Chronograph distance
- Thread starter Crabbypatties
- Start date
Id say at the muzzle.. fps drops pretty fast as you go out . Then you want to keep a consistent same distance from muzzle to crony.
For a example on how fps drops per crony distance.
For a example on how fps drops per crony distance.
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Thank you for that information. I guess I wasn’t clear enough and I apologize for that, I’m wanting to get my initial speeds from the muzzle. I want to know how fast I’m shooting my ammo
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Ya, i took a chance on a cheap china bolt on muzzle crony ($30 amazon+/-) and i like it for that reason..
I dont bolt it on but rest the muzzle end in the mount yoke and just shoot my strings. Nothing fancy but seems to work well for this at the muzzle reading.
Kinda like here
I dont bolt it on but rest the muzzle end in the mount yoke and just shoot my strings. Nothing fancy but seems to work well for this at the muzzle reading.
Kinda like here
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I have to get mine out of the sun so I shoot about 7-10 feet from the muzzle since I shoot from shaded positions.
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I have noticed a deviation in speeds when placing the muzzle close to the chrony. I’m guessing the muzzle blast is interfering with the readings.
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(Air gun)
Not this one .. Its been pretty rock steady. Heck i rarely get a error with .177 as well.. well satisfied with it / go to first . Only thing mine is older and dont have a fps/mps like the later ones seem to do now. Still just simple math to convert . I'd buy again in a minute..,
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I'd suggest testing at two ranges. Close to the muzzle end and also out at a measured 10 yards from the first set-up. You can get the pellet bc that way and establish an accurate drop chart.
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Several chronographs will calculate your velocity at the muzzle if you input distance to the chrono. To do so, they need either something like radar, or at least three screens (like some Oehler chronos). Generally though, velocity taken a few feet from the muzzle will give you a velocity that is closer to actual muzzle velocity than your shot-to-shot variation - in other words, as good as it gets for all intents and purposes.
GsT
GsT
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I believe that in order to properly calculate the BC you need to have a reading at the muzzle and at the target.
I'm still learning myself, though.
I'm still learning myself, though.
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I used to use a "Shooting Chrony" light based chronograph. I used it mainly with my powder burners and it had to be placed several feet from the muzzle due to the muzzle blast. But for my airguns, I use either a barrel clamp on chrony or a similar tripod mount unit. Either is used inches from the muzzle. The longest distance from the muzzle for the clamp on is the length of the in shroud moderator. It's about 120mm long so chrony is probably less than 6 inches from the end of the barrel. I put the tripod one a few inches further away but not far. They give the same reading.
I don't think you need a lab radar to get the velocity at your target but you have to get gutsy enough to shoot through your chronograph at the target location. That would be easier with something with a bigger window than the little units I'm using. But you can get a pretty good idea of the bc by carefully shooting groups at a range of distances and then playing with a ballistics program to get the software to match the trajectory from your shooting. I use chairgun and when I am done I can print out a shooting card to know my holdovers or dial ups.
I don't think you need a lab radar to get the velocity at your target but you have to get gutsy enough to shoot through your chronograph at the target location. That would be easier with something with a bigger window than the little units I'm using. But you can get a pretty good idea of the bc by carefully shooting groups at a range of distances and then playing with a ballistics program to get the software to match the trajectory from your shooting. I use chairgun and when I am done I can print out a shooting card to know my holdovers or dial ups.
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+1 for muzzle
they *can* be impacted by blast - even on air rifles. Things like the graphite lube, or lots of crud out of a moderator may cause incorrect readings or start to foul it so it doesnt read at all - or erratically, so cleaning/maintenance of anything barrel mounted will eventually be required at some stage
they *can* be impacted by blast - even on air rifles. Things like the graphite lube, or lots of crud out of a moderator may cause incorrect readings or start to foul it so it doesnt read at all - or erratically, so cleaning/maintenance of anything barrel mounted will eventually be required at some stage
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I was testing my PCP and had it out of stock to play with hammer spring. On my bench setup it was probably a foot from chrony. When I put it back into stock to test accuracy it moved closer. Probably 4-6”. Readings were off. Initially 915-920 and when very close dropped to 885-890.
Initially thought something was wrong. Took it back out of stock and back to 915-920.
So distance definitely impacts reading. I now am curious and gonna try mine 2-3 feet away. The muzzle blast probably throws it off.
Initially thought something was wrong. Took it back out of stock and back to 915-920.
So distance definitely impacts reading. I now am curious and gonna try mine 2-3 feet away. The muzzle blast probably throws it off.
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hmmm I dont think its muzzle blast - when you trigger the sensors from muzzle blast its typically in the 1300-1400fps range.
What model of chrony is it?
I'd say it could be more from the muzzle blast making the chrony move or vibrate slightly - put a bit of paper in front of it - or tape a bit to the chrony itself to see if its getting some blast.
What model of chrony is it?
I'd say it could be more from the muzzle blast making the chrony move or vibrate slightly - put a bit of paper in front of it - or tape a bit to the chrony itself to see if its getting some blast.
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It’s one of the cheap optical ones.hmmm I dont think its muzzle blast - when you trigger the sensors from muzzle blast its typically in the 1300-1400fps range.
What model of chrony is it?
I'd say it could be more from the muzzle blast making the chrony move or vibrate slightly - put a bit of paper in front of it - or tape a bit to the chrony itself to see if its getting some blast.
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