Diana Chaser Power Mods. 

I broke my Chronograph so I can't remember the velocity but I do remember I got the Muzzle Energy to almost 11 foot pounds with a Crosman hollow point so that's not bad for a CO2,... I have a PCP, a Gas Ram rifle, Springer &Multi Pump but the Chaser is my most used around my property

Yeah, I gained a little more than 20% muzzle energy but my shot count is down to 20 shots but I am happy with it.

@@davidyummus6259 It's a good tradeoff for you and me, but some may complain about low shot count. I have the .177, and thinking about getting a weaker spring. Like you, I think a stronger hammer spring is not the way to go. The trigger pull is too nice to compromise.

@@davidyummus6259 Forgot to say, 20% more power is not trivial. That would put my .177 from ~625 up to ~750. I would sacrifice 15 shots for that!

@@Bob_Adkins My chrono is now dead but at the time it was closer to 23% so with a common Crosman 14.3 hollow point, the muzzle energy came in at like 10.7

The drill bit I used to drill out the cylinder was 27/64 (10.5mm) & I drilled it 5mm deep (approx 3/16) & replaced that spring. I did drill out the ports on the .22 but I kinda wish I didn't lol,... Did the same cylinder mods to the .177 but did NOT do the ports & I think I like it :) Still don't have a Chronograh, work has been tight with the dreaded virus but I hope to have one soon to do some pellet speed tests. My shot count is down so I think & really do have more air behind the pellet.

The Crosman 2240 is a 22 pistol. Running some numbers a typical 22 weighs 0.927g (sorry, I find grains meaningless) and 600fps would produce 15.5J = 11.43 ft lb The sweet spot for a competition target pistol, which are all 177, is just under 500fps. If going faster was more accurate they would tune for faster. There is a sweet spot. The volume of a 22 barrel is greater than a 177, so it needs more gas released into it. The speed of release, the gas flow rate, is important. This is the venturi between valve and barrel. The transfer port and valve hole may be opened, but not the hole in the barrel. The hole in the barrel may be arrised to smooth the lip and remove any burr, but with greatest care - by hand with a fine diamond jewellers tool. Tuning a venturi is a black art. Ideally it wants a slight convex profile through it, with rounded shoulders, to improve gas flow rate. It's more witchcraft than science though, there's a lot of stuff going on, that is is CO2 not air, it goes around corners, the pressure and velocity, rate of change, - there's only so much we can do - like use a tapered reamer from both ends (my old dad would have been able to make a curved hole by making the reamer wobble off axis, master toolmaker). I surmise we need two things here - the right quantity of gas and the right gas flow rate. It's no good still releasing the gas after the pellet has left the muzzle. There is a sweet spot. The best if not only way to find it is by grouping tests. I know they call the 2240 the Ratcatcher but a pistol is a very poor hunting weapon, it takes too long to bring to bear. First you must hit the vermin, and they disoblige by moving. I get a hair over 2 ft lb from my 85yo Webley Junior, it can and has many many times killed a rat point bank, execution not hunting. The rat trap. My CP2 pistol produces some 4.6 ft lb, that too will easily execute a rat. A pistol is for shooting targets and killing tin cans.

After cutting off the threads of the valve cap and grinding the inside of the cap for more capacity. Compare the threads you now have, by how far it screws in.The remaining threads you now have not used and exposed in the valve body, can now be ground off to give more volume, but not too far up to damage the threads needed for the cap.

Exactly! Amateurs almost everywhere without cheap ass chrono. They even can’t say even an estimate of what they achieved. I bet doing all the modifications would break performance significantly. Uneven shots and 1/3 of them. Even drilling port I think breaks self regulation and stability. Only increasing chamber volume little bit would be reasonable approach. How much is the question because further down the line we get loss of accuracy at some point. All I want to achieve is to stay under legal limits and also not have 1/3 of shots from one co2. Probably there were some reasons to not to give full legal power. Number of shots or uneven power, faster wear of seals , trigger etc. I don’t know. At least I think if chamber was drilled too much it’s easy to go back by placing some 3D printed tube filling that space to previous volume. I’ll get chrono soon.

Bob did you gain fps,?

Take the burrs out of the action tube where the hammer rides and rebuild the whole thing properly and the 177 pistol can deliver over 500fps in stock form, which is more than it says on the box. The box says the long carbine 177 barrel can deliver 600fps, I have not run it through chrono but believe it will go over that without modifying any parts. I use the CP2 as a target pistol and find that 480-490fps is ideal where it is most efficient and delivers a very small spread of fps over some 55 shots. For the 177 4.5mm the maximum transfer port is 3.5mm or the pellet can get stuck in the port.

A quick down and dirty from my 177 set up as pistol but with the long barrel - various pellets average 570fps. This is with stock springs, no spacers, stock valve, but all nicely slicked up and gas tight, slightly enlarged transfer port. Highest energy 7 ft lb. I do intend to build up a long barrel, parts are on order. However I intend to optimise for the long barrel i.e. for grouping not power, and expect to achieve a little over 600fps and up to 8 ft lb I have already discovered that pushing the pellet too fast the grouping deteriorates. A lump hammer is for breaking bricks not driving tacks. First you have to hit it.

Since last I have acquired a second CP2 and set up as long rifle. It appears to have been assembled better than the first, less work needed to fettle it. Essentially out of the box the first 177 shots were over 600fps, about 630 fps and the CO2 self-regulating to +/-3.5 fps, which is very good and near enough match standard. And around 5 mags at that on a colder day, and two more when it is warmer. The point is the velocity does not change much with temperature when it self-regulates, only the number of shots. With a little more work and practice I've got it to punch 6mm grouping holes in a card target, and I am not a good shot. About 7.5 ft lb, which is about as much as I think we should ask of this little airgun long rifle, which essentially has a target pistol mechanism, if we want accuracy for short to mid range. Do not ask it for too much power because the accuracy suffers badly, the spread goes to pot, and the shot count is disastrous. On its first capsule, after zeroing the scope, I spotted a rat, stood, shouldered and potted it at 20 metres. Power is adequate.

I'm not sure what you mean by wedge,... I think I understand what you mean because when my gun is NOT cocked & the hammer spring is NOT compressed, I hear the hammer move around freely so there is a little room for a shim to take up that slack but if pressure was put on the spring by stretching the spring or adding too many shims then wouldn't the hammer open the valve ?

@@davidyummus6259 Google traduction problem. I mean "shim", a piece of cylindrical metal that I put inside the hammer in front of the spring. Yes, must carefully choose the length of the shim. The hammer spring must not be too compressed, otherwise, it will press open the valve. It's a kind of equilbrium between the strenght of the valve spring and the hammer spring.

@@christianlau2870 Okay, that is what I thought,... I have replaced the valve return spring for a lighter one so I have already reduced the resistance of the valve opening so I will have to go easy on the shim ;)

You have no idea what joules are about !😆😆😆😂😂😅😅😅😅..

@@dinofabrizzi2116 and you ? Do you know how to calculate the energy of the pellet ? E=1/2*m*v^2 with v in m/s and m in kg, ... and E in joules. 1 fps = 0.0254*12 m/s

@@TheCellCreator the nominal 850psi is towards the upper end and some 5860kPa (~60kg/cm2 which is an oddball unit). There will be pressure from the spring but it is insignificant compared to that. I can compress the spring flat between finger and thumb. I weigh about 100kg and 60kg is about 130-lb. Anything less than 5% is generally considered insignificant. As with a car engine, the valve springs are there to return the valves not keep them shut, the gas pressure inside does that. The springs cannot be so strong that the cams cannot lift them. The surface area of the valve is that of a frustum of a cone. I have not calculated that but is is far less than 1 cm^2. The hammer delivers a considerable blow to open it briefly against the gas pressure. I use "back of envelope" calculations because it doesn't really matter what the numbers are to understand how it works, ballpark is good enough. And we are limited as to what we can do to the system. Have fun.

@@TheCellCreator I have a "service box" of springs to try out. What increase in fps are you getting by using a lighter spring? 3kg is 5% of 60kg so it is "not significant" in engineering terms (back of envelope) i.e. variation in vapour pressure may be greater. But note the surface area of the valve is considerably less than 1cm^2 - so the gas is applying less than 60kg and then plus the 3kg. The valve spring must not produce significant pressure (must is not the same as does not) - The principle for self-regulation is to get the impact of the hammer to balance the gas pressure so that the same quantity of gas (PVT and all that) is released each time whatever the vapour pressure. The same principle is used on an industrial gas bottle regulator, spring and diaphragm. For that our valve spring must not produce significant pressure, it must rely on vapour pressure - and still work reliably (nb more Timex than Swiss Watch). Bear in mind that I am deliberately tuning the pistol to produce just under 500fps for best grouping accuracy. I have already found that pushing the pistol to 520-540fps /reduces/ its accuracy. Shooting target at 10 metres there is little drop from the 177 until below 420fps i.e. dead capsule. 460-490fps will go clean though a tin can. In summer I was getting over 65 good shots with less than +/-4fps (480-490-ish), with like another 20 shots for plinking as the capsule died. Adjusting the hammer spring, as is possible with some Crosman, can dial in the sweet spot, but imo tuning the regulation will be at the valve assembly. My experiments with a lens dew heater indicate that the entire breech and barrel has to be kept at stable temperature, not just the capsule and valve. Probably thermal mass and conductivity, gas laws. Not a practical solution. Lagging the lot might work but the dew heater is awkward. Long time since I've wound heater tubes ;) Besides which when it is too cold for the CO2, it is too cold for me to play in the garden ;)

@@TheCellCreator there's some witchcraft too. The weaker spring will open for longer duration, which releases a greater quantity of gas. However the Crosman 2300S puts a sleeve inside the valve chamber to reduce its volume to improve accuracy. The logic here may be to use less gas, to have a higher pressure in the valve chamber for longer for more shots per capsule, for greater consistency (spread), less fps spread, better grouping. I'm getting +/-4fps spread (overall spread, not standard deviation) which is as good as some competition PCP target pistols. Some of the stuff is counter-intuitive, and I'm after accuracy over power.

@@TheCellCreator It was a wish list but then read of reliability problems. I now reckon the CP2 can offer better accuracy. It has an expensive rear sight I would have to discard for a red dot, my eyesight. And I would need a silencer on it, thus discarding the fancy front sight. I do like the adjustment knob on it which I think can be done to the CP1 but not the CP2 due to the way the back end is fastened (there may be a way around that). There is stuff to be learnt from the 2300T.

@@TheCellCreator glad to hear no problems. Problems are usually exaggerated and where they've done something stupid. Silencer? I have presbyopia (age) cannot focus on iron sights and target. But not astigmatic. Hence the red dot I am not a good shot, but that's why I shoot pistol, not because it is easy. Either hand or both. Arthritis, right shoulder is strongest, left is most stable. Right eye. Legs can pack up and need to shoot seated. Resting on a bag is not as much fun, may as well clamp it in a vise. From what I have seen of the 2300S on YT, the CP2 is easily as accurate.

You would still have the limitation of the liquid CO2 vapour pressure. And at 33p per capsule probably more expensive. Those refillable and bulk tank systems are used with airsoft, they work at reduced pressure. See "Green Gas" With scuba the pressure in the tank goes down each time you use it, which is a drawback. With a typical cylinder about 50 fills. Note this is ballpark stuff. And anywhere from 30 to 400 shots per fill. The PCP version of the CP2 typically 30 shots, it is a small pistol type cylinder. The CO2 capsule can deliver double that. Bulk buying CO2 is actually pretty economical.

The size of the Pierce Valve/Hole I think would determine "Recovery" time of how long it takes to re pressurize/fill the chamber after a shot but I like that you are thinking,... I think you are correct that the most important is how long the Poppet Valve is open to release pressurized air & then I think Port size to let a large VOLUME of air out at HIGH pressure & yes I think if you went too large on Port size then you could actually LOSE Pressure & this is what happened (I think) on my .177 version. I'm thinking of a Garden hose with adjustable nozzle to describe my thoughts on Port size,... You need VOLUME of water AND Pressure with a garden hose nozzle adjustment so there is a sweet spot,... I chose to lower the tension on the Poppet Valve return spring instead of a stronger Hammer spring to allow the Poppet Valve to open easier, therefore earlier & maybe stay open longer from less resistance to close it. I absolutely gained more power from more air flow because I only get 20 shots before I drop power instead of 30 to 35 with the factory rifle but I honestly don't know which Mod made the difference, I should have done one at a time but I think the lighter return spring leaving the valve open longer may have been the trick,... The only reason I made more room in the chamber was to ensure that a LOT of air was available when the valve opens, any excess just stays in the chamber so nothing lost I think. Did I gain or lose by opening the chamber ?... I have no idea but if I bought a new Rifle then I would certainly start with the valve return spring to open the valve more before doing anything else.

@@davidyummus6259 I believe your absolutely right. Your one of the only ones who decided that a stronger mainspring will be harder on the gun and a lighter valve spring will be just as good. Is there something that stops the poppet valves travel? With a lighter spring there the main spring and hammer should send it farther back? Can that be modified so it will take advantage of your larger chamber? I just got an air bug so this now interested me I want to get a decent increase and keep maybe 30 shot count. You have good common sense.

@@joe-dp3ng I made the same mods to my .177 version but it's not as good, maybe even lost power due to me drilling the .177 Ports the same oversize as the .22,... The Poppet Valve on the .177 sometimes stays open & dumps all the air from the Cartridge so the light spring I chose at the hardware Store is probably right on the edge of being to light.

@@joe-dp3ng looking back, I wish I added the lighter spring to open the vale longer without doing any other mods but I did not have a Chronograph for testing.

@@davidyummus6259 ok got it. But can you tell me the one best thing to do so I can gain some but not to much? I want to learn from what you did. I have always known it's best to get info. Thanks in advance.

proyectoniebla ...you can get adapter at......Sales@AlliancsHobby.com...hope this helps....👍

Will do.

Amigo aonde encontro essa válvula disparadoura pra comprar aqui no Brasil não acha

Yeah :) Let me think about putting that together ;)

I didn't bother cutting it as even at full length it was much weaker than the factory one

@@davidyummus6259 Thanks Dave !😄🙏

It did but not really a lot but again, I didn't & still don't have a chronograph to know for sure,... Making more room in the cylinder for more air made a good difference.

Seems like a relevant point that warrants an answer

Not exactly because Co2 goes through tiny hole in puncturing pin. It doesn’t have time to refill valve chamber in that small time window. The same goes further with port. What is the point of drilling bigger hole in port when valve is smaller anyway. The smallest diameter limits the flow of gas anyway , in that case the valve is the limiter. In my opinion increasing chamber volume and modifying the springs will give the most gain but I would firstly start with springs and chronograph. Then I would calculate how much volume I get by modifying the chamber, probably not too much and I wouldn’t do it because it’s permanent. Springs alone give more time to escape co2 more efficiently. Increasing chamber will lower the number of shots which is also not good

No I don't but it's simple,... Tight but simple. 3 set screws hold it in place to the breech but they are small & easy to lose so remove them on a towel or blanket or something,... 2 o'rings, one either side of the port, be careful that you don't twist the barrel, rock it gently back & forth as you pull it out so you don't damage those o'rings & use a drop of oil on them when re installing the barrel,... If you need to replace them, they are a Metric, 1mm cross section, 9mm outside diameter & 7mm inside diameter. There is also an o'ring on the inside of the end of the barrel which is used to seal the bold when closed.

@@davidyummus6259 thank you David.