GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Matt15 on December 15, 2016, 05:28:30 PM
-
Awhile back, I posted my .25 disco here: http://www.gatewaytoairguns.org/GTA/index.php?topic=117753.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=117753.0)
It shot 8 shots 849-864-828 for a 16 fps spread
I just recently drilled the barrel port out to .180" from the stock .140".
I ran it over the chronograph this afternoon and after I messed with the velocity adjuster I settled on this string:
2600 psi fill
1) 834
2) 839
3) 855
4) 862
5)868
6)870
7) 868
8( 866
9) 859
10) 850
11) 840
12) 834
End pressure was 1700 psi.
I then shot a 12 shot group at 25 yards and ended up with 1 large hole the could be covered by a dime.
I am looking forward to shooting this gun at 50 yards and hopefully shoot for the NUAH club.
-
The Squirrels are gonna hate this gun! Nice job.
Steve
-
25 gr. Kings?....
Bob
-
The Squirrels are gonna hate this gun! Nice job.
Steve
Thanks! My first shot at a squirrel sitting on a tree 30 yards away was a head shot.
25 gr. Kings?....
Bob
Yes, I used Kings. The max shots at coil bind was 912, 913, 905.
I will be adding an SSG soon to hopefully gain another shot or two and to get a tighter spread. I am hoping for 830-845-830 over 15 shots with the SSG instead of 830-870-830 over 12 shots.
Inside the valve, I have the stock disco valve spring. Is it possible that is choking the air off? It is a thick wire so when it opens, it may close the gaps fast and cut off the air supply. I may remove that spring and run it without it.
-
Good work on the .25 Disco!
-
Thanks!
-
The squirrels are going to loose their minds! ;D
Nice string, Matthew.
-
The squirrels are going to loose their minds! ;D
Nice string, Matthew.
Thanks Mike!! This is my first pcp and I love how easy it is to load and shoot in the woods. ;D
-
I seriously doubt you are opening the valve enough to cause the valve spring to choke the flow.... That occurs at 1/4" of lift, and at those velocities you are probably only at about 1/16".... Even your maxed out shots will be under 1/8" lift, IMO....
Bob
-
Thanks Bob! Right now my throat is .25" and my t-port/barrel port are 3/16" ID. I am thinking about putting in a 5/16 OD transfer port like you use. I will then drill the t-port to 7/32" and make the barrel port 1/4" long by 3/16" wide.
-
Today, I installed a 5/16" OD t-port so that I could increase the port sizes to 7/32". I drilled the tube and breach to 5/16" and filed a 5/16" flat on the valve and barrel.
The barrel port, I drilled to 3/16" and then lengthened it to 1/4" long. This made it oval and the pellets load with out catching on the hole.
Before I did this the max velocity was 913 fps with 25.4 gr JSB pellets with a 2600 psi fill.
With the bigger ports, at 2600 psi it shot a JSB 25.4 gr. pellet over the chrony at 985 FPS which is 54 FPE. When I shot I could feel a puff of air from the t-port so I will get that fixed.
-
Hey Matt,
You're pretty close to me. When it warms up we will have to get together and shoot something. :-)
-
Sounds about right, Matt.... My regulated 2560 shoots 52 FPE with Kings at 1900 psi with 7/32" ports....
Bob
-
So I got the t-port sealed and I shot it over the chrony. I got 1031 FPS or 60 FPE with a 25.4 gr pellet and 2600 psi fill. 8) I did a three shot string: 1031, 1022, and 1004 fps.
I think that is pretty good considering I have a 20" barrel.
-
You should get the Magnum airpower 3000psi screws and then fill to 3000psi and use the 34gr JSB and have one heck of a disco
-
You should get the Magnum airpower 3000psi screws and then fill to 3000psi and use the 34gr JSB and have one heck of a disco
I bought the 2600 psi screws before he came out with the 3000 psi screws. I plan on getting some 3000 psi screws and shooting 34 gr JSB and some of Nick's swagged ammo.
-
Sounds like you need to back off the hammer spring a little, unless you can safely use a higher fill pressure.... You should be able to get a nice, tight 3 shot bell-curve if you do one or the other.... You're pushing those Kings pretty fast, backing down the hammer a bit might be the better choice....
3000 psi fill and 34 gr. could also work out....
Bob
-
Sounds like you need to back off the hammer spring a little, unless you can safely use a higher fill pressure.... You should be able to get a nice, tight 3 shot bell-curve if you do one or the other.... You're pushing those Kings pretty fast, backing down the hammer a bit might be the better choice....
Bob
I will be backing it down to around 950 fps for 25.4 gr Kings. That was just a 3 shot string at max power mostly to see how fast power dropped.