Why the power change ?

[max abell 196]

Hi all just had my fac S410 extra serviced at airarms which is only about 15 miles from where i live they replaced all the washers/seals /clips ect

I got a printout of the gun and out off 10 shots when tested it went from 33.09 ft.1b up to 34.12 ft.1b

it states at the end of the printout average energy 33.58 ft 1b

Can anyone tell me why the power is going up and down on test i have not long been into air rifles and dont pretend to know a lot about them i have and still do used a .22 rimfire that i have used for years but am very intrested in air guning can someone advise me why the power change on my gun on test thanks max

[Phantom 631]

Hi there Max

 

You will always get a slight deviation in power shot to shot, just as you will with a .22 rimmy.

Its only a few feet per second and is not going to make much differance to the quarry at all.

If its regulated, then I would expect only a 2 to 4 fps differance, but I'm thinking sub12 there, the range may be higher on an FAC rated rifle.

 

Here are a few graphs of your output, lower end, high end. As you can see with an optimised zero there isn't really any apparent difference the avarage line of trajectory is between the two.

 

Low End

High end

 

 

Phantom

[jasper65 6]

My gun for some reason seems to have a sweet spot where the power is at its max before it finally drops off and Re-charged.

 

I fill her up to the recommended 190BAR and it shoots fine but the power is a good 20 - 30FPS down comapared to when the gun drops down to 150BAR?

 

Out of Interest are these Daystate Air Rangers supposed to be factory regulated? surely if this is the case shouldn't my gun run (give or take) a few FPS near enough bang on from a Fill to the drop off? at the moment it definitley has a sweetspot...

 

Jasper

[SEAN3513 7]

as far as im aware,most pcp's are regulated

 

the factory regs are pretty hit and miss, it is only the after market regs that give a more consistent shot rate.

 

my logun pro and air airms have sweet spots......my rapid 7 is after market regged and it is very consistent.

 

thats my experience anyway

[Phantom 631]

To some extent your correct Sean,

PCP's have two kinds of regulators:

 

A precision engineered unit between the hammer valve and the air cylinder. (ie aftermarket regulator)

or

what most people call 'unregulated' where the hammer valve relies on the air pressure inside the air cylinder to close the valve after a shot. The manufacturers call this 'Self-Regulating'

Its the second type that is most common and why you notice a 'sweet-spot' in the power curve.

My S200 has the latter, its 'un-regged/self regulating' if I go above the sweetspot my shots are very inconsitent, dropping by ft/lbs because the air pressure in the air cylinder causes the valve to A/ not open all the way or B/ the air pressure closes the valve before the correct amount of air gets through or C/ a combination of both.

Once into the sweet spot, the spring that opens the valve functions correctly opening the valve to the correct opening and keeping it open for the correct amount of time. Giving or allowing the correct (give or take) amount of air through. This is not 100% precise hence a few fps either way.

As the air pressure in the cylinder keeps the valves closed, once the pressure gets below the threshold the valves can open a little and thats what makes them vent the last of the air.

 

The Aftermarket regs, or the ones on very high end guns do this to almost perfection, they tend to be very high precision parts and use springs that combat the affects of the air pressure in the cylinder.

 

Phantom

[Buster321c 1,010]

As stated the usual suspect is power curve , but it might benefit for a hammer and rail polish , you`d be surprised what difference that can make to consistency .

[max abell 196]

Thanks gents for the info will try and work out at what pressure on the gauge the rifle shoots best at

[RiffRaff 5]

Hi there Max

 

You will always get a slight deviation in power shot to shot, just as you will with a .22 rimmy.

Its only a few feet per second and is not going to make much differance to the quarry at all.

If its regulated, then I would expect only a 2 to 4 fps differance, but I'm thinking sub12 there, the range may be higher on an FAC rated rifle.

 

Here are a few graphs of your output, lower end, high end. As you can see with an optimised zero there isn't really any apparent difference the avarage line of trajectory is between the two.

 

Low End

High end

 

 

Phantom

 

jeeze tony you need to get out more way to much time on your hand fekking about with chair gun,,, an regged guns have more than 2-4 fps variation even MR Ripley only manages 5fps variation mind you thats better than some daystates

 

Niel

Edited November 8, 2010 by RiffRaff

[Phantom 631]

jeeze tony you need to get out more way to much time on your hand fekking about with chair gun,,, an regged guns more than 2-4 fps variation even MR Ripley only manages 5fps variation mind you thats better than some daystates

 

Niel

 

Thats me I'm affraid, forver trying to help people out. If you'd the post correctly, I said 2-4 in a regged gun

Gives me something to do when the weather aint in my favour and the bunnies aint playing ball.

 

 

Phantom

[Buster321c 1,010]

A spread of even 15 FPS is nothing . It will make hardly any difference from shot to shot . A difference of 2-4 is a very tight tolerance ., ide be surprised to see a gun performing consistently at that .

[RiffRaff 5]

jeeze tony you need to get out more way to much time on your hand fekking about with chair gun,,, an regged guns have more than 2-4 fps variation even MR Ripley only manages 5fps variation mind you thats better than some daystates

 

Niel

 

Thats me I'm affraid, forver trying to help people out. If you'd the post correctly, I said 2-4 in a regged gun

Gives me something to do when the weather aint in my favour and the bunnies aint playing ball.

 

 

Phantom

see above