Leaving a gun cocked...

Jump to latest Follow Reply
K

kmd1984

Member
Feb 20, 2016
997
14
Utah, United States
So, what's the latest data on leaving a PCP gun cocked!? I am not a gun Smith, and I have little knowledge on how the mechanisms of a PCP air rifle really work, but I would think that leaving it cocked for hours is not going to hurt anything. Is that correct?

That said. I would like to have someone chime in who knows, not just take a guess, I already did that. : )

thanks, 

Kmd 

p.s. Bobcat Mk2 .25 
 
Yep. Agree with both statements. The spring under pressure will eventually lose "some" of its power. Depending on the amount of time, the loss would be negligible but it "could" change the performance. But the safety issue is of far more importance and consideration. If you are talking about hunting and leaving it cocked all day while you walk around, yep, no problem. Leaving it on your shooting stand for an hour while you break for lunch. Yep, probably ok too. In those 2 cases I think "be sure the safety is engaged". But other than that, just leaving the gun around charged and live is a bad idea. 

Of course, just my 2 cents.

Crusher
 
Upvote 0
Thanks for the input everyone...

I appreciate people bringing up "safety", but like mubhaur and markT pointed out, this is not about the safety issue, it is just about the technical aspect.
After doing some more research on the internet, I came across this answer, and I believe it answers [somewhat] my question the best.

Quote:

Alan C Reynolds, BSc Honours in Mechanical Mechanical Engineering, Trent Polytechnic (1978)

This is an old question with a new life. The older answers are awesome

Springs take in what is called permanent set. This is when a spring is compressed and held in that position for a long time. If this does happen it is often because of poor design.

In a compressed spring the stresses are complex because of a combination of bending and torsion. These combined loads should not exceed the material yield. Indeed, most would design to less than 50% of yield. (This is not always possible.)

If taken past yield the spring will lose some stored energy equivalent to the reading stress. So it will not all of its spring.

Another consideration is temperature. This is often overlooked in any spring design. Mechanical properties of materials can vary significantly with temperature.

Finally, for certain materials you will get a form of creep. This is more likely in thermoplastic materials than metals but not exclusive. Again if this occurs it is due to poor spring design.

I hope this helps

Alan.

End quote.

So, the question is not if a spring gets "weaker" or not, rather than how are air rifles designed? Are they designed so the hammer spring gets compressed past its "yield", or not?! I guess it depends from air rifle to air rifle. 

That said. I almost want to just try it. : ) How hard is it to replace the hammer spring on a Bobcat Mk2? If it is not that hard and I can do it myself, I am willing to order a spring (just in case), and let my rifle sit around cocked for a weeks or so. I know that some have accidentally done that already [leave their gun cocked foe a long time], but none were with a Bobcat Mk2. Again, I guess the design is matters the most...

thanks,

Kmd

p.s. I am going to send FX Airguns an email and see what they say. 
 
Upvote 0
Good post. 

Stress in a material is defined as Force/Area. Note there is no mention of time in this simple stress formula, hence there is no time function in the stress formula. Once a spring takes its initial set, if the free length shortens any more than this, then the spring design and the material it was built from were not up to the task asked of it. Which is just as Alan C. Reynolds eluded to in his quote above. And just for thought - when the spring free length does get shorter, the spring does not get weaker. It still has the same rate of deflection, but it is now just shorter with less preload in the same application, with all other things being equal.
 
Upvote 0
"AirGunShooter"Good post. 

Stress in a material is defined as Force/Area. Note there is no mention of time in this simple stress formula, hence there is no time function in the stress formula. Once a spring takes its initial set, if the free length shortens any more than this, then the spring design and the material it was built from were not up to the task asked of it. Which is just as Alan C. Reynolds eluded to in his quote above. And just for thought - when the spring free length does get shorter, the spring does not get weaker. It still has the same rate of deflection, but it is now just shorter with less preload in the same application, with all other things being equal.
Click to expand...
Great info... Thanks for the input.
 
Upvote 0
I have other guns at the ready for protection, they are loaded, safely stored but highly available throughout the house My pcp's are target guns, i see no purpose in keeping them cocked. When i am finished target shooting any of the 3 pcp's they generally have about 2000 psi in them, i don't refill them until i plan on shooting them again.

The guns are wiped down and cased, not cocked, not topped off, but with safety on.

Just as i don't fill my tanks scuba or scba to the limit, i don't fill the guns to the max psi either. Two of them to 2500 and the other to 2800 psi.

The guns are right at the top of their sweet spot and i am not pushing the pressure, they are not regulated, and i get enough good shots with excellent accuracy and consistency. I rest my old eyes while i re arm, refill and shoot again.

I have no research or scientific facts to support my procedures, other than to me safety and common sense.

Excellent service and reliability, maintenance wise, I have replaced one breach O ring in 7 years.
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu