Beeman R1/HW80 Caliber Change

I'll cut to the chase as I'm time crunched today. I have a .22 cal Beeman R1 (HW80) and I wanted to convert it to .25 cal. Long story involving having a .25 cal R1 years ago, the gun was stolen, couldn't replace it with another .25 cal at the time so I bought a .22 cal and...blah..blah..

So, after almost three years of looking, I was finally able to pin down a .25 cal barrel/breech block last week. The replacement Weihrauch barrel assemblies don't come with a cocking lever arm attached. The cocking arm is riveted to the bottom of the breech block. A spare rivet is not provided--but can often be ordered. I opted to not order the rivet.

No pics of rifle disassembly as we've covered it before here. I pounded out the rivet holding the cocking lever to the .22 cal breech block and set the .22 cal assembly aside--maybe for good.



Often, the rivet can be reused, but not this time. The pin has a 5mm shaft diameter.

Lacking a piece of metric drill rod, I turned down a piece of 0.250" W-1 steel to the required 5mm diameter. Actually, it needed to be 4.99mm.

Cut the new pin a few thousandths longer than the width of the breech block.

Used a file to bevel each end into a slight dome.

I've seen a couple one-off replacement cocking lever pins that have used e-clips on each end. That looked like it would require widening the slot in the forend of the stock. Too much work for a guy like me. Figured there was another way.

Center punched the breech block.

Didn't bother to fixture the breech. I lined up and drilled through with a #36. Not shown: Tapped the hole with a #6-32 plug tap.

Filed a small flat on the pin for the set screw to bear against. This will lock the pin in position yet make it easily removable.

Breech block, pin, set screw and cocking lever. What more could a guy ask for?



Blued the pin with Birchwood Casey Permablue paste.



Set screw snugged down. Lucked out on the length of the screw. It's flush with the block. I like this more than the factory's method of assembly.

Done! Reassembled the rifle and now I can work my way through those thousands of .25 cal pellets that have been mocking me on the shelf. Should I ever want to revert to .22 cal, it's now a ten minute swap with the replaceable pin.

Something else soon.

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.