Two CF-30's

[Toxylon]

Earlier this year I happened on a bunch of three old Spanish springers. As the bunch mostly consisted of Gamo CF30’s, or the only Gamo I’ve been interested in, and the asking price was very reasonable, I took the plunge.

The Gamos are of 1999 and 2000 vintage, or about a quarter century in age (man, the time flies!). They are both in .177 cal. I would have wanted a .22 cal for variety, comparison purposes and whatnot, but those seem really rare here.

The CF’s beech stocks are pretty beat up (which annoys me more than I would’ve thought), but the actions are rust- and scratch-free, a curious combo. All in all, I get the feeling these guns, especially the 1999 one, have been heavily used, which isn't common with airguns.

Shouldering these older, wood-stocked Gamos feels instantly comfortable and effective, as well as 100% open sights-friendly, something my shortly owned plastic stocked CFS failed at completely, on every count.

Surprisingly, these consecutive-year guns are a little different in stock length, which can be felt, too. The guns weigh the same to within 20 grams, or 3.2 kg / 7 lbs. They are definitely handy, in both weight and length.

Cocking is a little spring noisy as is typical for Gamos, and of medium effort on both guns. My CFS had a much lighter cocking stroke, which is the sole strong point for it, even if of no consequence to me.

Loading the pop-up breech has proven tricky. The breech hole is close to the receiver top, it has no lead-in, and the hole is (obviously) parallel to the receiver. Anything but perfect pellet alignment on three axis prevents a tiny .177 cal pellet from going in, so it’s a chore, at least a hundred pellets or so in.

I would have assumed the pop-up breech retreats back into shooting position with the cocking lever being returned to battery, but at least with both of my CF’s, this isn’t so. It feels a little agrarian to need to manually push the wobbly breech plate down.

The older CF has a stunningly good trigger for a steel trigger Gamo; it has a light first stage that stops reliably at a false second stage wall, which breaks with a shorter and cleaner pull than I’ve ever felt in a Gamo or similar trigger gun. Sure, there is some mushiness there, but this is a very usable trigger pull. The younger gun’s trigger pull is typical Gamo, or long, vague and creepy. For comparison, my plastic trigger CFS had indeterminable, unusable mush all the way.

Gaylord has mentioned how Gamo steel triggers turn pretty good after thousands and thousands of shots; I think I have proof of that now. I was all ready to make a trigger roller mod, if not getting a GRT, but that isn’t necessary.

The older CF shoots mid-weight .177 cal pellets at around 10 fpe with pretty wide spreads, so the gun isn’t healthy. Even at that meagre power, the gun is dieseling pretty heavily. I’m willing to bet the mainspring is shot out; the seals may also be compromised, although a tissue test didn’t show leakage.

The younger CF didn’t register at all at the chrono, despite cocking normally and exhibiting no weird sounds or sensations. It dawned on me that the barrel is blocked, a first for me. I intuitively look into any breakbarrel bore I don’t know, but that isn’t going to happen with a fixed-barrel gun with a pop-up breech. Getting anywhere with this gun requires a complete teardown.

With the older CF, preliminary accuracy seems promising, especially with the deviation, dieseling, uncleaned barrel, unknown pellet preference etc.

Both these guns have the dreaded 10mm section of unrifled muzzle bore, which every expert advises getting rid of. That will require re-crowning, as well as re-fitting the underlever catch. The underlevers are wobbly in both guns, which is another accuracy-draining bug.

I have some Gamo parts from my 440 Hunter days that fit the same-powerplant CF’s. What I don’t have is the dual breech seals for the CF’s, which are very expensive for what they are, and only available to me from foreign sources. I would be really happy to modify easier-to-get seals (O-rings) for the CF’s, but as of now I don’t know what works as blanks for the modding.

[Novagun]

Kiaora Toxylon,
Sounds like you are on the track of sonething good. Just a couple of hints you might to consider . You might find the the sticky out bit of the muzzle will take a 1/2 x20 NF die. The striation take the cut and leaves a usable threaded muzzle . I did it on my Cfx before I cut and recrowned. Recrowning is not difficult because the steel is very soft. I have used two methods to hold the cocking lever . One was s rare earth magnet and the other a fabricated plastic clip that clips around the barrel. Both work well.
Less clatter than the factory clip . I modified the piston head on one to take a 25mm Weihrauch seal. That made quite a difference to the shot cycle. Smoother. Custom airseals in Australia have a few gamo parts.seals etc. Bit pricey but good stuff. I wouldn't bother trying to track down
factory Gamo seals.   Those of that vintage were too hard.
The pop up breach is something I haven't seen here
Please keep me/ the forum up to date with progress.

[Toxylon]

Thanks, Hugh!

Did I get you right that you would tap the outside of the barrel with the 1/2 x20 NF die so far that the threads would reach well past the smooth bore, then cut the smooth bore off and leave the new muzzle with a new crown threaded for a moderator?

I have heard of rare earth magnet underlever holders - it would be a hoot to install one and see how it works. Feels like a much more elegant / foolproof concept than a clip.

CAS piston seals have been a complete bust in my guns so far, shooting really low velocities and degrading the shot cycle of several guns. They also take well over a month plus customs time to get here, so I'm not sure I'll go that way. However, I have an unused CAS Gamo 25mm seal that I got for my 440 before it bit the dust. I'll sure test it in these CF's.

I'll check some further AG discussions for alternative sealing materials for the popup breeches. Then there's a large seal that seals the plastic breech block inside the cylinder in the CF guns. I have some UK notes on that, also suggesting softer, more pliable materials over the OEM

[Novagun]

You can thread the muzzle for the lenght of the necked down part. This is the same length as the smooth bore part . Cutting at the neck gets you to the rifling .
Just in case the CF30 is different the plastic brake or maybe the foresight on the 30 is attached by way of striations
/ ridges that are pressed into a portion of the barrel that is turned down from 16 mms to about 12 

[Toxylon]

Took the blocked-barrel CF30 apart. It was a bit of a chore, from hooking the fixed barrel-receiver assembly to my compressor to drifting out the extremely tight cocking arm axle pin.

All the internals, from the uppermost trigger sear to the bottom of the comp tube, were soaked in lubes, ranging from silvery moly paste to black moly grease, to brown, watery mud type oil. Gamo sure didn’t ship their guns dry, 20+ years ago.

To my surprise, the mainspring was in one piece and pretty straight. Once the piston saw the daylight the problem became obvious: there was a huge chunk of the piston seal perimeter missing - a literal 3mm wide channel from the front of the seal to the rear. It looks to me like a case of extreme gas cutting, resulting from the over-lubing done at the factory. Well, I’ve seen reports of CF guns exploding their pop-up breeches from factory-provided detonation with the first shots…

At any rate, such a leak in the powerplant would kill any pressure inside the chamber, explaining the power being less than what is needed to push a pellet out of the bore. The gash in the seal would also allow free travel of any combustibles to and from the compression chamber.

The surprisingly long steel rear guide in the CF has an OD of 13.0mm, and it fits somewhat closely to the 13.3mm ID mainspring, only because of a kink in the spring bottom.

The standard, heavy (67g / 2.4 oz.) steel tophat of the CF’s is completely loose in the spring. For some idiotic non-reason, the tophat has a neck diameter of just 12.5mm. Why is this simple lump of steel 0.5mm smaller in OD than the rear guide? There is no explanation. While there are 13mm ID replacement springs for the CF’s, there are no 12.5mm springs.

The plastic comp chamber bottom of the CF series guns has an inlet Delrin band for a seal. The seal in this gun had pretty bad scoring at the receiver cutout side, from factory assembly, and likely some from the pre-deburred extraction today. It’s pretty close to needing a replacement, which I’m not thrilled about.

The pop-up breech has a stepped brass insert in it. As I noted previously, there’s virtually no lead-in to it, which makes loading pellets just too tricky. I’m really tempted to chamfer the breech mouth a little. Obviously, any work done there must not compromise the breech seal’s ability to seal.

The breech seals themselves are flat O-ring material seals, 13mm OD, 7mm ID, 2mm height, flat on the bottom, slightly rounded on top, and very supple still. One of them has started fraying, though. These are the seals that are around 7 bucks a piece, for a staggering price per pound. I'm thinking of locating correct ID / OD O-rings and sanding them flat-bottomed, for a replacement.

[Toxylon]

The main reason for the teardown, the blocked barrel, has proven a tough nut to crack. Once I had the barrel-receiver assembly down to a single piece of steel, I could prod the pellet blockage from either the muzzle end or the breech end, using a long, stiff carbon fiber rod to save the rifling.

No amount of prodding, pushing, tapping, or finally bashing the rod against the pellet blockage, from either direction, has gotten the pellets moving more than a bit. There are some 15 Meisterkugeln pellets in there, bunched up together into a three-inch lead slug, far away from either end of the barrel.

 I have sprayed WD40 down the bore for lubrication, letting it seep through, and have even heated the barrel at the site of the blockage with a heat gun to expand the bore some before prodding, but no luck.

[Novagun]

15 pellets stuck in the bore. Doesn't look to me that you are ever going to shift those without drilling. Slowly. I think it could done with some imaginative fabrication of a long reach drill that won't damage the rifling. Maybe gunsmiths have such a tool. Sooner or later you are going to have to go for broke.

[mikeyb]

The main reason for the teardown, the blocked barrel, has proven a tough nut to crack. Once I had the barrel-receiver assembly down to a single piece of steel, I could prod the pellet blockage from either the muzzle end or the breech end, using a long, stiff carbon fiber rod to save the rifling.

No amount of prodding, pushing, tapping, or finally bashing the rod against the pellet blockage, from either direction, has gotten the pellets moving more than a bit. There are some 15 Meisterkugeln pellets in there, bunched up together into a three-inch lead slug, far away from either end of the barrel.

 I have sprayed WD40 down the bore for lubrication, letting it seep through, and have even heated the barrel at the site of the blockage with a heat gun to expand the bore some before prodding, but no luck.

If I could get the barrel "bare" steel (no plastics, seals, or springs) I'd try to melt out the lead. IMO other methods risk damaging the bore. Your rifle, your choice. Best wishes regardless :-)

[Novagun]

Yes mikeyb has a point but heat tends to distort steel especially tubes . I would make up a couple of delrin guides so the drill tip would not could not  touch the rifling. One small hole as a pilot then another to clean out all or most of the lead. Take your time . I would not try to drill 15 pellets in one go  pellet at a time.
Decision to make and good mechanicing .

PS the thought of heat frightens me. You would have to get the barrel very hot so the lead didn't solidify before it ran out of the barrel and even then some might stay inside 

[Toxylon]

My take on trying to melt the lead out:

I have used 200 C hot air to heat the barrel so far. I wouldn't even dream to heat the barrel into tempering temps, or around 250+ C, even though I'm not afraid of softening the already soft barrel. Lead needs about 330 C to melt (a hard pellet such as Meisters likely more), and, being enveloped by thick steel, the steel itself needs to be appreciably hotter than the medium to be melted. Like Hugh said, distortion is the boogyman.

Now, once you have running lead inside the bore, like any liquid, it will leave a trail residue behind, like ultra-heavy, lopsided leading. How do you go about removing that?

I want to keep things simple and cheap here, being this gun cost me 30 bucks, it may not even be accurate once I get the bore cleared, and it will likely only be a side gun to me even if it were.

I'm thinking of getting 4mm OD brass tubing, gluing a 2mm drill bit securely to one end, twisting or tying a crosswise handle to the other end, centering the tube in the bore with masking tape "rings" and augering my way through the pellets, one by one, until the mass starts to move.

[mikeyb]

NOT a torch project. Uneven heating and distortion likely in that case. I'd heat the ENTIRE barrel uniformly to ~630F to melt out the lead. Something like a forge furnace turned down to "sleep" mode? Not something everyone has in their back pocket.

With many airgun barrels already being soft steel I don't think uniform heating to lead melt temps would be a problem.

I would be able to cobble together a long tubular temperature controlled "tempering oven" with parts I already have but it's not something I'd use often... Well maybe more often than I think!?

Turned down to 50% (~315F) it might make an excellent welding rod oven for drying out my older stick electrodes. Something I could and would use far more often than de-leading jammed barrels.

Using the kitchen oven for drying old welding rods is not a good idea on several levels ;-)

[Toxylon]

Good points, Mike, as always.

Alas, there's zero chance for me to rig up a barrel-length oven setup. I'm a backyard airgun mechanic (for now).

...

For some time now, I have tried to get the CF30 barrel off the receiver, to make every barrel-related operation (from de-glogging on up) easier / more effective.

The CF series barrels are connected to the receivers via a fine thread (see hard-to-read pic), secured by a grub screw (see pic). I have taken the grub screw out, and I have soaked the joint with WD40, and have heated the joint to 200C+, both tricks that usually work well with stuck bits of steel.

Turning the barrel with quite a bit of muscle only succeeded in getting the splined front sight base off the barrel. That was on the to do-list, anyway, so no worries.

To get the barrel joint finally moving, I would hook a smooth, round steel bar through the pop-up breech hole in the receiver, and squeeze the revealed barrel front spline with a pair of pliers wrench (I think that's the term) with smooth jaws, transferring a really hefty amount of torque into the barrel joint, but the wrench jaws would slip in the end, with zero movement of the barrel.

Then I'd take a pair of locking pliers and try the same. After pretty tremendous amount of torque, even the locking pliers would slip rather than the barrel turn, and the toothed jaws would score the barrel surface (see pic). It's the spline surface, which will be hidden if not removed, so I don't consider this a bust. But the barrel is still tightly in place.

All the suggestions for removing the smoothbore section of the barrel outright seem to assume there's no need for open sights, as the front sight base of the CF's only fits the turned down barrel section, and there isn't enough meat in the base to widen the opening enough for the 16mm barrel proper (only up to 1mm of plastic wall left). But I need open sights on my guns.

[Toxylon]

One option would be to enlarge the smoothbore section substantially, so the pellets would have no contact with it, and the air blast would have a generous way out, as well.

My BSA Mercury has such a barrel, with the .177 cal bore enlarged to 9mm for a depth of one inch, and that antique springer is among my most accurate self-contained guns.

Truing the crown at one inch down a still-narrow opening wouldn't be all that easy, though. No rocking the electric drill with a brass screw in it.

[Novagun]

Looks like you have done your best trying to get the barrel out. Any more could well end up with an oops..barrel could take a twist with more powerful tools .Careful careful drilling.
The pellets must be too near the centre of the barrel to just cut a bit off the end . I have done that with a CFR and the barrel length made up with a brake to house the cocking lever . That turned out to be a very accurate Gamo.

[Toxylon]

While stuck with the stuck up barrel, I took the older, functioning CF30 apart. Remember, this gun shot only about 10 fpe, when a .177 cal CF series gun should do up to around 14 fpe. Visible dieseling and high spreads further warranted the teardown.

Doing same-model guns back-to-back has definite advantages, as far as familiarity and routine-building goes.

I had thought the older CF might have a fatigued mainspring, but no. The spring was in one piece and had a ton of springy preload. It did have a decent cant in the middle plus the usual low-quality mainspring snakiness, but nothing that would cut a third of the muzzle energy.

The piston seal was in remarkably good shape for a Gamo, too, especially at supposedly 25 years of age, plus apparently much use. It was pretty tight in the chamber, however. My past experience has shown that a piston seal just a little tight can rob a surprising amount power, even with guns more powerful than this lightweight, light-piston underlever.

The breech seals were pretty good, too. However, the forward seal had a crushing type of injury in one spot, likely contributing to a leakage.

As an aside, the mainspring and rear guide were swimming in moly grease, while the piston had almost textbook lubing, only way too much of it: there was a silvery band of moly paste on both ends of the piston, plus typical yellow-brown factory grease covering the piston body. Leave the latter off, and dial down on the high-moly paste, and you would have a decent lube job, something Weihrauch or Diana never did.

To get the gun going, I did the following:

1) I sized the piston seal on my micro lathe, from 25.6mm down to 25.3mm. With that, the piston registered a perfect ~2lb. resistance in the chamber.

2) I cleaned the receiver as usual, and deburred the cutouts.

3) I took the two best breech seals between my two CF's, cleaned them and revived them with a bit of silicone oil. Plenty of plump flexibility.

4) With the powerplant out of the way, I cleaned the barrel with copious amounts of patch pulling, both dry and Ballistol-soaked.

5) I deburred and smoothed the underside of the stamped linkage lever connecting the cocking lever to the pop-up breech.

6) I very slightly chamfered the brass pop-up breech opening for easier loading, after checking the breech seals didn't touch anywhere close to the opening (to not introduce leakage).

7) I smoothed and polished the OEM tophat forward end, and fitted the loose tophat neck with a shrink tube cover, for a tight fit on the spring.

8 ) I lubed the piston with a little Honda 77 moly paste covering the piston seal sides, the front bearing and the rear of the piston only.

9) I re-used the OEM mainspring off the newer CF, after leveling and polishing the spring ends (way more work than usual, with the factory leaving them with heavily convex surfaces).

10) I wiped every external metal surface on the gun with Ballistol.

11) I assembled the receiver into the newer CF stock, which is 5mm longer and fits me better, while also having a little less scuffed up finish.

12) I installed flat washers under the star washers in the front stock screws.

...

After battling with fitting the odd-dimension / style barrel-receiver assembly handily and securely to my spring compressor, I took to pushing the mainspring in manually, using a padded bit of board against my chest, pressing down on the barrel with my torso, and tapping the crosswise pin in with a rubber mallet, which I just barely reached to do with my right hand.

CF mainsprings are really long (41 coils), and have much preload. They are much longer than Gamo 440 springs, while also having a smaller ID. I don't know how general Gamo-style springs (such as Maccari's E3650) would work in a CF, but at factory spec, they are really different, despite the CF series being described as much the same as a 440, only a fixed barrel.

The Titan #13 should fit a CF really well (better than OEM), but at this juncture, I want to see how a mildly enchanced CF with factory parts shoots.

With the assembly, the hardest part again was inserting the cocking lever axle pin, now with two separate moving parts (lever plus breech linkage) and four separate holes needing to be lined up while pounding on the pin with a brass punch really hard.

It'll be a while before we'll see how the gun shoots, as the rest of my August is really booked up, but it'll be really interesting.

[Toxylon]

So, the CF30 finally saw action this past weekend. Turns out my proven fixin’ tricks didn’t really work on this platform.

The CF shoots now at just a hair under 10 fpe, improving none from the earlier situation. What’s worse, deviations are pretty drastic, in the order of up to 40 fps over a dozen shots.

Even with the modest lube job I did, the gun still diesels quite a bit, a first for me at this juncture. I think the CF platform is extremely prone to dieseling, what with new CF’s sometimes shattering their pop up breeches from factory-lube-provided detonation.

Even at 10 fpe, the Gamo is still really loud. Plenty of mech noise from the undersized factory steel spring guide, but that’s not the issue to me, but the muzzle report. BANG! she goes.

The cocking stroke feels gritty and friction-y, despite me lubing all moving joints before reassembly. Some cockings are surprisingly smooth (maybe 1 / 20), most are not.

The pop-up breech works pretty iffy, even though I cleaned and lubed it before reassembly. It is only rarely that the pop-up breech both raises and lowers as it should with the movement of the cocking lever. Most of the time the breech doesn’t go all the way down with the lever returned to battery, but needs to be manually pushed the last quarter inch or so to a fully down position. On occasion, the breech doesn’t really want to stay fully up, even when the the cocking lever is pressed all the way down, but starts a partial, gravity-fed descend on its own, making loading really clumsy. This is not a field-rated loading apparatus.
 
An altogether nastier issue are the occasional (maybe 1/50) misfires that happen because the pellet didn’t leave the pop-up breech on discharge. On one such occasion I could see the pellet had basically crashed against the barrel breech, way off-center (see pic). As even these pellets loaded normally, and I never fire the Gamo without ensuring the pop-up breech is down, I’m not sure how this happens. Does the breech jump up slightly on discharge? Could it happen without me noticing, shooting with open sights, and the breech directly in my line of sight? Don’t think so.

It seems the gun isn’t sealing properly, even though the seals are factory seals that have been checked and properly lubed, outside of one: it is possible the hard plastic seal in the plastic TP block isn’t doing its job, due to scoring from factory, and age. That could explain away the lack of velocity and consistency, but doesn’t do anything to the flimsy, hiccup-prone loading.

Maybe this is not a gun for me, and further, now costly, work on it isn't warranted. Fixed barrel guns that load directly into the breech were adopted for a reason.

[Novagun]

Looks like you have a dud Gamo. Perhaps the the whole CF30 line is dodgey . Never mind Diana has had some duds.
Did you make any progress on the blocked barrel?

[Toxylon]

Hugh,

I got pretty soured on the whole return to Gamoland idea and haven't done anything to either gun. I always have other guns that need this or that, and reward me from giving them attention, so the risk of abandonment (for undetermined time) is real within my springer rack.

[Novagun]

Now we both have Gamos just waiting . I can't complain at the service and experience I have had from mine . I was in the gun shop today and saw the line up of plastic barrelled Gamos. None of then had crowned muzzles . I thought that was imperative. The muzzles were pretty clean cut but no chamfer at all .
Another manufacturing step eliminated, I suppose , for profit gain . The Stoegers,were the same 

[JPSAXNC]

The CF30 is one of my favorite air guns, powerful enough and accurate enough. The trigger took some getting used to, but the long pull made me a better shooter.