'll venture that the transfer port hole size is to blame. Too big means that the air rushes through too fast to cushion the piston at the forward end of it's travel. The piston, instead, slams into the front of the tube. It's almost like dry firing the gun.

The hole is approximately 0.169" in diameter. For a transfer port hole in a spring piston gun, that's really large.

More soon.