HW99S woes!

[Eligus]

My new HW99S (.177) was underpowered from the start so I polished and re-lubed the internals, still only getting about 9ftlbs. I ordered a Titan #1 spring (their recommendation for the 99) but it was too wide to fit in the piston with a sleeve in place. Original spring 20mm O/D, Titan #1 21mm O/D. I did try thinning the Titan down a bit but it wasn’t successful.

So I looked through Titan’s list and ordered a #7 , 19.5mm O/D with wire 0.05 thicker than the #1, slightly less I/D. Fitted it today (without any cutting). It took a fair bit of effort to cock and fired with a bit of a jump – however it only produced 8.8ftlbs!

I’m stumped. Where do I go from here? I’d much rather fix it myself than send it off.

[bigtoe01]

My new HW99S (.177) was underpowered from the start so I polished and re-lubed the internals, still only getting about 9ftlbs. I ordered a Titan #1 spring (their recommendation for the 99) but it was too wide to fit in the piston with a sleeve in place. Original spring 20mm O/D, Titan #1 21mm O/D. I did try thinning the Titan down a bit but it wasn’t successful.

So I looked through Titan’s list and ordered a #7 , 19.5mm O/D with wire 0.05 thicker than the #1, slightly less I/D. Fitted it today (without any cutting). It took a fair bit of effort to cock and fired with a bit of a jump – however it only produced 8.8ftlbs!

I’m stumped. Where do I go from here? I’d much rather fix it myself than send it off.

the seal will have been damaged as you withdrew it and fresh installed it, plus right now its oversprung by a mile

order a seal, strip the gun, deburr all the sharp edges, wash it out, order some of this grease here . Then install new seal to piston, grease up the seal and the spring and the piston skirt with the new grease, carefully install it with the OEM spring back in...and shoot 20 pellets to distribute the grease around...then chrono it.

[Murphy]

Or just get a gun with a proper sized cylinder!

[flatrajectory]

Ah, good old titan springs.........the 21st. century Ox.!!!!!!

If its hard to cock and kicks like a mule it must be parfull...innit.

Excuse my little rant ,it's the 3 glasses of Presseco.....lol.
Pete.

[TonyL]

the seal will have been damaged as you withdrew it and fresh installed it, plus right now its oversprung by a mile

order a seal, strip the gun, deburr all the sharp edges, wash it out, order some of this grease here . Then install new seal to piston, grease up the seal and the spring and the piston skirt with the new grease, carefully install it with the OEM spring back in...and shoot 20 pellets to distribute the grease around...then chrono it.

As per the above.

Plus..check / replace breech seal and go easy on the grease.

Tony...Whilst on my many searches in the past for alternative lubes, I'd come across this. I notice that you'd mentioned this stuff a few weeks ago, presumably due to the PTFE content and your liking of the Ultimox stuff and with this being far cheaper. This and your interest in cycling.

How long have you used it and would you say that it's a viable (or better) alternative to the moly grease we've used for so long?

[bigtoe01]

As per the above.

Plus..check / replace breech seal and go easy on the grease.

Tony...Whilst on my many searches in the past for alternative lubes, I'd come across this. I notice that you'd mentioned this stuff a few weeks ago, presumably due to the PTFE content and your liking of the Ultimox stuff and with this being far cheaper. This and your interest in cycling.

How long have you used it and would you say that it's a viable (or better) alternative to the moly grease we've used for so long?

its near identical make up to ultimox, does not burn, can also be used on O rings...and is cheaper...plus i use it on the bikes

done 2 springers with it now...ones my lgu...working great,

[TonyL]

Cheers for that, T, will get some bought and give it a go.

[rhyslightnin]

the seal will have been damaged as you withdrew it and fresh installed it, plus right now its oversprung by a mile

order a seal, strip the gun, deburr all the sharp edges, wash it out, order some of this grease here . Then install new seal to piston, grease up the seal and the spring and the piston skirt with the new grease, carefully install it with the OEM spring back in...and shoot 20 pellets to distribute the grease around...then chrono it.

This good for a ram seal Tone? I've been using this stuff in spray form for ages...

[bigtoe01]

Piston seal yes....ram internals, I can not see a reason why it would not work BUT its not the recommended lube

[Eligus]

Someone else suggested that it might be 'oversprung' with the Titan spring so I had another bright idea . Rather than just shorten the spring I was thinking of collapsing a few coils and fitting it that end into the piston with the theory that not only would it reduce the spring power (it's just about fully compressed at the moment) but would also add a piston weight i.e, the collapsed mass of the coils.

Anyone ever tried this and is it feasible?

[TonyL]

You could give it a try, and it MIGHT work, depends on now oversprung it was.

99s do shoot sweetly...compressing the coils will have a similar effect to weighting the piston, but you might get away with it. First stage recoil slightly higher; depending on other dynamics, it might reduce surge a little???

Do you still have the standard spring? If so, and if it's in fine fettle, you might want to re-fit that, having ensured that the piston and breech seals are okay and see how you go? If seals are fine and power a little low, maybe add a little preload to the standard spring?

[BTDT]

What's the piston stroke of the 99S?

[Rickenbacker]

What's the piston stroke of the 99S?

71mm according to Bruce, here Sir http://www.airgunbbs.com/showthread....ious-springers

[BTDT]

71mm according to Bruce, here Sir http://www.airgunbbs.com/showthread....ious-springers

Thank you

According to the info I have, the uncompressed spring is 255mm long. The final piece of the jigsaw; do any 99S owners know how much preload that will give?

[TonyL]

Sorry Jim.

When I fitted the Wonky Donky spring and guides to my 99, I didn't take any measurements.

I'm sure Bigtoe or Wonky may be able to help out, though.

Hope you're okay and still loving the Technical Airgun articles. Keep them coming!

Unfortunately, I haven't managed to put many shots through my recently acquired .177. Just a few last week to establish an approximate zero. It's doing 10.5 with 'Domes and is so very sweet straight out of the box that, unless anything were to start feeling untoward, will be left untouched, certainly in the short term. Very mild mannered, with minimal sight picture disturbance and no twang at all. Was thinking of dropping some moly paste in on the cocking link, but all seems fine.