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PostPosted: Mon Feb 25, 2019 9:30 pm 
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Joined: Sun Feb 10, 2019 4:24 pm
Posts: 12
Location: Edmonton
Hey guys, is there any way to find the BC of the pellets?

or how do you guys find the drop of the pellets at different distances?

Thanks


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PostPosted: Mon Feb 25, 2019 9:55 pm 
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Joined: Fri Jan 22, 2010 1:17 pm
Posts: 1711
Location: Kingston, ON
Download and use Chairgun Pro.
https://www.hawkeoptics.com/chairgun-an ... -life.html

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PostPosted: Tue Feb 26, 2019 3:26 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 5727
Location: P.G. B.C.
or use 2 chronographs, for accuracy, one set near the muzzle, the next one at 100yards from the first - or a specified distance - then do the math of the vel. lost.

I use ChairGun.

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Daryl

Air Force Condor .25
Umarex Gauntlet .22
Air Force Talon .177
HW97 KT .177
HW98 .22
Brocock Concept .22
Artemis PP700S-A Reg. .22
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PostPosted: Tue Feb 26, 2019 7:29 pm 
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Joined: Sun Feb 10, 2019 4:24 pm
Posts: 12
Location: Edmonton
Thanks guys.

I got the BC from the Chairgun app and then I used my "Ballistic Advance Edition" app to find the drop. I will verify that distances at the range soon.


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PostPosted: Tue Feb 26, 2019 11:37 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 5727
Location: P.G. B.C.
The chairgun program will set out the drop every 5 yards or meters if
you want it to with whatever kill zone (area brackets) you want.

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Daryl

Air Force Condor .25
Umarex Gauntlet .22
Air Force Talon .177
HW97 KT .177
HW98 .22
Brocock Concept .22
Artemis PP700S-A Reg. .22
Artemis PP800 Rebel Reg. .22


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PostPosted: Sun Mar 10, 2019 7:19 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1218
Location: United States
I thought I posted on this already, but fyi Chairgun can't calc trans sonic. At least not when I used it last which has been a while. I doubt it ever will but who knows. This means you plug in a known # for a pellet, like .020, it'll be ok <890fps, but it won't factor the BC change when you go above ~890fps, and that # changes steadily up to 1130 or somewhere which is drastically diff. So if you're up in that zone you'll have a hella time figuring out your pellets BC because the pellet will slow more quickly at first, then less quickly as it slows until you get ~890. BC still changes at <890, but to a much lesser degree.
If you look at BC #'s people post online you'll see they vary, drastically. It depends on so many factors, then add human error and misc errors, so you get drastically diff #'s.
All that matters imo is you choose one with good BC that you like, then learn how much it drops at xx distances in your gun. Not much else you can really do.
If you really want the BC #'s then you'd need two Crony's, accurate distance measuring, and lots of time. Also be certain both crony's are matched, so shoot with one in front, then trade places to confirm they each read equally. Typically the second one will read less, just be sure the front and rear show the same diff regardless of which is in front/back.


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PostPosted: Sun Mar 10, 2019 8:09 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 5727
Location: P.G. B.C.
A lot of these air-gun ballistics are new to me. Much of my shooting is over 3,000fps and some well over 4,000fps, where I've found an on-line
chart that works perfectly with my bullets and loads, out to 1,000 yards/meters.
It also works for the .17 cal pills, too (at 3,600fps to 4,500fps), out to 500 yard gophers anyway.
The only deterrent to this type of program is you have to know the BC before hand. Knowledge of atmospheric conditions also makes a difference
but is less important than the BC. BC's can be found in most bullet maker's manuals or on their web sites. Finding the actual numbers from people
who set up multiple chronographs, usually shows lower numbers than mfgr's claims. Plugging in the 'proven' #'s usually gets drop figure accuracy to fractions
of an inch.

This is the one I use for PB guns.
It has worked well for me.
http://www.shooterscalculator.com/balli ... ate+Chart+

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Daryl

Air Force Condor .25
Umarex Gauntlet .22
Air Force Talon .177
HW97 KT .177
HW98 .22
Brocock Concept .22
Artemis PP700S-A Reg. .22
Artemis PP800 Rebel Reg. .22


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PostPosted: Sun Mar 10, 2019 10:18 pm 
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Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8903
Location: Coalmont BC
ChairGun has improved drastically over the years.... When I first did my testing and calculated BCs using the first ChairGun, I found huge changes in the BC as the velocity approached Mach 1, because ChairGun was using a drag model that used a constant drag coefficient.... Since the Cd varies by a factor of 3-5 in the Transonic region (Mach 0.8-1.2), for all projectiles, this gave terrible results.... Later versions of ChairGun used the G1 drag model, designed for bullets, which compensates somewhat for that rapid drag rise.... The latest version can use a drag profile called GA, which is designed to be even closer to airgun pellets.... so if you do a BC measurement using the latest version of ChairGun it is about the best out there....

Unfortunately, ChairGun has been discontinued by Hawke.... The "Legacy Version" may still be available for download on their website, but they have announced they will no longer be updating it, nor even changing it to be compatible with changes to operating systems, in the future.... It has a BC calculator built in, and it's the best that we have currently.... For how much longer is anybody's guess.... :(

https://www.hawkeoptics.com/chairgun-an ... -life.html

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Sun Mar 10, 2019 10:28 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 5727
Location: P.G. B.C.
tks for the information, Bob.

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Daryl

Air Force Condor .25
Umarex Gauntlet .22
Air Force Talon .177
HW97 KT .177
HW98 .22
Brocock Concept .22
Artemis PP700S-A Reg. .22
Artemis PP800 Rebel Reg. .22


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