Springer fps in hot weather

[rlancast]

My 97 and Prosport fps has reduced quite a bit in the hot weather. Are your springers the same? Can only think of metal/piston seal expanding?

[bill57]

It's more likely to be air density. In warm weather air is less dense than in cold conditions, so when the gun is cocked, there are less molecules in the cylinder. It's as if your gun has been slightly short stroked in warmer weather.

[Adam77K]

Likely to be the plastic of the piston seal expanding more than the metal of the cylinder.

If it was air density then warm guns taken from a car or house outside into cold weather would be sucking in air at ambient temp and would show the difference immediately. But they tend to take longer to acclimatise, a good 20 minutes or so. In winter if I have a comp in the morning I leave my rifle in the unheated utility room overnight.

[TonyL]

Likely to be the plastic of the piston seal expanding more than the metal of the cylinder.

Yes, as above.

[flyingfish]

It can also be the lube becoming thinner and moving

[TonyL]

And exactly WHAT happened with yours when it went really, really cold?

[cooper_dan]

How much is quite a bit? My tx drops about 15 fps from winter to summer. I try to ignore it. Other countries can have much more severe temp changes from morning to miss afternoon in which case it could be an issue

[flyingfish]

And exactly WHAT happened with yours when it went really, really cold?

Yep, the seal contracted to the point where it no longer sealed