Disco numbers

[Kazman]

Well its been a real long time since i posted . I bought an XL 1100 and a Disco last fall . The Disco was used the XL1100 was new . The XL had problems from the start so i sent it back . That was last fall .Winter set in so i stopped shooting till today . I put both rifles over the chrony after spending a few hours this afternoon putting a few hundred shots through each . Here's the results for the Disco . Remember , i bought this rifle used and , supposedly , nothing was done to it .
I pumped ( by hand ) the pressure up to just over 2000 psi .
 First up was the JSB Red . 876,887,898,904,919, 923, 918,918,911 .
 JSB Black 933,921,928,914,921,924,
Crow Mags , 934,918,908,917,902,
Crossman Hollow point . 924,914,923,914 .  Do these numbers seem a little high ? I'm shocked .
 My XL1100 averaged about 60 fps slower using the Reds , then , comparing the JSB Blacks , my XL is approx 120 fps slower . Do i just have a factory freak with the Disco  ? 

[rsterne]

.177 or .22?.... and what are the pellet weights?....

Bob

[longislandhunter]

For a completely stock .22 disco those numbers are indeed high.  It is .22 correct?

Jeff

[Kazman]

Yup .22 is correct . What i'm worried about is , if the Disco numbers are high , that means the XL1100 are low again . I shot both guns back to back so i don't see it being any difference . Factory freak unless the guy i bought it off did some work but he said it was stock .

[Kazman]

.177 or .22?.... and what are the pellet weights?....

Bob
.22 , i think the JSB Reds are 15.9 and the Blacks are 18.1 . Not sure about the Crossman's. 

[rsterne]

Those numbers are wayyyyyyyyy too high for a stock .22 cal Disco.... I'm guessing that the gun has a heavier hammer spring installed.... Does it have an adjuster on the back for hammer spring tension?.... If not, then the spring is either bigger wire or shimmed.... or both.... I got almost exactly the velocities you posted (~920ish) for the 16 gr. JSB Exacts (red) with just a spring change, still using the stock rear plug.... Change the spring, pick up ~70-80 fps....

The only other possibility is that you are shooting the PCP too close to the Chrony.... Try it with the muzzle at 3 feet from the first sensor.... The air blast can give wildly inaccurate results.... and a Springer has much less muzzle blast because the pressure pulse occurs much earlier in the shot cycle....

In addition, it would be helpful if you post a complete shot string from 2000 psi down to about 1000 psi for each pellet weight.... I can't tell from your numbers if the four strings you shot are all part of the one fill or not.... If you did them in the order posted, all from one fill, that could help explain the fact that the 18 gr. pellets were faster than the 16 gr....

Bob

[Furseeker]

I agree with what's been said above, my Discovery is bone stock and the best I've done with CPHP in .22 is about 860fs. I'm at about 4,500 feet above sea level here in Utah, so I don't get as fast as some of the lower elevation guys get.

[Kazman]

I agree with what's been said above, my Discovery is bone stock and the best I've done with CPHP in .22 is about 860fs. I'm at about 4,500 feet above sea level here in Utah, so I don't get as fast as some of the lower elevation guys get.

Those numbers are wayyyyyyyyy too high for a stock .22 cal Disco.... I'm guessing that the gun has a heavier hammer spring installed.... Does it have an adjuster on the back for hammer spring tension?.... If not, then the spring is either bigger wire or shimmed.... or both.... I got almost exactly the velocities you posted (~920ish) for the 16 gr. JSB Exacts (red) with just a spring change, still using the stock rear plug.... Change the spring, pick up ~70-80 fps....

The only other possibility is that you are shooting the PCP too close to the Chrony.... Try it with the muzzle at 3 feet from the first sensor.... The air blast can give wildly inaccurate results.... and a Springer has much less muzzle blast because the pressure pulse occurs much earlier in the shot cycle....

In addition, it would be helpful if you post a complete shot string from 2000 psi down to about 1000 psi for each pellet weight.... I can't tell from your numbers if the four strings you shot are all part of the one fill or not.... If you did them in the order posted, all from one fill, that could help explain the fact that the 18 gr. pellets were faster than the 16 gr....

Bob

You have a good point there with being too close to the chrony . I'll give it another try some time later this week and re-post the numbers . My XL1100 sounds and feels more powerful but on the chrony ( maybe due to the airblast of the Disco ) produced lower numbers .