Disassembling a Gamo Hunter 220, Part 1

I picked up a Gamo 220 Hunter a while back for a pittance.

What a boring stock.

Removing the front screws.

See the yellowed dried up lube?

Rear screw.

The stamped piece centers the stud on the stock and presumably spreads the recoil.

Plastic bushing on the cocking arm.

Removed.

The end cap is a cheap piece of rubbery plastic that fits poorly.

I broke the barrel to take the detent force off of the pivot.

It tooks a bit of torque to unscrew.

The linkage won't come apart yet...

The e-clip at the upper right corner needs to be removed along with the spring behind the linkage piece.

I put the spring and e-clip safely away.

The linkage rotates off now.

There's a small plastic shoe that slides along teh stock under all that old lube.
More to come...

Crosman 147 BP Stock Refinish, Part 2

Thought I'd try fitting the rubber butt pad with a hand sander. Spoiler alert: It doesn't work.

The rubber flexes away from the sander too much.

Here's a few minutes trying to fit the toe. It's curved...

Not good. Most people I know who fit rubber recoil pads use a disc sander. I was trying to avoid working inside the house--mainly because the rubber dust gets everywhere.

Out of sheer curiosity, I mounted a sanding drum into the 3-jaw chuck on the Taig lathe, and profiled the butt pad by eye in about 60 seconds. Likely not the way to do it if you're on that fourth cup of espresso.

Looked pretty good. I sanded the stock down to 220 grit.

The pad is pretty dusty from the wood sanding. It'll get cleaned off later.

After the sanding, a rag dampened with some distilled water is run across the wood. As the water evaporates, it lifts wood "whiskers" from the sanding. Allow the stock to completely dry then sand again with 220 grit to remove the fuzzies.

A coat of a redwood oil based stain. Given my past history staining vintage Crosman stocks, I opted for a stain with a lot of pigment. My hope was that the redwood stain would give enough color to the wood to make it look like cherry. Why not just use cherry stain? I tried that. Cherry colored stain makes these stocks turn light pink. And I really wouldn't be using the 147 much if it looked like a pink underbelly...

The forend looks like a brick. Functional, but a bit too blocky.

Put the sanding drum back to work reshaping the front end.

Softened up the nose.

I'm probably going to regret working these as two separate pieces.

Redwood stained. The through holes I drilled (in Part 1) to get the roll pins out really stand out in this pic.

And then I decided to do more work. The metal on the 147 BP was in so-so shape cosmetically. I completely disassembled the gun and started by stripping the old paint off the trigger housing assembly with a wire wheel.

The paint on many vintage Crosman trigger guards take a beating every time the guns are disassembled as they're pulled through the wood stocks.

Pump arm, barrel assembly, pump tube, trigger guard are all looking tired. The bluing had all gone plum. Pump guns get a lot of handling by nature--especially by the time they turn 43 years old.

Epoxy spray paint from Rust-Oleum. I've used this stuff before on the compression tube of a Baikal IZH-46M. The 46M tube was thinly blued when new and didn't age well. Hit it with two coats of this and it looks factory finished and incredibly tough.

Downside? The drying time. I could bake it and get it over with sooner, but my wife would probably not take kindly to gun parts in the oven. I'll give it a couple days at least. If it holds up for the next ten years, what's 48 or so hours anyway?

Some .177 cal felt cleaning pellets.

Only need two...

One to keep paint out of the muzzle...

And another to plug the breech.

Don't want paint inside the compression tube. A piece of 1/2" PVC pipe fits the ID of the tube perfectly.

Painted everything and hung to dry. Also ended up painting the end plugs and front sight.

One coat of Birchwood Casey Sealer and Filler and I rubbed the stock down with 0000 steel wool.

Most of the grain is filled now. Hopefully several coats of Tru-Oil will finish the job.

A pretty good slathering. Now, some drying time and several more coats.

Still more to come...

Crosman 147 BP Stock Refinish, Part 1

Another gun from the "doesn't get used pile" is a $35 gun shoppe acquired Crosman 147 BP multi-stroke pneumatic. Due to it's trigger arrangement, it's what Crosman collectors call a second variant and therefore from around 1965 or 1966. The 147 BP is the .177 version of the .22 caliber Crosman 140. The BP stands for BB/Pellet. I didn't even realize that it was the BP model until I cleaned the bolt and found the magnetic tip designed to hold the steel BB. Anyway, I brought it home, and confirmed it leaked like a sieve.

Rambling airgunner sidebar: This gun is probably responsible for any and all inner hatred I harbor for multi-pump pneumatics. I believe I disassembled the rifle somewhere around 12 to 14 times. You've seen Army recruits assemble their guns blindfolded? Yeah, I can do that with the 147. At first, the question was, "where isn't it leaking from?" Spring piston guns? I cut my teeth on. CO2 guns? I can figure out. Single stroke pneumatics? OK, can do. A multi-stroke pneumatics from about 1966 with a bad pump cup, bad check valve, and bad exhaust valve? Are you kidding me? This was a gun just full of learning curves.

Eventually though, the gun was repaired and set aside--being deemed too ugly to shoot.









Lots of raised grain and a few dings and dents in the wood. I recently refinished a Crosman 180, and I wanted a similar cosmetic transformation. Of course, the gun is actually in fine shape considering it's age. The fact that it still shoots--and shoots well-- is truly a testimony to the engineering and materials used 43 years ago. Hopefully by now, readers know I'm pretty tongue-in-cheek when I'm talking about these devilishly designed multi-stroke guns...
Essentially, I think my vintage Crosman problem is one of aesthetics. I suppose I just can't warm up to old varnish finished air rifles. If I'm going to keep it, I guess it's gonna have to get gussied up. At the risk of being labeled as a one-trick pony and being permanently type-cast, I'm afraid that this refinish will be sort of similar to the Crosman 180 refinish previously mentioned. Sorry 'bout that. The guns share a lot of similarities not only in finish, but also in several components like sights and trigger mechanisms--which is too be expected as the guns overlapped during time of manufacture. It's hard to not make the comparison as I've been working on both guns almost simultaneously. The 147 got a few modifications (rear sight and recessed stock nut) that won't get blogged as they're already covered in depth during the 180 write up.

Sort of jumping ahead, I pulled the action and hit the stock on the sander.

Half an hour later, I was about here.

While I'd decided on a simpler refinish than the 180 got, I still wanted some pride of ownership (multi-stroke not withstanding--grrr).

Mixed up some fast setting 2-part epoxy, adding a liberal amount of the sawdust from the above sanding/stripping step...

and filled the dents and dings. Overfill slightly.

A chicken pox stock.

The next day, I lightly sanded all the filled areas.

The pump arm was a slightly bigger hurdle. The lever arm is held by two roll pins--and the holes don't go completely through. How do you get them out??? I found a very small drill bit that passed through the center of the roll pin. Using the drill press, I drilled through the wood on the far side.

You can just barely see the holes--they're that small.

The small holes become a guide.

Using a larger diameter bit that matched the OD of the roll pin, I drilled the guide holes out till I hit the roll pins.

Now, I've got holes on both sides of the pump arm.

Set a drift.

And hammer the pins out.



One more time.

And we're free.

This seems somehow all too familiar...

Wanted something that looked good, but didn't take 2 weeks of free time to finish. I scrounged around and found a couple old Weihrauch butt pads that looked sort of promising.

At some point, I also made a clean cut on the butt of the stock for the rubber pad.

I think this came off a Beeman R1 a few years ago.

Like the 180 stock, I sanded the butt of the 147 BP on a granite plate until it was truly flat.

Then I sanded the rubber pad dead flat as well.

A transfer punch located the upper screw hole.

This was followed by drilling and snugging down just the single upper bolt.

Once the upper bolt was snug, I repeated the transfer punch, removed the pad and drilled the second, lower screw hole. Here, I've reinstalled the pad and begun to tighten the second screw.

It's oversized to allow for fitting. Unfortunately, I didn't think the 2 screws held the pad tight enough to the wood for the sanding. Hand pressure alone was gapping the pad too much for my liking.

Yeah, Gorilla Glue. I love this stuff. Now I'm in limbo as I wait for it to dry.

More to come.

Slavia 630 Piston Seal, etc.

I'm getting some seals for the 630 through a complex mechanism but figured I should try and make a seal for one of the 630s.

I needed a longer gage for measuring the bore of the tube. I hit on the idea of attaching a pin vise to the telescoping gage as an extension. I should invest in a bore gage at some point.

Cutting the face of some 75D urethane flat.

Drilling.

Boring the recess.

Grooving.

Snaps right on! Notice my precision drawing.

Facing to length.

Grooving.

I decided to size the seal with a grinding stone in the dremel. Because I had cut the groove it generated a lip that tapered back to the body under the cutting force, which was ideal.

You can see the tapered front.

The piston was a bit rough at the front and back.

So I polished it up.

The machining on the piston is rough. The middle part doesn't matter as it doesn't contact the tube at all.

I only noticed that odd trigger spring contructed from flat spring steel when it fell out of the stock an onto the floor. This is where it goes. The rest of the rifle goes back together in reverse of disassembly.

The rifle was smooth but only about 320fps, which isn't good. So I tore it apart again and took another few thou off of the piston diameter. Put it back together and I'm getting about 520 fps with CPL's which is close enough to the 170 m/s (557 fps) of the factory spec.

Now to figure out a replacement front sight and rebuild the rear sight.

Crosman 600 Bulk-Fill / Barrel Extension

The Crosman 600 semi-auto has long been considered one of the finest achievements in CO2 airgun development. The 600 uses a small portion of the CO2 gas to cycle and load the gun. It's a true semi-auto, not a revolver like most all the CO2 repeaters on the market today. Ten .22 cal pellets are loaded along the top left side via a built-in spring loaded magazine. (It's actually possible to load one or two additional pellets if they're short--like the Eley Wasp) The CO2 powers a "toggle" action that aligns the forward pellet with the barrel where it's then immediately fired down the barrel. The 600's are typically very pellet sensitive, though the two I have both like .22 cal Eley Wasps, H&N Match Wadcutters, RWS Hobbys, and Crosman Wadcutters. The guns were designed back in the late 1950's and first marketed in 1960. I'm a huge fan of the ray-gun look. The ergonomics, sights and trigger pull are pretty tough to beat. National Match Shooters may note that 600's will often outshoot Ruger Mk 2's offhand at 50 feet on a good day. At the least, it'll be interesting.

The vintage Crosman data indicates that the pistols will fire a 14 grain pellet at 340 fps and 40 shots are available from a 12 gram CO2 cartridge. I've never managed more that 35 shots and I've found the average velocity to actually be about 305 fps. Max velocity with a similar weight pellet is indeed in the quoted 340 range, but the velocity seems to drop pretty quickly into the low 300's and remain there until the gas exhausts.

The stock barrel length is 5". The barrel is easily removed by loosening a single set screw at the rear of the barrel.

Set screw is on left. Top of pistol frame. A 7/64" allen wrench does the trick.

Uh, so what am I doing? Well, a second 600 recently presented itself and I couldn't resist. My single complaint (aside from the gun only holding 10 pellets) is the low shot count per cartridge. The 600 is often--and accurately--described as a "gas hog." One solution to the gas consumption is to increase the on-board CO2 carrying capacity. Many vintage Crosman CO2 guns don't seal the cartridge against the valve. The valve seals the gas tube at one end and the cap seals the other end with the CO2 cartridge in the middle. These guns can benefit from higher shot counts and cheaper CO2 refills by adding an extension tube and a bulk-fill cap. The tube simply adds volume, while the bulk-fill cap allows filling from a paintball tank. Cheap refills and more shooting.

OK, so the bottom 600 has been converted with a bulk-fill adapter and gas tube extension from Bryan & Associates. Tim at Mac1 is another great choice for bulk CO2 parts.

While the gun will work with the 5" barrel in place, it looks absurd with the extension. I had a spare 2260 rifle barrel in my parts stash. One problem: the 2260 barrel diameter is 7/16" or 0.4375". The stock 600 barrel is 0.370" diameter to fit inside the frame.

Eyeballed the length and cut the 2260 barrel down to about 15".

Chucked into the Taig lathe and faced off the cut.

Switched tool bits and cut a tapered lead for the business end of the breech. A high speed (and very light) cut finished the surface like a mirror. This is essentially a "forcing cone" to use a revolver term. The pellet jumps from the toggle into the barrel under rapidly expanding CO2 pressure so I think that is an apt comparison.

Turning down the barrel to 0.370". A live center is being employed to stabilize the end of the barrel at the other end of the bed.

Primarily used a ti-nitride indexable tip to make the cut. Higher speed, heavier cuts.

Finished with a carbide tipped right-hand knife to create a shoulder. The barrel will slide into the 600 frame, seat on the shoulder and lock with the set screw. Length of the 0.370" diameter portion is absolutely critical. Too long, the toggle will hang up on the barrel. Too short, the gap between the toggle to breech is too great allowing CO2 to leak and pellet velocity suffers. Careful and repeated measurements were taken and the length was set at 4.945" from breech end to the shoulder.

Time to cut the muzzle to final length. Another precision cut.

Faced.

Another pic.

Cut a slight recess to protect the crown. Once finished, I cleaned the barrel thoroughly of swarf then lapped the bore with J-B non-embedding paste.

Hand filed a small flat fot the set screw.

Sort of like this...

Installed. Barrel ended up at 14.25" long. 9.25" longer than stock.

Couldn't help but make some chronograph comparison notes: We all know that adding barrel length to CO2 guns increases velocity as the CO2 continues to expand behind the pellet.

Stock gun, 12 gram Co2 cartridge, 5" barrel

341* highest velocity
320
314
315
315
310
310
306
309
308
325
318
313
310
307
300
310
300
600
296...

Ending velocity at #33 shot (gas exhaust) was 281 fps.

Bulked gun, with the 14.25" barrel:
468
473
472
472
475
478
470
478
478
476
482
480
479
483
480
481
486* highest velocity
477
482
476
482
486
475
466
474
482
481
477
473...

Ending velocity at #69 shot (gas exhaust) was 376 fps--still 35 fps faster than the first and most powerful shot from the 5" barrel.

So, the bulk extension tube essentially doubled the shot count while the 14" barrel added approximately 165+ fps over the stock 5" barrel. 165 additional fps--how often do we see a gain like that?

Downsides? The weight of the tube extension and barrel makes for heavy leverage during offhand shooting. I can do it, and I'm getting better, but it's not the gun for the weak of wrist.

Upsides? You can empty a 10-shot magazine in about 2 seconds and just watch the target bull vaporize. In a couple seconds, a tin can at 50 feet looks like you used a shotgun. --And I don't have to burn through CO2 cartridges anymore.

Installing a Morgan Adjustable Recoil Pad on a Baikal 513M Air Rifle

This is how I mounted a Morgan #4 Curved Recoil Pad on my Baikal 513M Air Rifle.
I decided to start selling Morgan Adjustable Recoil Pads to generate a little income to subsidize all my airgun purchases and blogging. I set up a web page where I sell the pads . The main reason for installing one of these recoil pads on an air rifle is not to tame the recoil of the airgun but to drop the butt of the rifle, and lengthen the pull for a more comfortable fit.

The stock butt plate on the Baikal 513M.

Removed. If this were a firearm I'd probably fill the counterbored holes, as it was I just plugged the actual screw holes with dowels.

Now to mount it.

I marked the centerline of the butt.

Although the hole spacing is identical, I need to offset the recoil pad so that it is centered on the buttstock..

To do this I flipped the bottom plate over to ensure that the adjusting mechanism was entirely on the butt.

I marked the new screw locations with pencil.

I drilled for one screw hole.

Notice the original hole is plugged.

I temporarily screwed the pad on and took care to align the second screw hole on the centerline.

I used a transfer punch to mark the 2nd hole. I wrapped some masking tape around the end of the butt to protect the finish.

Drilled and screwed on.

I then flipped the stock over and scribed the contour of the butt on the plastic.

Now I have a guideline for trimming.

I used my favorite file for plastic, a Nicholson Magicut file

Almost there.

I then sanded carefully with a sanding block.

Looks good.

I sanded it smoother with some 400 grit paper. In hindsight I should have gone to 600 and maybe even 1200 to get a better finish. I did rub it with plastic polish which shined it up a bit in the later pictures.

The bottom half of the pad mounted with the adjusting screw in place.

Overall I'd say it took me about an hour of patient work. I have yet to do one of the aluminum recoil pads but that would require a belt or disc sander, or a lot of physical work to trim to size.

The drop I need to be comfortable with this air rifle.

The Baikal 513M in the rifle in the center. Notice an old style aluminum pad on the Diana 45 air rifle above it.

Prototype Roll Pin Pusher

This is an idea I've had for a while as a way to avoid hammering roll pins out.

Marking the parts.

Spot drilling.

Drilling under 1/2"

Reaming 1/2"+

Flip the parts and use a dowel pin to align the previously drilled holes.

Reamed halfway through, the other part is just drilled to 1/2"-13 tap drill.

Some other holes..

Slotting the parts.

I almost slotted into the one hole that doesn't need slotting...

But instead needs tapping.

Drilled and reamed 1/4" the end of some 1/2" all thread.

Facing some 1/2" diameter tubing.

Making a 1/4" shank, roll pin punch.

Small pilot on the end slips inside the roll pin.

In use pushing out a roll pin from a Sheridan forearm.

Hmmm. I suspected the end of the tube would do that. I'm not upset as you'll notice that the forearm already has a huge chunk out of it. I bought the Sheridan for $35.00 at a gun show. My plan is to make or replace the forearm.

I made a slip fit delrin pad for the end.

Just a slight pressure mark, I think I'll make a new pad from UHMW or other softer plastic.

The screw needs a handle but two nuts with a wrench work fine for now.

Adjustable...versatile...not a bad father's day project.