Is there a way to guess/assume your rifles fps

Joined: June 17th, 2011, 12:59 pm

May 30th, 2017, 8:31 pm #1

Without a chrony? Like say if you zero her at 20yds then shoot at 50yds then go to chairgun, mess with the fps until you see the drop at 50yds matches what you see on your target?
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Joined: May 2nd, 2013, 12:17 pm

May 30th, 2017, 8:44 pm #2

if the BC you assume is correct for the pellets you are using. You will also have to make sure there is no wind, either head, tail or cross wind as they will all affect drop.
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Joined: June 17th, 2011, 12:59 pm

May 30th, 2017, 9:48 pm #3

Ok, thank you nt
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Joined: May 4th, 2008, 12:30 am

May 30th, 2017, 9:54 pm #4

Without a chrony? Like say if you zero her at 20yds then shoot at 50yds then go to chairgun, mess with the fps until you see the drop at 50yds matches what you see on your target?
You can do a splat test, use the same pellet in the rifle you want to determine the FPS on, and check that splat. That is splatology.
Another way is to just shoot into a block of pine, that give you an idea of performance. But if you are really interested in FPS, the best way is use a chronograph.

After a while you get a feel for the speed by hearing how quickly it hits the target at whatever distance. These methods are not that accurate but they do give you a basic idea if a gun is shooting faster or slower than another. Our ears can detect the fraction of a second that it takes to hit a target. The chronograph is great to get the benchmark speeds and also to find big or small differences in a string of shots. If the guns report is really loud, these subtle differences can be missed with our ears. But be prepared for the chrono not seeing every shot in a string, and you know that was the shot that was not consistent with the others. Nothing's perfect. Chrono's are fairly cheap, unless you shoot them up regularly.
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Joined: June 17th, 2011, 12:59 pm

May 30th, 2017, 10:01 pm #5

That is the point brother.can we guesstimate what the fps is by the amount of drop from a 20us target to a 50yd target. So let's say the drop is 1"...from a 20yd zero. With just that little info can one guess with the help from chairgun, find out what the fps of the gun is
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Joined: September 4th, 2012, 11:45 pm

May 30th, 2017, 10:04 pm #6

Without a chrony? Like say if you zero her at 20yds then shoot at 50yds then go to chairgun, mess with the fps until you see the drop at 50yds matches what you see on your target?
Seems like the app that Joe Wayne Rhea posted about in this recent post on The Yellow might be a more accurate alternative. No chrono required, just your phone or iPad and a little bit of setup. Seems a lot less fiddly and potentially a fair bit more accurate than guessing at the pellet BC and conditions.

http://www.network54.com/Forum/79537/me ... ect+Review
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Joined: May 17th, 2004, 4:36 pm

May 30th, 2017, 11:25 pm #7

Without a chrony? Like say if you zero her at 20yds then shoot at 50yds then go to chairgun, mess with the fps until you see the drop at 50yds matches what you see on your target?
A long time ago, Robert Law and ARH sold ballistic putty which is basically duct seal. You shoot into the putty with the muzzle a few inches away and measure penetration by inserting a pin or toothpick. There might be an old table on the web somewhere. As others have suggested, if you have a rifle of similar caliber and you know the velocity, shoot that one and compare it to the rifle you're testing. At least you'll know whether its faster or slower. I found this from an old Doc Beeman article:

Americans frequently test their airguns by firing into soft wood. Unfortunately wood probably is one of the worst possible testing materials because its grain, type, and condition varies tremendously with wood species, dryness, etc.. However, some very rough "ballpark" ideas of penetration can be had by this method. These notes refer to .177” caliber airguns. Guns firing at 630 fps will usually completely bury their pellet into soft pine or redwood. An 800 fps sporter will frequently tear completely through a 1” finished board, splintering out the rear as the pellet leaves! Aluminum beverage cans provide more uniform testing material, but maximum penetration depends on hitting them exactly square. A 640 fps match test air rifle could go right through six cans. A magnum sporter could rip through over 10 cans. Even a match air pistol could go completely through four!

Ballistic putty is one the best materials for testing airgun projectile penetration. It is relatively uniform and so dense that penetration depths can be rather easily measured from the surface. It is far denser than flesh. A soft lead, round nose pellet from a 780 fps gun will penetrate a total of about 3/4" into this material at room temperature at about one foot firing distance. (Don't forget to add the length of the projectile when measuring penetration depth!).
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Joined: May 12th, 2001, 1:29 pm

May 31st, 2017, 12:46 am #8

Without a chrony? Like say if you zero her at 20yds then shoot at 50yds then go to chairgun, mess with the fps until you see the drop at 50yds matches what you see on your target?
http://www.network54.com/Forum/79537/me ... %26quot%3B
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Joined: June 17th, 2011, 12:59 pm

May 31st, 2017, 1:49 am #9

Seems like the app that Joe Wayne Rhea posted about in this recent post on The Yellow might be a more accurate alternative. No chrono required, just your phone or iPad and a little bit of setup. Seems a lot less fiddly and potentially a fair bit more accurate than guessing at the pellet BC and conditions.

http://www.network54.com/Forum/79537/me ... ect+Review
seem to change with relative ease and what about the setting on the app? Are there any?
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Joined: June 17th, 2011, 12:59 pm

May 31st, 2017, 1:50 am #10

A long time ago, Robert Law and ARH sold ballistic putty which is basically duct seal. You shoot into the putty with the muzzle a few inches away and measure penetration by inserting a pin or toothpick. There might be an old table on the web somewhere. As others have suggested, if you have a rifle of similar caliber and you know the velocity, shoot that one and compare it to the rifle you're testing. At least you'll know whether its faster or slower. I found this from an old Doc Beeman article:

Americans frequently test their airguns by firing into soft wood. Unfortunately wood probably is one of the worst possible testing materials because its grain, type, and condition varies tremendously with wood species, dryness, etc.. However, some very rough "ballpark" ideas of penetration can be had by this method. These notes refer to .177” caliber airguns. Guns firing at 630 fps will usually completely bury their pellet into soft pine or redwood. An 800 fps sporter will frequently tear completely through a 1” finished board, splintering out the rear as the pellet leaves! Aluminum beverage cans provide more uniform testing material, but maximum penetration depends on hitting them exactly square. A 640 fps match test air rifle could go right through six cans. A magnum sporter could rip through over 10 cans. Even a match air pistol could go completely through four!

Ballistic putty is one the best materials for testing airgun projectile penetration. It is relatively uniform and so dense that penetration depths can be rather easily measured from the surface. It is far denser than flesh. A soft lead, round nose pellet from a 780 fps gun will penetrate a total of about 3/4" into this material at room temperature at about one foot firing distance. (Don't forget to add the length of the projectile when measuring penetration depth!).
BillS, thank you, nt
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