Performance of .22 Cal TJ Liners

[LewisP12]

I have a .22 cal 1:14 twist TJ liner shooting 44,g gr HP at 860 fps C.T.C 0.35 -0.5" at 85 m.

I can only manage 10 accurate shots before the accuracy heads south, would somebody have some advice on how to increase the shot count. 

 

[Fire_at_will]

How are you getting the accuracy to come back, cleaning barrel? If so, you my want to do a through polish on it.

 

[biohazardman]

You did not state what gun, if it was regulated or not nor the fill pressure. For a smallish reservoir, regulated or not, gun that may be a good shot count before the air pressure and velocity falls off and accuracy goes south. If you have a hammer spring adjuster start there by turning the power back a little and see what happens. If the gun has a regulator, that can be adjusted, you could turn it down a bit. But you probly want to keep the velocity near where it is, if you want the accuracy to remain the same, so you may need to adjust your hammer spring as well. I wish you luck on your tuning journey.

 

[LewisP12]

# Fire_at_will : Yes, I have to unscrew the silencer off and then pull a cloth through the barrel a few times, every time after 10 shots.

#biohazardman : The air rifle is a Kral Puncher One, similar to an air force, I have done some valve modification and have seen 1025 fps with 47gr FN slug (110 fpe not maxed out). I have settled on the following tune:

844 - 200 bar

839

850

864

874

866

861

863

874 - 190 bar

868

850

859

851

846

844

851

844 - 180 bar

I want to explore what it takes to shoot long distance air rifle gong shooting, a farmer friend has a 600 m rifle range. I can regulate the air rifle and get the velocity ES% down to below 1 %, the conditioning of the barrel to me is the weakest link. I still have a weeks leave so I am heading out to the range tomorrow, to start at 100 m and move up in increments of 25 m at a time. 

 

[LewisP12]

First Range Results

85 m CTC 12 mm 0.4 " 0.4 MOA

125 m CTC 26 mm 1.02" 0.816 MOA

150 m CTC 73 mm 2.87" 1.9 MOA

175 m CTC 94 mm 3.7 " 2.11 MOA

200 m CTC 122 mm 4.8 " 2.4 MOA

After the 125 m grouping, I started to become disappointed with the results, after 200 m grouping I adjusted the hammer spring from zero to two out of frustration. 

225 m CTC 81 mm 3.2 " MOA 1.4

250 m CTC 120 mm 4.7 " MOA 1.88

Before going to the range, I spent 3 sessions ( many hours) testing which velocity yields the best accuracy, I tested from 800 - 1025 fps. 860 fps grouping were by far the best at 85m, but range testing shows not from 150 m outwards.

I now have a base line of accuracy to measure from before I start hand and fire lapping the barrel.