The KL-3B Fast Deer -- Part 2

The Fast Deer repair continues.

Well, the interior of the Fast Deer's compression tube wasn't so hot.  The ridges and valleys around the cylinder wall were several thousandths deep.  Can't imagine how the piston compression could be consistent from shot to shot with gaps like that.   Lacking any other evidence at the moment, I've got to assume that these surface imperfections are causing the 240+ fps velocity variation.

We have a couple machines at work for precision honing IDs.  This is one of our horizontal hones from Sunnen.

Interchangeable mandrels hold varying diameters of abrasive stones.  Each is expandable within a small range.  I believe mandrels are available from as small as 0.060" up to 6.500".    Bob, our honing department specialist, was kind enough to get me set up and give me somebasic instruction so I wouldn't hurt myself--or break his machine. 

The compression tube is slid over the mandrel which is expanded inside the bore until it just starts to kiss the inside.  The work can be hand held or affixed to a support.  RPM, diameter of the mandrel and stroke are all adjustable on the fly.   Honing is done with a flood of oil on the part.  (turned off for the pic)  Here, the mandrel is bottomed in the tube.

And almost withdrawn.

Didn't quite take the tube to 100% clean up.  Just wanted to take the worst of the gouges out.   Here's a shot fresh from the hone. Bore still covered in oil.

Here's the tube again before the honing.

And after.  A fingernail barely feels the scratches now.  It looks worse than it feels.  The fine scratches trap and hold lubricant--a good trait of a piston bore. 

More in a couple days.


The KL-3B Fast Deer -- Part 1

Nick sent me this a long while back. A Fast Deer KL-3B sidelever from Norinco in the semi-rare .22 caliber.  I've been reluctant lax getting to it as I assumed it's pretty much identical to the BAM B3-1 (also sent by Nick) covered in depth here. 

There are some minor differences between the two guns, but more to the point, there are different problems.  Before tearing into the rifle, I test fired the gun across the chronograph with RWS .22 caliber Hobby pellets.  478, 257, 277, 258, 493, 249 fps...  Ouch.  Well, what's a 244 fps variation across six shots between friends?  A far cry from the 7 fps velocity spread I found with the B3-1.


The KL-3B isn't too horrific looking, but the trigger and trigger guard look positively huge compared to the rest of the gun.  I believe I've used the word, "cartoonish".  The rotating safety on the right side looks like the launch switch for a rocket from 1966.  No sights were included. 

I actually love the flat bottom of the forend.  It's a great place to rest the rifle on an open hand or the top of the knuckles.

Stock is way too glossy.  Looks like it's sprayed in plastic. 


Did I mention the sidelever?  The lever mechanism is a serious piece of milled steel.  This is the single best made part on the entire rifle. 

On with the show.

Removed the rear trigger guard and  forward mounting screws.


Action lifts right out.  Insane looking safety stays in the stock.

It functions as a trigger block.

The front mounting block is dovetailed to the breech.  Trust me--this is not the cheapest way to do this.

Ratcheting anti-bear trap safety.

Mainspring is dry.

The trigger is a "direct-sear" type.  It latches right to the piston without an intermediate lever.  Probably breaking in the neighborhood of nine pounds.  OK, OK, maybe more.

Back to the show.

Removed the screw holding the cocking lever to the end cap.

 And the lever pulls right off.

Behind the cocking lever is a secondary anti-bear trap device that captures the piston when the cocking lever is open.  The screw stud must be removed.

Look at that incredible cocking lever.  Great profiles from the mill.  The side lever on Diana Mod. 75 10-meter match rifles aren't in this league.

Put the action in the spring compressor and drove out the cross pin with a brass drift.

With the pin clear, the giant trigger and supremely heavy trigger spring pull out.

And the spring compressor is backed off...

...allowing the end cap to come free.  Note the stud removed a few steps above.


The end cap has a built-in spring guide. 

Mainspring is canted.

The ratcheting anti-bear trap mechanism up close.  It has to be removed in order to withdraw the piston and sliding compression chamber.

The front pin was stuck.  Had to tap it out with a thin punch.

 With the last pin out...

...the ratchet plate is pivoted up and out.

Tab fits into the compression tube.

Finally,  the sliding compression tube and piston are free.

Note the flat on the side of the cocking rod.  The secondary anti-bear trap safety rides in this flat when the cocking lever is open.  This is a nice design.

Some contact marks on the piston body.

Piston seal is leather.   Looks to be in good shape. 

The inside of the compression tube is not good.   It's badly scored.  This is just a poorly finished part.  Never mind that it's just the key component in the entire power plant...

The long striations are likely to blame for the erratic velocity numbers.  The seal isn't consistently closing off those voids.  This could be a small problem. 

More in a few days.

Wednesday, December 25, 2013

Finishing the Shroud for the Aluminum Breech

It's been far too long without a post.   Lot of distractions as well as the new job have kept me out of the basement and garage over the last few months. 

I was looking for a project that didn't entail going out into the 15 degree F garage yesterday, so this rose to the top of the pile by default--or perhaps by aversion.  This is the Crosman aluminum breech project from a few months ago.  The shroud is a bit plain.

Removed the breech from the gun.

While the loading bolt is out of the gun, it needs a magnet to hold it open during loading.  That's a tiny rare earth magnet in the jaws of the caliper.

Chucked the bolt in the Taig lathe and spotted the hole.

 Followed with a #31 bit.

 Epoxied the magnet into place.

A quick clean up pass on the lathe and it's done.

OK, on the the main feature.  Removed the vanilla shroud off the barrel.

I got asked about holding round work pieces the other day, so I thought I'd take a moment to show the basic procedure.  When you need to clamp a round item, a collet is the ticket.  This is a 0.750" 5C collet.  "5C" is a size.  It refers to the dimensions of the collet body--the length, diameter,  taper angle, body thread... There are dozens of collet size "standards" out there, but 5C is the most common for work holding.  There are other collet types that are typically used to hold tooling--my milling machine, for instance, accepts R8 size collets.  Apologies if this is too "step-by-step".  Just skip ahead if you don't need the details.

The shroud (the work) goes into the collet then the collet is mounted in a special holder.

In this case, I'm going to use a six-sided (hex) block.

 Collet is loaded into the block...

End of the collet is threaded for a lockring.   Tightening the lockring pulls the collet into the angled front of the block causing the nose to slightly collapse inward tightly gripping the workpiece so it can't move.

Block then gets clamped in a vise.  Mounted a stop on the vise, so each time I remove the block it can be reinstalled to the same location in the vise.  A six-sided hex block allows for easy, 30 degree rotation of the workpiece while maintaining center.  It probably sounds much more complicated than it really is.

Since I've gone this far, here's an easy way to drill the shroud.  With some layout dye, I scratched lines every 0.500" down the length of the shroud.

Supported the muzzle end with a second vise holding a v-block.

A #4 (5/16") center drill was used to spot and drill each hole.  Locked the y-axis and simply cranked the x-travel to every second line (1.000 inch intervals) and drilled.  

Rotated the block 60 degrees (2 turns of the block in the vise) and drilled on the same series of lines as the first row.  Repeat a third time.

Next, rotated the block 30 degrees in the vise and drilled the mid lines.

These holes are also 1.000" apart, but offset by 0.500" from the first series of holes.  Rotate the block 60 degrees and drill, then repeat.

Removed the layout fluid and deburred. 

 Some polishing...

 And reassembly.

Dressed up in fancier grips from an earlier 22XX project.

The gun has a bit more flavor now.  The raw aluminum definitely gives it an unfinished tool-room feel.  Well, like I said, it's a project gun. 

Thanks for reading. 
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