Quote from: Bob Pratl on April 04, 2017, 07:01:42 AMPA assembly is a power adjuster? I didn't know Crosman makes them. What does this do for me? Would it allow me to adjust the hammer spring so that it's just allowing CO2 to escape until the pellet leaves the barrel, and no longer? That's my current understanding of how power adjusters and hammer spring mods work, but I'm not sure I understood that right. What is a valve sleeve and why do I want to reduce valve capacity?Yes Crosman PA from 2300S - part number 2300-124 - Includes 6 parts including the spring. It allow varying the force applied to the hammer and so the exhaust valve stem.Go to:[had to remove link]and open the EVP (exploded view of parts)The valve sleeve limits the volume inside the valve - part number 2300-037 - actually called spacer but looks like a sleeve.Go to:[had to remove link]and open the EVP 9exploded view of parts)Also reread the post by rsterne; noise and excess CO2 use or efficiency and quieter.
PA assembly is a power adjuster? I didn't know Crosman makes them. What does this do for me? Would it allow me to adjust the hammer spring so that it's just allowing CO2 to escape until the pellet leaves the barrel, and no longer? That's my current understanding of how power adjusters and hammer spring mods work, but I'm not sure I understood that right. What is a valve sleeve and why do I want to reduce valve capacity?
Can you fill me in a bit on the BHB mod? I think I understood that they are hammer O-rings, and they're supposed to reduce hammer bounce? What exactly is the negative effect of hammer bounce?Hammer bounce is the effect of the hammer being uncontrolled. You cock the gun then release the trigger to send the hammer into the valve pin to open the exhaust port. The gas is sent up thru the transfer post and send the pellet on it's way. Once the valve is empty the exhaust valve closes to recharge the valve. This can send the hammer back into the hammer spring which send it back forward hitting the valve pin again momentarily discharging wasted gas, albeit with less force. Sounds like the gun is burping. before they began making things like the SSG and TSS the best way to control the hammer (also cheapest even today) is to build up o-rings between the hammer and valve body thereby controlling the hammer from restriking the valve pin.
but I'm not really the kind of person that saves up to buy all the good stuff at once. I chose to just buy the 2240 so I could get started and just already have fun shooting it. Finished my tin of 250 pellets today a week after buying it. I'll add upgrades every month probably. Might not be the most efficient way of doing it, but it was the most instantly gratifying way and I'm a millenial.
Also, is the CO2 capsule closed off by the piercing thing when the valve is open?
Quote from: kj on April 05, 2017, 01:12:21 AMif you look at the pic of the lpa site you posted , look at the bottom, that is a 3/8" dovetail that is cut perpendicular to the scope rails. here's some pics i took...in the pics with 3 breeches , the middle one is the type that accepts the lps site. the top type has the rear cut to accept the original plastic site, the bottom siver/aluminum has niether. if you can't tell from pics on vendors website if the breech will accept the lpa site, ask them . breeches from crosman also come in a short type that i don't have. never had a desire for less room for mounting optics. i prefer the flat sided type breech, like the silver/aluminum breech for asthetic reasons. i had a dozen special made in aluminum and afew in brass. had the aluminum ones anodized in blue, black and natural. the blue ones i also had engraved. as long as you can mount the optics you like , choice in available breeches is a matter of taste. the crosman ones are the only ones i know of that have the perpendicular dovetail for the lpa site. down side is they only have 1 barrel hold down screw. though an extra one can easily be added.Ah, the old "we'll sell you this but it only works with this other product of ours" trick. No worries. Do you know of any sights that are similar to the LPA that will fit on a standard dovetail? If not I guess I'll buy the Crosman breech and have an extra hole with threading made like you suggested. I do also like the shape of your aluminium one though. How does the black anodization match up to the blueing (I think it's blueing) on the stock barrel and main tube? Is it the top one in your picture? And what does it mean to anodize something in "natural"? What color does it come out as?Also, you say you had a dozen special made, how do you mean? Specially made to your specifications? Where did you have this done? Related to my question 6 in my original post. There's a metal workshop on my street, do you think they'll have the equipment there to make something like that for me? I've looked through the window and I saw that they did have the (don't know what it's called in English) horizontal drill machine. What kind of equipment is needed to make stuff like this?Quote from: rsterne on April 05, 2017, 01:12:48 AMDisco valve = from a Crosman/Benjamin Discovery PCP rifle.... It is the same basic valve as a 22XX valve, with an extended front end, sealed into the tube with O-rings.... Internally, the dimensions are the same as a 22XX valve, but it has a harder poppet to withstand the higher pressures.... I am not suggesting it for your use, there would be no advantage, I just mentioned it because the porting is the same, and the same modifications would apply.... Yes, the idea is to get a smoother, slightly increased gas flow, and then shorten the valve dwell to conserve CO2.... The first part of the impulse does more of the work of accelerating the pellet, and there is no point in keeping the valve open after the pellet leaves the muzzle, of course.... A stock 2240 does exactly that, you can reduce the hammer spring preload and save CO2 without losing any velocity initially.... Here is what happens with a 2240 with a 14" barrel as you change the hammer spring preload.... The 7.5" barrel will benefit less, if at all, from increased preload.... and note it only effects the first few shots anyways, when there is some liquid CO2 getting into the valve (very wasteful) and before the gun cools.... Shots are about 30 seconds apart....and here is what happens with a 24" barrel showing what you can achieve by tuning to conserve CO2.... Sorry, I don't have similar charts for a 2240 with 7.5" barrel, but you get the idea....BobAh, got it on the Disco valve. The thing is, Fivestar and kj recommend a pro-top, and fivestar mentioned I should get a Disco valve to go with it. So is the pro-top a modified hammer/striker? Does that mean it can't go with the p-rod trigger as that would require a p-rod hammer/striker that kj posted?The red line in the lower chart is amazingly flat! What does SSG stand for?Quote from: kj on April 05, 2017, 01:18:57 AMstriker hammer are generally the same thing, the difference here is that the p=rod one is 3 pieces, hammer, striker/acetal pin. the acetal pin is just a small piece of nylon that locks the striker from moving on its' own....the striker is threaded into the hammer and can be adjusted for throw from outside the gun if using the p=rod end cap, which is also 2 pieces and needs one hole drilled and tapped to fit your gun. then the pre-load can also be adjusted.the crosman website has a section with all the manuals with exploded parts diagrams. you'll need to get familiar with that so you can get parts numbers for ordering. you need them to order, customer service isn't going to look up all the parts for you..lolpeace kjI'm not sure I quite understand what this is for. What do you mean by "throw", which you said can be adjusted? I think what I'm getting from this is that you can screw the striker deeper into the hammer, so that it's shorter, in order to decrease the amount of time it leaves the valve open. Am I right? It also looks a bit lighter than the stock hammer, does it make any difference in vibrations when firing?Quote from: kj on April 05, 2017, 01:22:37 AMdutch, you also do well to look up some of bobs' , rsterne , past posts on co2, lots of excellent info there for sure, i've leaned alot from him over the years.fivestar, anthony is also a wealth of info for sure. he produces the pro top. using the protop allows removal of the piercing pin and gives a straighter co2 flow path. worth considering. hats off to bob and anthonypeacekjAwesome to see both of them so willing to advice me. Anything in particular that I can read that you think would be comprehensible for me with my current level of understanding?Quote from: avator on April 05, 2017, 01:59:07 AMSorry for the delay in responding.I just took a stock 2240 barrel and measured it for the barrel band and muzzle brake to get my length and chopped it off then recrowned it. I wasn't going for shot count or power... it was pure "cool". I wanted a stubby and had a bunch of stuff laying around. I must be honest, I did steal a couple parts from Betty Lou's 2260 HPA carbine that the mailman just delivered replacements for today. I think I get 35 or so shots from a C02 and waste a ton of it. The muzzle brake is from a 2260 I think? I've never chronied it so all I can tell you is that anything within 20 meters gets hammered. And those .22 benji destroyers turn into shrapnel. The BHB and shorter hammer spring all but eliminates hammer bounce and possibly flattens the string out some. The power adjuster allows me to have a little more control on shot count. I begin a C02 cart with it backed out the slowly turn it in throughout the shot string until I completely lose POI. I usually end up dry firing 6 - 8 times to empty the remains of the C02 cart for replacing. It's just a fun gun to have in the fishing box or in the glovebox/under the seat. Sometimes we are in our barn/bar/shop/indoor shooting range late in the evening with our scoped plinkers. Various night creatures visit uninvited. Willie G. Stubbs is a great guy to have laying in wait on the shooting bench.No worries, I don't have time to be on here checking for replies all the time either, but it's ok if this thread moves slowly. I don't have money to buy all the parts at once anyway.You've certainly achieved the cool factor on that gun. It's illegal to use an airgun in public places here and you can't carry it on you in such a way that it's within easy reach. Otherwise I probably would have made it like yours as well, carry it to the beach and shoot some cans there. Can you fill me in a bit on the BHB mod? I think I understood that they are hammer O-rings, and they're supposed to reduce hammer bounce? What exactly is the negative effect of hammer bounce?
if you look at the pic of the lpa site you posted , look at the bottom, that is a 3/8" dovetail that is cut perpendicular to the scope rails. here's some pics i took...in the pics with 3 breeches , the middle one is the type that accepts the lps site. the top type has the rear cut to accept the original plastic site, the bottom siver/aluminum has niether. if you can't tell from pics on vendors website if the breech will accept the lpa site, ask them . breeches from crosman also come in a short type that i don't have. never had a desire for less room for mounting optics. i prefer the flat sided type breech, like the silver/aluminum breech for asthetic reasons. i had a dozen special made in aluminum and afew in brass. had the aluminum ones anodized in blue, black and natural. the blue ones i also had engraved. as long as you can mount the optics you like , choice in available breeches is a matter of taste. the crosman ones are the only ones i know of that have the perpendicular dovetail for the lpa site. down side is they only have 1 barrel hold down screw. though an extra one can easily be added.
Disco valve = from a Crosman/Benjamin Discovery PCP rifle.... It is the same basic valve as a 22XX valve, with an extended front end, sealed into the tube with O-rings.... Internally, the dimensions are the same as a 22XX valve, but it has a harder poppet to withstand the higher pressures.... I am not suggesting it for your use, there would be no advantage, I just mentioned it because the porting is the same, and the same modifications would apply.... Yes, the idea is to get a smoother, slightly increased gas flow, and then shorten the valve dwell to conserve CO2.... The first part of the impulse does more of the work of accelerating the pellet, and there is no point in keeping the valve open after the pellet leaves the muzzle, of course.... A stock 2240 does exactly that, you can reduce the hammer spring preload and save CO2 without losing any velocity initially.... Here is what happens with a 2240 with a 14" barrel as you change the hammer spring preload.... The 7.5" barrel will benefit less, if at all, from increased preload.... and note it only effects the first few shots anyways, when there is some liquid CO2 getting into the valve (very wasteful) and before the gun cools.... Shots are about 30 seconds apart....and here is what happens with a 24" barrel showing what you can achieve by tuning to conserve CO2.... Sorry, I don't have similar charts for a 2240 with 7.5" barrel, but you get the idea....Bob
striker hammer are generally the same thing, the difference here is that the p=rod one is 3 pieces, hammer, striker/acetal pin. the acetal pin is just a small piece of nylon that locks the striker from moving on its' own....the striker is threaded into the hammer and can be adjusted for throw from outside the gun if using the p=rod end cap, which is also 2 pieces and needs one hole drilled and tapped to fit your gun. then the pre-load can also be adjusted.the crosman website has a section with all the manuals with exploded parts diagrams. you'll need to get familiar with that so you can get parts numbers for ordering. you need them to order, customer service isn't going to look up all the parts for you..lolpeace kj
dutch, you also do well to look up some of bobs' , rsterne , past posts on co2, lots of excellent info there for sure, i've leaned alot from him over the years.fivestar, anthony is also a wealth of info for sure. he produces the pro top. using the protop allows removal of the piercing pin and gives a straighter co2 flow path. worth considering. hats off to bob and anthonypeacekj
Sorry for the delay in responding.I just took a stock 2240 barrel and measured it for the barrel band and muzzle brake to get my length and chopped it off then recrowned it. I wasn't going for shot count or power... it was pure "cool". I wanted a stubby and had a bunch of stuff laying around. I must be honest, I did steal a couple parts from Betty Lou's 2260 HPA carbine that the mailman just delivered replacements for today. I think I get 35 or so shots from a C02 and waste a ton of it. The muzzle brake is from a 2260 I think? I've never chronied it so all I can tell you is that anything within 20 meters gets hammered. And those .22 benji destroyers turn into shrapnel. The BHB and shorter hammer spring all but eliminates hammer bounce and possibly flattens the string out some. The power adjuster allows me to have a little more control on shot count. I begin a C02 cart with it backed out the slowly turn it in throughout the shot string until I completely lose POI. I usually end up dry firing 6 - 8 times to empty the remains of the C02 cart for replacing. It's just a fun gun to have in the fishing box or in the glovebox/under the seat. Sometimes we are in our barn/bar/shop/indoor shooting range late in the evening with our scoped plinkers. Various night creatures visit uninvited. Willie G. Stubbs is a great guy to have laying in wait on the shooting bench.
Bob Sterne is the only guy I know that has that special calculator to figure that out.
this gmac breach will fit the lpa site about hammer /striker. yes the striker screws in and out of the hammer. the throw is the distance in which the hammer/striker travels to hit the valve stem. the further out the striker the shorter the throw, the shorter the throw, the less power, the less co2 is released by the valve. the hammer is drilled all the way through . when using the p-rod endcap one can stick a long allen wrench in and change the throw without didassembly of the gun. the p-rod end cap also has a spring guide the will screw in and out and can be reached through the back of the p-rod end cap. this part works like a power adjuster by increasing or decreasing hammer spring preload/tension.the top breech is black anodized aluminum. nobody could tell you how the anodizing will match crosman black paint unless they have the exact piece you're asking about. variations in anodizing are big depending on pre anodizing finish, what chemicals are used and what dye is used . the bottom silver breech is natural anodized. anodizing is more than just coloring. it imparts a corrosion restance and surface strength to the aluminum. there are also different types of anodizing that impart different qualities to the aluminum. read up on it if you're intrested.most machine shops won't set up to make 1 custom part. since i make alot of guns , i buy batches of custom parts made to my specs. search for bobs posts on co2, some good ones on co2 in low temps etckj
Quote from: Dutchie on April 04, 2017, 09:54:03 PM but I'm not really the kind of person that saves up to buy all the good stuff at once. I chose to just buy the 2240 so I could get started and just already have fun shooting it. Finished my tin of 250 pellets today a week after buying it. I'll add upgrades every month probably. Might not be the most efficient way of doing it, but it was the most instantly gratifying way and I'm a millenial. Slow and methodical is the way to understand what is happening with various changes. Not saying I always do so.
The Pro-Top has it's own piercing pin so it allows the elimination of a valve stem mounted piercing pin. The stem mounted pin in itself causes shot to shot inconsistencies and requires a minimum striker hit to just puncture the powerlet. As to the use of a Disco stem and valve body... the Disco valve has the same volume as the 2240 however it is a better made valve body . It has a more precision seat that works really well with the harder Disco stem and has the bonus feature of 8/32 anchor screws of which in the case of a 2240 you will only use one which is another improvement in consistency when compared to the small head 6/40 anchor screw that the 2240 comes with that will allow the valve to move from front to back in the tube.When you buy a power adjuster just be sure that you can actually back it out to less pre load than the original rear tube plug provided..because, again, with a Pro-Top you won't need a repeated hard hit, and heavy striker, because now the only thing the striker will be doing is opening the valve and not piercing the powerlet. And if you use it the harder Disco stem it will respond quicker and with less initial lift shrouding than the OEM soft stem. Another plus is the Pro-Top will allow the valve to be disassembled and parts replaced from the front of the tube without removing the valve..and it doesn't use the little pink face seal that frequently gets pulled out on the end of a powerlet.
I've been following along because I just bought a Sheridan 2260MB and did the mods on the valve so I'm looking for all the info I can get too. I found this thread from a while back that has some mods and also a slow-mo video of the hammer bounce and thought it would be a good read for the OP.http://www.gatewaytoairguns.org/GTA/index.php?topic=105520.0
Here's a little visual aid for the bstaley buffer (bstaley o-ring buffer, BSB, etc).When you use the Prod hammer/striker assembly you are able to make the striker stand out from the outside edge of the hammer. The outer edge of the hammer makes contact with the stack of o-rings (I think they're #113's) that is at the base of the valve which stops the hammer and absorbs further strikes from rebounds. The striker, because it's adjustable, can be screwed out to adjust how far the valve stem is pushed in from the hammer strike.Here's a picture of a 2240 valve with 4 o-rings and the tip of the valve stem sticking out.I use 5 o-rings so there is almost no contact with the valve stem when the striker is fully recessed. This allows me to increase the amount the valve opens by screwing the striker out. From no contact to as far as the valve will open.I think this is the graph I made comparing shot strings of my 2240 before and after the bstaley mod.Red line is pre, blue line is post. Vertical axis is feet per second, horizontal axis is number of shots. There may be other mods in the mix with these numbers, I can't remember what had or hadn't been done previous to the bsb mod. I may have played with different hammer springs and might have angled the exhaust coming from inside the valve. No matter though, you can see the effect.Also there's a HUGE thread covering Bob Sterne's SSG (stopped spring guide) development. He put out a Leap Year challenge to take a stock 2240 and only adding in an SSG, see who could get the most total energy from a single co2 cart. I put the details of my results in that thread. I got around 100 shots at about 4 FPE. I was trying to get the most energy out of the cart so the energy needed to be low so as not to waste co2. When I installed it to use, I brought the fpe per shot up which reduced the number of shots but still gave me more than stock and a much better string.Blue
Bob Sterne is the only guy I know that has that special calculator to figure that out.To calculate what exactly?It was kinda meant to be funny.... Bob has all those fancy graphs and spreadsheets. He's been the guru for a long time... He's light years ahead of me. I just run mine over a chrony.... sometimes.
I would say that any thing you do with that short barrel is a waste of C02. From what I've been researching the short barrel waste gas regardless of what you do. If I'm wrong then someone will chime in. If you want a 300FPS gun it might work but it's only good for shooting paper. You don't have to spend money to get more power and see if you like the power vs C02 usage. Do this mod and see what happens. It's gonna be louder than before but you should get a few more FPS. It was a big difference on my 2260MB with a 24" barrel. There's a reason everyone uses longer barrels===results are so much better both in accuracy and power.
Yes, stock 2240/2250/2260 valve and stem.I don't think I've heard of anyone using a stock hammer with the BSB mod. I imagine you could eventually find a combination of o-rings or I've heard of people using a small section of hose to get the exact length of a buffer they want. If you can find the length that allows the valve to open the amount you need for the speed you're looking for then contacts the buffer stack and absorbs enough remaining energy to prevent a bounce back forcefull enough to bump open the valve, I think it could work. I think it would be A LOT of work to dial in a tune that way.The nice thing about the Prod hammer assembly is that it's easier to be able to adjust the striker than disassemble each time to change the buffer in front of the valve.I think I dialed in the tune I was looking for with a Crosman Challenger power adjuster installed. After I found what I was looking for I removed the power adjuster, clipped the spring to give me a similar spring rate to when it was in the power adjuster but with a stock endcap. I wanted a clean look on the back and wasn't going to adjust it again.Here's a picture of my 2240, Crosman aficionados can't resist showing pictures of their baby's.Blue
I'm pretty sure that all the Pro-Top does is pierce the CO2 cartridge when you screw in the front cap, instead of the valve having a piercing pin.... I don't think there is a corresponding trigger group or hammer that they make....Bob
Advertise Here
Share This!