HW97 tune story??

[ptpalpha]

Take a look at what Jim Maccari writes about a similar issue:
http://www.airrifleheadquarters.com/catalog/item/251488/43397.htm

[RinCG]

Most of the "late" 97's do have issues with compression tubes, compression chambers and piston run out.
 Without correction, will be on slow side or hard on wear parts.

Can you tell us more about these issues?  HW97 shooters -- are you familiar with these problems, too?

+1    Any more comments would be appreciated.

I've searched in the past as I felt my numbers were always lower than what was reported on the 'net. I couldn't possibly own all the HW's in the world with slow chrony numbers.  Not that I truly qualify to add more personal experience than a couple HW's have given me first hand info about. I wish I had all the tools other than my wallet to tell you more of what needs to be done. Long reach measuring tools will tell the tale. Those with machinist friends and/or machinist ability and proper tools at their disposal could see what the tolerance/hardware issues are and fix them.  An air maestro is what will solve the issues a home installed kit won't fix. I've never claimed to be anything other than a tinkerer.
After hiding my chrony I think my guns shoot very well.   

[Tomcat]

Take a look at what Jim Maccari writes about a similar issue:
http://www.airrifleheadquarters.com/catalog/item/251488/43397.htm

Scary thought, but thanks for the info.  I hope I don't have any such issues.

[Tomcat]

An air maestro is what will solve the issues a home installed kit won't fix. I've never claimed to be anything other than a tinkerer.
After hiding my chrony I think my guns shoot very well.   

You may be correct.  I will see how the kit performs.  Hopefully it will make me happy.

[Tomcat]

My Vortek kit arrived a couple days ago.  It made quite a difference in my velocities.

I took the rifle apart and cleaned all the grease from the piston and compression chamber.  Removed the original seal and installed the vortek seal after polishing the piston again.  It is mirror shiny now.  I also polished the rod end that mates with the sear.  I polished the outside of the compression chamber also.
 
I haven't received the Ultimox 226 grease recommended by Motorhead, so I used the grease sent with the vortek kit.  The kit (sho high power) comes with 5 washers or spacers.  Not having any experience with the kits, I went with three to see where that put me.  Somewhere I read no washers netted about 12 ft lbs and 5 washers about 17.
 
The seal was way too tight, and I couldn't get it into the compression chamber as it came.  After installing the seal on the piston and finding it was too tight, I chucked the piston and seal in the metal lathe and proceeded to file it while spinning.  I was making very little progress so I switched to sandpaper.  I kept trying it and finally got it to where it would slide inside the comp. chamber with about 2-3 lbs of force.  I read somewhere that is about what you want.  Not sure how accurate that is.
 
I polished both sides of the spacers and the end of the spring.  The back end of the spring was already fitted into the plastic guide and sleeve that make up the PG2 kit. Anyway, at that point, I used very little of the lube that came with the kit, and reassembled the rifle. Oh, I did get a new breech seal also.  The old one looked good, but I have a new one now. New one is harder material.
 
My first impression was that it is harder to cock than it was.  I shot a few at the pellet trap without the scope.  The shot cycle was more snappy than it was and there was no twang I could detect.  I thought at that point the cycle was more harsh than before the kit.
 
Chrony results showed a definite increase in velocity and power with the three spacers.  I only checked 2 pellet types so far, RWS Super Domes @ 8.3 gr and H&N FTT 8.64 gr.
 
The S domes shot at 933fps average compared to 847 fps before the kit.  Energy is 16.05 with an Extreme spread of 11 fps.  Of course it is not broken in yet after the installation. 
 
The H&N 8.64 gr came out with 903 fps average for 15.6 FPE and a spread of 20 fps. compared with 791 fps and 12FPE before the kit. Only two shots out of the ten were pretty low or the spread would have been much better.
 
I will probably remove one or two spacers to tame it a little, maybe down around 13-14 fpe. 
 
I shot it a few times with the scope at 10 yds, and I think it is a little harder to shoot accurately now.  I didn't shoot very many shots though.  I put a pellet on the scope turret for a couple shots and it moved some but didn't fall off.  I will have to shoot it more to determine what if anything I will do next.  Not sure I will remove spacers or not at this point.
 
Bottom line, it sounds a little more snappy and although I had a very minor boing with the shot cycle, it is now gone.  My velocity is up to where I am happy, maybe too high, but I can fix that.  The velocity increase made it worth the $90, and the minor difference in shot cycle is a bonus.

I am happy with the results.  I'm into a honey-do project, so the ag's will have to be put on hold for a while.

Thanks for reading.

Tom

[nced]

Well, I went to tinkering again this morning.  I put the original metal tophat back in along with two delrin spacers.  Got it shooting S. Domes @ 825fps now.  The shot cycle is still good.  I decided to leave it alone at this point.  I e-mailed Vortek, and since my order for the tune kit had not yet shipped, they graciously allowed me to cancel.  I may be missing a great improvement, but since I have never experienced a Vortek drop in tune, I am happy with what I have at the moment.  That could all change again .  Still open for any thoughts or ideas.

Thanks

Tom

Tom,
Personally getting to tune a lot of HW's ... Find the factory piston seal more times than not is marginal in having a good fit to compression bore ( Sizing down a slightly oversize Maccari or Vortek ) has given better results than using the OEM seal.

Another more recent practice is complete elimination of Moly lubes and spring tars.
Instead I prep action by thoroughly degreasing with Naptha and lube entire action with ULTIMOX 226 / Krytox synthetic lubes.  This free's up the action even more 

Hi Scott,

Can you give any more information about the amount and location where you use the Ultimox 226 without giving away your secrets?   I can still get the Vortek kit if you would think that is the best option.  I have tried to call Vortek, but get no answer.  I sent another e-mail and asked them to just sit on the order and not cancel it until I can decide what to do.  Do you think the SHO kit is what I should get?

My 97 is with the 26mm diameter piston and tube.  My rifle has never performed to the level that Brett and others are/were getting.  I am sure the buttons are not causing any drag now, but maybe the moly lube and spring tar are causing some loss.

The older I get, the more problem I have making decisions. 

Thanks for your help.

Tom

Well.....I've been using Dupont Krytox and Ultimox lubes for a couple years now after nixing both "tar" and molly paste soooo......I have no problem with giving up MY SECRETS  My current .177 R9 is fitted with a home rolled oring sealed piston cap, however when I tested the new design HW piston seal (the one with the thick parachute edge) I found that the performance was similar to my oring seal. My R9 is currently tuned to shoot 8.4 grain JSB Exact pellets at 850fps, however at the 2014 National Field Target match the gun was tuned to shoot the same pellet at 865fps.

Anywhoo.......back to my "SECRETS"......
I stripped all internals of my R9 with non-chlorinated aerosol brake cleaner and thoroughly dried the parts and receiver. Then I simply wiped a THIN film of Dupont Krytox GPL 224 on EVERYTHING INTERNAL and cycled the piston back and forth by hand to distribute the lube inside the receiver tube! Low tech approach to application  "worked a treat" with my R9! I do have to mention that I also "prepped" my receiver by honing it with oiled 400 grit wet-or-dry silicon carbide abrasive wound on a PVC mandrel to straighten out the receiver since it was constricted a bit at the end plug. When I tested out the new design HW factory piston seal I found that it functioned perfectly with the receiver prepped for an oring seal and Krytox lube.

I recently did an oring sealed piston job for a friend with a HW97 and here are a few pics to show the amount of Krytox being used.......
Krytox on spring coils........
Uploaded at Snapagogo.com

Here is a pic of the compression tube as it came from the receiver showing a rather coarse honing was applied....either by HW or by former tune work.........
Uploaded at Snapagogo.com

Comp tube after honing and bore straightening because the tube as installed in the gun was "belled" with the larger diameter toward the transfer port (not good for oring sealing). For some reason the piston was previously buttoned behind the piston seal and I really don't have a clue why since there is little cocking foot  pressure in this area, even for the HW95/R9! The installed "blue seal" was rather loose fitting on the piston button so perhaps the buttons were there to compensate.

Uploaded at Snapagogo.com
By the way......you can see the thickness of the Krytox used on the piston and oring seal, and the comp tube has already been lubed by cycling the piston back and forth by hand. Krytox/Ultimox is rather tenacious stuff that doesn't "outgas" like molly bearing mineral oil based lubes so it remains for a long time. Matter of fact, according to Dupont it requires a special (pricey) solvent to remove Krytox if you want to (a plus feature for me)! This pic also shows the rather heavy "steel slug" under the piston head that was removed before fitting a new spring kit.

[Tomcat]

Thank you Ed.  I appreciate your information.  I really like the photos.  It gives a newbie tuner like myself a very good idea how much lube to use.  I finally received my Ultimox 226 today.  Since I have just put my 97 together with the Vortek PG2 kit and I used the supplied lubricant, I probably will not try the Ultimox for a while. 

I am working on a home remodel project, so my airgun tinkering will be limited for a while.

Thanks again for your help.  The photos were great.