Different size cylinders and power.

[TonyL]

I've never experienced the oversprung phenomenon meself.

Less spring has always lowered the power, but I suppose I've never tried using that much too much spring.

I have, Phil.

Once with a friend's oversprung HW35.

And also when a BBS member pm'd me asking advice on an issue with an '80.

In both cases, reducing the spring upped the power and massively improved the firing cycles.

I'd suggested it earlier in the thread as, going by Pete's description, the preload amount and difficulty in fitting sounded a little scary.

Hope you're keeping well, sir.

[look no hands]

Its all got to be worth a try. A cheaper way would be O ring for the piston seal. Maybe even a groove cut in the piston behind the standard seal would be ok and possibly some sort of bearing or o ring at the rear of the piston to stabilise it. I can't remember the exact design of the outer piston from memory but with the ram complete, its centralised by the rod of the dummy piston.

I'm still on the lookout for a fenman to do the same thing with and when I find one, I won't be beat

Although the O ring seal sounds good, I'm not sure if it would work (I'd have to take it back out and have a look), if you look at the photo's on THIS thread I posted earlier, you'll see the piston at the top of the second and third photo's, I'd be a little worried about cutting a groove in the front of the piston as the whole thing is under extreme pressure (I don't want to teach you to suck eggs as you already know this) and if I or the next owner (if I ever decide to sell it) want to turn it back to a rammer then I wouldn't want the piston to be weakened by having the groove cut into it, not sure how much 'meat' there is on that perticular part either and if it could be cut deep enough to hold an O ring in place, as you can see the rear part of the piston could easily take a bearing but I don't really feel it needs it.

Pete

[robs5230]

Although the O ring seal sounds good, I'm not sure if it would work (I'd have to take it back out and have a look), if you look at the photo's on THIS thread I posted earlier, you'll see the piston at the top of the second and third photo's, I'd be a little worried about cutting a groove in the front of the piston as the whole thing is under extreme pressure (I don't want to teach you to suck eggs as you already know this) and if I or the next owner (if I ever decide to sell it) want to turn it back to a rammer then I wouldn't want the piston to be weakened by having the groove cut into it, not sure how much 'meat' there is on that perticular part either and if it could be cut deep enough to hold an O ring in place, as you can see the rear part of the piston could easily take a bearing but I don't really feel it needs it.

Pete

What I meant initially was an extension with an O Ring seal rather than parachute , the second comment about one behind the seal was thrown in but as I coudn't remember the design of the piston yes you're right.
Any head extension to the piston will in effect short stroke it. With an o ring seal that effect would be less.
Just out of interest do you know the stroke length and TP diameter ?
I'm also going to go back and read the whole thread as I didnt see what pellet you chronied with

[robs5230]

pete, just seen you used AA field.

I'd try again at the same settings with JSB Express. It may just sort it.
All my springers are set for express in .177 and doing 10.6. which I find has the perfect trajectory and very clean kill ability.
They do drop considerably in power with an 8.44 pellet.

[look no hands]

What I meant initially was an extension with an O Ring seal rather than parachute , the second comment about one behind the seal was thrown in but as I coudn't remember the design of the piston yes you're right.
Any head extension to the piston will in effect short stroke it. With an o ring seal that effect would be less.
Just out of interest do you know the stroke length and TP diameter ?
I'm also going to go back and read the whole thread as I didnt see what pellet you chronied with

Not sure of the stroke or TP info as I just wanted to see if I could get decent power first before going in too deep, as we all know they can be a bugger to get up on power, if it had produced decent power from the off then I was going to look into the other 'stuff' afterwards, I always use AA domed pellets for most of my rifles, 8.5 grains .177 in this case.

Pete

[look no hands]

pete, just seen you used AA field.

I'd try again at the same settings with JSB Express. It may just sort it.
All my springers are set for express in .177 and doing 10.6. which I find has the perfect trajectory and very clean kill ability.
They do drop considerably in power with an 8.44 pellet.

I'll have a go at shortening the spring first as it's not very nice to shoot at the moment (it was actually nicer to shoot as a rammer), hopefully with a coil or two removed it might become better and who knows it may even go up in power

Pete

[robs5230]

I'll have a go at shortening the spring first as it's not very nice to shoot at the moment (it was actually nicer to shoot as a rammer), hopefully with a coil or two removed it might become better and who knows it may even go up in power

Pete

However you end up, I'd aim for 10.6 with express. Much better shot cycle than the 8.44 and with the same trajectory as an 8.44 doing low 11's

[Bluefan]

Well mine works Perfect and is full power and easy cocking for a carbine
The Theoben That is !
In fact if I go to the next Springer thingie (which I might ) I will bring it so you can all have a go
It has a FWB Sport mainspring ( the loooooooong one ) but Mine has a pin holding the end Block rather than a circlip

I have to admit he's right about his Theo and I'll hold you to that springer thingie promise (you still mindin my 95)