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.

[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.