2560 HPA Velocity vs. Air Use
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
»
"Bob and Lloyds Workshop"
(Moderators:
Rocker1
,
ezman604
,
amb5500c
) »
2560 HPA Velocity vs. Air Use
« previous
next »
Print
Pages: [
1
]
Go Down
Share This!
Author
Topic: 2560 HPA Velocity vs. Air Use (Read 1410 times))
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26960
GTA Forums Person of the Year 2017
Real Name: Bob
2560 HPA Velocity vs. Air Use
«
on:
November 21, 2012, 04:33:01 PM »
I finally got my 2560 assembled today, running on a 17 CI tank (it was advertised at 18, but I actually measured it at 280 cc = 17 CI) regulated at 1600 psi.... I used 10 shot strings of three different pellets at each hammer spring preload and recorded the total psi drop, which allowed me to calculate the volume of HPA used per shot.... I then graphed the velocity at each setting vs. the volume of air released by the valve as follows:
There is a big jump in air consumption at the final hammer setting, as those shots resulted in the valve still being open when the pellet left the muzzle.... The increase in muzzle blast was significant.... You will note that the plateaus which indicate very little additional velocity gain is taking place start at about 10 cc for the Lasers, 12 cc for the Kings, and 14 cc for the EJ Points.... That is consistent with other data I have from many guns that indicates that heavier pellets can stand a bit more preload at a given pressure before "hitting the wall".... Since the volume of the barrel (23.5" long from the transfer port to the muzzle) is 18.9 cc, I was also able to plot the velocity vs. the position of valve closure as follows:
This places the point at which very little velocity is gained at about 53% of the distance from the breech to the muzzle for the Lasers (at 1080 fps), 63% for the Kings (at 965 fps), and 74% for the EunJins (at 815 fps).... I'm sure that those values will provide for an interesting discussion.... but they are not inconsistent with data I have from numerous other guns....
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).
Print
Pages: [
1
]
Go Up
« previous
next »
GTA
»
All Springer/NP/PCP Air Gun Discussion General
»
"Bob and Lloyds Workshop"
(Moderators:
Rocker1
,
ezman604
,
amb5500c
) »
2560 HPA Velocity vs. Air Use