Benjamin Sterling HR-81 Tear Down Part 1

Started to tear down the Sterling the other night.  Technically, this is a Benjamin Sterling as it was made in Racine, WI.  This gun is a .20 cal.  And .20 cals are typically Sheridans, so shouldn't it be a Sheridan Sterling?   I probably ask too many stupid questions.















Started by removing the two forward stock screws.  Note, these are SAE fasteners--not metric as on the original British made Sterlings.

Removed the rearmost screw in the trigger guard and action lifted out of the stock.

Popped off the circlip on the rear sight elevation pivot.

Unscrewed the right side bolt and the sight and elevation spring came off from the base.

Two small screws and a recoil pin hold the sight base to the upper tube.

Just a pic of the holes in the tube.

As I had no idea how much preload was on the mainspring (--though I swear that several old sources reported that the preload was absolutely minimal) I threw it into the mainspring compressor.  The brass drift is in the through hole in the end cap to act as a handle.  

End cap was unscrewed and the spring pre-load backed off.

That's a good 3+ inches of pre-load on the spring.  I sure wouldn't call that "minimal".  I think we should add this gun to the list of "should use a spring compressor for disassembly/reassembly."

Thirteen and a half inches of spring.  Shades of the Feinwerkbau 124.

This is quite possibly the longest factory spring guide I've ever seen.  The steel guide is roll-pinned into the threaded end cap.  Does anyone know if the British version has a threaded end cap or was this a tongue-in-cheek warning shot at the old Beeman "Tap the Cap" ad campaign?

There's another end cap on the upper tube.  Double threaded end caps.  It's like they're hitting Beeman with both barrels.

Threaded the mounting bolt into the bottom of the cap...

and unscrewed it from the tube.

Like so.

Couldn't get the pivot's lock bolt to move with a regular screwdriver.  The small ratchet handle in the Chapman kit provided enough leverage.

After its removal, the main pivot bolt is unscrewed from the right side.

With the pivot bolt removed, the cocking lever can be pulled out enough to disengage from the piston.

Interesting.  The compression tube is bolted to the breech block.  

Pressed out the sear pivot with a brass drift.

The sear is now free to drop down enough to allow the piston to pass.

Piston didn't want to come out.  Really tight.

 

Awesome.  My brand new, old stock gun has a smashed piston.

Double ring seals with a center bumper. 

It's cracked, too, just for good measure.

I'll assume that's why it didn't want to come out of the tube.  I can probably salvage this a couple ways.  But the pertinent question is why? 

More soon.

Slavia 618 Re-tune

Yes, it’s me. Sorry for the lack of postings lately but life has a way of getting busy when you have two jobs and two kids. Good thing Derrick is so prolific!
Back in September some friends came over to shoot airguns with their kids. The Slavia 618 (pt.1, pt.2) is a great size for a child but a few pellets into being shot it just refused to work. So I put it on the rework pile. I finally had a chance to take it apart. I expected there was a problem with the home made seal, but what I found was another issue.

The guts.


I think I can chalk this up to inexperience on my part. I clearly was  a little heavy handed with the lube. The piston was gummed up in the cylinder and there was altogether too much heavy airgun grease.


I also decided it would be a good idea to smooth the piston where it makes contact with the bore.


Polished up on the beartex wheel.


I used moly sparingly on the contact surfaces and seal.


Derrick’s favorite, Slick Honey, is perfect for low power airguns. I put a thin smear on most of the other surfaces.


I was able to find my fancy spring end block insertion tool. Not bad considering I last worked on this in 2008.


Just a twist to get it to catch.


I replaced the heavy, slightly too large trigger spring with a much lighter spring. Not sure if it make a difference.

Back together and it’s back to a functioning state. I’ll probably find that most of the first airguns I worked on have too much lube…live and learn.

New Muzzle Brake on the FWB 124--Final

A little scotchbrite on the brake gave it a good enough finish for now.  I was going to blue it, but after looking at the various airguns, I decided to install it on the old two-tone FWB 124 as is.  If it ends up finding a permanent home here, I'll run it down to Akron Plating and let them give it a coat of hard chrome to better match the compression tube.   















It's hard to take a decent pic of rifles that are over 40" long and have them show up well on the blog.

The brake matches the hard chrome fairly well.  I've given it a coat of wax to prevent corrosion.

The trim size works well with the slenderness of the stock.

The setscrews are dead flush when tightened.

Think I may be overhauling the Sterling next time around.  I've got several other project guns here including both a Rochester and old Benjamin pumper in many pieces.  Also, just picked up an unfinished walnut stock inlet for a Crosman 160.  There's lots of possibilities.  Nick should be back with a project soon.

Check back.

Fill Plug for the Hand Pump

This was a quick project.  Threw this together while working on the muzzle brake. Wanted a plug to fit in the female foster fitting on the end of my Benjamin hand pump.  It's really just to keep the fitting clean of dust, dirt, debris while the pump is in the basement or while traveling.
















A spare male foster fitting was used to supply some basic dimensions.  Chopped off a small piece of acetal rod.

Faced the acetal in the Taig and added a small bevel.

Cut a couple grooves for o-rings.  This is all just quick freehand so far. 

Need to get the other end to about this diameter. 

A really small homemade parting tool did the trick. 

A few comparisons to the foster part showed where to make some additional relief cuts.  

Two green o-rings will help me find the plug when I set it down on a dark floor. 

About ten minutes later--and it even fits.

A New Muzzle Brake--Part 2

Happy 2012 from Another Airgun Blog!

















Still working on the muzzle brake.  I flipped the brake around and milled the back end square.

Off on a quick tool tangent:  Turned an indicator holder from a piece of 5/16" key stock. It fits in a spare tool post holder.
















This is mounted to the headstock in one of the various t-nut channels, either on top, or on the back. 

After adjusting the runout, I got out the compound crosslide.  (It's on the right)

I'm sure we've shown this before, but the compound mounts to the top of the crosslide and allows the cutter to travel at an angle respective to the work.

With a steady rest mounted to help prevent deflection, many light passes cut the taper.

Then back to the mill for a couple mounting screws.  A couple pieces cut from a target protect the workpiece.  Spotting for the hole here. 

Through drilling.

Tapping M4 x 0.7mm. 

Snugged a handle around the body of the tap.  The tap itself is barely held in the Jacob's chuck for alignment. 

Mentioned about a month ago about needing some new countersinks.  Over the course of a couple weeks, I replaced everything I had and then some.  I've found that gun shows are often excellent hunting grounds for machine tools at low prices.  Now, when I need a countersink, I feel like Rodney Dangerfield in the pro shop in Caddy Shack.  Hey!  I'll take one of these, two of those...

Used a 90 degree single flute cutter to chamfer the edge of the hole. 

Still need to finalize what to put this on and make sure it fits then get a finish on it.

More soon.

Drilling More Holes!-- A New Muzzle Brake--Part 1

Still playing with the spin index.    From the first time I saw one, I thought it would be the perfect "muzzle brake making device".  And why not?  The spin index allows for precise rotation of the work for drilling or milling.  Well, I've got to make one just for the cheap thrills from another piece of 0.875" DOM tubing.  No particular gun in mind for this at the moment.  Rather foolhardy, as the ID of the tube is around 0.635"--about 16mm, so it won't fit many rifles without reducing shims. 















Faced the end of the tube off.

Did some layout and marked off 0.375" intervals.

Squinting makes all my projects look better.

Located center.

Picked a short and stout drill bit as I don't want to spot each hole.   I believe this is a letter N.  The diameter wasn't critical.  What was critical was having enough rigidity in the bit that there was no wandering while drilling through both walls.

Staggered the holes.

Wanted a bit more aggressive look to it, so I milled off the end, cutting halfway through the outermost ring of holes.

It'll need tapered--as well as a couple threaded holes for set screws.   Hmmmmmm...I suppose this will fit the R1 or Marksman Mod. 56 FTS.  I'll find something.

Check back soon.