Air Arms Has anyone ever tried this with a ProSport?

[Sawney Bean]

I concur. It's not all about fitting plastics and thinking your new damped gun is doing the business because it feels and sounds deader.
In practise, out on target at 40 yds you will find its no different on target but you just lost 1 inch of drop due to slowing the gun down. Equally with very light pellets that Steel Top hat is going to hit home a bit harder at the base of the chamber than it should.

I suspect AA set it up with some mid weight 8.4s to 10s maybe a mid point of .177 and .22 but then get critisised when someone comes along with his 7 grains...and goes off and fits a plastic kit...
Don't forget your plastic kit much more temp sensitive to ambient temp diff too.

At 17 fpe mine seemed to be pretty hold sensitive with 8.4's, 8.6's and 10.8's. At 12.5 it's much more controllable.

 

[AirShot]

So how do you diagnose what a particular gun needs?

Feel, experience and experimenting. Takes time and patience but most are just in a big hurry. After doing the timming enough times you get a feel for it. Piston bottoming out creates a harsh thud at the end of the stroke that can jar your teeth when the rifle is shouldered. Bounce is when the piston creates a cushion that forces it back then forward again, destroying accuracy. Fine tune until until this dissapears and the harshness is gone. Doesn't take much to make a big difference...

 

[AirShot]

At 17 fpe mine seemed to be pretty hold sensitive with 8.4's, 8.6's and 10.8's. At 12.5 it's much more controllable.

That is because the velocity is controlling the piston timming when it reaches bottom. Your hold sensativity can be part of the timming being off. Do you feel a harsh thump at the end of the shot cycle ? Often high velocities are the result of a piston bottoming out when the shot is on the harsh side. Often taking weight away from the top hat will ease that up. Experimenting will sort it out. Trying to weaken the spring to lower velocity in a higher powered springer will only lengthen the lock time and if your follow thru is not perfect, your accuracy will suffer. This is why a shorter stroke is better for lowering velocity.

 

[dormitionskete]

Feel, experience and experimenting. Takes time and patience but most are just in a big hurry. After doing the timming enough times you get a feel for it. Piston bottoming out creates a harsh thud at the end of the stroke that can jar your teeth when the rifle is shouldered. Bounce is when the piston creates a cushion that forces it back then forward again, destroying accuracy. Fine tune until until this dissapears and the harshness is gone. Doesn't take much to make a big difference...

Thank you. I'll try to pay more attention to that when I get it back together again and am able to start shooting it again. Much appreciated.

 

[EMrider]

Tuning and futzing around with spring guns is fun, but it can be very easy to overthink the process and obsess over relatively small details. I have owned my .177 pro sport for a decade and I shoot it often. Shortly after I bought it, I felt that it was over-powered with the OEM spring and would likely shoot better at about 12fpe. I dropped in a Vortek 12fpe kit and seal, and have never looked back. That was about 9 years and many thousands of pellets ago. It still shoots consistently at 11.8fpe with JSB 8.4s.

If you want a 13-14fpe gun, buy a standard power spring or kit and clip a off a few coils. If 12fpe is your objective, buy a 12fpe spring or kit. It does not have to be complicated.

R

 

[Steveoo]

So how do you diagnose what a particular gun needs?

It has a lot to do with Pellet choice, but also how well the gun is sealing. With no gas loses around the seal and slower start heavier pellet, you can afford the Steel Top hat and get good cycle manners, big velocity, super flat trajectory and a great vermin gun. I wouldn't mess with it once running like that. My prefered choice with 8.4 to 10 grains.
Swap out the steel top hat, you will need to come down in pellet weight, as the milder manners of the 1st stage recoil will also bring with it a touch of secondary bounce with medium weight pellets which can wreck accuracy more than a damped 1st stage recoil, even though the gun might feel better.
It's one of the reasons why a lot of shooters have started popping back in their steel Top hats...
However, it seems with the export spring at 15 plus you boys seems to be having some hold sensitivity issues...
I'm talking from UK spec with the 11.4 -13 territory..

 

[Sawney Bean]

Tuning and futzing around with spring guns is fun, but it can be very easy to overthink the process and obsess over relatively small details. I have owned my .177 pro sport for a decade and I shoot it often. Shortly after I bought it, I felt that it was over-powered with the OEM spring and would likely shoot better at about 12fpe. I dropped in a Vortek 12fpe kit and seal, and have never looked back. That was about 9 years and many thousands of pellets ago. It still shoots consistently at 11.8fpe with JSB 8.4s.

If you want a 13-14fpe gun, buy a standard power spring or kit and clip a off a few coils. If 12fpe is your objective, buy a 12fpe spring or kit. It does not have to be complicated.

R

I did the same thing with my TX and at this point I’m happy with it. I bought it because I wanted a tack driver, not a powerhouse.