"Taming" an Impact so it won't shoot through a shed covered in metal

[Jim81]

Gonna do some ratting with a dairy farmer and he has the average metal covered roof and sides. Even though he has said he doesn't care if I put holes in it as it's not in good shape anyway, I still don't want to risk that. My Impact is a .25. I shooting JSB King 25s. Would the lowest power help prevent that with a lighter pellet? Or should I get a different caliber barrel (.177?) for that application. What's the range?? Don't know for sure. Probably no more than 25yds for most shots.
I had an old piece of metal roofing and the .25 went through that like it didn't even exist. I did shoot the tin with a break barrel .177 and it only dented it.

 

[Mark_Walt]

Although I can't give you specifics on a particular metal roof I can say that when you tested did you shoot it from the average distance that you'll be shooting the pests at? Also did you shoot the roof on an angle like the shot will most likely be? I have an impact in .25 and did buy a .177 barrel for it. The .177 barrel was unable to shoot sub 2" groups at 25 yards so I would say if you do get a smaller caliber then I would suggest a .22. The FX .177 is not anywhere near the accuracy of the .22 and .25 IMHO and the opinion of Darren at AOA. AOA ended up giving me a full refund for the barrel as they were unable to get it to shoot accurately. Was this an isolated event? I don't know, but AOA was unable to get the barrel to shoot well.

 

[riazp]

I purchased a brand new .177 barrel two months ago, for exactly the reason that you explain above, out of the box it was more accurate than my original gen 1 first batch impact .22! Don't get me wrong, I love my Impact I just don't shoot it in .22 anymore as the .177 at 50 yards is like a laser, at 100 it is grouping at 1.5 inches with consistency, if I sort 10.34 JSB's then it will do 1 inch, this is indoors of course. Polishing the lead in, transfer hole with 3m fabric and the barrel with some JB bore paste I feel really helped to reduce those wild flyers, the mag however really needed work to accept and feed any .177 ammo that you would want to feed it well...

I have my Impact shooting at about 915 FPS, so about 20FPE with the 10.34. I get 190 shots at the reg pressure of 108 bar hammer tension set for default .25 distance and on power C.

I must add however that I have ordered a .22 X barrel, and a new silver Impact with 700 twist X, the new impact is because I don't think that I am going to change the .177 setup, maybe one day if I get a bonus I will X barrel it, maybe not...

The barrel lottery reminds me of when I used to build high dollar Gaming PC's that customers wanted to overclock, some CPU's just took the load no problem at all, while others barely reached above stock config, if my new .177 is anything to go by, I would definitely recommend it, in fact if I had to do it over I would get a twist x in .177

 

[Aftica]

Out of the 3 calibers I got the impact in .30 .25 and .177, 177 is the one being used the most. The flight path of .177 is completely different but also totally useless in hige winds. I shoot swedish beer cans and pine cones at 100-110 meters all day when the wind is behaving. Not so scary to use inside and dirt cheap ammo. 100-120 nok / 11-12 dollars for 500 jbs's. And that calibre spends a lot less air so I find the .177 to be the most fun and used. use the others as Well but it's more noisy, more expensive, also super fun when you really plan to do some damage.

 

[Glem.Chally]

I think he's more talking about walls as he's planning on shooting rats, unless they're the kind that dwell in the rafters. Get it down to 500 or 600 and try that, you'll still have accuracy and plenty of wollop for a rat and a HUGE shot count at this power level

Bigger diameter pellet (.25) and lower speed should help keep the unwanted penetration down.

 

[LDP]

"Glem.Chally"I think he's more talking about walls as he's planning on shooting rats, unless they're the kind that dwell in the rafters. Get it down to 500 or 600 and try that, you'll still have accuracy and plenty of wollop for a rat and a HUGE shot count at this power level
Bigger diameter pellet (.25) and lower speed should help keep the unwanted penetration down.

+1. from what I have seen you will need to be around 12 fpe to reduce the chance of getting holes. I dont know exactly how low but I would start around 12 fpe. You might be able to get an answer on a UK forum or youtube. They have been using the .25 for rats over there at sub 12 fpe so they probably know if penetration is acceptable.