Temperature Affecting Power..? Spring Rifle

[Skot Ruthless Teale 1,701]

Eyup guys,

 

I heard about pcp's being affected by temperature, but does it make a difference to spring rifles..?

 

The reason I ask is because, if I remember correctly last time I chronoed my HW95K with jsb exact im sure it was doing about 10.8 ft lbs.. this was in pretty cold weather, outdoors withing the last few months..

 

Just been out with it today and it was reading between 11.53-11.70 ft lbs.. ? weather says its about 14 degrees C . I had been out in the field a good 20 mins before i started shooting so the gun should have been settled to the outside temperature right?

I fired about 15-20 shots (trying hopelessly to check zero) before then chronoing the rifle..

 

so can a difference of 10-15 degrees C affect a springer by around 0.7 - 1 ftlb ????

 

Thanks in advance, SKoT

[Skot Ruthless Teale 1,701]

going to chrono my hw97kt tomorow i have a previous results sheet from feb so il see if theres any difference there.. ive used that a lot more tho so it might have crept up after fully bedding in, if it wasnt already that is.

[zini 1,939]

Yes it does effect a springer Skot. I have a clip that SFS sent me of a experiment they did with Davys VHTV Spectre. Room temp chrono results followed by 7 hours in a cold room.

 

After 7 hours in a really cold room the power dropped for about 3 to 5 shots before returning to what it was.

 

Its something to do with gun grease and the piston head.

[Will 1994 5]

Viscosity of the grease is my guess

 

will

[Skot Ruthless Teale 1,701]

theres so many factors to how powerful an air rifle is.. i think it would be quite easy for it to go between 8 to 13 ftlbs depending which factors are in place at any given time, what do you guys think..?

 

legal limit 12 ftlbs is pretty hard to stay under then really..

best set your gun to 5-6 ftlbs to make sure it stays under the limit then??

better safe than sorry.........

 

LOL

[barrywhite 282]

I did a little test on a few spring guns at the same time when cold and warm .I feel the guns got a little bit more powerful when cold .I think the springs are stiffer when cold my guns have minimal grease in them .

[barrywhite 282]

also in a cold air cylinder of a spring gun there are more air molecules in the cylinder than when it is warm .So when the piston slams to nothing and warms the air there is a little more air to warm up .So a cold spring air gun is like an air gun with a bigger cylinder and a stiffer spring .I only did my test once with at least three guns but I did get more power from cold spring guns at that time .could not be bothered to test more.This is my theory from one test so dont beat me up.

[Skot Ruthless Teale 1,701]

its mental !! on any given day your gun will be probably doing a slightly different power!! cheers barrywhite for sharing your experiences

[gurtwurz 792]

When we did the southern hunters last year at iden ferns it was -5° and my pro sport was shooting more like a .177 than a .22. Same as barry's saying,i put it down to cold air being denser than hot air so therefore you get more in the cylinder than you would on a hot day. However, the pellet may travel faster on a hot day due to the hot air the pellets flying through would have less drag in it cos its less dense than normal.

The temperatures affect on the grease in a springer will also affect it so theres quite a few variables to think about. As usual, the best way is to check zero when you go for a shoot and have a few practise shots to see what the rifles up to in the conditions your shooting in.