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Chrony Question For Airgun Shooters

March 16 2017 at 3:37 PM
Frank Alessio  (Login fsa70)

This is mainly addressed to airgun enthusiasts. How far do you keep the muzzle from the Chrony ? Also, how much of a difference is there at different distances ?

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Steve in NC
(Login pneuguy)

For traditional airgun calibers (.177, .20, or .22) and velocity (<1000fps)...

March 16 2017, 6:13 PM 

...1 foot is adequate. Bigger bores and/or higher velocities may need more.

Expect to lose about 1 to 4fps per foot.

This message has been edited by pneuguy on Mar 16, 2017 9:00 PM

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James Dingle
(Login JamesDingle777)

Hey Steve, Chair Gun says I'm "allegedly" getting

March 17 2017, 12:31 PM 

600fps at 100 yards with a JSB 18.1 doing an average of 861fps over a 50 shot string. That 861fps is tested by a Chronograph at unknown distance from previous owner. I don't have a chrony and wouldn't be willing to risk sending it through at 100 even though this exact information put into Chair Gun Pro has me DEAD on nuts at 100 yards. Taking the cap off of water bottles 6x magnification hold 3rd mil-dot right on top of cap.
Still getting 600fps and retaining, what, 14FTLBS? From what I'm seeing, there is a huge variance you can see in fps before POI change at 50 yards. I believe I've been told a 40fps variance will cause a 1/4" drop at 50 yards.
So are my figures wrong or can some pellets like JSB 18.1's retain more energy/velocity and loose less than 1fps per foot?

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Steve in NC
(Login pneuguy)

Rate of velocity loss isn't constant, but proportional to velocity.

March 17 2017, 4:20 PM 

So a pellet that loses 1fps per foot at 861fps would lose only approx' 0.7fps per foot at 600fps.

Still, there are definitely some super-slippery pellets that lose less that 1fps/foot even at higher velocities.

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Quinton Lewis
(Login Domer_Pyle)

Usually about 6" or so

March 17 2017, 9:14 AM 

Never tried any further than that

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(Login 21grains)

Re: Usually about 6" or so

March 17 2017, 8:32 PM 

12" to center of Chrony to Muzzel, Gun in SanAngelo Gun Stand so it won't move. Works w/no Error's ever.....Franky

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