GTA
All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => German AirGun Gate => Topic started by: HectorMedina on January 26, 2023, 08:56:48 PM
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I do not often work on HW's
To me they are complicated.
But a friend is a friend. And when my good friend WJ Emailed to cry about his R-7, I listened.
His chrono readings were real low (like just under 400 fps in a 0.177" cal rifle), and accuracy was absent.
I then told him about the first one I had done and he said:"no, I don't want a power up. I want something for my non-airgunner friends and families to shoot when they come visit"
OK, sounds nice, so, send it over!
The gun arrived in one of my "crunches" and it took a LOOOOOOONG time to be up for work, but patience and perseverance always pay off.
So, when I finally got to it, I found a few things that were not quite "Kosher".
The accuracy reported was truly abismal:
(https://imagizer.imageshack.com/v2/800x600q90/924/9Nb0T2.jpg)
The chrono readings were even worse than expected, and when I opened the gun I finally understood: This gun had passed by a "tinkerer".
The compression chamber had been "cross hashed":
(https://imagizer.imageshack.com/v2/800x600q90/922/gMWyYo.jpg)
The spring had a non-existent "closing" on one end:
(https://imagizer.imageshack.com/v2/800x600q90/923/VL6Eh0.jpg)
You can see a piece of the spring just waiting to break off and scratch everything inside.
The guide was not a guide in the sense that it floated in the spring.
And EVERYTHING was "caked" with Moly. Even the fork/barrel block was caked:
(https://imagizer.imageshack.com/v2/800x600q90/923/C5zKyP.jpg)
I put every metal part into a bath of diesel, and let it soak for a complete day.
At the end of the "bath", took a brush and cleaned everything as best as I could.
Then disposing of the old diesel and into a bath of "simple green" which is a water soluble degreaser.
And then, after a wash and rinse, some drying and rubbing.
While I had the gun apart, something felt "familiar" about the piston, and so I went looking into my parts and "BINGO!" found it:
(https://imagizer.imageshack.com/v2/800x600q90/924/fvyRN5.jpg)
The HW50 piston is an exact replica of the LG50 (53, 55, and early LGV) pistons!
Apart from the extra long tail of the LG piston's stems (a necessity, given their triggers), the pistons are exactly the same.
SHAME!!!
I decided to put an internal sleeve in the piston because the piston itself is much thinner in the HW50 than in the LG's.
(https://imagizer.imageshack.com/v2/800x600q90/923/SK26qf.jpg)
I then installed a guide/spring/top hat set from ARH, but lubed all internals with Ultimox 226.
(https://imagizer.imageshack.com/v2/800x600q90/922/33lizh.jpg)
Seals had been suspect, but once cleaned of the caked in moly paste, the parachute was able to do its job properly and the seal was, in essence, in very good condition. Breech seal was also totally flat, but there were no leaks, so it was left alone.
With the mechanism assembled, I felt that the gun "rattled". There was no noise, but something was loose. So we looked into the muzzle weight. Bingo! loose. Even with the shim, the MW was loose. There was no way a gun could be accurate with a loose MW.
So we shimmed the MW and tested 5 different pellet types:
JSB RS's.- 5.4 ft-lbs (575 ± 4 fps)
JSB Xp's.- 5.5 ft-lbs (560 ± 2 fps)
JSB Xact.- 5.3 ft-lbs (531 ± 5 fps) 4.52 mm's / 8.44 grs
JSB Xact.- 5.0 ft-lbs (518 ± 3 fps) 4.50 / 8.44
JSB Xact.- 5.0 ft-lbs (520 ± 5 fps) 4.53 / 8.44
And then shot some targets to ascertain if we had a shooter or not, this was the result with the best 2 pellets:
(https://imagizer.imageshack.com/v2/800x600q90/923/m6BFeQ.jpg)
As you can see, the Xp's are the best pellets in this barrel. Xp's come only in 4.52 mms / 7.89 grs. configuration, but they do match the barrel and the rifling nicely.
A group of 0.286"X 0.322" outside to outside is more than respectable in a gun this size.
It was illustrative that smaller headed pellets dropped the MV by 13 fps, and overly large pellets (4.53 / 8.44) also were below the "golden egg" by 11 fps.
From a practical standpoint, the gun is too light, even for these power levels. The shot cycle seems "buzzy" and "jumpy". My FT LGU has a better shot cycle at twice the power.
But the charge was to return the gun to an accurate/pleasant gun to shoot and that is what we did.
Can these guns be powered up? yes, but they become a little less enjoyable to shoot for non-die-hard airgunners.
Keep well and shoot straight!
HM
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Nice info Hector, but I'm a little confused, is it HW50 or HW30?
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Hi Hector,
I realise that you are Mr. Diana! ;D The HW 30 is the same as the R7. The HW 50 is the same as the R8. The HW 95 is the same as the R9.
Judging by the velocity numbers, I assume that it is an HW30/R7. ;)
-Y
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Yup!
Sorry!
This is what happens when you write at some late hour after a whole day of wife and kids, LOL!
Apologies! yes it is an R-7 / HW30.
:-[ :-[ :-[ :-[ :-[ :-[ :-[ :-[
HM
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I was interested in the cross-hatching pointed out as being problemati. Was anything done to alter or modify that to 'repair' it?
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Drew,
My understanding is that Cross-hatching the comp tube helps retain Moly in the little grooves. Clean the comp tube and leave the grease in the "scratches" so no dieseling. Krtox or Ultimox binds to the metal so so scratches to store lubrication are needed or wanted. My understanding anyway.... ::)
-Y
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A 5.5fpe hw30 is not healthy unless the intent was to achieve that power level with the tune.IMO
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A 5.5fpe hw30 is not healthy unless the intent was to achieve that power level with the tune.IMO
Agree ! Unless detuned 5.5 ft lbs is low. Depends on your elevation though! My R7 shoots nice
right out of the box at 685 fps with 7.3 gr AA Falcons !
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Drew,
My understanding is that Cross-hatching the comp tube helps retain Moly in the little grooves. Clean the comp tube and leave the grease in the "scratches" so no dieseling. Krtox or Ultimox binds to the metal so so scratches to store lubrication are needed or wanted. My understanding anyway.... ::)
-Y
That's not the real reason for cross hatching in engine building either.
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Yup!
Sorry!
This is what happens when you write at some late hour after a whole day of wife and kids, LOL!
Apologies! yes it is an R-7 / HW30.
Time with your wife and children is better than airguns anyway. Most of my guns sat unfired many years for that reason. I wish we could do it again.
HM
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I was interested in the cross-hatching pointed out as being problemati. Was anything done to alter or modify that to 'repair' it?
Nope
When measured, the Compression section of the Cylinder did show to be uneven/non uniform; 3-5 thou of difference between high spots and low ones.
Unless sent out to a proper hone, trying to polish out the hashing would have accentuated the non-uniformity.
AND we need to remember the desire of the owner: A smooth, easy cocking, easy shooting airgun for non-airgunners.
Keep well and shoot straight!
HM
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Drew,
My understanding is that Cross-hatching the comp tube helps retain Moly in the little grooves. Clean the comp tube and leave the grease in the "scratches" so no dieseling. Krtox or Ultimox binds to the metal so so scratches to store lubrication are needed or wanted. My understanding anyway.... ::)
-Y
Cross Hashing / hatching was intended to hold lubricant, yes, but mostly because of the diesel effect adding power to the shot cycle.
;-)
HM
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A 5.5fpe hw30 is not healthy unless the intent was to achieve that power level with the tune.IMO
The idea was not to "power it up" but to make it suitable for non-arigunners.
Even at the 5.5 ft-lbs level, the shot cycle is not "stellar".
By comparison, this HW30 has pretty much the same shot cycle quality as a 1950's LG55. The old Match gun is a bit smoother, but it also weighs almost 2# more.
Keep well and shoot straight!
HM
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Time with your wife and children is better than airguns anyway. Most of my guns sat unfired many years for that reason. I wish we could do it again.
Thanks for your kind words.
HM