CO2 and Hammer Strike....bigger is NOT always better.......

[BigTinBoat]

With the help of a great mind here (rsterne) I am learning about the inner workings of a CO2 gun. I picked up an AS2250XT that was running off a regulated tank, but I didn't get the tank with the deal. I decided that for the summer I would run it off of 9oz CO2. I shot it a while and it did well, until I got my .22 Disco. I didn't like the bigger arch what I was getting with the 2250 and since I had a bunch of .177 pellets and a .177 Disco barrel I decided to swap them out. I cut the .177 barrel to 18.5” and shot away. I then picked up a 12G adapter and decided to see how many shots I would get. I was disappointed when I got the “burbing” at only my 27th shot and didn't shoot anymore for fear of the pellet getting stuck in the barrel. Oh well, no biggie as I was planning to be shooting off a 9oz bottle. Fast forward a month and I finally got me an F1. Reading all that I could about CO2 and hammer springs, and watching a spray of CO2 come out on each shot I set out to see what I could do.

First thing I did was shoot the gun over the Chrony. With the CPUM pellet (10.5) I Was getting avg of 590FPS, and with the CPHP (7.9) I was getting 635FPS.

Next thing I did was order (3) 22xx hammer springs. Then I took the gun apart and tried everything I could to improve power. The spring in the gun looking to be the same wire as the 22XX but it felt a bit harder to compress. I removed this spring and put a spare Disco spring in the gun. I also put a lighter valve spring in, polished the hammer, drilled out the barrel TP just a bit and cut and installed a new piece of poly for the TP. I shot it over the Chrony and was getting avg of 615fps with the CPUM(10.5) and 670 with the CPHP(7.9). The most accurate pellet I found at 10yds was the CrosPointed (7.4) at 690FPS. I tired some 7.0 RWS and was at 701fps.

Now here is where my efficiency minded personality comes into play 'cause I know I'm blowing out lots of extra CO2.

I take out the Disco spring and put the original spring back in. Velocity average is identical.
Next I remove the original spring and put in one of the new 22XX springs – same result.
Next I did what Bob suggested and started cutting a coil at a time until I start dropping significant FPS. Wound up cutting off 4 coils (1/2" total - but 1 coil at a time) before I dropped any FPS at all, and it lost 40fps. Took another new spring (bought 3) and cut 3.5 coils off. Put this one in and it's again shooting 690 with the 7.4's. Even with TKO I can tell it's a LOT quieter and also much easier to cock.
Just tonight I popped in a 12g and it shot and average of 688FPS over the first 12 shots. I was shooting pretty quickly and was not worried about the FPS as I didn't have a Chrony during my first test, but I got to 39 shots before I got the “burping” like I did with the original hammer.
So just by lightening the hammer spring I made the gun over 33% more efficient, and I was shooting at about 35fps more. I'm thinking had I not done the other mods that raised the FPS I would have seen even more efficiency gained.

Of course I still have my original spring and will likely be using it when I get a regulated bottle when winter rolls around. The gunner I bought it from was shooting it at 1100PSI I think. Anybody have a 13ci bottle they want to get rid of cheap?

[Ribbonstone]

Stronger hammer strike will almost always release more co2, it's just that some of that co2 isn't pushing the pellet, just being blown out after the fact.  Like Bob, better to keep decreasing striker spring tension until you notice a real difference in speed and safe that wasted co2.

Nothing is ever perfect.  Adjust it to shoot it's best at 90F, and you're likely to be back to a snow-blower by 60F.  Set it up to do it's best at 60F, and will often find it shooting SLOWER (or even valve locked) at 90F.

[rsterne]

Glad to see you confirm that too much hammer strike only wastes CO2.... Like Ribbonstone said, however, if you are tuning for maximum velocity, there will be a different optimum hammer strike for each temperature....

However, if you want to take the time to find it, and are willing to give up a bit of performance in the hot weather, you can tune the gun to be self-regulating over a WIDE range of temperatures.... In fact, since you tried 12 quick shots that averaged 688, you may already be close, because normally that would cool the gun quickly enough to cause dropping velocity....

Anyway, congrats on finding a much more efficient tune that shoots just as hard as when you were wasting CO2.... and also thanks for sharing your experience....

Bob

[BigTinBoat]

I give 95% of the credit to me attempting this based on the posts made by both of you guys (rsterne and Ribbonstone), as well as Nervoustrigger. My "learning" curve was shortened considerably based on your guys "trials".

Thanks Again!

the only "negative" side is that I know it will cost me more money. Now that I think this gun is giving me the most it can for the least amount of CO2, I want to get another similar gun and do the same with HPA.

[rualert]

     Big Tin Boat, (quote) Anybody have a 13ci bottle they want to get rid of cheap? (/quote) Most paintball shops have 13 cu.in regulated bottles, they are normally set at 850 FPS or very close, as they were intended for guns that were designed to run on CO2. Shimming the regulator up to 1100 - 1600 PSI is pretty simple. Also Expert HPA and JDS Airman both sell regulated bottles set to the output you request. I have one myself with a 1600 PSI bottle, and it's quite fun. I would not exceed 1800 PSI, and actually feel safer at 1600 PSI. I'll have to dig up the numbers, but it was shooting very well with the 1600 PSI bottle, I did need a disco hammer spring, and since this was prior to the 1701 pistol with the adjustable sear/trigger, I installed the two srtage super sear from AOA. You will be very happy with the rifle on regulated HPA. Tons of shots at the power level you set it at. Still very tunable so you can keep it efficient too.

Casey

[Ribbonstone]

OR you can leave it at 850psi.  Won't get mega power, but with 2150psi to work with (3000 to 850psi) can get some serious shot count at about 12-14foot pounds.

[BigTinBoat]

     Big Tin Boat, (quote) Anybody have a 13ci bottle they want to get rid of cheap? (/quote) Most paintball shops have 13 cu.in regulated bottles, they are normally set at 850 FPS or very close, as they were intended for guns that were designed to run on CO2. Shimming the regulator up to 1100 - 1600 PSI is pretty simple. Also Expert HPA and JDS Airman both sell regulated bottles set to the output you request. I have one myself with a 1600 PSI bottle, and it's quite fun. I would not exceed 1800 PSI, and actually feel safer at 1600 PSI. I'll have to dig up the numbers, but it was shooting very well with the 1600 PSI bottle, I did need a disco hammer spring, and since this was prior to the 1701 pistol with the adjustable sear/trigger, I installed the two srtage super sear from AOA. You will be very happy with the rifle on regulated HPA. Tons of shots at the power level you set it at. Still very tunable so you can keep it efficient too.

Casey

Casey - this was exactly my plan. Again reading these GTA posts I see that it's basically different arrangements of Bellville washers to get the desired pressure. At first was looking at the SHP from Ninja for like $85 then I saw a post on here where someone(I think it was Ribbonstone, if not it was rsterne) actually replaced the spring assembly of one of the $59 Ninja Paintball 13ci reg's, with just the washers, to get like 1400psi. I have a fastenal store on my way home from work and I think they probably stock the washers. Couple months ago I saw a 13ci for $40 but didn't want to get it before I had the AS2250. Like they say, hind sight is always 20-20.
I was thinking of 1000-1100 as that's what the owner I bought the gun from had it tuned to and I'm thinking (hoping) I can get 800-900fps on it, with the CPUM's.

OR you can leave it at 850psi.  Won't get mega power, but with 2150psi to work with (3000 to 850psi) can get some serious shot count at about 12-14foot pounds.

This was my thoughts until I get the courage to disassemble the regulator

[Ribbonstone]

Know I’m the “odd guy out” here, but a blessed to have other rifles to shoot fast, so set the HPA guns to do what the PCP’s cannot: shoot 165-180 shot per fill at a very uniform velocity (and about 12-14 foot pounds).

[rsterne]

Build one for the Canadian <500 fps rules (I use about 450 psi).... 7.5 FPE in .22 cal and well over 300 shots per fill.... *grin*.... total preload on the 2240 spring is only 1/16" (ie that's how far the end cap sits above the end of the tube before you push it in and install the rear screws)....

Bob

[rualert]

     Found one of my older spreadsheets, so here's a screen shot of the graph, it has the stock 800 PSI reg, then the 1600 PSI regulated bottle both on the graph for comparison. I didn't try to stand on it, and still haven't yet, but I'm guessing I can push it much higher if I want. However, like Bob and Ribbonstone both stated it's great to fill the little 13 cu.i. bottle, and basically shoot it all day long. And can you say flat shot string. 

Casey

[rsterne]

Interesting observation about your graph.... The average velocity is 42% greater on 1600 psi, which means exactly twice the FPE from twice the pressure.... Neat, huh?....

Bob

[rualert]

Interesting observation about your graph.... The average velocity is 42% greater on 1600 psi, which means exactly twice the FPE from twice the pressure.... Neat, huh?....

Bob

     Pretty cool when the physics works out the way you would expect them to huh?

Casey