SSG in .25 disco

[Matt15]

I installed an SSG in my .25 disco. Here is the shot string I have it at right now.

I used JSB Kings 25.4 grain and a fill pressure of 2500 psi

807
817
807
846
849
855
876
879
892
893
910
899
900
890
873
871
857
838
824
805

The end pressure was 1000 psi

So that is 20 shots with an average of 41.6 FPE and a eficiency of 1.01 FPE/CI.

I may try filling to 2300 psi to start the string of at 840 FPS and end at 838. That would give me a flatter string and a average of 43 FPE over 15 shots.

[Machinist]

Be helpful to see a shot string without the SSG to make a side by side comparison. Original striker? Striker spring?

A pic of your SSG would be nice too. And the whole gun.  And groups at 25, 50 and 75 yards.

How loud is this bugger?

40 FPE can ruin a varmints day fast.

Steve

[Matt15]

Here is the original string. 12 shots with a beginning pressure of 2600 psi and 1200 psi end.

This is with a .180" t-port. The string above with the SSG is with a .219" port.

1) 834
2) 839
3) 855
4) 862
5)868
6)870
7) 868
8( 866
9) 859
10) 850
11) 840
12) 834

Here is the gun. I will be painting it all black as soon as it gets warmer.



Here is my original two posts with info on the gun. http://www.gatewaytoairguns.org/GTA/index.php?topic=117753.0
http://www.gatewaytoairguns.org/GTA/index.php?topic=118846.msg1146026#msg1146026

[Machinist]

IIRC a lot of guys lost velocity when they installed an SSG. They tried desperately to get the power back.  You have the opposite. Max 910fps with SSG and 870fps without SSG.  Did you use a stronger spring or make any other changes?

My 22 Disco has a pretty bad ES. Like over 100fps for 20 shots.  Not really ideal. I think that can be improved with adjustments/mods.  Did you use the original striker? 

Cool that you get a bunch more shots. Thanks for the strings and  other data. Looks like you have a clamp to secure the breech to the tube. The little screw crosman uses is pretty weak.

Steve

[Matt15]

I drilled the barrel port out from .180" to .219". That is how I gained more fps. Sorry about the confusion. 


Here is the accuracy at 50 yards. The two shots low and to the right were me siting the gun in. The group has 6 shots inside 1.5". I was in a hurry so I think I can do better.