Springer Tuning Projects.

[robs5230]

What's your reason for thinking this? The only difference is a shorter stroke and hence a bit more cocking effort.

Hi Maxiumus
I'd possibly question increased cocking effort.
My 280 pro with a full length barrel could be cocked by a small child. Effortless, though has had a bit of work to smooth things out.
I think the stroke issue is that the 280 is running near optimum where the 34 being made for higher powers is overspecced and will have a lazier cycle.
Having said that, none of my 3 280's lack power in any respect. And they are all .177. When set up correctly, the 280 needs careful attention to keep safely under sub 12

[maximus]

Hi Maxiumus
I'd possibly question increased cocking effort.
My 280 pro with a full length barrel could be cocked by a small child. Effortless, though has had a bit of work to smooth things out.
I think the stroke issue is that the 280 is running near optimum where the 34 being made for higher powers is overspecced and will have a lazier cycle.
Having said that, none of my 3 280's lack power in any respect. And they are all .177. When set up correctly, the 280 needs careful attention to keep safely under sub 12

My 280 is a standard length 177, and I have 34's in std and factory carbine length, both 177. My 280 "is a little stiffer to cock than the carbine 34 and no where near as easy as the std length 34 The 280 was bought 2nd hand and whilst it looked near mint on the outside the piston had loads of holes drilled in it. Power wise I struggled at first but found the breach seal was not working although in good order. I shimmed it up and that has cured it but it's just doing 11 with super domes, less with everything else.
The barrel on mine is the same diameter as the 34's and to me the stock is not inferior to the 34 in any way.

[robs5230]

My 280 is a standard length 177, and I have 34's in std and factory carbine length, both 177. My 280 "is a little stiffer to cock than the carbine 34 and no where near as easy as the std length 34 The 280 was bought 2nd hand and whilst it looked near mint on the outside the piston had loads of holes drilled in it. Power wise I struggled at first but found the breach seal was not working although in good order. I shimmed it up and that has cured it but it's just doing 11 with super domes, less with everything else.
The barrel on mine is the same diameter as the 34's and to me the stock is not inferior to the 34 in any way.

On the power subject.
My pro compact full length has been tuned down to 10.6 with express and domes are 9-9.5 easy to cock
the first K I bought is doing 11.2 with superdomes and just marginally less with express. I think its over sprung.
The second K i have is a sandwell one. Producing 11.7 with express and 11 with superdome. Cocking is easy.

If yours is reading highest with superdome I'd think that its also oversprung and cocking effort could be reduced

[maximus]

On the power subject.
My pro compact full length has been tuned down to 10.6 with express and domes are 9-9.5 easy to cock
the first K I bought is doing 11.2 with superdomes and just marginally less with express. I think its over sprung.
The second K i have is a sandwell one. Producing 11.7 with express and 11 with superdome. Cocking is easy.

If yours is reading highest with superdome I'd think that its also oversprung and cocking effort could be reduced

You could be right, I have contemplated chopping a bit off the spring for that very reason but was bothered about it just reducing the power and being left with a spring that was too short! I added weight back into the piston via a brass top hat and washers, it shoots nice enough though I cant stop the spring from twanging totally despite having tight fitting guides and piston sleeve. Might be a twangy spring or could be a bouncy piston. I may try a different spring one day but all I have in my spring stash are various cut down titan no.1's which all seem to stiff when in and definitely over spring the action. I like the Dianas though and they are usually what I reach for when I want a shot these days.

[robs5230]

You could be right, I have contemplated chopping a bit off the spring for that very reason but was bothered about it just reducing the power and being left with a spring that was too short! I added weight back into the piston via a brass top hat and washers, it shoots nice enough though I cant stop the spring from twanging totally despite having tight fitting guides and piston sleeve. Might be a twangy spring or could be a bouncy piston. I may try a different spring one day but all I have in my spring stash are various cut down titan no.1's which all seem to stiff when in and definitely over spring the action. I like the Dianas though and they are usually what I reach for when I want a shot these days.

Just dropped a 4mm preload washer out of this what I was thought over sprung K. Now doing 11.2 with Express. Not tested domes yet. I have to chop spring now which has compressed coils both ends. Easier to cock and will be even easier yet when sorted. Power will still rise with express.

[maximus]

Just dropped a 4mm preload washer out of this what I was thought over sprung K. Now doing 11.2 with Express. Not tested domes yet. I have to chop spring now which has compressed coils both ends. Easier to cock and will be even easier yet when sorted. Power will still rise with express.

Hmm, might have give my spring the chop then! Currently it's the factory item but with the extra preload of the top hat and thrust washer.

[robs5230]

Hmm, might have give my spring the chop then! Currently it's the factory item but with the extra preload of the top hat and thrust washer.

Steady as you go Max.
My goals are not necessarily yours.
I purposely set my springers as I do to be more efficient with express. Check accuracy with express before you chop.
And if you do, chop carefully. You end up in fine territory with a very small amount of change making a big difference.

On another note. The seal in this 280 is black. I thought they were all blue. So thats me corrected

[Barryg]

On the power subject.
My pro compact full length has been tuned down to 10.6 with express and domes are 9-9.5 easy to cock
the first K I bought is doing 11.2 with superdomes and just marginally less with express. I think its over sprung.
The second K i have is a sandwell one. Producing 11.7 with express and 11 with superdome. Cocking is easy.

If yours is reading highest with superdome I'd think that its also oversprung and cocking effort could be reduced

One thing to look for on Diana break barrels is transfer port barrel alignment especially on .177 as this can affect the performance if part of the TP is blocked by the misalignment, it was years before I discovered this on my 34 all sorted now

[maximus]

One thing to look for on Diana break barrels is transfer port barrel alignment especially on .177 as this can affect the performance if part of the TP is blocked by the misalignment, it was years before I discovered this on my 34 all sorted now

How did you sort it Barry?

[Barryg]

How did you sort it Barry?

I will post some pics after lunch Max, her in doors has just dished it up

[maximus]

I will post some pics after lunch Max, her in doors has just dished it up

Enjoy!!

[Barryg]

How did you sort it Barry?

It might be just the old T01s that had the problem, this is my one before and after.
Before
https://imgur.com/cyaaYKn

After
https://imgur.com/2o9WhYc

All I did was to shim the breech face high spots
https://imgur.com/DDbD7AJ

Also my 34 had visual barrel droop before correcting but you can now see no droop
https://imgur.com/6qk95T4

[robs5230]

It might be just the old T01s that had the problem, this is my one before and after.
Before
https://imgur.com/cyaaYKn

After
https://imgur.com/2o9WhYc

All I did was to shim the breech face high spots
https://imgur.com/DDbD7AJ

Also my 34 had visual barrel droop before correcting but you can now see no droop
https://imgur.com/6qk95T4

Ooh, the first pic doesn't look good. Lovely remedial work though.
Diana's are noted to have "inbuilt" barrel droop. Even the sidelevers. Mine luckily dont seem to be affected visually and zero no problem with normal mounts.

[robs5230]

One thing to look for on Diana break barrels is transfer port barrel alignment especially on .177 as this can affect the performance if part of the TP is blocked by the misalignment, it was years before I discovered this on my 34 all sorted now

Just checked all 3 of my 280's.
They have a clear witness mark from the breech seal on the front of the cylinder, perfectly centred around the transfer port so I'm good here. Breech seals are correspondingly centred around the bore.

[clarky]

My 280 is a standard length 177, and I have 34's in std and factory carbine length, both 177. My 280 "is a little stiffer to cock than the carbine 34 and no where near as easy as the std length 34 The 280 was bought 2nd hand and whilst it looked near mint on the outside the piston had loads of holes drilled in it. Power wise I struggled at first but found the breach seal was not working although in good order. I shimmed it up and that has cured it but it's just doing 11 with super domes, less with everything else.
The barrel on mine is the same diameter as the 34's and to me the stock is not inferior to the 34 in any way.

The problem with the 280 when compared to the 34 is its piston.
Just to the rear of the seal assembly are 2 indentations which fix the head into the end of the piston but it bulges the piston diameter slightly by approx 0.3 mm out of round....or 0.3 mm across top dead centre of the thickest part compared to the rest of the true piston which is otherwise good.
To ammend this nuisance which causes cylinder wear and and slight noise, chuck the piston along its true area about an inch back from the bulge.....clock it true if needed and skim the bulge off with a Tip tool.
Only takes 10 mins but transforms the gun.
The latest 34 from Steyr has no such bulge and a higher quality finish to the piston.
Both guns need new slide fit guides in Delrin or PEEK....and run beautifully.
I have routinely out shot the equivalent HW95 with the 34 and by a significant margin.
I cannot fully inform as to why this is. Trigger control and let off might just to fall to the HW as expected but the 34 trigger not something that would put you at a disadvantage.
Lock up might just be better ...
Its since the 34 has been put onto a parachute ....its just so improved. Rifling is outstanding.
Try a benched group of 20 mm at 50 mts....now try it with the HW....
The Diana does it despite a less than ideal transfer port too.
Thus my latest tuning project other than a super smooth 580 fps HW45 is to sleeve my 34 s port to 2.8