by Tom Gaylord, a.k.a. B.B. Pelletier
Neat fix for bulk-fill CO2 guns
Crosman’s 116 bulk-fill pistol is a .22-caliber single-shot pistol.
Today, we’ll look at the velocity of the Crosman 116 .22-caliber bulk-fill CO2 pistol. A couple things will complicate this test. First is the fact that the pistol has adjustable power. I’ll account for that with several power adjustments, but that isn’t all that’s going on.
The bulk-fill process is itself somewhat complex; because if the bulk tank doesn’t have enough liquid CO2 in it, or if the tank and the gun are both warm, the fill will be less dense and will therefore produce fewer total shots. Let’s look at the fill process before we examine the gun.
The bulk-fill process
Filling an airgun from a bulk tank requires that the filling tank has sufficient liquid CO2 inside to transfer the maximum amount possible to the gun. When I say the maximum amount possible, I mean what’s maximum under safe operating conditions. It’s possible to overfill a CO2 tank or gun and create a dangerous condition.
CO2 pressure is controlled by the ambient temperature rather than by compression. If you make the CO2 storage vessel volume smaller somehow, you don’t compress the gas inside. Instead what happens is more of the gas condenses into liquid. It will continue to do so right up to the point that there’s 100 percent liquid inside the tank.
While that sounds good, it isn’t; because when the liquid inside the tank heats up, it tries to expand into gas again. As long as there’s space inside the tank for the liquid to evaporate into gas, you’re safe; but when the safety volume is filled, all the liquid CO2 can do is increase in pressure. It does so at an astounding rate, quickly developing over 10,000 pounds per square inch at temperatures that are still well within human tolerance. That’s why tanks rated for CO2 storage contain safety burst disks to prevent the tank from becoming a dangerous bomb. It’s also why several airgunners have been startled when their tanks’ burst disks actually burst while stored in their cars on hot days. Once the burst disk ruptures, all gas is lost and the burst disk must be replaced before the tank can be used again.
These days, most airgunners get their bulk tanks filled at paintball stores; but in my day, they filled them at home. There were even larger bulk tanks of CO2, holding 20 pounds of liquid. They came from the food and beverage industry, or they were large fire extinguishers. I own 2 of these 20-lb. CO2 tanks that I use to fill my bulk CO2 tanks for guns.
The 12-oz. paintball tank is coupled to the 20-lb. CO2 tank for filling. This big tank has a siphon tube, so only liquid escapes the valve when it’s in the upright position. Couplings are custom made for this.
Once the smaller bulk tank has been filled, it’s time to fill the gun. Remember, the object is to transfer as much liquid CO2 as possible for a dense fill. That doesn’t give more power — it gives more shots. The CO2 controls the pressure, depending on the ambient temperature.
The 12-oz. paintball tank is then coupled to the CO2 gun like this. With the CO2 tank hanging down, the liquid in the tank is just behind the valve, where it will flow readily from the tank into the gun. This paintball tank has a special adapter with a wheel to control the opening of the valve.
Filling the gun takes just a few seconds. It actually makes a sound, and you can tell when it’s full because the noise of the transfer stops abruptly. The outside of the gun may become cold and wet with condensation when the new CO2 inside evaporates to gas. As long as you do this transfer at room temperature, everything will be safe, for the liquid CO2 will evaporate and stop the fill before the gun accepts too much liquid. The gun is now full and ready to test.
Because the pistol has adjustable power, I tested it on high power first. I found that there were 21 good powerful shots with the gun set on the highest power. Then, I adjusted it to medium power and finally to the lowest power. Medium power was very close to high power in all respects, but on the lowest power the total number of shots per fill increased to 32.
This is a Crosman gun, so Crosman Premier pellets sounded like the best place to begin. On high power, they averaged 390 f.p.s. The range went from a low of 384 to a high of 409 f.p.s. At the average velocity, this pellet generates 4.83 foot-pounds at the muzzle.
On medium power, they weren’t much slower — averaging 386 f.p.s. But on low power, they averaged 331 f.p.s. for an average 3.48 foot-pounds of energy.
Next, I tried RWS Hobby pellets. In .22 caliber, these weigh 11.9 grains and average 423 f.p.s. in the test pistol. That’s a muzzle energy of 4.73 foot-pounds. The low was 413 f.p.s., and the high was 435 f.p.s. On medium power, Hobbys went an average 402 f.p.s.; and on the lowest power, they averaged 369 f.p.s. That’s good for a muzzle energy of 3.60 foot-pounds. On low power, the low velocity was 355; and the high was 383 f.p.s.
The last pellet I tried was the RWS Superdome. This pellet weighs 14.5-grains in .22 caliber and is a favorite among many airgunners for all 3 powerplants. On high power, Superdomes averaged 376 f.p.s. The low was 362, and the high was 391 f.p.s. At the average velocity, Superdomes generated 4.55 foot-pounds. On medium power, they averaged 367 f.p.s.; and on low power, they averaged 345 f.p.s. On low power, the low velocity was 341, and the high was 348 f.p.s. At the average velocity, they generated 3.83 foot-pounds of muzzle energy.
The trigger-pull on the test pistol measures 4 lbs., 2 oz. That’s a little heavy, but it’s very crisp, so it’s going to be okay for target work. There are no provisions for adjustment on this trigger; so if I want to change the pull, I have to do some gunsmithing.
I noted that when the gun was fully charged, the velocity always started lower and climbed into the good range — just like a precharged gun that’s overfilled. On the lowest power, the gun sometimes failed to discharge. CO2 guns aren’t supposed to do that, so I assume either the valve return-spring has weakened over the past 60 years, or someone has been inside the valve and changed things. Either way, that’s a good reason for an overhaul. The transmission sealer worked and now so does the gun; but it doesn’t work exactly as it should. That’s also probably why the number of shots per fill was lower than expected.
To what can I compare this air pistol? How about to a Crosman 2240, which is also a .22-caliber single shot but runs on 12-gram CO2 cartridges, but in many other ways is like the test pistol? The 2240 has a 7.5-inch barrel, so it’s a little faster than this 116 with a 6-inch barrel (Premiers averaging 448 f.p.s. to the 116’s 390 f.p.s.). Its sights are fully adjustable. The grip, while a bit larger, feels very much the same. So, if a 116 and bulk-filling aren’t in your future, know that there’s a good alternative.
I do think the test pistol is shooting a little slow for a 116. Maybe it would be best to get it overhauled to see what one in top condition can do
35 thoughts on “Crosman model 116 .22-caliber bulk-fill CO2 pistol: Part 2”
It seems to me that you have to be a little more careful filling with the bulk fill CO2 tanks.
I haven’t messed with bulk fill CO2 but I have a few 12 gram cartridge guns. I know how they act when shooting.
Here is my question. Ok I have my new .177 cal. Discovery I just recently got. The pressure gage shows compressed air at like 2000 psi. And CO2 I think at 1200 psi. for the maximum fill pressure.
Wouldn’t it be easier on the o-rings and thread sealing for how long they would last and maybe be less acceptable to leaks if you used CO2 instead of compressed air ?
And now days like the Marauders and Discovery being Dual Fuel guns as they say. They have the degassing tool that allows you to empty the air reservoir before you change types of fuel.
Another question. What kind of bad things can happen if you mix compressed air and CO2 in the air reservoir ?
On your mixing of air and co2 i would imagine any moisture in the air would turn to ice upon release of the valve, so lock up, even tearing of your seals would occur. At least that’s my opinion
To answer your question I want to ask if you know the quickest way to make a wooden bucket leak? It is by never using it. The wood dries out and shrinks and the joints open and leak.
The same is true for pressurized airguns. Keeping a PCP inflated all the time is the best way to keep it from leaking. The seals in a gun do not benefit from a lack of pressure on them. The dry out, harden and shrink.
As to your question of was the HW barrel modified to fit the Talon SS? Yes indeed. The breech end had to machined to be like a LW barrel for AF rifles. It will now fit any of the AF line up. It is an OLD Talon SS though. It does not have the additional barrel screws in the side.
I also have a 12 inch Eun Jin .22 barrel for it. If you have access to a machine shop, which BB did when he worked for AF, you can fit just about any brand barrel to it. I am wanting a 18 inch LW .22 barrel which I am going to shorten to about 16 inches for this TSS so as to have a little space inside the shroud to work with but have a longer barrel to help improve efficiency and probably accuracy. I will not be able to make it as quiet as with the 12 inch barrel, but that is not a major issue for me as long as it is not an ear ringer.
Eventually I will likely end up with a 24 inch .22 LW barrel, but it may be already installed in another air rifle. I just wish they made a 36 inch barrel. ;o)
I had my marauder pistol out the other day. It was filled to 2800psi, It was fairly hot 95 or so I shot 2 magazines 16 rounds total. After shooting I looked at the pressure and it was up to 3000psi.
My question can you damage a PCP gun by leaving it in the heat?
You might be able to damage one. Depends on how much heat and pressure you throw at it. May deform the valve. Don’t know how much it takes to blow one up, and am not going to try to find out.
At the very least, you will probably experience partial or even full valve lock until it cools off enough to get the pressure back down. Keep in mind that air temperature is one thing, in the sun too is still another thing (gets hotter than the air), and in the sun in a vehicle gets worse. Try to keep it as cool as possible in hot weather.
That’s pretty dramatic! I would suspect the gauge if that happened to me.
Of course a PCP can be damaged by pressure, but not by the pressures you are talking about. I don’t think your gun rose that high in 95 degree heat. I think there is something up with the gauge.
I have seen that happen on multiple guns setting side by side outside also. Don’t think the gages on both guns were doing the same thing at the same time. I believe it is more the direct sun.
Concerning your “odd note”. I believe that’s the weak spring, I met such malfunction a couple of times in different CO2 pistols. Weakened striker spring may be a result some previous user shot it all the time turned as high as possible, thus wearing it.
I agree with you. Whether it weakened from time or someone purposely weakened it, the result is the same. That’s why I am thinking I need a complete overhaul.
I think you are right. My 112 (the 8-inch barrel version of the 116, also .22 cal) actually had lower velocities than my 116, and the spread was higher, too. Replacing the striker spring helped both problems.
Paul in Liberty County
And my only co2 gun is the 2240, so I know virtually nothing about bulk full other than paintball tanks… It sure is an easy one to just pull out, fire 10 shots at a target and then continue working on my rc planes (nothing like mixing hobbies!). I really like that gun and now that it has a tko brake on it, it’s easy on the ears too! It’s definitely in the more bang for the buck, fun gun class!
I’m not a CO2 guy so here is a novice’s question.
Do I remember reading that you can get a better fill from bulk by putting the gun in the freezer for awhile?
Do I also remember reading that you should weigh the gun and keep in on a scale while you fill it to prevent overfill?
Am I mixing things up?
You are right about the cold helping the fill. But to weigh the gun before and after you need to know the weight of a full fill for that gun, and that is information that’s not going to be easily found.
Here are my thoughts. If you put the gun to be filled into the refrigerator for an hour before the fill, and then shoot it immediately after filling, it’s probably okay. The CO2 doesn’t have a chance to build dangerous pressure that way, which it probably won’t anyway, because the gun doesn’t get cold enough in the refrigerator to accept an overfill.
The danger comes when Bubba starts thinking about this. He says, “If the refrigerator is good, the freezer must be even better.” and he quickly crosses the line into dangerous waters. Bubba the airgunner goes by many nicknames — Lefty, Stumpy and Three-fingered Mike. That’s why I don’t give suggestions like this anymore.
Is it really (practically) possible to overfill a CO2 tank, freezer or no freezer? Doesn’t the pressure of the gas depend solely on the temperature with the rest remaining liquid?
Yes, it is VERY possible to overfill a bulk-fill CO2 gun. But you must understand what that means.
If you stick the gun into the freezer and lower its temperature to 0 degrees, F, it will accept more CO2 liquid when it is filled. In fact, you might get a 95 percent liquid fill that way. At that point, the gun is overfilled, but the pressure inside is well below the danger point. In fact, it is lower than a gun that has been filled normally, as long as the gun’s temperature remains very low.
However, as the gun warms back up and the temperature of the liquid inside rises, more evaporates to gas, raising the pressure in the small space that’s available. At around 40 degrees F the pressure will now be higher than what the gun is rated for, and if the gun’s temperature keeps rising, so does the pressure. At 60 degrees the pressure inside the gun may be double what the gun is rated for and at 90 degrees it may be 4 times the rated pressure. At some point the gun will explode like a bomb, because there is no pressure relief valve or burst disk in the gun.
So you have to understand how CO2 works to appreciate what an overfill does.
Wow! Good information. I’m always learning. Thanks.
That’s what some people were doing with the Nitrous bottles for the drag strip cars (freezing them before filling).
And they have heated bottle warmers for them to get the pressure above 900 psi. They then have a purge solenoid that allows them to purge the pressure down to the 900 psi so each run will get a consistent amount of nitrous mixing with the fuel. Makes the run more consistent and safer for the engine keeping the mixture more stable.
And I have seen Nitrous bottles blow the safety pressure relief valves on hot days at the drag strip. You have to have blow down tubes that exit the vehicle so it wont fog you out when it blows.(nice big white cloud).
Then I should be able to turn almost any barrel down to mach the breech end. Maybe would have to make 2 new barrel collars I guess depending on the diameter of the barrel.
I wonder if I could get a .177 cal. Discovery barrel to work? Hmm I will have to look into that.
And yep BB I know what you mean about they say to keep some or even a full charge of pressure in PCP guns. Just like old cars it is worse to let them set and not drive them. All the seals will dry up too. (in the engine, transmission, brake cylinders and so on).
But why does Crosman say to de-gas all the pressure out of the guns before changing from (compressed air) to (CO2) or vise versa ?
Why does Crosman say to degas their guns after firing? Liability.
How would you describe a CO2 gun that has gas in it? In one word — loaded. It doesn’t matter what you put into the barrel — a nail, a frozen pea or a number 2 pencil. If you can put it into the barrel, the gas can blow it out again.
I know they have to state things in their manuals for liability purposes.
But no that’s not what I’m talking about. I think your talking about if you work on the gun or something that you need to let all pressure out (which is true).
But they make it sound like in the manual that you should not leave any amount of CO2 in your gun when you decide to fill the gun with compressed air on-top of the CO2 charge that is already in the gun. To me that would be a compression explosion waiting to happen.
The heat generated from the high pressure air would cause the CO2 to expand rapidly. Not good for your gun or you for that fact if I’m thinking right.
CO2 will never cause a compression explosion. It is a fire extinguisher.
But mix CO2 and air and you might have condensation, which is undesireable inside a reservoir.
I should of said a expansion explosion not a compression explosion.
The compression explosion is a oxygen source mixed with a combustible gas while adding a ignition source.
I know CO2 Is not flammable.
People tryed it to cool the outside of the intake on engines and found that not to be a good Idea because it would get drawn in to the combustion chamber and kill performance.
A Expansion explosion is when two sources of products get mixed and they rapidly over pressurise the the volume of the container. Could be chemicals or could be gas or a mix.
Oh and Nitrous ain’t combustible either. Its a super cooler and oxygen adder. But it will sure make a nice explosion if not mixed correctly with a fuel source in the combustion chamber. Saw many engines hand grenade with the wrong mixture of gas and nitrous.
The reason I bring this up is I saw somebody get hurt at a Motel I worked at when I was a kid. A drain was clogged and 2 different people put 2 different drain cleaners down the sink. Guess what some body got burned by the chemicals when it exploded.
And no I didn’t pour anything and I didn’t get hurt.
I’m trying to be clear about what I mean. But maybe I ain’t wording it right.
Sorry. I misunderstood you. I have no idea what an expansion explosion is, or what causes it.
I use the 12 oz bottles in my welder. One time I wanted to get a good fill so I put the bottle in the freezer in the morning. After work I took it out of the freezer and had it filled at the air soft store. The next day I went to use it and the disk had burst. It was in the car so maybe it got extra warm – I don’t remember. I filled that tank many times, only did the freezer trick once and only had the disk burst once.
I have seen CO2 tank burst disk blow many times. Thank goodness they do, because if they didn’t, the explosion of the tank would be far worse than a 40mm grenade from a grenade launcher.
I wasn’t there when it burst. That’s OK, don’t need that much excitement.
I’ve picked up a 20 lb. tank and fill the little ones myself now. I get a little scared every time. Any safety tips?
Wear safety goggles. Don’t pick any tank up by its valve handle, don’t let a tank fall. Store the tanks in a cool place.
I have been toying with the idea of converting one of my guns to bulk fill. You said that transfer of co2 should be done at room temperature. Where I live room temperature a lot of the time is 90 degrees. Is it safe for me?
Most of the time in Texas where I live it’s 100 degrees plus, and I bulk fill all the time. It’s completely safe — just don’t store any CO2 guns in your car.
I’m going to keep an eye on my gauge. It may have been do to the radiant heat also (it was a very sunny day the gun was hot to the touch)
Is that an original adapter you used from the tank to the gun. If so, could you tell me where you located one so i could purchase one my self? If not could you tell me what you used to adapt it.
Those adaptors are not original. They were made by one or another of the boutique makers who pop up and then go out of business.
Try Dennis Quackenbush for adaptors. He has been around for decades and makes a lot of stuff like this for CO2 guns.
Just be positive about what you want to adapt to what. What gun do you want to fill and from what bulk tank do you want to fill it?
I want to fill a model 116. I want to use a paint ball tank.
Okay, then you need the type of adaptors that are shown here. One is to attach the paintball tank to your gun and the other is to attach the paintball tank to a larger tank to refill it. If you get the paintaball tank filled at a paintball shop, you only need the adaptor to attach to the gun.
There is also another way to go. Read this report:
Thanks you for your help.