Reanimating a HW80K, Part 6

With most of the problems sorted, I cleaned the parts.

All clean...

I decided to minimally lube it, so a very thin smear of heavy tar on the spring.

Some moly on the top hat & washers.

A thin smear of moly on the piston. I just wanted to test for function and make sure the repairs held. Plus I figured I'd see what it did with the original o-ring and breech seal before replacing them.

After cleaning the trigger unit in a friend's ultrasonic cleaner I used some Starret "mouse milk" instrument oil.

The trigger unit is easier to replace when cocked.

Someone had modified the sear.

They rounded over the top. Why? I have no idea.

Using a punch to wiggle the shims back into place.
Then I did some testing. The stock screw tab repair held like a champ. The barrel hasn't moved. 2 good things. Velocity was down though. Before working on it it was at about 760 fps w/ 14.3 gr. pellets. After cleaning and reassembly velocity dropped to about 720 fps w/14.3 gr pellets.
I assume that cleaning out all the caked up lube reduced the ability of the worn o-ring to seal.
Also the minimal lube likely increased drag on some parts.

The other issue was that it wouldn't always catch when cocking. Not an ideal situation.
What would happen is it would fire several times fine then fail to catch. If I then clicked on the safety and pulled the trigger it would click and then it would catch when cocking. I was a bit puzzled so I asked on the Yellow forum. The answer as to what was happening was indeed found here on the Straight Shooters forum. However the trigger parts I had did not look modified or polished as that posters did. Another guy emailed and suggested that I tighten up the trigger weight spring screw. That did indeed fix the problem. So too little tension on the spring allowed that condition to occur. I fired a number of shots after adjusting and it never once failed to cock.

I tore it all apart again.

Machining the new breech seal. They're $3.00 from Maccari and I wish I'd bought one last order. But I didn't.

I wanted to try something new for cutting off the urethane. Some mini boxcutter blades.

It worked like a champ.

Just a single screw holds the blade to a stem.

The new seal. I made it just a hair thicker than the old one.
I also replaced the o-ring on the piston with a #213 buna o-ring. I'm guessing that the old one was something harder though and I may get a polyurethane or viton o-ring in that size later on.
I also tried out Derrick's secret lube, Buzzy's Slick Honey . It's sold alternatively for bicycles and for paintball guns but is a good grease for many things. You can see some specifications here and here. Anyway I put some thin smears on the top hat, spring guide, inside of the piston and a little on the spring. Not too much, just enough to get everything slippery. None on the o-ring seal or head, obviously.
Put the rifle back together and fired about 50 shots through it (and no failures to cock). Velocity was about 773 fps. on average. So the new o-ring and breech seal as well as being a little slicker helped a bunch. I want to shoot a couple of hundred rounds through it before I pronounce it done though. Next I need to make some screw cups and repair the wallowed out screw hole in the stock. I could use a good scope mount as well as a cocking handle. The 80K has a short barrel and it's tiring to fire many shots as you don't have as much leverage.

Reanimating a HW80K, Part 5

On I go...

Turning down some mild steel to 5mm.

Threading 5mm x .8

Cutting off.

Threaded into the misaligned screw hole.

I soft soldered it in (with Tix Solder). Unfortunately my torch tank valve caught fire. Everything is ok. But I need a new tank before I use the acetylenne torch again. It was somewhat exciting.

Cut nearly flush.

Peened.

Filed flat.

Aligning the tube.

Picking up the screw hole centerline with the head of a 5mm screw.

Marking centerline.

Held vertically, same thing.

This is where the hole should be.

Setup on the drill press.

The hole drilled. Unfortunately my solder job let go (due no doubt to the fiery distraction while soldering) and it turned slightly in the threads. That is it's held in but could rotate.

So I added a few punch marks to keep it in place. It's not going anywhere. I hope. I tapped it 5mm x .8 and that I could tap it says to me that it's in there solidly.
I tightened up a screw and the plug seemed to be holding fine. I later found a rather large electric soldering iron in my collection of tools so I flowed the solder again, now it won't move, which is good.

Look at that! The screw head is where it's supposed to be.

The misaligned screw is the existing one, the straight one is my repair.

Again, the left screw is the repair.

Oh yes, there will be more to come. Next up is cleaning off all the asphalt/grease/oil/dirt from every part.

Reanimating a HW80K, Part 4

On I go...

I turned up a plug for the muzzle.

A slip fit.

And added a center in the end.

I mounted the barrel between centers on the lathe. The muzzle and breech end are in line.

The plug...

Running an indicator along the barrel shows that it's straight but...

Not concentric. If it were bent then there would be a deviation in the middle of the barrel but the change in indicator reading was linear.(and I repeated this test all the way around) At least that's my analysis and I'm sticking to it.

So I chucked up the barrel in the 4 jaw and turned down the breech end a bit so it would be a slip fit in the breech block.

Slathered it up with Loctite 620. The technical sheet (.pdf) says that it will fill a gap of up to .25mm (.009") if left to cure for 72 hours at full strength. Sounds good to me! Full strength as far as I can tell is 2400 psi. It should stay put.

The excess squeezed out. I twisted the barrel around as I pushed it in to smear it evenly (I hope). I replaced the pin to keep it all aligned properly.

I left the barrel upright in hopes it would stay relatively concentric to the bore of the breech block and not sag. After only a few hours it felt rock solid.

Yes, still more to come...

Reanimating a HW80K, Part 3

On I go...

Checking the barrel with a straight edge. My friend Jim had visted earlier and looking at the rifle felt the barrel was belt to the side. I saw this as well...

It does seem as though it's bent. But that shouldn't necessarily cause an accuracy problem?

Playing around I was pulling in the barrel. At the juncture of the top of the barrel with the breech block I saw a thin line.

And when I pulled up on the barrel a line of grease appeared (hard to see). This is odd and while I'm certainly not an expert as far as I know the barrel should not be loose in the breech block.

Only one thing to do...I pressed out the well hidden pin that locks the barrel in the block.

It's countersunk.

But the flared over end straightened out.

Pressing out the barrel.

It was straight knurled.

The grease I wiped off of the knurled portion.

And the grease I wiped out of the breech block.

So at the end near the muzzle end of the breech block it is .6279" dia.

In the middle .6332"

At the breech end .6342"

The hole is tapered from .632" at the breech end...

...to .636" at the muzzle end. So the hole is too big and tapered and the barrel too small and tapered. Thus it was only really anchored by the breech end. This would certainly cause some trouble with accuracy?
I can only guess as to why the barrel is in this condition.

Obviously there's more to come...