HW/Weihrauch HW80 Piston Seal Rotation

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harrympope

harrympope

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Jun 28, 2015
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richland Washington
I just received a used HW80K Long Range Hunter .177 and it was "Honking" on the cocking stroke and a bit "buzzy" as well and diesling a slight bit.I stripped it down figuring I'd find a tight seal(or dry tube) was the cause if the honking but I didn't. It was about perfect in size.When inserted in the compression tube with my finger over the transfer port it stayed put,when I took my finger off it dropped down.
Also i removed unkown lube at amounts i wouldn't use myself. After a de grease,tighter guide and re-lube all is quiet and solid.

The thing that I did notice is is the piston seal rotates? Is this good or bad?

Also no top hat on the 80 I'd noticed.
any advantage to adding one?
 
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Piston seal rotation is quite common on HWs. I've seen it on alot of new guns with factory seals. I've also seen on a few aftermarket seals. Albeit with less frequency.
I notice more rotation with dieseling guns. I believe the additional combustion pressure stretches the seal and it rotates by the swirl effect of the air exiting the compression tube via the offset transfer port.

I have found that stretched loose old piston seals can cause wandering POIs. The same stretched loose seals may still chrono well but print poor targets. I change the seal if one of my guns isn't printing well and hasn't had a fresh seal in 10k rounds. That usually fixes the problem. Or I'll find a broken spring in the process. Then it gets both.

Hth
 
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Most new seals including aftermarket will rotate with a light drag when first installed if you twist them by hand. But they will usually stay oriented where you left them, if the gun runs clean.

Used seals will spin pretty freely by hand as they get stretched by compression heat. Again they normally stay oriented if the gun isn't dieseling.

20221108_202428.jpg


20221029_200625.jpg


20220730_091221.jpg


20221029_200620.jpg

All these seals came out of very low use almost new Weihrauchs. Note it's the burnt ones that show rotation during use.
 
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Put some goop in the seal before mounting let dry.. rotating seals cause inconsistencies. Get rid of stock seals and use a quality fitted aftermarket seal. Many people end up with WAY to loose of a seal as they want the most velocity they can get with less drag. The finger on port piston drop opis NOT a good way to size a seal. In actuality your slamming or prematurely detonating the pellet before TDC
THE RIGHT SPRING AND SIZED SEAL will not always be slide down fit..
 
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I noticed this with some arh seals fit on the piston button/ anvil .

I think the seal should be able to rotate but not be so loosey goosey. I feel it should turn but with some resistance and minimal " flopping/ wobbling" on the button/ anvle .

On the arh seals I discovered this edge lips are not the same and makes the difference in what I feel ( opinion) should be right

sealidsize 2.jpg
Notice one ( cream) has a higher/ thicker wall then (orange)

Then
slamming .jpg
The looser seal just after a handful of shots seemed to be slamming and punching a transfer port mark in the seal face..

I also prefer a seal fit that don't drop on its own bit there's a fine line of too snugg and too loose . Then that's a experience thing to what you find best for your tuning jobs . I like the little snug cause it will ware in some towards the loose , but too snug will just bogg the shots down as you shoot .. like I say a fine line ...lol

Now that buzz... If your seal too loose it may not cause that stopping cushion or air pressure and causes the piston / spring to over extend at the end of the shot cycle maybe slam and rattle/ buzz.
 
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thanks for all the input guys.
The seal was in good shape and appeared to have no damage.As far as fit,I've always had good luck with the "fall by its own weight system " but it looks like according to some here my theory is wrong?
I just got done with a quick test fire and it seems like it will be fine.This is the last group at 30 yards.I didn't get chronograph readings as I was too lazy.

20231115_135558.jpg
 
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Hateful McNasty said:
Well kinda looks like a not broke don't fix thing to me ..🥴
Click to expand...
When I got into it it appears the spring may have been shortened as well. But I didn't have a reference. And was too lazy to look up how many coils it should have. The ends of the springs were polished pretty nicely though. I will know more with the chronograph. But it was surprising the lighter pellet shot as well as it did.

What about the lack of a top hat?
 
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I don't use one .. I just stick with arh hornet spring and just clean up the ends and drop in ... Not in the kit form ..

I assume the x2 guides in the kit means guide and tophat (??)

Hornet MK6-R9,10,11-HW95-85 FAC. Kit

Maccari Custom Airgun Shop. Airguns and related accessories. Springs,tune kits,gunstocks,Beeman, Rws, Webley and many others. Sales and service
www.airrifleheadquarters.com


Anyway I just get a plain old spring
https://www.airrifleheadquarters.com/catalog/item/251488/1256921.htm

34 coilx .128 wire

For the R9 I shoot for 850+/- fps with cphp .177. .

I not used a vortec spring or seal / kit
 
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Ya, I got good experience in blowing at least one .. I joke in my group posts there's always the one to blow it...lol

Just shot this after a barrel cleaning, 50yards, r-9, cphp .177

r-9,50y,Blewit the one.png

Ya, always that one 🤔...lol

Anyway looks like you got a darn good shooter in that 80. I just don't see you needing to "fix" anything about it ..
 
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