Diana Model 16 Disassembly, Part 2

Just a bit more

The spring guide slides out.

The spring guide.

Two pieces joined together. The use of sheet metal in this design is interesting.

The spring is a bit wiggly…also there is little if any lubrication evident.

The cocking arm is captured by its little ears.

The cocking arm slides out the back end of the receiver tube.

The barrel detent. Staked in place.

The piston, also made entirely of sheet metal, welds and rivets.

The sear is an insert.

Oh, there’s some lube, reduced to putty by age.

The leather piston seal is riveted in place. That is inconvenient. I hope I can massage it into shape in place.

The other end of the rivet.

It doesn’t look as bad now, although that leather is really pliable.

I pried the breech washer out.

Ii was backed by a cardboard domed shim.

Interesting. The seal should be fine for reuse.

The breech end. The barrel is brass (or a yellow alloy of some sort). The entire barrel assembly is best left as-is I think.

That’s all the parts. Now to clean, steel wool the rust, lube and reassemble. Not happy about the spring but I don’t have a spare that size. May hit the hardware store and see what they have.

Diana Model 16 Disassembly, Part 1

Well I finally found an airgun at a yard sale. In the past couple of years I haven’t seen anything but the most common Crosman and Daisy airguns for sale. Finding something Derrick and I haven’t already torn down is harder still! So I was happy to find a Diana Model 16 “rifle” (it’s a smoothbore) at a yard sale yesterday. I have always wanted one because of the odd hinge system for the break barrel. It is definitely sized for a small child. This one is postwar as it’s made in Great Britain rather than Germany.

That’s a 2’ ruler.
DIANA      MOD. 16      MADE IN GREAT BRITAIN

Most of the screws use the cool looking, yet annoying to remove, slotted nut.

That’s a front sight!

This is the unique hinge. Notice that the barrel locking detent is in the cocking arm, not the receiver or barrel.

You can see the piston sear.

There is a bit of rust…The breech washer is carried by the receiver rather than the barrel assembly.

Removing the trigger guard. I don’t like that it relies on a wood screw, as this does need disassembly from time to time. That said, the screw hole was not stripped.

I used snap ring pliers to engage the slotted nut while I removed the cross bolt/trigger pivot. See my spiffy new Panavise? It came in handy.

Front screws have a lock washer…it doesn’t want to come out of the wood.

Action removed.

The spring rests in an angled pocket in the stock.

The only real damage to the stock was a small chip in the butt.

The trigger.

Removing the cocking arm pivot bolt.

Punched out the retaining pin. There is no preload on the spring.

The pin.

Had to tap the end cap off, it’s a friction fit.

Not particularly exciting.

The spring & piston wouldn’t come out.

Problem #1, the edge of the slot is folded down past the end of the spring guide. Not sure if this is intentional.

What’s up with all of that lint?

The spring guide also has a twist detent…

Now it comes out…I had to rotate/pry it with a stout pick.
More to come…

Daisy 747 rebuild

Sorry about the dearth of postings lately.  I recently made a career change and found myself working two jobs for a couple months before taking the plunge.  There was simply no time for anything else.

One of my friends sent me a Daisy 747 to have a look through.  The valve wasn't sealing properly on the compression stroke of the lever.  You can generally assume that's the problem when the air is coming out of the barrel during charging or immediately after.












It's Matt's 747!

The basic tear down is identical to the 717 and 727 guns that Nick and I have previously covered. 

I cycled and dry fired it a few times.  It was immediately apparent just how much better this adjustable trigger is compared to the trigger unit in my 717 model.

The adjustable piston head had the typical chewed up notches.  Daisy should really make this from something more robust than a zinc die casting.

Left panel removed.

Pump lever removed.

The compression tube is aluminum.  I'll have to check my older 717, but I think the older guns have brass tubes.

Piston head.  I don't think this seal is bad, but it still gets replaced. We're this far, so why not?  This o-ring is a #115, by the way.  

Injection seam from the mold.

This flashing is the problem with using a die casting.  I found pieces ranging from dust sized to this throughout the compression tube.  Most of it was on the piston.

Chucked the head in the Taig and took a clean up pass to remove the seam.  Also cleaned up the adjustment notches.

Here's the likely leak offender--the valve stem seal.

I stoned off the face of the valve both to square it up and remove any potentially loose casting material. 

This o-ring seal is also not really suspect, but like the other, it gets replaced.  And like the piston head seal, it's also a #115.

I used a grease on the o-ring seals.  Should last longer than the oils that are typically used.

Matt supplied a repair kit when he delivered the pistol.  The valve stem seal is an earlier design. 

Looks like it's been sitting around for a while.  It's probably 20 years old.

Fortunately, I bought several replacements from Daisy when I was fixing my 717.  Because one is none and two is one...

New style on top, old on bottom.  My guess is that they're actually interchangeable, but I'd prefer to take one more variable out of the equation.

Reassembly was simply a reversal of the procedure.  Did grease the cocking linkage with moly as well as re-stake the cocking lever pivot pin.  (It was so loose, it fell out of the cocking arm at one point)  Not shown:  Polished and cleaned up the trigger pull a bit more.  After all this, the gun still had a tiny leak when initially charging the gun.  Went back in and reseated the valve stem seal using some minimal pressure to get it to conform to the valve seat.  A week and 100 shots later, there's not even a tiny hiss of air when charging--all the air is now going (and staying) inside the valve. I still want need to chrony the gun before sending it home to Matt.

Really astonished at how superior this trigger is compared to the one in my gun.  Looks like the grip frame is different as well as the trigger itself and trigger return spring.  I'm calling Daisy and upgrading the parts in my gun next week.  The 747 is absolutely worth the $40 premium it brings over the basic 717.

Thanks for checking in.