Saturday, October 31, 2009

Morgan Adjustable Pad - A Bolt for an Old Model

Part of this is a shameless plug for Nick. At this point, most of you know that he sells Morgan adjustable butt pads. I've had five rifles set up with them in the past. Why? Because categorically, an adjustable butt pad is the single biggest addition that one can make to a rifle to improve the ergonomics. The pad can be raised or lowered easily--providing the correct head position for scope or sight alignment. Depending on how the pad is installed, it also typically extends the length of pull by about an inch and a quarter. For many of us, that's also not a bad thing. Nick stocks two models of the pads: the plastic-base #4 "New Model" and the machined aluminum base #14 "Premium". While the basic #4 model is easier to fit, the #14 Premium model isn't that much harder to attach and it still costs less than a cheap scope. If you get one, you'll end up with a couple for all your "go to" guns--they're that nice.

A new style "Premium" #14 Morgan pad is on the left. It is much nicer than the old version on the right.

The new Premium model has a machined base to fit against the gun. The pad can be set for height incrementally on the machined sliding interface. The old model has a die-cast base with interlocking grooves. It works really well but Morgan's casting die was damaged a few years ago and Morgan took the opportunity to refine and update the design.

I bought the old vintage Morgan a week ago at a local gun show. It was missing the main adjustment bolt that holds the rubber recoil pad to the base on the gun. Figured I'd just go buy a bolt and be done with it. That didn't quite go as planned. The slot is substantially wider on the old base. The new base looks like it was redesigned to accept a more readily available 3/8-24NF bolt.

FCC Disclaimer: Due to new FCC regulations I should mention that I got the new Morgan from Nick Carter. I do not believe any money traded hands. Nick and I send airgun stuff back and forth on a regular basis and rarely is cash money involved. It just comes out in the wash.

The head of the bolt from the new pad didn't fit the counterbored slot in the old base. The only thing that matched up was the bolt threading. 3/8"-24. It's probably not possible to commercially obtain a bolt with this oversized, shallow head in this thread size. I'd venture that this was a custom fastener made by--or for--Morgan years ago.

Following the path of least resistance, I bought a 1/2" diameter shaft axle bolt. The new Morgan mounting bolt is on the right for size comparison. The head on the axle bolt is huge, allowing excess material for fitting to the slot in the old base.

A piece of 220 grit emery paper on a granite surface plate was used to remove the casting irregularities on the old base. This step is critical to obtain a flat, true fit against the gunstock. With the new Premium model, this step is already done by the manufacturer.

Here's the slot that the bolt head must recess into. The larger slot is 0.661" across the flats, the smaller counterbore is 0.429".

Installed a nylok nut on the axle bolt...

And chucked it into the taig fitted with a 3-jaw scrolling chuck. The nut is kinder to the soft aluminum jaws on the 3-jaw than grabbing the coarse threads of the bolt.

Turned the shaft down to 0.368"--roughly the OD of a 3/8"-24 bolt.

Had to reposition the tool post to get right up to the bolt head. Left a small shoulder to fit into that small inner 0.429" slot in the base.

Once at size, I changed to a left-hand knife and finished the shoulder to 0.423" in diameter and 0.080" tall. Then faced the inside of the bolt head to make it flat.

Cut the original threads off.

Mounted it back into the Taig and set up the threading die holder on the tailstock assembly. Not shown: First cut a slight taper to ease the start of the die. As always, used lots-o-cutting fluid.

Cut about 4 or so full size thread then took it out of the lathe and went to the vise. Threading die went into a die stock.

Easier this way. Cut thread to the small shoulder then flipped the die over and re-cut the thread full depth to the shoulder.

Filed 2 of the flats down to fit the slot in the base. Used the bench grinder here too.

File (or grind) and test fit. File (or grind) some more and check again. Stopped at 0.657". It was faster than setting up the milling attachment and plenty good enough.

Got a nice fit that just clears without binding on the sides, and maximum surface contact in the counterbored slot.

Faced the head of the bolt down to 0.110" thick. It must sit below flush in the slot or it will drag against the gunstock.

How long to make it? The nut in the recoil pad sits 0.578" deep from the face of the metal plate. Measured that amount from the base, then threaded a 3/8"-24 nut down to mark the location to cut as well as chase the thread afterwards.

A wire wheel deburred all edges.

Finished with Formula 44/40 bluing solution.

Final fit. Aside: The base is about 1.64" at the widest point and 4.60" top to bottom.

Pad is down tight and achieved full thread engagement.

The rehabbed vintage Morgan. Now, the question I should have asked first: Since it's been previously fitted, do I have a gun that it will still fit? A quick look at stock dimensions in my notebook is not particularly encouraging. I did some very quick and dirty measurements months back for Nick when he was deciding which pads to stock. The Air Arms Pro Sport and the Beeman R1/HW80 look to be pretty close.

It'll be a few days before I know for sure. Worst case? I'll fit the new model Morgan pad to a gun instead and this one can wait a bit longer.

Update: I checked the measurements on all the airguns in the safe. Nothing fits. Judging (Guessing) by the size, my best bet is probably going to be a vintage Crosman 160/180 or a more current 2260. Something like a reasonably priced QB78 will probably also fit the bill. I'll keep an eye out.

Wednesday, October 28, 2009

Crosman 622 Disassembly, Part 2

On I go...
EDIT 11/04/09: I added some more info in the text based on what I've found leafing through the service manual and putting it back together

All of the guts.

The trigger, bushing and spring.

The hammer assembly.

That screw is loctited in and I could see no reason to tempt breaking it off. The hammer looks fine so I'll leave it alone.

The bolt assembly, and valve & tube assembly.

The bolt. This will get more attention as I go into rebuilding the 622...

The spring on the pawl has a large and small end. The small end goes around the plastic pawl.
EDIT 11/04/09: I'm not so sure about that now, seems the large end does...

The bolt is riveted, somewhat, to the pump link.

That screw holding the tube to the valve is not stock.
EDIT 11/04/09: This screw is a stock screw.

Neither is the setscrew on the other side.
EDIT 11/04/09: I still think this one isn't stock.

Both screws removed, and the tube comes off.

The problem with this design of rifle is that a small boss on the receiver holds the tube and the front of the valve against the CO2 pressures. Not good. So likely the previous owner tried to fix it with screws. Which led to a chunk of the valve body breaking...
EDIT 11/04/09: No, it probably broke because it's a bit of bad design on an otherwise great rifle.

The setscrew just bore on the inlet valve assembly. Not good either, really.

Standard 38 piercing pin and seal.

At least I have a bunch of those laying around, although this one looks fine.

The exhaust valve, spring and inlet valve assy.

Another view.
Well she's all taken apart, now I have to figure out how to pin the valve to the tube (Mac1 Airguns will do this for you, if I was less foolish I'd probably send this to him) so that everything is retained stress free. That'll take a bit of thinking.

Tuesday, October 27, 2009

Crosman 622 Disassembly, Part 1

I picked up this Crosman 622 with a "WTB beaters" ad on the yellow forum (I need to run another one of those...) It had a jammed clip (easy to get it unstuck) but seemed to need a complete overhaul...I couldn't get the clip to index and "in for a penny" as they say.

The rifle with the butt stock removed.

The rear sight removed.

Setscrew holds the barrel to the receiver.

Loosening the barrel band.

Barrel slips out.

Two screws hold the forestock on.

Removed. Those two bushings ride on the tube.

They have a plastic insert.

Unscrewing the receiver LH screw...

Pretty stripped...not good. So project #1 will be helicoils in the receiver screw holes (holes...keep reading.)

This little plastic thing is used for unsticking the clip, used only on later models.

Where it goes.

And the back side...

The trigger group.

Safety removed.

Safety and stock nut.

That spring has a detent plunger at the other end.

Pretty caked with grease.

The other side of the receiver. That screw isn't stock...

Definitely not stock. And slightly too long, causing the valve assembly not to sit flat against the receiver and not allowing the two pieces to close...
The things you find in used airguns.