GTA

All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: fairly on August 27, 2015, 02:53:40 PM

Title: BT65 .25 - Baby's First Recorded Shot String
Post by: fairly on August 27, 2015, 02:53:40 PM
I put about 40 ballistol laden patches through the barrel, till they came out clean. Accuracy seems to have gone up from that alone. 

First time using a Chrony. Gathering data is fun, and also not as consistent/easy as I imagined.
The light changed between my first and second shot strings, and only 5 of 27 shots were recorded. Frustrating when you're pumping these tubes by hand and sweat.

Starting from 200 bar and ending up at around 140.

1. 891
   891
   896
   914
   909
   913
   927
   927
   946
   939
   948
   954
   960
   961
   966
   986
   977
   976
   980
   972
   964
   963
23.  954

L - 891
H - 986
ES - 95
SD - 29

Two shots are missing from the middle of the string,  I fired the gun twice with no pellet in the breech.   :P

What technique do you guys use to determine the optimum slice of shots?

Cheers,
-d

Edit: Added L,H, ES and SD.
Title: Re: BT65 .25 - Baby's First Recorded Shot String
Post by: Mod90 on August 27, 2015, 05:26:32 PM
Not a terrible string, but there's always room for improvement. How it is there now that es is almost 10%, for general shooting it should be at about 4-5%. For long range shooting it shouod be as low as possible, 2-3% is good. 1-2% is even better. Also imo that sd is a tad high. I personally prefer an sd of no more than 5-10fps for long range shooting. Looks like you still had a few shots to go till it got back to your starting velocity.

The optimal string for your gun would depend on what you plan on using the gun for. Lookks like theres room to tighten up the es & sd.  Good thing there are mods you can do to help these aspects. Like plugging the excess holes in the valve & adding a washer to the valve stem for starters. Or maybe if you're so inclined you might install a regulator.

It all boils down to what you would like to be able to do with your gun. Once you set the bar for whats required, adjustments can be made to reach your goals.
Title: Re: BT65 .25 - Baby's First Recorded Shot String
Post by: Ribbonstone on August 27, 2015, 06:26:10 PM
Really got "on its game" about 1/2 way thought that string.  Considering the 986fps max, then 4% would be the shots as low as 947fps, which isn't happening until the end of that string. Actually, one or two more shots might have gotten the last numbers down lower than 947.

The two "blank" shots probably wasted more air per shot than you'd think...without a pellet, they can squirt out a lot more air at the shot.

Honestly, rather than doing anything, I'd shoot it a bit...the moving parts tend to smooth out/wear in and fiddling around with any setting now would just have to be re-fiddled with once it smoothed out.
Title: Re: BT65 .25 - Baby's First Recorded Shot String
Post by: hotshot on August 28, 2015, 10:29:06 PM
Get a regulator fitted. Every shot comes out inside a 10 fps spread from the get go.

Plus you can increase the fill presure with no valve lock problems, so more shots per fill.