by Tom Gaylord, a.k.a. B.B. Pelletier
Today, I’m going to tell you about a low-cost fix I got from airgun maker Dennis Quackenbush for bulk-fill CO2 guns.
Dennis bought a Crosman model 116 bulk-fill pistol that leaked, and rather than changing the seals, he injected automatic transmission sealing oil into the gun and sealed it that way. What this sealer does is rejuvenate the synthetic seals and make them swell to do their job again. Dennis said the procedure worked well in his gun.
Could I do the same? In the past, I have written about “fixing” CO2 guns by injecting several drops of Crosman Pellgunoil into the gun with the charge of CO2. That works for both bulk-fill guns and for those that use cartridges. This would be the next step. I just happened to have a Crosman model 116 bulk-fill pistol on hand that hasn’t worked in the 5 years I have owned it. I think I paid $30 for it at an airgun show, and did so hoping to fix it with Pellgunoil. I tried, but the seals were too far gone, and it didn’t work. So, I set the gun aside, always intending to do something about it.
When Dennis told me his trick, it was like getting an entire carton of round tuits! I went to the local automotive store and picked up a plastic bottle of automatic transmission sealer. I purposely did not ask Dennis to tell me the brand of sealer he used; because if this trick is going to work, it should work with any sealer on the market. So, for $5.50 plus tax, I bought what is probably a lifetime supply of bulk-fill CO2 sealer.
I picked up a bottle of automatic transmission sealer at an auto supply store.
How does it work?
To get the sealing oil into the gun, you put it in with a charge of CO2 gas. On a bulk-fill gun you remove a brass screw at the end of the reservoir that opens the port for filling. Drop the transmission sealer oil into the opening with an eye dropper. Then attach the bulk CO2 tank and open the gas flow. The first few times I did this, nothing happened. The gun continued to leak gas. But some of the sealer was blown into the gun each time I tried to fill it. Then, on the third try, the gun finally held some gas. I could actually hear the inner seals as they swelled and the gas stopped leaking. That fill only put in enough gas for about 6 weak shots; but it set things up for the next fill, which I believe was complete.
Crosman’s 116 bulk-fill pistol is a .22-caliber single-shot pistol with power and accuracy that surpasses many of today’s air pistols.
After the next fill, I had shots at the power I expected from this pistol. Since I’ll test it for you in a 3-part blog that’s coming up, I’m not going to report the power today, nor the shot count, but I expect to get 25-30 powerful shots per fill from this gun. That’s what similar models gave in the past.
The pistol’s fill port is covered by a brass screw on the muzzle end of the gun. Remove the screw and attach the bulk-fill tank to this port, snug it against the rubber seal at the bottom of the port and open the tank to let the gas flow. The fill takes about 2 seconds. This port is where several drops of transmission sealer oil are placed before the tank is connected.
Now that the pistol is holding gas again, I plan to test it for you completely. That’ll be a treat because these old gas guns are both powerful and accurate, as well as having advanced features such as adjustable sights and power.
My thanks to Dennis Quackenbush for passing along this tip. It won’t always work, of course, but it’s just one more maintenance trick for your bag!
by Tom Gaylord, a.k.a. B.B. Pelletier
Today’s report goes out to all those readers who are just getting into airguns, as well as those who have been in airguns awhile but feel there are many things they’re either missing or don’t fully understand.
We have a new blog reader who goes by the name Essbee. For the past week, he’s been asking the kind of specific questions that tell me he doesn’t understand something as well as he would like to. Then yesterday, he sent in this set of questions:
Thanks. How does The Benjamin Marauder compare with German guns (RWS & Weihrauch) in terms of quality and durability and ease too. No doubt the Germans are pricey in PCP hence ruled out but their quality is no problem. Could I have a report for or against on the quality of Benjamin Marauder as compared to German technology and craftsmanship.
What are the chances the gas will leak on PCP guns. If it does how will it be fixed and at what cost? In contrast the air springers have no such problem. What do you say on this? What is the record at your end of PCP repairs vs air springers?
Hence I was comparing an RWS 34, RWS 350 Magnum and RWS Air King 54. Considering the cocking effort, weight and velocity it seems RWS 34 stands up very well in .22 with longer barrel. Am I correct? For hunting which is the best?
How do I answer this?
If you read the questions, you’ll see they’re a combination of technical questions and requests for my subjective opinions. I find it very difficult to answer questions like these because they require more time and space than we have available. So, what I do is try to guess about who’s asking the question, then answer from that standpoint as best I can.
New airgunners come from a variety of backgrounds. They can be youngsters who have never really sampled the shooting sports at all. Everything is a mystery to them. Or they can be adults who may know about the shooting sports but have never really participated in them. You might think that would make them the same as the youngsters, but it doesn’t. Adults do have some life experience to relate to, so they can understand things that youngsters haven’t experienced yet. My answers to adults have to be slightly different than the same answers to youngsters.
The questions can also come from adults with lots of shooting experience but who are just getting into airguns. When that’s the case, we have a common basis of shooting upon which to build, but they still won’t be familiar with things like the artillery hold or with canting issues at close range.
Some of these adults may have served in the armed forces and may be even more familiar with firearms than most people. That makes my answers even more difficult because there are things about airguns that the military never thought of.
Some of the questions come from law enforcement officers, both retired and active duty. They’ll have an even different viewpoint, and my answers will have to be presented differently.
So — how do you get into airguns?
I obviously can’t answer everyone in the same way. But I do think there are fundamental things that ALL new airgunners need to think about. So here we go.
1. Start small
Don’t buy that super-duper ultra-magnum that you see advertised. Forget the advertising hype, unless all you want is something to brag about. If that’s what drives you, go somewhere else because I can’t help you. I’m in this for the enjoyment of the hobby — not for posturing, looking good or counting coup.
Get a weak but accurate airgun as your first gun, and then learn to shoot it. Forget scopes unless you’re almost legally blind. Learn to shoot with open sights. Learn to follow-through on every shot. Learn to call your shots, which is to state where they went before you look through the spotting scope.
I would tell you to get a Diana model 27, but they don’t make them anymore; and many of you would rather purchase a new gun. Okay, get an Air Venturi Bronco. That rifle was created to be the modern equivalent of the Diana 27. Is it? Probably not, because there are too many things that aren’t the same. But the Bronco is accurate, it has a good trigger, it’s both light and easy to cock, and it comes in .177 caliber so the pellets are cheap. And the rifle, itself, is a great bargain.
Want a different choice? Okay, consider a Stoeger X5. For around $90, you get everything the Bronco has except the great trigger and some of the accuracy. But it’s very good and is a wonderful way to break into airgunning. Find something like that.
Want an air pistol? How about a Beeman P17? Oh, you can find bad reports about this pistol if you look, but they number in the dozens, while thousands of pistols have been sold. I have had 2 and both were quite reliable. One was a test gun from Pyramyd Air and I bought the other one after returning the test gun. The one I have now has many shots on the clock, as well as many years on it, and still performs as good as it did when it was new.
Want a spring pistol? Try the Ruger Mark 1 pellet pistol. It’s inexpensive, accurate, easy to cock, and the trigger–while heavy–is manageable.
I said to start small with a low-powered pellet gun and learn how to shoot it. That’s the best advice I can give anyone who wants to get into this hobby. Yes, the powerful guns are neat and the super-accurate guns are a ball to shoot, but they also require some understanding that only comes with practice. I want you to get as much trigger time as possible, and a lightweight, inexpensive, accurate gun is the way to do that.
2. Buy good pellets
I know that saving money is a good thing, but I don’t want you to miss out on the thrill of a lifetime just so you can save a dollar a tin on bargain pellets. Stop kidding yourself that you can buy good pellets at a discount store. That was never the case, and today it’s quite far from the truth. You might be able to buy some adequate pellets at a discount store, but where does that leave you? With a Bronco that shoots 1.5-inch groups at 25 yards instead of one that shoots 3/4-inch groups. Is that what you want? You know the best way to save money is to never shoot at all. If you’re going to shoot, give yourself a chance of hitting.
3. Stop fighting the trends and start applying yourself
A popular definition of a crazy person is one who keeps doing the same things and hopes for different results. I see shooters who aren’t using the artillery hold because they say it’s too hard. Well, of course it’s hard, but all the best shots do it. Don’t you want to see what kind of shot you can be? If you try to buck the trend and avoid things like the artillery hold, you’re acting like a NASCAR wannabe who doesn’t like cars that are set up for the racetrack. Sure they’re hard to drive, but they’re also the only kind of cars that win the races!
You want to shoot groups at 100 yards, but you don’t want to use a scope level. Great. That’s like an ice-skater who wants to be in Hush Puppies all day because the skates hurt his ankles. You can’t shoot tight groups at 100 yards without leveling your rifle for every shot. So, if you don’t use a scope level, you’ll have to find some other way of doing it.
I know it sounds simple, but just shoot. That’s why you decided to get into airgunning in the first place. It’s so easy to shoot at home. I fire from 100 to 1,000 rounds each and every week.
The more you shoot, the more chances you have to improve. Not that all people do improve, mind you, but at least you have the chance.
I’ve found that 20 shots on your own is worth a lot more than 20 conversations about shooting on the internet. Go on and have the conversations — but do the shooting, too.
This is what I would tell a new airgunner. Too often — always, in fact — they come to me with their eyes sparkling with thoughts of buying this or that mega-magnum rifle, I know they’re heading for disaster. I cringe when I see this because I know the conversations we’re going to have much later when all they’ve done finally sinks in and they realize this wasn’t the way to go.
Here’s a little story to illustrate what I’ve been saying. I watch certain internet gun sales websites and from time to time certain guns are listed. Let’s single out the Smith & Wesson 500 Magnum for this story. When I see the ad, I can guess what it will say. This fine gun is almost new in the box. It’s only been fired a few times. Comes with a fresh box of ammunition and only 6 cartridges have been fired. Now, why do you suppose that is?
by Tom Gaylord, a.k.a. B.B. Pelletier
Today’s report is a guest blog from reader Fred from the Democratik People’s Republik of New Jersey. It came from his ingenuity in dealing with a need that arose in the field. I’ve linked it to the recent .177 Marauder reports because it seems to fit.
If you’d like to write a guest post for this blog, please email us.
Over to you, Fred.
Fixing a Marauder magazine
by Fred DPRONJ
A number of factors led to this blog — the first being a scheduled benchrest .22 rifle competition my league was going to hold following our 25-yard bullseye competition. The second was, I believe, blog reader John. Or was it Mike? No matter. But whoever made the comment mentioned later in my report…thank you!
I had gone to the range several days ahead of the benchrest competition to sight in my .22 cal. Benjamin Marauder. For fun, I decided to take on the rimfire boys with my air rifle. It took roughly 6 pellets to get the scope sighted where I wanted. However, I could not see where pellet 7 landed. Two more shots and I was incredulous. The rifle had gone from hitting the 10 ring to missing the entire target paper and backer. At this point, I looked at the magazine and discovered it was not rotating to feed the next pellet. It was stuck after firing pellet 6. I assumed the internal spring had broken, so I packed up and went home discouraged. I didn’t have another .22-caliber Marauder magazine, so I might have to use my Ruger 10/22 for the competition.
However, I recalled John (?) mentioning in the blog comments that these magazines could come apart. At home, I carefully examined the magazine under magnifying glasses and saw that what I had believed to be a rivet in the center of the magazine was actually an Allen screw.
A 1.5mm Allen wrench fit; after initial resistance, the screw was removed.
The magazine is really an elegant engineering solution for the task of feeding pellets with a bolt action. It consists of 5 parts — an outer case, a coiled spring, the circular pellet holder, the clear plastic cover and the the screw that holds everything together. When I disassembled it, nothing appeared broken.
If you look very carefully at the coiled spring, you will note that the ends are different. While both ends are bent at 90 degrees, one is bent away from the coils while the other end is bent down to stick into a hole in the bottom of the magazine case.
One end of the spring is bent out at a 90-degree angle, while the other end (not visible here) is straight in line with the coils. This is the end that sticks into one of the holes in the bottom of the magazine case.
The end that you see in the above picture goes into one of three holes in the magazine case. Each hole gives a different amount of pre-load to the spring.
I decided to insert the spring into the hole nearest the bottom of the case, next to the cutout that slides over the breech when the magazine is installed. In the above photo, that hole appears at the 9 o’clock position, and you can see the cutout that goes around the breech very clearly.
Here’s the magazine spring. Now you can see both ends. The end on the left goes into one of those holes in the bottom of the magazine case, and the end that sticks out on the right fits into the slot on the underside of the pellet holder.
The straight end of the spring that sticks out, away from the spring coils, goes into the slot in the underside of the pellet holder. It’s just a matter of approximating position of the holder’s slot to the spring and moving it back and forth until the spring end clicks in. You easily feel when it pops into the slot.
The pellet holder has a circular groove in it, and the brass pin of the cover moves in it. The groove is almost a complete circle, but the part that isn’t grooved allows the cover to rotate the pellet holder against the coiled spring when the magazine is loaded.
The magazine case with the spring and the pellet holder in place. Notice the circular groove in the pellet holder, next to the numbers. This is where the brass pin of the cover fits, allowing the pellet holder to move as the pellets are pushed out of the magazine by the bolt.
With the pellet holder in position, I pressed it down and slid the clear plastic cover over it and then aligned the cover with the magazine case and inserted the Allen screw. [B.B.'s note: The brass pin in the bottom of the clear plastic cover has to be inside the circular groove of the pellet holder, and the pellet holder stop (the portion of the pellet holder that protrudes) must be to the right of the shelf inside the magazine's outer case.]
I slide the clear plastic cover over the pellet wheel to keep it in constant contact with the coil spring so the end of the spring would not come out from the notch on the underside of the pellet holder.
The secret of my feeding problem was now revealed. The screw that holds the cover should be tightened only enough to remove any excess slop between the clear plastic cover and the magazine case. Too much tightening and the cover binds the pellet holder, preventing it from turning. The screw has an interference fit so it won’t back out when you rotate the clear plastic cover to load. Lifting and rotating the cover 90 degrees and releasing, the cover now snapped back with authority — indicating the assembly screw was tight enough and the magazine spring was doing its job. I was now set for my benchrest competition.
If this procedure seems confusing, believe me — it clears up when you have the 5 parts of the magazine in your hand. I have given you all of the references you will need to assemble your own magazines, should you attempt this yourself.
[B.B.'s note: I disassembled and assembled my Marauder magazine several times following these instructions. They do work.]
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, blog reader Vince continues the saga of converting a steel spring rifle to use a gas spring. We last read about this project in Part 2 of I’ve got gas, where he showed us the pitfalls of making such a conversion to a Gamo breakbarrel. Let’s see how he does the second time around with a Crosman rifle.
If you’d like to write a guest post for this blog, please email us.
Back when I tried reworking the Crosman gas spring retainer, I discovered that drilling a straight and properly located hole on a round surface is a bit, well… tedious. And hard to do, at least without the proper drilling jig.
Of course, it would be very expedient to use the spring tube itself as a jig. After all, it’s perfect — as long as I can keep from damaging it, that is — because all the holes are obviously already in the right places. Put the retainer in place, pop in the pin and go at it through the existing bolt hole.
Two minor problems became apparent. First, the hole is too large to properly guide a 1/4-inch bit. Second, the edges of the bit might damage the existing hole in the spring tube. But both problems have an obvious, simple and cheap solution: a bushing.
A bushing for under $1.00 from McMaster-Carr.
I got mine from McMaster-Carr (part #2868T44) for less than 70 cents. If you’re feeling rich, you can probably get an equivalent at Home Depot for about $3.00. The important thing is that it has a 1/4-inch inside diameter, a 5/16-inch outside diameter, and that it be made from brass, bronze or steel. Plastic probably isn’t a good idea.
The process is simple — and THIS time I’m doing it on a Crosman rifle instead of a Gamo. No particular reason, I just wanted to show that it works on the Crosman platform as well. Specifically, this is a Crosman Sierra Pro, but mechanically it’s the same as the other Quest variants.
It looks like a Gamo, talks like a Gamo…
I ran into a bit of a problem sliding out the piston — it seems that the scope stop screw that I identified in this picture was binding the piston. Backing it out one turn solves the problem. As expected, the threaded hole in the Crosman gas spring retainer doesn’t align with the one in the spring tube — just like the Gamo.
The Nitro-Piston gas spring retainer…
…and why it doesn’t work.
So, what we’re gonna do is turn it 90 degrees and drill a hole on the other side.
This is where we have to drill.
See that little ledge sticking into the hole? I’m going to grind it out of the way:
Ground a flat spot, just in case.
In retrospect, though, this step may have been unnecessary.
Setting up the jig is about as straightforward as it gets. After installing the gas spring retainer and securing it with the retaining pin, I place the bushing in the hole in the spring tube and start drilling. The steel is pretty soft, so it’s not that difficult.
The bushing sits in the hole and is the jig for drilling. Simple!
But I only drill about half way and for a very good reason. If I keep going like this, I’ll hit something I don’t want to hit. Not a water or gas main, but that retaining pin is very definitely in the path of that drill bit. The solution is to slide the pin almost all the way out (but still engaging the retainer on one side); so when the bit breaks through, the pin won’t be damaged. Drilling the rest of the way thus proves uneventful.
Don’t want to drill through that pin.
Next comes the tapping — M8x1.25 inches, which is very close to 5/16-inch NC. If you don’t have a metric tap, get one. Do NOT try to make the SAE size work. You’ll regret it if you do! But my old and worn tap steadfastly refuses to start because it wants something a tiny bit bigger than 1/4 inch, so I have to bore out the hole to 17/64 inches. That makes all the difference, and a few minutes later I have a properly tapped hole.
Just a smidgen bigger…
…before I can tap the hole.
A quick test-fit shows that everything goes together just as it should.
As for the rest of the work, it’s a simple matter of cleaning everything out, lubrication and assembly. If you recall, the gas spring got scratched up from rubbing on the piston in my Gamo 220, so I colored those scratches with a Sharpie. That way, if I wind up with more rubbing in the same place, it’ll be readily apparent.
After a good cleaning, everything goes back together just as I described for the Gamo. But don’t forget that little disc that goes into the retainer.
I suspect this may be important.
One thing I sort of glossed over last time is how to get that pin installed. Since the gas spring has all of about 1/8 inch of preload, the pin can be started using a screwdriver to pry the retainer into place.
Prying the retainer to start the pin.
That’s good for getting the pin started. But you won’t be able to get it the rest of the way through because that spring is still pushing the retainer rearward, and the itty-bit of slop in the whole thing means that the holes won’t quite line up on the other side of the tube.
The solution is easy enough. Once it’s started, tap the pin in until it gets to that point. Then, lay the action on its side with the protruding pin downward, and push down on the spring tube while tapping the retainer with a hammer or mallet. The impact of the hammer will make the retainer jump forward just enough to momentarily line up the holes and allow the pin to start coming through. Three or four taps ought to be enough.
Tapping the retainer allows the pin to slide home.
The only minor difference between this Crosman gun and the Gamo is the endcap, which on the Crosman slides inside the tube. It’s a little different from the one that comes installed on the springer:
The gas spring endcap is on the left, the original on the right.
The gas spring version just slides into the rear after it’s all together, and we’re done!
Don’t forget to tighten the scope stop screw.
The action reinstalls in the stock with no mismatched screw holes.
Shooting it demonstrates the same sort of changes in behavior as with the Gamo I converted, only more so — and less so — all at the same time. For one thing, it runs a little hotter than it did in the Gamo. With the same RWS Basic pellets, it did the following:
That’s an average of just about 1000 f.p.s., or 15.5 foot-pounds of energy. This represents an improvement of just about 100 f.p.s. over the original Crosman powerplant.
Firing behavior and feel, however, wasn’t as vastly different as it was in the Gamo. The Crosman “sproings” a fair bit less than its Spanish forebearer (the rear guide tends to be a tighter fit); and with a tarred spring, the smoothness of the firing cycle is pretty close to that of the gas spring.
After I returned the Crosman to its original configuration, I was able to examine the gas spring for any damage. Oddly enough, there was some scratching again but nowhere near as bad as the last time and only on the front 1 inch of the cylinder. So, it’s not related to the centering of the gas spring at all. I suspect the end of the cocking link may have been rubbing it.
I remember a while ago a reader asked about the specs of the gas spring, in particular its pressure. I decided to measure that using my high-precision bathroom scale (!) and a Chinese hydraulic press. This was a quick and dirty way to get a ballpark figure. The pressure was almost constant as it was compressed but not quite. It did creep up just a bit, starting at about 130 lbs. and ending in the vicinity of 150. Overall length of the spring is 10.25 inches with a cylinder diameter of 0.715 inches.
And that pretty much wraps up my gas attack. Exactly where does that leave us?
Well, we’ve shown that the gas spring conversion is certainly doable. It’s not as straightforward as I would have liked — buy a few parts and stick ‘em in — but it’s not beyond the realm of the average handyman. The gas spring itself pretty much lives up to its reputation… smoother, somewhat harder to cock for a somewhat elevated power level. The big mechanical advantages — no coils to break, no degradation from being cocked for long periods of time — are already well-known. The main subjective advantage, the smoothness of the firing cycle, all depends on how bad was it to start with. In a 10-year-old Gamo, the improvement is likely to be rather spectacular (especially in an untuned gun), but if the rifle is already a smooth shooter, less is going to be gained. I guess it just comes down to personal preference — whether it’s worth $50 and a couple hours of your time is up to you.
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, we’ll finish the conversion of a Gamo 220 from steel spring to gas spring, and blog reader Vince gives us a report on the outcome.
If you’d like to write a guest post for this blog, please email us.
Take it away, Vince!
When we last saw the Gamo 220, I’d disassembled the powerplant and compared the old parts to the parts I ordered from Crosman. Today, I’ll install those new parts and test the gun for you.
The gun is laying on the bench, ready for assembly. The new piston slides in, followed by the gas spring. Be careful when sliding the piston seal past the end of the cocking slot and tuck the soft seal material away from the sharp edges of the cocking slot so the seal isn’t damaged. A flat-bladed screwdriver works well for this.
The new piston that works with the gas spring is slid into the spring tube. Notice that I’ve lubricated both ends of the new piston with moly grease.
The new gas spring (Nitro Piston) slides in after the piston. The small end of the spring fits into the socket inside the new piston I mentioned in Part 1. No lubrication is required.
The trigger and cocking link go back in (reverse order of removal), and the plain plate gets dropped into the rear spring retainer.
I’m dropping the plain plate into the rear spring retainer.
Now, I’m starting to sweat a bit. You see, I KNOW that the gas spring has a TON of pressure on it even when fully extended (very much unlike a coil spring) — so, how on earth am I gonna compress it enough to reassemble the gun? Oh, well, I’ll cross that bridge when I come to it –which is, well, right about now. After I install the rear retainer, I notice something.
There’s almost no preload on the gas spring
Almost no preload at all! THAT’S right. Because the gas spring is ALWAYS at or near full pressure, there’s plenty of preload pressure as soon as the piston comes off its stop, so very little preload travel is required.
What is preload?
When a conventional coiled steel mainspring is installed in a spring gun, it’s usually longer than the space into which it must fit. It is, therefore, necessary to compress the spring by some amount to get it to fit inside the spring tube. This compression causes the spring to be under pressure even when at rest — this is called preload. If you’ve ever seen a long, empty flatbed trailer on the interstate that looked bowed up in the center because there’s no weight on it, you’ve seen what no preload looks like. It takes several tons of weight just to get that trailer flat again — and much more to make it bow the other way.
Airgun tuners can add spacers that preload the mainspring even more when it’s resting, which causes it to develop greater power when compressed because it’s closer to its maximum potential that exists at the point when all the coils are touching. But gas springs don’t work that way. They’re under full compression (internal gas pressure) when they’re at rest. All cocking the gun does is move the internal piston against the already-compressed gas that’s ready to blast it back when the sear releases it. There’s a very small amount of additional compression of the gas, but it isn’t what makes the gas spring work as well as it does. The gas spring unit is always at full potential — even at rest.
So, this gas spring unit has very little farther to go at this point…under a quarter-inch, in fact. THIS sure makes things easy for me. Pry the retainer forward on one side while starting the pin through the other. [Note: If I used a mainspring compressor, I wouldn't need to pry anything. I would just tighten the compressor until the assembly pin holes lined up, then insert the large crosspin.]
The crosspin will go in, but the hole for the rear spring retainer bolt (that large-headed bolt I removed when I disassembled the powerplant in Part 1) doesn’t line up with the hole in the spring tube. This is a problem.
Immediately, a problem becomes apparent. Look at the hole where the rear spring retainer bolt goes. It’s not lined up with the hole in the tube. There’s approximately a .080″ misalignment here. This ain’t gonna work. My first inclination is to simply elongate the hole. But when I reinstall it, there’s another problem.
There’s a gap between the plate on the spring retaining bolt and the trigger assembly. It won’t support the trigger this way!
The trigger isn’t properly supported by the plate that’s attached to the bolt. Worse, this changes the spacing between the front and rear stock screws and doesn’t allow the action to be reinstalled.
Hmmm. I’m wondering if this is exactly what Crosman (or BAM) had in mind — preclude an easy conversion with existing parts (since the same problem would exist on a normal Quest). That leaves me thinking: Can I just butt the gas spring against the original Gamo spring retainer?
If you look at the picture of the new rear spring retainer above, you’ll see that there’s a small plate that drops into the cup that retains the gas spring cylinder. The cylinder wants to butt up against a flat surface, and the Gamo retainer has a large (approx. 1/2″) hole in it. I need a metal plate to go over it. Wait a minute! I’ve got one right here in my pocket!
A perfect spacer for the new gas spring and it costs — well, about a quarter!
And, so, it gets reassembled. Believe it or not, the whole thing works.
Time to test!
I’ll run through this pretty quickly — the velocity is now up to about 964 f.p.s., which represents a muzzle energy of about 14.5 ft-lbs. Not killer, but obviously a lot better than the detuned gun. Accuracy shouldn’t be changed — or should it? Oftentimes, guys will detune their guns to make them more accurate — or to simply make them easier to shoot. That might have some merit, as I now couldn’t break 0.37 inches at the same range. Not a big difference, and I’m certainly not gonna suggest that the gas spring decreased accuracy. But I don’t think it helped.
So what’s it like to shoot?
First of all, everything anyone ever said about “thunk” vs. “sproing” is absolutely correct. The gun “wumps” with a gas spring, and you can actually feel a kick back into your shoulder. Nothing like a typical centerfire gun, although maybe something like an 1894 shooting low-velocity .38 specials might be comparable. But that’s just a guess.
Cocking the gun is another matter. Effort peaks at about 33 lbs., which isn’t all that high — except for the fact the effort before that peak is certainly a lot higher than with a normal coil spring. This is what we’d expect, of course, with the relatively constant pressure of the gas spring. It isn’t unbearable, but it does take some getting used to.
Back to a coiled steel mainspring
After about 40-50 rounds, I decided it’s time to restore the gun back to original spec. I rummage around my spring box and find a REAL low-mileage Gamo spring, and put it all back together the way God intended it. NOW, I can really get a back-to-back series of impressions.
First, the velocity did drop a smidgen. It’s now down to an average of about 943 f.p.s., or a little under 14 ft-lbs. Second, and despite the tar on the spring and rear guide, we DEFINITELY are sproinging ourselves rather energetically. Lastly, the cocking effort is predictably much milder. Peak effort is down by 5 lbs., and the effort before that peak is even easier. Accuracy is unchanged from the gas spring.
How did my quarter, er, my impromptu gas spring backing plate pan out? Not too well.
The pressure of the gas spring punched a deep divot into the quarter.
The flip side doesn’t look any better.
I flattened it back out with a hammer, and I’m really hoping it’s still legal tender. Anyway, as I sort of expected, the relatively soft quarter didn’t do well. The backing plate really ought to be steel, 0.060 inches (1.5mm or 1/16″), just like the original.
But the bigger problem wasn’t the quarter.
There’s a serious indication of metal-to-metal galling.
There was some serious metal-to-metal contact going on here between the cylinder of the gas spring and the inside of the piston. If you look at the above pictures of the quarter, you’ll see that the indent isn’t centered. The pocket in the original rear spring retainer keeps the spring cylinder right in the middle, and apparently that’s real important because it won’t center itself.
And that’s about it for now. If this is going to work, we need a simple and cost-effective way of keeping the gas spring centered properly without permanently altering the original parts…and do it in a way that the average tinkerer can accomplish on his own. The first thing that comes to mind is to drill and tap a new hole in the new rear spring retainer, opposite of and slightly forward of the existing hole. I tried that, and found (predictably) that getting the hole in just the right spot is a bit difficult without a custom drilling jig.
For now, I’m just going to give it some thought.
WAIT! I JUST GOT AN IDEA….
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, we’ll have the first part of a guest blog from reader Vince. For those who don’t know him yet, Vince is our “go-to” guy for fixing all sorts of strange vintage airguns. In this post, he tells us the tale of a wild idea he just had to try.
If you’d like to write a guest post for this blog, please email us.
Over to you, Vince!
“Nitro” is da bomb, right? I mean, in current usage, “Nitro” anything means hot, fast, powerful and overall bad. This normally benign element sure shows its alter-ego when combined in properly mischievous proportions with oxygen to form nitrous oxide. More fun can be had by mingling it with oxygen, carbon, and hydrogen in various arrangements to come up with nitromethane, nitroglycerin, nitrocellulose or TNT (trinitrotoluene). So, yeah, “Nitro” IS da bomb — in every sense of the word.
Now, when Crosman started producing the Nitro Piston series of air rifles — well, it sends the imagination reeling, doesn’t it? That is, at least, until we come back to reality and realize all they’re doing is using something called a gas spring, which uses pressurized nitrogen to exert pressure on a piston-rod and cylinder assembly. Push the rod in, and it pops right out again, with different degrees of enthusiasm, per the individual design of the particular gas spring.
The advantages of the gas spring in an airgun application are numerous. Because there’s no metal coil spring inside, the gun doesn’t FEEL like there’s a metal coil spring inside. No twang, sproing, buzz or anything else of that nature — and no twisting or torquing reaction as the spring extends and slightly unwinds. Because gas doesn’t fatigue, a properly functioning gas spring will never take a set or get weaker with time. This also means you can leave it cocked for as long as you want with absolutely NO effect on spring life.
What’s not to love?
Well, specifically, those two little words…”properly functioning.” Yes, the gas will never fatigue, but sometimes it leaves home and never comes back. And if the gas spring DOES leak, there’s nothing left to do except go get another one. And almost certainly, it means going back to the manufacturer — and praying that they still have them available.
You see, gas springs are something of a specialty item. They kinda have to be designed around a specific application. There are universal gas springs out there, but the chances of finding one with parameters comparable to your airgun is gonna be difficult. Unlike a coil spring you can’t just get a longer one and cut it to length. You can’t tell what sort of rate a gas spring has (or had) just by measuring things, like you can with a coil spring. I believe you can still get custom coil springs made on a case-by-case basis, but making a gas spring is a bit more involved. Heck, you can make a crude coil spring yourself using a paper clip and a pencil. Sure, it won’t be good for much — but it shows that the basic process for making one is, well, pretty basic.
That’s why I’m not terribly tempted by all these Nitro Piston (of any sort) air rifles that are out there. Will you be able to get it working 50 or 75 years from now? I certainly won’t, cause I’ll probably be gone by then. But that’s beside the point. I’ve got future generations in mind here! I don’t want little Billie- or Betsy-Bob cussin’ out their great granddaddy simply because he bought a gas spring rifle they can’t fix. Heaven knows they’ll probably have enough reason to do that anyway. Why add fuel to the fire?
That’s when I got to thinking. How about gas-springing a spring gun? When the gas stuff craps out, I (or whoever) will easily be able to cram in all the old conventional spring stuff and the gun will be back in business. After examining the Crosman gas guns (for some reason this makes me think of the “fart gun” from Despicable Me), it seemed obvious that they’re based on the ubiquitous Quest platform. That rifle, as we all know (except for those of us who don’t) goes back to the old BAM B18/B19 air rifle. Which, in turn, was a near-clone of the old steel-barreled Gamo series of the time (Shadow, 220, 440, 890, etc.).
Seems to me that a proper pickin’ of replacement parts ought to let ANYONE with a Quest variant (which are as numerous as the stars in the sky) or a Gamo 220 variant to gas ‘em up without giving up long-term serviceability. The best part is that Crosman is generally the most tinkerer-friendly airgun company out there. Not only do they sell parts — ALL parts — for many of their springers, but they’ll sell them to anyone. And they’ll let you keep your first-born, your arms and your legs, and your very soul because their prices are so reasonable.
So it is that I started combing through the parts list for the Storm and the Titan GP air rifles. My suspicion of the close relations was confirmed by Crosman’s designations for these guns — both start with C1K77. I believe C designates the gun family, the 1K means 1000fps, and the 77 points to .177 cal. In any event, the commonality of parts (especially the cocking link, trigger assembly and piston seal) tells me I’m on the right track. Things can get a little tricky, as some parts that are virtually identical might have different part numbers depending on cosmetic details (like lettering). Trusting my own judgment, I came up with a list of 5 parts that I THINK will fill the bill:
Back spring guide…..BT9M22-00-2
I ordered the parts and waited. As a side note, I told the customer service rep at Crosman what I was trying to do, and he seemed rather interested in my results. I think I’m gonna just send him a link to this blog. As another side note, there’s some commonality between Crosman’s part numbers (which were revamped a couple of years ago) and Stoeger’s. Of course, both guns are made by BAM in China.
A week or so later, the package arrived!
The parts received from Crosman. The camera perspective distorts the gas spring at the hottom. It’s really straight.
Picking a guinea pig is easy. I immediately turn to a tried-and-true, long-time member of my collection: a Gamo 220.
My Gamo 220 was the guinea pig.
The Gamo 220 is a bit of a mule, frankly. All the 1000 fps Gamos of that period used essentially the same powerplant with a 25mm bore, a 100mm stroke, and the same 29 lbs./in. spring. The Shadow, which was the first decent airgun I ever bought, had a nice-to-hold, if utilitarian, synthetic stock and the low-grade rear sight. The significantly more expensive 440 had a nice-looking wood stock with Gamo’s “better” micro-metric rear sight (which, incidentally, is actually inferior to the lower grade one). The upscale 890 was a sightless 440 that came with a scope.
The 220, price-wise, sat in the middle — with a completely unadorned, mud-brown and slippery wood stock with about as much aesthetic appeal as an old shoe. It lacks the utilitarian friendliness of the Shadow and the visual appeal of the 440/890. It really was the least-appealing of the Gamo magnum breakbarrel lineup. Why do I have one?
As a result, it periodically becomes a test-bed for projects when I don’t want to mar up a NICE gun. Projects like this one.
The first thing I do is baseline the rifle for accuracy and power. In the accuracy department, it didn’t disappoint — a 0.30-inch 5-shot group at 36 feet. That’s about what I remember for the gun. Power-wise, however, was a different kettle of fish. I used RWS Basic pellets for velocity and averaged only 814 fps with a spread of 22 fps. The spread isn’t too bad, but the velocity stinks and represents a measly 10 ft-lbs of power. Oh, well. Frankly, I don’t even remember what guts are in this thing.
The gun comes apart in pretty much standard Gamo/Quest fashion, starting with the three stock-to-action screws. Once the action is out of the stock, you go to the rear of the spring tube, where the big bolt comes out first.
The big bolt comes out first. Then, the pin is drifted out, but only after the end cap is restrained.
The pin is next, but the rear retainer has to be suitably restrained in order to contain the approximately 2 inches and 60 lbs. of mainspring preload typical for these Gamo’s. Or not, as the preload in this gun turned out to be less than an inch. What happened? We’ll find out soon enough.
Next step is removing the trigger, which means the barrel has to be broken open so the trigger can slide backwards a bit.
Break the barrel to put slack in the cocking linkage. The slotted bar that runs back to the trigger is the link for the anti-beartrap device.
Then, the cocking link gets pulled down, freeing it from the piston and allowing you to disengage the anti-beartrap link.
The cocking link can be disengaged from the piston, then the anti-beartrap link disconnects from the cocking linkage.
At this point, the piston just slides out. So — what’s up with that low power and lack of preload?
Wow! That mainspring sure is short. And that rear guide AIN’T Gamo.
Oh, yeah — that’s right. I detuned this thing with a Crosman 500X spring. Incidentally, that spring is part #B12-1-00-4A, for anyone who wants a real pleasant detune on a similar Gamo or a Quest variant. That’s why velocity was so low and why I could cock it with my pinkie! That also explains the lack of preload.
But the guide? Near as I can tell, it was a custom guide I picked up somewhere. It’s dimensionally close enough to the normal Gamo parts that I can be sure it isn’t affecting power.
The spring guide in my 220 (top) and a regular Gamo spring guide.
As a matter of curiosity, I looked at the two pistons side-by-side.
The new piston that goes with the gas spring (bottom) has a slightly shorter stroke than the old piston.
The upper one is the original — and it’s a little shorter, but it appears that, for whatever reason, the gas spring wants a slightly shorter stroke than the coil spring. Also — although it’s hard to tell from the pictures — the inside of the old piston has a flat surface for the top hat, while the newer one has a shallow hole meant to locate the rod end of the gas spring. You will see why this is needed in the next installment.
That’s where we are going to leave this story for now. Vince has the old parts out, and the new parts ready to install. We’ll see what happened in the next installment.
by Tom Gaylord, a.k.a. B.B. Pelletier
Let’s begin our look at the effects of the rifling twist rate on accuracy and velocity. This will be a huge test. I know many of you will want to know THE ANSWER sooner than I get to it. All I can do is ask you to be patient because this has never been documented for the public, if indeed, it has even been done before.
We’re testing the 1:22″ twist barrel that Dennis Quackenbush made for the Talon SS test rifle. I’ll use the velocity figures that I recorded for the factory barrel several months ago in the 10-part Talon SS report. After I’ve tested the 1:10″ twist barrel (in the next report), I’ll also retest the factory barrel following the exact test structure I’m using for both Quackenbush barrels. I know my rifle very well and don’t expect the numbers to be that far off. So, you can accept today’s figures as gospel, but I’ll retest the gun just to make sure.
I followed a fill process that’s very exacting, so each test is the same as all others. I’m not going to bore you with the minutiae, but I discovered while testing the gun on the lowest power setting that the velocity climbed after about 5 shots immediately after a fill, so I refilled the reservoir after each test on low power. On the higher powers, the gun is very stable across the useful fill, so those tests did not all begin at 3,000 psi. They were tested with 2,600 psi to 2,800 psi in the air reservoir — a range where the velocity is extremely regular.
I’m going to use only two pellets initially. Until I learn something about the performance of these barrels, it’s not worth spending endless time running down “facts” that don’t really matter. Later, if the data indicate a need for expanded testing, there will be additional velocity tests with other pellets.
The best way to view the results is when they’re grouped by power setting. Each pellet was tested with the rifle set at three different power settings. Since my gun doesn’t have a scale on the power adjustment window, I put a piece of tape there and marked it for the two higher power settings. The lowest setting is with the power screw indicator as far to the left as the window permits.
Tape marks the two higher power settings. When the screw head is centered on the index mark, the power is correct. When the screw head is as far to the left in the window as it will go, the power is on the lowest setting.
Power setting 0
On zero power with the factory barrel, 14.3-grain Crosman Premier pellets averaged 486 f.p.s. the range was from 451 to 522 f.p.s. That is an average energy of 7.5 foot-pounds.
On zero power, 15.9-grain JSB Exact pellets averaged 507 f.p.s. The range went from 498 to 521 f.p.s. At the average velocity, this pellet produces 9.08 foot-pounds on this power setting. And the spread is 23 f.p.s.
The velocity spread for both pellets is on the high side, with Premiers being the highest at 71 f.p.s. That tells us the valve is not too stable at the lowest power level and a full fill of air.
On zero power with the 1:22 barrel, Crosman Premier pellets averaged 534 f.p.s. The spread went from 499 to 569 f.p.s. — a range of 70 f.p.s. At the average velocity, this pellet produces 9.08 foot-pounds of muzzle energy.
On zero power with the 1:22 barrel, the JSB Exact pellet averaged 521 f.p.s., with a range from 482 to 528 f.p.s. That’s a spread of 46 f.p.s. At the average velocity, this pellet generated 9.59 foot-pounds of energy.
Again, there was a high velocity spread for the Premier pellets, and the JSBs were tighter. With both pellets, the muzzle energy increased with the 1:22″ twist over the factory barrel.
Power setting 6
On setting 6, the Crosman Premier pellets averaged 787 f.p.s. from the factory barrel. The range was from 775 to 800 f.p.s., so the spread was a tighter 25 f.p.s. At the average velocity, this pellet generated 19.67 foot-pounds of energy.
On the same setting, the JSB Exact pellets averaged 778 f.p.s. with the factory barrel. The range was from 769 to 785 f.p.s., so the spread was 16 f.p.s. At the average velocity, this pellet generated 20.57 foot-pounds of energy.
The Crosman Premier pellets averaged 840 f.p.s. from the 1:22 barrel on power setting 6. The range was from 831 to 847 f.p.s., so the spread was a much tighter 16 f.p.s. At the average velocity, this pellet generated 22.41 foot-pounds of energy.
On setting 6, the JSB Exact pellets averaged 817 f.p.s. from the 1:22 barrel. The spread went from 810 to 824 f.p.s. At the average velocity, the energy generated at the muzzle was 23.57 foot-pounds.
Power setting 6 boosted the power a lot. It also stabilized the velocity quite a bit with both pellets. As you can see, the 1:22″ barrel outperformed the factory barrel by quite a lot. This is especially noticeable when you look at the muzzle energy.
Power setting 10
The Crosman Premier pellets averaged 854 f.p.s. from the factory barrel on power setting 10. The range was from 850 to 860 f.p.s., so the spread was a very tight 10 f.p.s. At the average velocity, this pellet generated 23.16 foot-pounds of energy.
On setting 10, the JSB Exact pellets averaged 823 f.p.s. with the factory barrel. The spread went from 821 to 825 f.p.s., which is just 4 f.p.s. At the average velocity, the energy generated at the muzzle was 23.92 foot-pounds.
Crosman Premier pellets averaged 854 f.p.s. from the 1:22 barrel on setting 10 — the identical speed they got with the factory barrel on this setting. The range was from 844 to 863 f.p.s. Although the average was the same as for the factory barrel, the spread was much greater at 19 f.p.s. At the average velocity, this pellet generated 23.16 foot-pounds of energy.
On setting 10, the JSB Exact pellets averaged 815 f.p.s. from the 1:22 barrel. That is LESS than it was on power setting 6. The spread went from 809 to 819 f.p.s. At the average velocity, the energy generated at the muzzle was 23.46 foot-pounds.
Power setting 10 is as high as I ever run my Talon SS. I haver determined that with a 12-inch barrel any setting above this one just wastes air. While the velocities may be a little different with the different twist rates, I believe the general rule will hold that setting 10 is as high as any 12-inch .22-caliber barrel wants to go — at least with the powerplant on my rifle.
The results of this test
As you can see from these results, the gun is wasting air on power setting 10 with the 1:22 twist rate. It is much more efficient on power setting 6. And it does not give up any power to the factory barrel, leading me to wonder if a 1:22″ twist rate might not be a better rate for .22-caliber pellets in the middle power range.
The factory barrel edged out the barrel with a slower twist by getting 23.92 foot-pounds of energy from JSB pellets on power setting 10 compared to 23.57 foot-pounds with the 1:22″ barrel shooting JSB pellets on power setting 6. I don’t know what that says, but there it is.
We’ve learned a little from this test, and we now know there’s so much more to be explored. The results were not as dramatic as some might have anticipated. Many thought the slower 1:22″ twist would have sped up the pellets noticeably, but that didn’t happen. What it did seem to do was make the rifle more efficient in the middle range of power.
It’ll be interesting to see what the 1:12″ barrel does under the same circumstances. After that, I’ll retest the factory barrel at these test settings to verify they’re correct.