Diana K98 or Taming the bouncer

[deejayuu]

Thanks for looking.
Anyone tamed the K98 please?
Lovely to look at but horrible cycle in hand.
Aware of the restrictor and alarming result of removing it.
First thought is remove/resize restrictor then do spring match. Great fun.
Sleeve guide/spring to piston 'cos original is like the proverbial in a shirt sleeve.
Love the restrictor 'cos makes playing with TP dia. quick and easy.
Internals 28 mm bore x 115 mm stroke with 4 mm TP unrestricted.
Anyone short stroked one? Does it need it?

[tinbum]

Remove the washer, reduce the spring and make some snug guides and it's totally different. I have short stroked some, but it's easy to cock and pleasant to shoot without

[Barryg]

Thanks for looking.
Anyone tamed the K98 please?
Lovely to look at but horrible cycle in hand.
Aware of the restrictor and alarming result of removing it.
First thought is remove/resize restrictor then do spring match. Great fun.
Sleeve guide/spring to piston 'cos original is like the proverbial in a shirt sleeve.
Love the restrictor 'cos makes playing with TP dia. quick and easy.
Internals 28 mm bore x 115 mm stroke with 4 mm TP unrestricted.
Anyone short stroked one? Does it need it?

I have a 460 (same action )and I have it shooting really nice at 11 ft/lb without short stroking it

First job is to dismantle it and understand its simplicity then de-burr things like the cocking slot to smooth it out.

The spring is perhaps the most important part if you don't want to short stroke I have a amazing 40 coil that does the job.

Also look at the breech seal set up once you get it right there is none better

[TonyL]

Hopefully Alanok will see this thread and jump in. I had a few shots with his home-tuned one at a Boinger Bash and it shot beautifully.

[CapitalBee]

Hopefully Alanok will see this thread and jump in. I had a few shots with his home-tuned one at a Boinger Bash and it shot beautifully.

I was going to say the same. I seem to remember him saying he opened up the tp and fitted guides, among other things. As said, it shot very nicely.

[Shed tuner]

I was going to say the same. I seem to remember him saying he opened up the tp and fitted guides, among other things. As said, it shot very nicely.

opening up the tp = remove the restrictor washer, as per Nick's earlier post

[Phil Russell]

Remove the washer, reduce the spring and make some snug guides and it's totally different. I have short stroked some, but it's easy to cock and pleasant to shoot without

May I ask which washer? Maybe its obvious once you are inside ....
Reduce spring ... I assume reduce the factory spring?
All this makes me think the washer is on the tp?

Cheers, Phil

[tinbum]

May I ask which washer? Maybe its obvious once you are inside ....
Reduce spring ... I assume reduce the factory spring?
All this makes me think the washer is on the tp?

Cheers, Phil

Sorry, I wasn't very clear

The restrictor is a small washer under the breech seal, remove the seal carefully, put the washer in the bin and replace the seal.
Next you will need to reduce the (perfectly good) factory spring until you get to the power you want.

[jonnyone]

May I ask which washer? Maybe its obvious once you are inside ....
Reduce spring ... I assume reduce the factory spring?
All this makes me think the washer is on the tp?

Cheers, Phil

The restrictor is placed under the compression tube washer/seal, it's sandwiched between the seal and the tube.
I pulled the seal out using a large coarse thread wood screw (as carefully as possible so as not to damage it and thereby be able to re use it). Pull the restrictor out which is shim steel with a micro hole drilled in it, pop the seal back in and head straight to the chrono.
Putting that restrictor in at factory is akin to taking half the spark plugs out of a V8. It throttles back performance to a huge degree and makes the gun rather unpleasant on discharge. Removing it you have the opposite issue. It wants to let rip so you need to reduce spring input/ and or short stroke etc as per earlier advice.
I picked up a 98 at a gun shop and whilst it certainly is a very solid lump of gun I found it very front heavy and a bit unbalanced. But maybe it's just me.
It's built around a proven action though so the basics are spot on.
Dave

[Bluefan]

I was going to say the same. I seem to remember him saying he opened up the tp and fitted guides, among other things. As said, it shot very nicely.

Does shoot very well, think Alan may have lightened the piston too but may be misremembering that. Rally good to shoot but that ABT is a pia for southpaws.

[deejayuu]

Thanks for all input. Pretty much where we're up to but had no time to proceed so will get back on it soonest.
As found was hot with restrictor and without oops! Main spring noise culprit is spring to piston clearance.
For curiosity took 3 coils off the spring and synthetic sleeved piston leaving restrictor in place.
10+ on Exacts 8.44 and sounds/feels much tamer.
Next step is spring match with 3/3.5/4 mm TP
Prefer no restrictor for reasons which might provoke pop-corn saga
P.S. Guessing that the original spring would go to end float to get under 12 ft.lb without restrictor. Hence 250 mm spring at around 30 lb.f/inch would be interesting