Cutting one coil off of the standard seems to allow it to cock easier and shoot smoother. Tom will do this if you ask him to do it within the notes section in the online order form.
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How Bad Are These Shot Strings?
- Thread starter txaggie929
- Start date
Bad pellets. Two and four are acceptable but marginal. One and three are unacceptable. An SD below 10 is acceptable, over 15 is okay, but over 20 is probably unacceptable.
Opinions will vary
Opinions will vary
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I'm gonna go out on a limb and say that's not all that bad.
First, I have never gotten decent chrono consistency with CP's in any springer (my theory is the fit is weird - tight head, loose skirt - but that's a debate for another day LOL). They often shoot more accurately than the chrono suggests, but maybe they stay on the shelf for this particular R7.
Second, I'd note that your best string was the 4th one - better pellets, gun thoroughly warmed up. The 3rd string was also quite good but for one high-speed outlier; a diesel, or wonky pellet. And your JSB 7.3 speeds match my old R7, tuned with a Maccari kit. So I'd guess the piston seal and spring don't have any catastrophic issues.
10 shots is marginal for calculating standard deviation; a mathematician will tell ya 20+ minimum data points. As a compromise I do 15-shot strings. It's also useful to look at SD as a percentage of the average velocity; an SD of 1%, which your last string got close to, is really quite good for sporting use. To put it another way, an SD of 10 is poor for a 400 FPS pistol (2.5%), but good for a 1000 FPS rifle (1.0%).
So especially if the gun still has factory lubes etc., IMHO it's doing OK. Not that it would hurt to check out the internals, but if it was mine I'd shoot it heavily for a bit, and then run longer chrono strings, with more kinds of pellets!
First, I have never gotten decent chrono consistency with CP's in any springer (my theory is the fit is weird - tight head, loose skirt - but that's a debate for another day LOL). They often shoot more accurately than the chrono suggests, but maybe they stay on the shelf for this particular R7.
Second, I'd note that your best string was the 4th one - better pellets, gun thoroughly warmed up. The 3rd string was also quite good but for one high-speed outlier; a diesel, or wonky pellet. And your JSB 7.3 speeds match my old R7, tuned with a Maccari kit. So I'd guess the piston seal and spring don't have any catastrophic issues.
10 shots is marginal for calculating standard deviation; a mathematician will tell ya 20+ minimum data points. As a compromise I do 15-shot strings. It's also useful to look at SD as a percentage of the average velocity; an SD of 1%, which your last string got close to, is really quite good for sporting use. To put it another way, an SD of 10 is poor for a 400 FPS pistol (2.5%), but good for a 1000 FPS rifle (1.0%).
So especially if the gun still has factory lubes etc., IMHO it's doing OK. Not that it would hurt to check out the internals, but if it was mine I'd shoot it heavily for a bit, and then run longer chrono strings, with more kinds of pellets!
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MDriskill, an interesting and "in vogue" perspective which is.......follow the science! Will apply to my own SD observations.
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