HW50s .177 sneak preview

OEM spring, guide and piston seal.

Some pics of the internal components dissassembled, thoroughly degreased, critical areas smoothed over ( contact points on the jointed cocking lever, cocking slot, piston and of course all sharp areas inside the receiver. Not in the pics is a piston liner made of steel shim stock. Depending on the surface/part, I used an appropriately profiled diamond file, 600/1000/2000 3M wet or dry paper and 5000 grit 3M polishing paper. For the breech block securing fork: 1000 grit followed by 2000 paper wrapped around a flat steel bar, same amount/pressure of small circular strokes for each side: the idea being to decrease the friction coefficient and NOT flatten out completely the surface or obtain a mirror finish, not there. Barrel shims received a light polish over 2000 grit with oil always using circular passes.

Tabs: All sides of the tabs received equal number of light passes over 600 wet or dry to ease removal from the receiver. The trigger for this rifle's purposes is more than adequate so no tune needed, the blade and tension pull screw were replaces with Paul Short's custom work.

Piston exterior: Always using strokes in line with the long axis: smart passes over 600 wet or dry positioned over a layer of thick cardboard, followed by 1000, 2000 and final "buffing" over 5000 grit 3M polishing pad. Not an agressive mirror polish: again, just enough to smooth everything over to my satisfaction.

Piston stem rod smoothed over using similar method as above. 

I went with a standard ARH HW50s kit for this project: The bottom of the rear guide base that rests flush against the end block was smoothed over using 600/1000/2000 grit, as was the top of the top hat that is in contact with a 1.3mm polished steel washer that I slipped inside the piston after the steel piston liner. Reduce that friction baby, I want as much energy being transferred (smoothly) to that little JSB pellet.

I opted for a lightly used and well conserved V-Mach Hybrid C-Form piston seal (for 12fpe rifles), not because of personal preference but the precise fit on the piston head dictated so. The 26mm concave Ausssie seal will always have use in one of my 97s; the SGS seal goes back to the parts bin and the blue JM Hornet seal as of today has been sized and now lives inside of a mighty R9 .20 (worthy of another thread entirely!). The V-Mach seal needed gentle sizing only. The JM spring kit went inside the piston and everything got reassembled with appropriate lubrification. 





By the way, check out the interesting grain on an otherwise "dull" HW50s stock:





More to come my moly and poly brethren

V-Mach piston seal installed. Who else can appreciate the pearly smoothnness of this smoothed over top hat? No machining marks/uneven surfaces. Ready to rotate friction free against the polished and lubed steel piston washer. Slick is the word

The rear guide/load bearing base also got smoothed over, just enough to not reduce precious preload:

A sweet shooting rifle deserves a nice looking piece of lumber, wouldn't you agree?

ARH Grade 3 Walnut, checkered pistol grip and thin recoil pad. I like the classic and timeless, sporty look of the rifle in this stock.

The ensemble is complete (for now at least. ) Yes, it shoots as nice as it looks.

Once my .22 arrives I'll tune it up as well. Wait until you see the stock for the HW50s .22

Thanks for the comments and sharing your thoughts guys.

jmiller: When I first received the rifle it was doing low 770's with JSB 8.4s. Post tune it's now averaging low 780's (about 100 shots through so far), but its early days and the once the JM kit breaks in it'll likely gain some FPS. I did not use an OEM sleeve but a custom made .002" SS sleeve, so very lightweight/low mass. 

KWK: The finish on the tophat was acceptable especially if you're not too picky or detail oriented but I feel it benefited greatly from a quick "polish". I like them flat and very smooth. The guide material isn't specified on ARH's website but I suspect its Delrin. Would like to take a peek at your Webley Stingray. I've been interested in finding a UK made Longbow as its one of the springers that was fruit of the Webley Venom Custom Shop, and has Venom DNA.

JC: Thanks, agree the thin red pad is a nice compliment.

Broozer: Cheers and hats off to you for also working on your own guns, we become better airgunners through this experience. Re: piston seal fit size, how do I put this... It gets complicated. To better answer your question lets consider mid power HW's in the 10.5-12fpe range, and use the 97 platform as a specific example due to the ease of accessing the compression tube when disassembled. In my experience, most aftermarket seals need at least a little sizing for an ideal fit. I pay close attention to touch the spinning seal lightly in a way that maintains its original angles. If you test the fit in a dry tube and without lube on the seal keep in mind that friction will be further reduced once your tube is burnished and your seal lubricated. I don't want it fitting too loose (more on this later) or too tight, it's a feeling that is hard to describe but you know it once you're there. It's hard to use the OEM seal resistance as a reference because based on the age of the rifle or if it's been mistreated the lubes can thicken and harden, giving the impression that the resistance is higher. The OEM seals can vary in size, too. But if you have a cleaned, freshly burnished tube and a good fitting OEM piston seal- then I think using similar resistance will put you in safe territory. Gabe, your 50s looks balanced with that ARH Apex muzzle brake (?)on your 50s. 

One of CA's finest airgunners, that's YOU Lewis:

Thanks bud you're too kind. But to answer your question: IF I were looking for high velocity numbers right off the bat; IF 100% of my shooting were done indoors or always in the exact same temperature; IF I intended to use one specific pellet weight/head diameter; IF I had a perfect and true compression tube, etc : then YES I could use the method you described.  



Weihrauch and a pizza ? 12 paces, open sights, standing.