Strange springer power question?

[look no hands]

At 12.1, I'd be taking that extra coil off, Pete. The issue, to my mind, can often be down to the transfer port choking and not flowing the air quickly enough with the more rapid compression and pressure & temperature build-up. If an extra coil off dropped the power too much (I guess it won't), you can always put an extra washer or two in.

I'm going to Tone, I like my rifles at around 11ish, I'd like to put the slip washer back on the rear guide.

[maximus]

What make of spring is it please?

[look no hands]

What make of spring is it please?

No idea, it was with some fitted guides that I got for an Airsporter from the bay if evil.

[Shed tuner]

At 12.1, I'd be taking that extra coil off, Pete.

depends.. if there's still quite a bit of preload, yeah, another half coil plus colapse = 1 coils worth off makes sense.

However if the preload is getting low, one coil off might halve the preload, and therefore have a drastic affect on power...

[Hsing-ee]

This kind of springer fickleness just makes one want to bang one's head against the wall. Probably a lot to be said for a TbT kit where the thing has been worked out already, and while that is an extra expense the time and frustration saved may well be worth it.

[look no hands]

This kind of springer fickleness just makes one want to bang one's head against the wall. Probably a lot to be said for a TbT kit where the thing has been worked out already, and while that is an extra expense the time and frustration saved may well be worth it.

Not always the case, I had a V-mach kit once for my Prosport and I could not keep it under 12ftp, Steve even reduced the spring a couple of times, strange thing is, I fitted one of Tony Walls spring that matched the guide and it ran sweet as a nut without any more adjustment.

[TonyL]

depends.. if there's still quite a bit of preload, yeah, another half coil plus colapse = 1 coils worth off makes sense.

However if the preload is getting low, one coil off might halve the preload, and therefore have a drastic affect on power...

Agreed, JB. And excess piston bounce might also be an issue if preload was getting too low (depending on spring stiffness / spring force at onset of bounce)?

[maximus]

No idea, it was with some fitted guides that I got for an Airsporter from the bay if evil.

Spring is probably too stiff. The original BSA springs have quite a close pitch but I don't think you can get the exact same ones as a spare unfortunately.

[keith66]

Quite common, my fwb sport, standard spring is very long with a huge amount of preload, to the extent you have to use a spring compressor to get the thing in. Maccari old school kit, Drop delrin spacer into the piston fit short spring & push breechblock home with one hand then screw retainer bolt in with the other.
Power went up to 14 ft lds. Had to take 3mm off the spacer before it went under the limit, now has barely any preload at all.

[TonyL]

The difference there is the short / stiff spring. More than one way to skin a cat and the debate over which is preferable - long and soft vs short and stiff has been going for a while. The shorter & stiffer ones requiring much less preload, making stripping and reassembly much easier. But some feel the longer and softer approach gives a better cycle feel. Horses for courses.

[NickG]

Sounds like you need a longer softer spring.
If it's a parachute style seal ?, the friction exerted by the lip expanding against the cylinder wall, can get to the point that it slows the piston down if over sprung .

[TonyL]

Sounds like you need a longer softer spring.
If it's a parachute style seal ?, the friction exerted by the lip expanding against the cylinder wall, can get to the point that it slows the piston down if over sprung .

And you can get into a "vicious circle scenario", where fierce acceleration creates very quick pressure build up, with higher temperatures and higher expansion and the ensuing greater friction creates even higher temperatures, even higher expansion and even greater friction......even though all of this happens so quickly, it has to have an effect......