Why is the HW95 so bouncy??

[Geezer]

Could it be because the HW95 is a reincarnated BSF 55 which was always said to be hold sensitive.

Never found my 55 too hold sensitive, even for a 6.5 pound, 40” 12 ft-lbs carbine.

And no, I don’t think that’s the reason.

[TonyL]

Well, seeing as how many people really like the 99's firing cycle......same bore. According to Bruce's excellent thread on bore / stroke / TP etc., the 95 has a 14mm longer stroke and a piston approximately 30 grams heavier. The transfer ports are also very similarly sized. So, theoretically, reducing the weight of the piston by an ounce or so and lopping half an inch off the stroke should result in a similar prescription.

I think the cylinder on the 95 is a good bit longer. I'd have to free a couple of rifles from the cabinet in order to compare the dimensions. So, more spring space in the 95. But, maybe more crucially, what does this do to the weight distribution / balance? Many have commented in the past about the weird "long" feeling of the handling of the old school 85. Also, wacky as it sounds, maybe worth trying a 99 spring in the 95 but with a spacer behind? Less active coils would often be frowned upon, I know, but I said it was a bit wacky! Worth a looky or total non-starter?

And another wacky one.......could different users' different perceptions of the feel of the cycle actually come down to piston seal sizing too?

[TonyL]

Ok, thinking out loud here......no experience of tuning either the HW99/50 or the HW85/95.

But I do have an HW50S and a MK1 HW85 ready to enjoy and improve. The received wisdom is that the 50S in .22" should be easy to get lovely and this thread indicates the 85 will be much more tricky.

I think they both run a 26mm piston but the 85/95 has a longer stroke so short stroking it to the same as a 50/99 is the answer is it not?? This thread suggests it is not that simple. So from a basic understanding of what goes into a springers dynamics there must be differences in piston weight, transfer port etc

Is there much difference between them and can the 85/85 be turned into a sweet shooting 50/99 clone but with a longer cylinder???

Rich.

Well, seeing as how many people really like the 99's firing cycle......same bore. According to Bruce's excellent thread on bore / stroke / TP etc., the 95 has a 14mm longer stroke and a piston approximately 30 grams heavier. The transfer ports are also very similarly sized. So, theoretically, reducing the weight of the piston by an ounce or so and lopping half an inch off the stroke should result in a similar prescription.

I think the cylinder on the 95 is a good bit longer. I'd have to free a couple of rifles from the cabinet in order to compare the dimensions. So, more spring space in the 95. But, maybe more crucially, what does this do to the weight distribution / balance? Many have commented in the past about the weird "long" feeling of the handling of the old school 85. Also, wacky as it sounds, maybe worth trying a 99 spring in the 95 but with a spacer behind? Less active coils would often be frowned upon, I know, but I said it was a bit wacky! Worth a looky or total non-starter?

And another wacky one.......could different users' different perceptions of the feel of the cycle actually come down to piston seal sizing too?

Yep, that's where I was heading in post #57.

Oh no, I can hear Mr Geezer now, going round and round with this one!

[T 20]

Never found my 55 too hold sensitive, even for a 6.5 pound, 40” 12 ft-lbs carbine.

And no, I don’t think that’s the reason.

Buggered if I know then.

[maximus]

Buggered if I know then.

I think I'm nearly at the same conclusion as you Mick!

Now, mine isn't shooting too bad at the moment but accuracy is not near what it should be with any jsb, (lets face it if your gun will shoot them they are the best) so before I take it apart again I'm going to clean the barrel then shoot some more groups.

[TonyL]

Now, mine isn't shooting too bad at the moment but accuracy is not near what it should be with any jsb, (lets face it if your gun will shoot them they are the best) so before I take it apart again I'm going to clean the barrel then shoot some more groups.

Maybe a good plan, sir.

Now, I've never cleaned a barrel. Not felt the need to. But Jim Tyler, in an article a couple of months ago, explained why it can often be a good idea if accuracy isn't as expected when using a soft pellet (like the JSB) if the barrel has had other, harder pellets through it.

I'm sure you're au fait with the procedure, making sure you lead it back in afterwards.

Hope it works and be sure to report back.