Calculating B.C.
Select Gate
READ GTA FORUM RULES BEFORE POSTING
GTA Forum Help Desk
GTA Announcement Gate
Dealer Area
GRIP
AirgunWeb Airgun Videos
Airgun Repository of Knowledge
Vendors and Vendor Videos
AirGun Expo 2021
Airgun Expo 2022
Contests and Giveaways!!!
Welcome New Members
In Memoriam
GTA Contributing Members
Shot Show Videos
Hajimoto Productions
Airgun Detectives
Air Gun Gate
BB Guns and Such
"Bob and Lloyds Workshop"
American/U.S. Air Gun Gates
European/Asian Air Gun Gates
PCP/CO2/HPA Air Gun Gates "The Darkside"
Air Archery
Vintage Air Gun Gate
Air Guns And Related Accessories Review Gates
Hunting Gate
Machine Shop Talk & AG Parts Machining
3D printing and files
Buyer's, Seller's & Trader's Comments
Bargain Gate
Back Room
Target Shooting Discussion Gate
Target Match Rules
Shooting Match Gates
Field Target Gates
The Long Range Club
100 Yard Match
Discussions By States
Welcome,
Guest
. Please
login
or
register
.
Did you miss your
activation email
?
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Home
About
Help
Old GTA
Gallery
Search
Stats
Login
Register
Advertise Here
GTA
»
All Springer/NP/PCP Air Gun Discussion General
»
PCP/CO2/HPA Air Gun Gates "The Darkside"
»
Big Bore AirGun Gate
(Moderators:
Rocker1
,
GTA-Airgunner
) »
Calculating B.C.
« previous
next »
Print
Pages: [
1
]
Go Down
Share This!
Author
Topic: Calculating B.C. (Read 966 times))
Randbo
Plinker
Posts: 276
yes
Real Name: Randy
Calculating B.C.
«
on:
February 13, 2016, 04:26:54 PM »
I was shooting my Texan today trying to figure out the B.C. of the bullets I'm using. I am shooting bullets from a Lyman mold 457122 HP the wt. is 340 gr. Lyman says B.C. at 1400 fps is .265, so I put my chronograph at 3 yds. shot 3 shots refilled and then moved the chronograph out to 52 yds and refilled and shot 3 more. My 3 yd velocity was 787, 772 and 757 and my 52 yd. velocity was 751, 741 and 734 I figured the B.C. at .138 for the first shot, .155 for the second and .195 for the 3 rd shot. Is it normal to get this much variation with the slower velocity? or did I figure the B.C wrong?
Logged
michigan
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Calculating B.C.
«
Reply #1 on:
February 13, 2016, 04:41:44 PM »
Since you have a decreasing shot string, there is a very real possibility that the MV of the three shots you fired at 52 yards was not the same as the three you fired at 3 yards.... In addition, for the BC to increase as the velocity decreases is not unusual, but for it to change that much over that narrow a range of velocity would be unusual.... If you take your average MV (772) and your average downrange velocity (742), you will get very close to what you calculated for the 2nd shot (0.155)... I would use that....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Randbo
Plinker
Posts: 276
yes
Real Name: Randy
Re: Calculating B.C.
«
Reply #2 on:
February 13, 2016, 04:59:30 PM »
The 3 yd fps were the average of two 3 shot strings, refilling after every 3 shots the two 3 shot strings were 789, 774 and 758 and the second one was 784, 772 and 755. The velocity of the first 3 shots are fairly consistent after a fill, I did only shoot 3 shots at 52 yds. It was 15 deg F. with a 10 mph wind, on a warmer day I will have to check vel. at 100 yds.
Logged
michigan
Print
Pages: [
1
]
Go Up
« previous
next »
GTA
»
All Springer/NP/PCP Air Gun Discussion General
»
PCP/CO2/HPA Air Gun Gates "The Darkside"
»
Big Bore AirGun Gate
(Moderators:
Rocker1
,
GTA-Airgunner
) »
Calculating B.C.