How's about this for my old R9...

[Kragman1]

I have an early one in .20 that needs a re-lube.
And I figure that if I take it down for that, I'll probably freshen the piston seal.
Of course, if I do that, I might as well put in a fresh spring. 

See how that all works...? 😁

In reality, I'm probably not going to take it down just yet, but it got me thinking about what I should do when the time comes.

Best estimate on mine is 1996 production so I'm assuming it has the smaller tube. Beats me though.
Not looking to overpower it, but as always I do like to see my rifles make the right power for whatever they are.

From what I've seen online, a popular combination is the ARH Hornet spring and a Vortek piston seal.  Seems to preserve the nice cocking and firing cycle of an original (or possibly nicer) without losing (possibly adding) velocity.  Sounds like what I would want.

My goal is to keep it in the 15 or so fpe range, but quality shooting comes first.

I'm sure that there are many different ways to approach this, and many experiences to be shared.  If any of you can second the ARH/Vortek combo, or suggest something different, please do.

FYI, I'd be happy to turn a guide and top hat if required so that's not a limitation.

Thanks all

[Yogi]

Smaller tube?
What??

-Y

[Kragman1]

Yogi -

"Legend has it" that the early guns had 25mm tubes, vs 26 for most of them.
I'm sure that someone can confirm...

[KWK]

No, some just had diameter differences. But still basically a 26mm. Some are oversize. JM sells slightly different sizes for the 26 mm. Look at his site. Measure yours before ordering. Vortek are oversize and probably doesn't matter. His are "fit all".
HW77 Mark 1 was 25 and later Marks are 26.

[Kragman1]

Thanks for clearing that up!

[Deerstalker]

My 2018 year 95 is 26 mm and per recs from this board I used an ARH kit plus a Vortek seal along with GPL-205 Krytox lube.  Cocking cycle is soundless until piston latches & 17 FPE.

[Toxylon]

Sadly, chamber ID's are nominal with most if not all makes, even when you'd think it'd be trivial to make a short steel tube with an accurate 26mm etc. ID: for instance, a 28mm chamber can be 28.0 or 28.9mm, or anything in between in actual ID, which has a massive effect on piston seal fit, and therefore performance. But piston seals also vary greatly in their OD's, even when they have one nominal OD.

This is something I've learned first hand, and Maccari agrees with, as anyone reading his site can tell.

[Yogi]

Look up the history of the Air Arms Pro Elite.
Case study in out of round compression chambers.

-Y

[Mark 611]

There are people out there who can Sunnen hone a compression tube, this will usually correct the out of roundness, this is why ARH sells oversized piston seals, so you can fit the seal to the tube Diameter,