Time of year and air rifles

[The Squire]

Funny that, the cold weather hasn't knocked anything off the shot-count of my 99s. Maybe it's just the rifles you lot are using..

^^^^this^^^^
I was only thinking I'll have to check the Pro Sport over in the garage tomoz, plus the TX, HWs and rammers. This shot count sounds an awful condition, is it treatable?

[rabbitwrecker]

^^^^this^^^^
I was only thinking I'll have to check the Pro Sport over in the garage tomoz, plus the TX, HWs and rammers. This shot count sounds an awful condition, is it treatable?

Easily treatable - simply ditch the pfffttt-gun and use a proper air rifle, (springer or rammer)...

[lensman57]

Funny that, the cold weather hasn't knocked anything off the shot-count of my 99s. Maybe it's just the rifles you lot are using..

Must be totally devoid of lubrication, .

A.G

[Robet]

My 97 seems unaffected too��

Same with my 77K except the power goes up.

[Rossi2k]

The main problem is you are filling the gun at your house, where the air is nice and warm.

Get to the permission, where it is nice and cold and that gas in the cylinder contracts, it shrinks, so your shot count will go down. This could also affect your POI.

Hi all

Decided to take secretagentmole's advice and took a couple of air rifles along with my 7lt cylinder to the outdoor range yesterday. Both air rifles needed filling as both down into the yellow from last shoot.

The range is 35-45 minutes away. Once I got there got the rifles and cylinder out of the boot and onto the range stand. I filled the first rifle (HW100 KT) to max pressure and shot it down to its usual level before refilling whilst doing a shot count. I was down by one mag when compared to summertime. Admittedly the gun was in the boot of the car on the way over so it and the cylinder could have been warmer than I expected when filled.

I turned to the second rifle (Daystate Wolverine C) which had now been in the outdoor range area for about 2-2 & half hours and filled from the cylinder to max pressure. Again shot the rifle down to the usual level for refilling doing a shot count. I was down 1 mag on summertime amounts. I may have been able to squeeze anothr mag out of the rifle but it was touching the yellow and don't want to tempt fate

So it looks like there is a slight difference when filling at the range rather than at home, but for me it is negligible. Think I will be taking the cylinder with me to fill the rifles in this weather through as the upshot was being able to use the HW100 more

One other thing I noticed was whe the weather was misty / foggy in the morning compared to the sunshine in the afternoon (in the mendips the weather can change within minutes ) the mil dot adjustment change by at least half a mil dot. So looks like the weather you are shooting in can make a difference to your aiming point as well.

Cheers

Ross

[TonyL]

Same with my 77K except the power goes up.

That will be due to the greater contraction of the piston seal as compared to cylinder wall, giving a slightly slacker fit and, hence, faster piston acceleration.

If the spring was caked in too much grease, the greater viscosity of the grease when cold might balance out the above, but I wouldn't advise this.

Jim has written some excellent articles on this very subject in his Technical Airgun series.

[Robet]

That will be due to the greater contraction of the piston seal as compared to cylinder wall, giving a slightly slacker fit and, hence, faster piston acceleration.

If the spring was caked in too much grease, the greater viscosity of the grease when cold might balance out the above, but I wouldn't advise this.

Jim has written some excellent articles on this very subject in his Technical Airgun series.

Thought I could rely on you for an explanation Tone, thanks.

I don't worry about the power going over the limit 'cos I set it in the cold knowing it will only go down in summer.
Rob

[lensman57]

Hi all

Decided to take secretagentmole's advice and took a couple of air rifles along with my 7lt cylinder to the outdoor range yesterday. Both air rifles needed filling as both down into the yellow from last shoot.

The range is 35-45 minutes away. Once I got there got the rifles and cylinder out of the boot and onto the range stand. I filled the first rifle (HW100 KT) to max pressure and shot it down to its usual level before refilling whilst doing a shot count. I was down by one mag when compared to summertime. Admittedly the gun was in the boot of the car on the way over so it and the cylinder could have been warmer than I expected when filled.

I turned to the second rifle (Daystate Wolverine C) which had now been in the outdoor range area for about 2-2 & half hours and filled from the cylinder to max pressure. Again shot the rifle down to the usual level for refilling doing a shot count. I was down 1 mag on summertime amounts. I may have been able to squeeze anothr mag out of the rifle but it was touching the yellow and don't want to tempt fate

So it looks like there is a slight difference when filling at the range rather than at home, but for me it is negligible. Think I will be taking the cylinder with me to fill the rifles in this weather through as the upshot was being able to use the HW100 more

One other thing I noticed was whe the weather was misty / foggy in the morning compared to the sunshine in the afternoon (in the mendips the weather can change within minutes ) the mil dot adjustment change by at least half a mil dot. So looks like the weather you are shooting in can make a difference to your aiming point as well.

Cheers

Ross

This is what I have noticed at the outdooe range. Any other time of the year I need to give 1.5 mildot @ 50 yards with my KT 100, JSB 4.52, MTC EVX 4X16 F1. Since the turn of the weather I need 2 mildots. The gun is consistent around 11.4 ft.lbs so the extra 1/2 mildot must be due to the increase of the density of air in the colder climate. This means that the BC value of the pellet has gone down from 0.022 to about 0.017 with the subsequent loss of energy.

A.G

[Airsporter1st]

It will be the combined effect of many microscopic changes;

Almost every type of lube will be thicker & stickier when cold, a bottle filled inside a warm house will drop pressure as the air inside cools & contracts, metal rifle components will also cool & the metal will contract fractionally so sliding components may be a tighter fit, including the pellet in the barrel & cold damp air is denser than warm dry air so will effect the pellet in flight.

I suspect the pellet would become looser as temperature drops, rather than tighter, because lead has a higher expansion coefficient than steel.