Hw99 piston lightening?

[stiks]

Hi all,
Lightened the piston on my 98 and bored out TP.
Great results, quick and accurate.

I have a 99 which I enjoy also, light and accurate too, done some rudimentary work on it and it's smooth. No dreaded gruanching now either, sorted that.

I was wondering if anyone had bothered to try lightening the piston and opening up the TP on the 99. It's a short stroke already and nice to shoot, just wondering? ..... Might make it super quick with an export spring, might just smash the piston to hell, ruin it !!

Thoughts, other than why! :-)

[PhatMan]

stiks,

I always think that all the components of a 'springer' come together in one optimum configuration, and that will shoot best.

The trouble is figuring what that combination is

Lightening the piston is not always the way to go, as I found with my own experiments with my TX200 - I found that the best weight for it was 210 grams (the original Venom piston weighed about 175 grams, and I added brass weights until I found the optimum weight).

Why not give it a go, and let us know - you will be adding to the body of knowledge

Good luck

Best regards

Russ

[stiks]

stiks,

I always think that all the components of a 'springer' come together in one optimum configuration, and that will shoot best.

The trouble is figuring what that combination is

Lightening the piston is not always the way to go, as I found with my own experiments with my TX200 - I found that the best weight for it was 210 grams (the original Venom piston weighed about 175 grams, and I added brass weights until I found the optimum weight).

Why not give it a go, and let us know - you will be adding to the body of knowledge

Good luck

Best regards

Russ

Thanks Russ for the info. Yes I'm guessing it will be a fine balance with this particular rifle. I'll be trying small reductions and then possibly small increases in TP diameter. Think I'll get a new piston to play with. At least these rifles aint exactly expensive comparitively.
I'll post my results.

[NickG]

I made an ally skirted piston for my 99, I added a steel band to the rear for the cocking link to bear against, it is indeed super fast , but a little harsh also, the standard spec is about right in the 99, just a spit and polish tune a top hat and a rear guide to control the spring, i put bearings on the standard piston but it didn't really make any difference .

[stiks]

I made an ally skirted piston for my 99, I added a steel band to the rear for the cocking link to bear against, it is indeed super fast , but a little harsh also, the standard spec is about right in the 99, just a spit and polish tune a top hat and a rear guide to control the spring, i put bearings on the standard piston but it didn't really make any difference .

Erm, I can imagine that it could be a little harsh, not a lot of mass. I may try a little reduction in piston weight and a slight increase in TP diameter, just to speed it up a fraction. Not sure if it'll be worth the effort but I enjoy the process nevertheless.

My gut is telling me, as you say, may be it's as good as it gets. I've done the spit an polish bit, and you've just reminded me, I did add some Peek bearings, just because!

I'll see,...... I'm bored that's the problem!

[TonyL]

As Nick says, many feel that the standard specifications are pretty close to ideal with the '99.

Piston bearings....to my mind will sometimes improve the smoothness of the cocking stroke, but not so noticeable upon firing. I find that a polished piston coupled with an application of moly grease to the rear of the cylinder once the piston is pushed fully forwards works well enough.

Maybe interesting to try some in-depth pellet testing and see how much difference you feel different pellets make on the firing cycle?

[Hsing-ee]

My gut is telling me, as you say, may be it's as good as it gets. I've done the spit an polish bit, and you've just reminded me, I did add some Peek bearings, just because!

I'll see,...... I'm bored that's the problem!

Try working on a rifle that isn't the ideal proportions for the UK 12 fpe limit. I think this has been done to death on this BBS, that the HW99 or HW50 as it should be called, and the 25mm HW77 are pretty much perfect in regards to bore stroke and transfer port. Adjusting the spring power to the chosen pellet seems the only thing left to do really. I think some people vary the size of the TP on the 77 but it is by one or two tenths of a mm and even then it is questionable whether it was worth the trouble.

If you are bored, choose a rifle that is NOT efficient and work on that. An HW35 of some kind would be cheap, easy to work on and will set you many different but solvable challenges. I think a long-stroke 25mm version of the HW35 is something that could keep everyone entertained for a good while.

Or take a cheap Turkish rifle and turn it into a top-performing springer capable of beating a HW97 or AA TX200.

[stiks]

Try working on a rifle that isn't the ideal proportions for the UK 12 fpe limit. I think this has been done to death on this BBS, that the HW99 or HW50 as it should be called, and the 25mm HW77 are pretty much perfect in regards to bore stroke and transfer port. Adjusting the spring power to the chosen pellet seems the only thing left to do really. I think some people vary the size of the TP on the 77 but it is by one or two tenths of a mm and even then it is questionable whether it was worth the trouble.

If you are bored, choose a rifle that is NOT efficient and work on that. An HW35 of some kind would be cheap, easy to work on and will set you many different but solvable challenges. I think a long-stroke 25mm version of the HW35 is something that could keep everyone entertained for a good while.

Or take a cheap Turkish rifle and turn it into a top-performing springer capable of beating a HW97 or AA TX200.

Ha ha, from your response it does sound like it's been done to death! Apologies may be search would not of invoked annoyance.
Ok, if thats the consensus far be it from me to go against it, disagree or reinvent the wheel. If enough people have reached the same conclusion then thats undoubtedly correct.

I do not wish to purchase another and try to beat Weihrauch at their own game, I'm not clever enough! .... But thank you for your input nevertheless.

I'll turn my attention to the handling then, I've already fitted a barrel sleeve, I'll make the cheek piece adjustable and go shoot it.
I'll post a pic when completed.

Hi TonyL
My favourite pellet to date is Mosquito 14.35, I'm guessing JSB Express. Group well and I'm plessed with the firing cycle.
Yes the Peek bearings I fitted have made it smooth to cock, I did gain a few fps but nothing to shout about and may have just been the rebuild, consistency very slightly improved but ditto, ...... mostly i enjoyed doing it. I've been playing with springers for 40 yesrs and just as enthusitastic today! ...... Bowkett gave me a prototype single stroke to have a go with, I played with that too, but that's another story!

The work I did to my 98, was certainly worth it. No doubt it's also been "done to death" so ill not bore you with that.

[TonyL]

Ha ha, from your response it does sound like it's been done to death! Apologies may be search would not of invoked annoyance.
Ok, if thats the consensus far be it from me to go against it, disagree or reinvent the wheel. If enough people have reached the same conclusion then thats undoubtedly correct.

I do not wish to purchase another and try to beat Weihrauch at their own game, I'm not clever enough! .... But thank you for your input nevertheless.

I'll turn my attention to the handling then, I've already fitted a barrel sleeve, I'll make the cheek piece adjustable and go shoot it.
I'll post a pic when completed.

Hi TonyL
My favourite pellet to date is Mosquito 14.35, I'm guessing JSB Express. Group well and I'm plessed with the firing cycle.
Yes the Peek bearings I fitted have made it smooth to cock, I did gain a few fps but nothing to shout about and may have just been the rebuild, consistency very slightly improved but ditto, ...... mostly i enjoyed doing it. I've been playing with springers for 40 yesrs and just as enthusitastic today! ...... Bowkett gave me a prototype single stroke to have a go with, I played with that too, but that's another story!

The work I did to my 98, was certainly worth it. No doubt it's also been "done to death" so ill not bore you with that.

Ah, a long term Boinger tinkerer, excellent, and great to hear that your enthusiasm hasn't waned.. Our little springer powerplants are so endearing and the fact that, although seemingly so simple, still holds many a mystery.

Don't worry about the "done to death" aspect, as it's always good to hear of others' exploits, methods and thinkings.

And I can see what you're thinking re aiming to see if the '99 can be further improved. Lighter piston, quicker piston acceleration, slightly reduced recoil, maybe more bounce so tweak the TP and match spring force. So don't let us dissuade you from having a go, it's just that this little rifle boasts credentials so close to the ideal that most are more than happy with a little personalised hand finishing and sort any cocking lever issues.

We'd love to hear about your '98 tune.

[Hsing-ee]

Yes the Peek bearings I fitted have made it smooth to cock, I did gain a few fps but nothing to shout about and may have just been the rebuild, consistency very slightly improved but ditto, ...... mostly i enjoyed doing it. I've been playing with springers for 40 yesrs and just as enthusitastic today! ...... Bowkett gave me a prototype single stroke to have a go with, I played with that too, but that's another story!

The work I did to my 98, was certainly worth it. No doubt it's also been "done to death" so ill not bore you with that.

The 98 is a bit more of a conundrum, because it is a 17 or 18 fpe rifle. So do you short-stroke it or put in a narrow 22mm piston and long stroke it? Soft spring stiff spring, you can have all the variations.

Best thing with a Weihrauch is make a super super set-back trigger like the one Mally did.

[stiks]

The 98 is a bit more of a conundrum, because it is a 17 or 18 fpe rifle. So do you short-stroke it or put in a narrow 22mm piston and long stroke it? Soft spring stiff spring, you can have all the variations.

Best thing with a Weihrauch is make a super super set-back trigger like the one Mally did.

Ha ha, yes got a good well set-back trigger fitted already, one of the first things I thought was needed. It's made great improvement to control.

Cheers!

[stiks]

Ok chaps,
Here is what I have so far.
Lightened the piston by 10gr, TP diameter increased very slightly plus polish, cant put my hands on my gauges at the mo, guessing .2mm
PTFE piston sleeve.
Notice the staggered holes in the piston to prevent resonance tube harmonics.

Most expensive grease on the planet, Hawkins uses it to stop squeaks on his chair!

My shroud is needing a reblue.

Have very little machinery here, a pillar drill that was made when gods dog was a puppy, more play in it than an old steering box. I'm lucky if the bit sticks in the centre punch dot.
A dremmel, bench sander, bench polisher, that's about it for the high tech stuff! .... Oh and plenty of enthusiasm.

The export spring may arrive today.

I'll post a few pics as soon as it built and chrono'ed.

May be very little improvement, may ruin it I cant say, fun tinkering though which is what 80% of its about for me.

https://flic.kr/p/WC8J25

Can't remember how to post pics here from Flikr? .......

[PhatMan]

stiks,

You think the Krytox grease is expensive, the Krytox GPL105 oil made me squeal - £46.20 for 30 mL

Have fun

Best regards

Russ

[Shed tuner]

I made an ally skirted piston for my 99, I added a steel band to the rear for the cocking link to bear against, it is indeed super fast , but a little harsh also, the standard spec is about right in the 99, just a spit and polish tune a top hat and a rear guide to control the spring, i put bearings on the standard piston but it didn't really make any difference .

Yup

Esp in .177, the piston is already a fraction bouncy, so making it lighter is not a good idea.

[stiks]

stiks,

You think the Krytox grease is expensive, the Krytox GPL105 oil made me squeal - £46.20 for 30 mL

Have fun

Best regards

Russ

What! You sure that's not Channel 105 ?

Well it's back together, (where's a sticky out tongue emoticon when you want one) you "nay sayers" you! ...... I like it!
It's a little bit hot with 15.9gn, 11.8 - 12.3 but has the nicest firing cycle, just a very little bit harsh with 14.35gn for around 11.4/6
So if I collapse the spring, half to one coil, I'd like around 10.8/11.2 with 14.35gn pellets.

I'll let it settle down a tad before I do that. ...... But guys it's quick, snappy, nice firing cycle with 15.9gn pellets very good characteristics I feel. ...... My instincts might just have led me right on this one, for a change!

With a little extra weight afforded by my adjustable cheek piece plans this certainly has the potential to become my favourite field rifle. ... If it's as accurate as my similarly treated 98 there's a very bloody good chance of it, I'm chuffed.

I'll update you after some settling in.