HW90 potential

Ask me why I'm not shocked by this. Well, what is says is there is a weakness in the design at this point. I had to rethread the 5mm holes to 6mm and even then and with loctite blue -- they come loose when it is pumped to 26 bar. The recoil is more than this design can take, in my opinion. It needs greater thickness and length to make more threads and to allow more area to weld. But I still like my HW90 and will get it sorted. Charles
Tell me about it! The HW90 is the only game in town, so I'm sticking with it.

Vortek recently posted something about upcoming gas-ram kits for traditional springers.
 
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Absolument.

Mais 30 FPE peuvent profiter à ceux qui ont un .25 HW90. Les plus grosses pastilles ont vraiment besoin d'un peu plus de puissance.

Quand j'aurai le canon le plus court, je ferai d'autres tests de précision.
Hello ! Incredible this power ! With 30 FPE what is the precision with the HW90 .22 at 25 yards ? The Vortek vacuseal intersted me for my HW90 .22
 
The same exact thing happened to one of my HW90 cylinders. In your case I would send it back to AoA.

This is a problem with the HW90 and is caused by a weak weld and high recoil. Weihrauch must be aware of this problem. Look at the HW95's. The early HW95s have the welded on tangs. The later ones have a 'fixing block' which mounts on the bottom of the cylinder. It's got holes for the stock screws and a spring for the cocking arm. Here's a picture. https://twchambers.co.uk/twc-parts/fixing-block-with-spring/

This may be why Weihrauch supplies their breakbarrels with small, slotted forearm screws that keep you from applying lots of torque and possible breaking a tang. After my cylinder tang broke off, I became more concerned with the aftermarket brass forearm cups which come with socket head cap screws which can be tightened a lot. I had installed a set on my HW90, not sure if it contribute to the break but you never know. Nowadays I just moderately tighten the screws and count on loctite to keep them tight.

You can order a new cylinder from Krale. I did, and found it's a direct drop-in for a late model HW90. All I had to do was deburr it. Note that Weihrauch modified their piston assembly a few years ago. I don't know the date, serial number, or details of the mod. For more info check with T. W. Chambers airgun spares in England. ( https://twchambers.co.uk ). They answered my letters.

However, I got curious and was able to silver solder the tang back on.

Silver solder is almost as strong as welding, but requires much less heat. Something to keep in mind is that the solder merely flows into the break gap. It does not actually add more contact area. So you're left with a contact patch the same size as the original weld. It doesn't really solve the problem of a small weld area.

I had four temperature considerations. The barrel latching pin is hardened, you do not want to anneal it. The cylinder interior is polished, you do not want to discolor it. The cylinder itself is mild steel so I wasn't too worried about distortion. I wasn't too worried about the exterior bluing.

To locate the broken tang, I screwed a long screw through the broken tang. I then screwed it through the good tang, and adjusted the screw until the broken tang was positioned properly right over the break point. Not perfect but very close.

I used 'Muggyweld' 54% silver solder, and their proprietary flux. It's not cheap.

I started with a propane torch. That didn't have enough heat to properly flow the solder. I stepped up to MAPP gas (purchased at Home Depot). The soldering took only a couple of minutes. (I'm a total duffer with soldering and welding). MAPP is the way to go.

After soldering the only visible damage was to the exterior bluing. I had hoped to keep bluing damage under the stock. Unfortunately, some heat crept up the side of the cylinder, and you can see some bluing damage when it's in the stock. Somebody who knows what they're doing could probably do a better job. Also, a blob of solder slipped down the side of the cylinder, I ended up grinding some of that off.

The inside of the cylinder was still shiny, almost chrome like. No visible discoloration. The latching pin in the middle of the yoke seemed hard, I ran a file over it. So it didn't lose its temper. I put the cylinder in the stock, and installed the screws. Everything fit perfectly. I have not assembled the piston into the cylinder to see if it shoots properly. The main area of concern would be cylinder distortion. I don't have a way to check cylinder ID or out-of-round.

I cleaned it with steel wool and applied OXO bluing. It ain't gorgeous. More of an applied exercise.

View attachment 307297

View attachment 307298
View attachment 307318View attachment 307319
That first pic, that's a bad weld. Weihrauch should be ashamed of themselves.
Congrats on getting it to stick with silver solder. No, it won't stay. A good TIG welder would tac that piece back with zero effects to the interior and minimal external discoloration. TIG is intense, very focused heat and very fast. The weld is over in seconds vs holding a torch against the metal for ten times longer so the heat can transfer all through the tube.
Seeing the quality of that original weld, while I was TIGing the broken side I'd probably also reweld the unbroken side, also, though it does appear to be better welded. On the broken piece, the only thing holding the part on was the weld bead itself, the part metal never got hot enough to fuse to the tube. It's no wonder it broke.
 
That first pic, that's a bad weld. Weihrauch should be ashamed of themselves.
Congrats on getting it to stick with silver solder. No, it won't stay. A good TIG welder would tac that piece back with zero effects to the interior and minimal external discoloration. TIG is intense, very focused heat and very fast. The weld is over in seconds vs holding a torch against the metal for ten times longer so the heat can transfer all through the tube.
Seeing the quality of that original weld, while I was TIGing the broken side I'd probably also reweld the unbroken side, also, though it does appear to be better welded. On the broken piece, the only thing holding the part on was the weld bead itself, the part metal never got hot enough to fuse to the tube. It's no wonder it broke.
Thanks for the info! And you're right about the silver solder. I put it back in the gun and it promptly broke. But it was a good learning experience.

If it's safe to TIG weld the cylinder, then maybe I should check both my HW90's for weak welds. Take them to a good welding shop.
 
Over the last month I have been adding mods to the HW90 test mule. The goals were:
  • Examine the Vortek seal for wear.
  • Install a quality high-pressure Schrader valve
  • Install a silencer.
  • See how Krytox GPL-203 affects dieseling.
  • Generate a power vs BAR curve that covers the entire power range.
  • Draw some conclusions.
I want to thank Scax for the high pressure Schrader valves. He also sold me some Krytox GPL-203 and LPV lube for a very reasonable price. I bought a 16mm silencer adapter from DonnyFL and a 0 DB silencer from Arizona Airguns.

I first tore the gun down and checked the Vortek seal. There was some heat corrosion, mainly in the middle of the face. However, the edge is sharp all the way around and the sides are undamaged. I have no complaints about the Vortek seal and had no qualms reusing this seal. Keep in mind that the seal went through perhaps 50 cycles at 26 bar, and 500 cycles @ 22 bar. Early on it experienced some heavy dieseling, probably caused by too much moly lube. At one point my chrono recorded 1300 fps with a Crosman Premiere .22. That's over 50 foot-lbs. YIKES! That event may be what caused the corrosion. Because you can charge the HW90 ram to high levels, it's prone to dieseling unless you keep the cylinder bore scrupulously clean of combustible oils. To counteract dieseling, I reassembled using a thin smear of Krytox GPL 203 on the edge of the seal. It's a premium high temperature lubricant with less tendency to ignite.

Seal wear - side.jpg
Seal wear - top.jpg


Here's the new Vortek seal vs the original stock seal. Note the characteristic burn pattern on the stock seal. Weihrauch seems to ship HW90's at 26 bar from the factory, so some burn-in is unavoidable.
Vortek and stock - cropped.jpg



Schrader valve - The back of the HW90 cylinder has a port used to charge the ram with high pressure air. The port is sealed with a screw and an o-ring. In the port is a common schrader valve which tends to leak a little air. It's usually not a problem, because the real sealing is done by the o-ring and screw. The HW90 ram pressure (up to 26 bar or 380 psi) requires a high pressure Schrader valve. Regular auto/bike valves are not safe. Scax kindly sent me some high pressure valves for testing. The new valve was a direct replacement, and doesn't leak any more. The only consideration is the seating depth, which requires a tool with a thinned shank section at least 1/2" (12mm) in length. I had to modify my schrader valve removal tool. This picture shows the modified tool, original HW90 valve, Scax's valve, and finally the screw and o-ring.

Schrader-cropped.jpg


Next up was the silencer. Airguns of Arizona lists a 16mm Weihrauch silencer, but they're not in stock. I opted for a DonnyFL 16mm (non cone model) adapter which has a 1/2"- 20 thread, and a 0-DB silencer. Pictured is a Weihrauch cocking handle and a 0-DB silencer (both available from AoA) and the DonnyFL threaded adapter. The Weihrauch cocking handle is very well made, note the adapter sleeve which protects the barrel from the set screw. The DonnyFL adapter has no intermediary sleeve, so you end up with screw marks on the barrel.

Cocking handle and silencer assembly - cropped.jpg


HW90 barrels come with a dovetail at the end of the barrel which increases OD to a bit over 16mm. Since my HW90 is a test mule, I had no qualms about filing off the dovetail. It will never be used with iron sights. I don't have access to a lathe so used a fine mill-bastard file loaded with chalk to provide a smoother finish. The goal was to file just the dovetail 'wings' off and leave the center untouched. It was a very tricky job. If you screw up, remember that it will be covered by the adapter and silencer, or you can take it to a gun smith and have them cut a proper 1/2 UNF thread, which is a common silencer thread. I may still do that.

barrel filed 1 - cropped.jpg


Here's the file, and how the barrel looked after applying Oxpho blue.

file-cropped-jpg.312894


Once the dovetail was filed off, the DonnyFL adapter fit perfectly. I was worried it might be too flimsy to support a cocking handle, but it seems pretty stout. Unfortunately the set screws are too tall and protrude. It's on the underside so it doesn't bother me.

DonnyFL screws - cropped.jpg


Here's the gun after reassembly. The barrel is actually a HW95 carbine barrel from AoA. Mounts right up to the HW90. I have run both the full length and carbine barrels, there doesn't seem to be any difference in velocity or power.
HW90-final-cropped.jpg


I ran a shot string with Crosman Premiere 14.3 grain .22 pellets. I fired groups of five pellets. Starting at 26 bar I dropped ram pressure one bar at a time, stopping at five bar because the pellet didn't have enough energy to exit the barrel. Graphs are in feet/sec and foot-lbs energy vs bar. The graphs look 'saw toothed' because of the 5 pellet groups. I can post the actual numbers if anybody is interested.

Velocity - FPS - vs Bar.png
Power - FPE - vs Bar.png


Conclusions
  • Yes, it's possible to get over 30 foot-lbs of energy out of a .22 pellet in the HW90, if you use a Vortek seal. But it's not comfortable. That piston really slams, the gun feels like it's working hard. Target precision was all over the place, not sure if it's due to recoil, or whatever.
  • Power values at 25 and 26 bar look ragged. If it was dieseling, there should be spikes. So I don't think it's dieseling.
  • I'm not sure if Krytox GPL-203 helped to stop dieseling. But I'll try Krytox again in future builds.
  • I have a copy of the Beeman RX manual. It say that the gun should not be charged above 24 bar. That's interesting considering both of my factory new HW90's came set at 26 bar. Beeman probably tuned their RXs before delivery.
  • My preference is 20 bar which yields 23 FPE @ 830 FPS. Precision is pretty good, I was getting 1" groups at 10 yards with a red dot sight. Not super but I'm no expert. The gun is really pleasant at this power level.
  • The silencer made a significant difference to volume at higher power levels. The mechanical slam of the piston is still pretty loud but the higher pitched sizzling air sound is gone.
  • The silencer doesn't affect power/velocity.
  • The combination of silencer + carbine barrel has benefits.
  • UK power level (12 fpe) - Lock time feels a little slower than my HW95, the recoil ka-chunk is more noticeable. Maybe the heavier piston moves slower?
  • German power level (5~6 fpe) - Gun fires well. Cocking is ridiculously easy. Mechanical noise is definitely more than an HW30, the rabbits will hear it.
  • After the shot string, the stock screws were all loose. Use Loctite.
  • Brownell's Oxpho cream blue appears to be a close color match to Weihrauch bluing.
  • I should probably run some tests with a longer .25 barrel and some really heavy pellets.
 
Last edited:
Over the last month I have been adding mods to the HW90 test mule. The goals were:
  • Examine the Vortek seal for wear.
  • Install a quality high-pressure Schrader valve
  • Install a silencer.
  • See how Krytox GPL-203 affects dieseling.
  • Generate a power vs BAR curve that covers the entire power range.
  • Draw some conclusions.
I want to thank Scax for the high pressure Schrader valves. He also sold me some Krytox GPL-203 and LPV lube for a very reasonable price. I bought a 16mm silencer adapter from DonnyFL and a 0 DB silencer from Arizona Airguns.

I first tore the gun down and checked the Vortek seal. There was some heat corrosion, mainly in the middle of the face. However, the edge is sharp all the way around and the sides are undamaged. I have no complaints about the Vortek seal and had no qualms reusing this seal. Keep in mind that the seal went through perhaps 50 cycles at 26 bar, and 500 cycles @ 22 bar. Early on it experienced some heavy dieseling, probably caused by too much moly lube. At one point my chrono recorded 1300 fps with a Crosman Premiere .22. That's over 50 foot-lbs. YIKES! That event may be what caused the corrosion. Because you can charge the HW90 ram to high levels, it's prone to dieseling unless you keep the cylinder bore scrupulously clean of combustible oils. To counteract dieseling, I reassembled using a thin smear of Krytox GPL 203 on the edge of the seal. It's a premium high temperature lubricant with less tendency to ignite.

View attachment 312889 View attachment 312890

Here's the new Vortek seal vs the original stock seal. Note the characteristic burn pattern on the stock seal. Weihrauch seems to ship HW90's at 26 bar from the factory, so some burn-in is unavoidable.
View attachment 312892


Schrader valve - The back of the HW90 cylinder has a port used to charge the ram with high pressure air. The port is sealed with a screw and an o-ring. In the port is a common schrader valve which tends to leak a little air. It's usually not a problem, because the real sealing is done by the o-ring and screw. The HW90 ram pressure (up to 26 bar or 380 psi) requires a high pressure Schrader valve. Regular auto/bike valves are not safe. Scax kindly sent me some high pressure valves for testing. The new valve was a direct replacement, and doesn't leak any more. The only consideration is the seating depth, which requires a tool with a thinned shank section at least 1/2" (12mm) in length. I had to modify my schrader valve removal tool. This picture shows the modified tool, original HW90 valve, Scax's valve, and finally the screw and o-ring.

View attachment 312880

Next up was the silencer. Airguns of Arizona lists a 16mm Weihrauch silencer, but they're not in stock. I opted for a DonnyFL 16mm (non cone model) adapter which has a 1/2" coarse thread, and a 0-DB silencer. Pictured is a Weihrauch cocking handle and a 0-DB silencer (both available from AoA) and the DonnyFL threaded adapter. The Weihrauch cocking handle is very well made, note the adapter sleeve which protects the barrel from the set screw. The DonnyFL adapter has no intermediary sleeve, so you end up with screw marks on the barrel.

View attachment 312893

HW90 barrels come with a dovetail at the end of the barrel which increases OD to a bit over 16mm. Since my HW90 is a test mule, I had no qualms about filing off the dovetail. It will never be used with iron sights. I don't have access to a lathe so used a fine mill-bastard file loaded with chalk to provide a smoother finish. I finished it with Oxpho blue to prevent rust. It was a very tricky job. If you screw up, remember that it will be covered by the adapter and silencer, or you can take it to a gun smith and have them cut a proper 1/2 UNC thread, which is a common silencer thread. I may still do that.

file-cropped-jpg.312894


Once the dovetail was filed off, the DonnyFL adapter fit perfectly. I was worried it might be too flimsy to support a cocking handle, but it seems pretty stout. Unfortunately the set screws are too tall and protrude. It's on the underside so it doesn't bother me.

View attachment 312895

Here's the gun after reassembly. The barrel is actually a HW95 carbine barrel from AoA. Mounts right up to the HW90. I have run both the full length and carbine barrels, there doesn't seem to be any difference in velocity or power.
View attachment 312896

I ran a shot string with Crosman Premiere 14.3 grain .22 pellets. I fired groups of five pellets. Starting at 26 bar I dropped ram pressure one bar at a time, stopping at five bar because the pellet didn't have enough energy to exit the barrel. Graphs are in feet/sec and foot-lbs energy vs bar. The graphs look 'saw toothed' because of the 5 pellet groups. I can post the actual numbers if anybody is interested.

View attachment 312897 View attachment 312898

Conclusions
  • Yes, it's possible to get over 30 foot-lbs of energy out of a .22 pellet in the HW90, if you use a Vortek seal. But it's not comfortable. That piston really slams, the gun feels like it's working hard. Target precision was all over the place, not sure if it's due to recoil, or whatever.
  • Power values at 25 and 26 bar look ragged. If it was dieseling, there should be spikes. So I don't think it's dieseling.
  • I'm not sure if Krytox GPL-203 helped to stop dieseling. But I'll try Krytox again in future builds.
  • I have a copy of the Beeman RX manual. It say that the gun should not be charged above 24 bar. That's interesting considering both of my factory new HW90's came set at 26 bar. Beeman probably tuned their RXs before delivery.
  • My preference is 20 bar which yields 23 FPE @ 830 FPS. Precision is pretty good, I was getting 1" groups at 10 yards with a red dot sight. Not super but I'm no expert. The gun is really pleasant at this power level.
  • The silencer made a significant difference to volume at higher power levels. The mechanical slam of the piston is still pretty loud but the higher pitched sizzling air sound is gone.
  • The silencer doesn't affect power/velocity.
  • The combination of silencer + carbine barrel has benefits.
  • UK power level (12 fpe) - Lock time feels a little slower than my HW95, the recoil ka-chunk is more noticeable. Maybe the heavier piston moves slower?
  • German power level (5~6 fpe) - Gun fires well. Cocking is ridiculously easy. Mechanical noise is definitely more than an HW30, the rabbits will hear it.
  • After the shot string, the stock screws were all loose. Use Loctite.
  • Brownell's Oxpho cream blue appears to be a close color match to Weihrauch bluing.
  • I should probably run some tests with a longer .25 barrel and some really heavy pellets.

View attachment 312894
Thank you for the work you put into this job and for sharing your info. Well done
 
Over the last month I have been adding mods to the HW90 test mule. The goals were:
  • Examine the Vortek seal for wear.
  • Install a quality high-pressure Schrader valve
  • Install a silencer.
  • See how Krytox GPL-203 affects dieseling.
  • Generate a power vs BAR curve that covers the entire power range.
  • Draw some conclusions.
I want to thank Scax for the high pressure Schrader valves. He also sold me some Krytox GPL-203 and LPV lube for a very reasonable price. I bought a 16mm silencer adapter from DonnyFL and a 0 DB silencer from Arizona Airguns.

I first tore the gun down and checked the Vortek seal. There was some heat corrosion, mainly in the middle of the face. However, the edge is sharp all the way around and the sides are undamaged. I have no complaints about the Vortek seal and had no qualms reusing this seal. Keep in mind that the seal went through perhaps 50 cycles at 26 bar, and 500 cycles @ 22 bar. Early on it experienced some heavy dieseling, probably caused by too much moly lube. At one point my chrono recorded 1300 fps with a Crosman Premiere .22. That's over 50 foot-lbs. YIKES! That event may be what caused the corrosion. Because you can charge the HW90 ram to high levels, it's prone to dieseling unless you keep the cylinder bore scrupulously clean of combustible oils. To counteract dieseling, I reassembled using a thin smear of Krytox GPL 203 on the edge of the seal. It's a premium high temperature lubricant with less tendency to ignite.

View attachment 312889 View attachment 312890

Here's the new Vortek seal vs the original stock seal. Note the characteristic burn pattern on the stock seal. Weihrauch seems to ship HW90's at 26 bar from the factory, so some burn-in is unavoidable.
View attachment 312892


Schrader valve - The back of the HW90 cylinder has a port used to charge the ram with high pressure air. The port is sealed with a screw and an o-ring. In the port is a common schrader valve which tends to leak a little air. It's usually not a problem, because the real sealing is done by the o-ring and screw. The HW90 ram pressure (up to 26 bar or 380 psi) requires a high pressure Schrader valve. Regular auto/bike valves are not safe. Scax kindly sent me some high pressure valves for testing. The new valve was a direct replacement, and doesn't leak any more. The only consideration is the seating depth, which requires a tool with a thinned shank section at least 1/2" (12mm) in length. I had to modify my schrader valve removal tool. This picture shows the modified tool, original HW90 valve, Scax's valve, and finally the screw and o-ring.

View attachment 312880

Next up was the silencer. Airguns of Arizona lists a 16mm Weihrauch silencer, but they're not in stock. I opted for a DonnyFL 16mm (non cone model) adapter which has a 1/2" coarse thread, and a 0-DB silencer. Pictured is a Weihrauch cocking handle and a 0-DB silencer (both available from AoA) and the DonnyFL threaded adapter. The Weihrauch cocking handle is very well made, note the adapter sleeve which protects the barrel from the set screw. The DonnyFL adapter has no intermediary sleeve, so you end up with screw marks on the barrel.

View attachment 312893

HW90 barrels come with a dovetail at the end of the barrel which increases OD to a bit over 16mm. Since my HW90 is a test mule, I had no qualms about filing off the dovetail. It will never be used with iron sights. I don't have access to a lathe so used a fine mill-bastard file loaded with chalk to provide a smoother finish. I finished it with Oxpho blue to prevent rust. It was a very tricky job. If you screw up, remember that it will be covered by the adapter and silencer, or you can take it to a gun smith and have them cut a proper 1/2 UNC thread, which is a common silencer thread. I may still do that.

file-cropped-jpg.312894


Once the dovetail was filed off, the DonnyFL adapter fit perfectly. I was worried it might be too flimsy to support a cocking handle, but it seems pretty stout. Unfortunately the set screws are too tall and protrude. It's on the underside so it doesn't bother me.

View attachment 312895

Here's the gun after reassembly. The barrel is actually a HW95 carbine barrel from AoA. Mounts right up to the HW90. I have run both the full length and carbine barrels, there doesn't seem to be any difference in velocity or power.
View attachment 312896

I ran a shot string with Crosman Premiere 14.3 grain .22 pellets. I fired groups of five pellets. Starting at 26 bar I dropped ram pressure one bar at a time, stopping at five bar because the pellet didn't have enough energy to exit the barrel. Graphs are in feet/sec and foot-lbs energy vs bar. The graphs look 'saw toothed' because of the 5 pellet groups. I can post the actual numbers if anybody is interested.

View attachment 312897 View attachment 312898

Conclusions
  • Yes, it's possible to get over 30 foot-lbs of energy out of a .22 pellet in the HW90, if you use a Vortek seal. But it's not comfortable. That piston really slams, the gun feels like it's working hard. Target precision was all over the place, not sure if it's due to recoil, or whatever.
  • Power values at 25 and 26 bar look ragged. If it was dieseling, there should be spikes. So I don't think it's dieseling.
  • I'm not sure if Krytox GPL-203 helped to stop dieseling. But I'll try Krytox again in future builds.
  • I have a copy of the Beeman RX manual. It say that the gun should not be charged above 24 bar. That's interesting considering both of my factory new HW90's came set at 26 bar. Beeman probably tuned their RXs before delivery.
  • My preference is 20 bar which yields 23 FPE @ 830 FPS. Precision is pretty good, I was getting 1" groups at 10 yards with a red dot sight. Not super but I'm no expert. The gun is really pleasant at this power level.
  • The silencer made a significant difference to volume at higher power levels. The mechanical slam of the piston is still pretty loud but the higher pitched sizzling air sound is gone.
  • The silencer doesn't affect power/velocity.
  • The combination of silencer + carbine barrel has benefits.
  • UK power level (12 fpe) - Lock time feels a little slower than my HW95, the recoil ka-chunk is more noticeable. Maybe the heavier piston moves slower?
  • German power level (5~6 fpe) - Gun fires well. Cocking is ridiculously easy. Mechanical noise is definitely more than an HW30, the rabbits will hear it.
  • After the shot string, the stock screws were all loose. Use Loctite.
  • Brownell's Oxpho cream blue appears to be a close color match to Weihrauch bluing.
  • I should probably run some tests with a longer .25 barrel and some really heavy pellets.

View attachment 312894
Thank you very much, you have really done an excellent job of providing information in order to advance the community on this enigma which is the HW90!
I see that the seal has deteriorated quickly ! Do you think that in the long term it will not deteriorate more? It looks charred with a big crack in the middle that doesn't inspire too much trust for that longevity.

Concerning the silencer adapter, I fitted mine with a 16 mm "Best Fittings" adapter which I fixed by tapping gently with a plastic mallet. The barrel is slightly more than 16 mm in diameter because of the rail to fix the front sight and it is hard to enter, so it maintains itself. I didn't even need to tighten the 2 bottom screws. This 1/2 UNF adapter is very small, I ordered it on Kral Shop

20221212_161838.jpg


20221212_161800.jpg


20221212_161601.jpg


20221212_161643.jpg
 

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Thank you very much, you have really done an excellent job of providing information in order to advance the community on this enigma which is the HW90!
I see that the seal has deteriorated quickly ! Do you think that in the long term it will not deteriorate more? It looks charred with a big crack in the middle that doesn't inspire too much trust for that longevity.

Concerning the silencer adapter, I fitted mine with a 16 mm "Best Fittings" adapter which I fixed by tapping gently with a plastic mallet. The barrel is slightly more than 16 mm in diameter because of the rail to fix the front sight and it is hard to enter, so it maintains itself. I didn't even need to tighten the 2 bottom screws. This 1/2 UNF adapter is very small, I ordered it on Kral Shop

View attachment 312949

View attachment 312950

View attachment 312951

View attachment 312952

Hi,

That's a very good question about the seal. I first noticed the piston seal corrosion after the cylinder tab broke and I had to disassemble it. I'm not sure it's actually a crack, there doesn't seem to be an opening.

I left it in the gun out of curiosity. Since then the gun has been disassembled several times. It survived the testing, even at 26 bar, and was producing about the same power level as when it was new. However, I will be tearing it down soon and have extra seals on hand.

Regarding the adapter, I have a laser bore sight with a cone shaped stem which inserts into the barrel and seats against the the crown. The bore sight has been very instructive in sighting in scopes. It's super easy to adjust the crosshairs to the red dot against a wall. So it was important to be able to conveniently remove the adapter. Also I was curious about how to file the dovetail.

I like the Weihrauch silencer you bought. It did not occur to me to check Krale's accessories.
 
Yes, the HW90 is a real engima. We're in uncharted territory here!

That's a very good question about the seal. I first noticed the piston seal corrosion after the cylinder tab broke and I had to disassemble it. I'm not sure it's actually a crack, there doesn't seem to be an opening.

I left it in the gun out of curiosity. Since then the gun has been disassembled several times. It survived the testing, even at 26 bar, and was producing about the same power level as when it was new. However, I will be tearing it down soon and have extra seals on hand.

Regarding the adapter, I have a laser bore sight with a cone shaped stem which inserts into the barrel and seats against the the crown. The bore sight has been very instructive in sighting in scopes. It's super easy to adjust the crosshairs to the red dot against a wall. So it was important to be able to conveniently remove the adapter. Also I was curious about how to file the dovetail.

I like the Weihrauch silencer you bought. It did not occur to me to check Krale's accessories.

By the way, is your adapter UNF or UNC? I thought mine was UNC, maybe I'm confused here.
 
Hi,

That's a very good question about the seal. I first noticed the piston seal corrosion after the cylinder tab broke and I had to disassemble it. I'm not sure it's actually a crack, there doesn't seem to be an opening.

I left it in the gun out of curiosity. Since then the gun has been disassembled several times. It survived the testing, even at 26 bar, and was producing about the same power level as when it was new. However, I will be tearing it down soon and have extra seals on hand.

Regarding the adapter, I have a laser bore sight with a cone shaped stem which inserts into the barrel and seats against the the crown. The bore sight has been very instructive in sighting in scopes. It's super easy to adjust the crosshairs to the red dot against a wall. So it was important to be able to conveniently remove the adapter. Also I was curious about how to file the dovetail.

I like the Weihrauch silencer you bought. It did not occur to me to check Krale's accessories.
Thank you very much for your return.
If you have new information about the new seal, I will be there

Krale has good accessories, but I bought my second HW90 from them but it was defective and I was not satisfied with the after-sales service they made me lose money


Yes the adapter is a 1/2 UNF
 
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Next up was the silencer. Airguns of Arizona lists a 16mm Weihrauch silencer, but they're not in stock. I opted for a DonnyFL 16mm (non cone model) adapter which has a 1/2" coarse thread, and a 0-DB silencer. Pictured is a Weihrauch cocking handle and a 0-DB silencer (both available from AoA) and the DonnyFL threaded adapter. The Weihrauch cocking handle is very well made, note the adapter sleeve which protects the barrel from the set screw. The DonnyFL adapter has no intermediary sleeve, so you end up with screw marks on the barrel.
If you cut off some small pieces of pellet and stuff them down the set screw holes, that will protect the barrel from being marred when the screws are tightened.;)
 
I got in more high quality schrader valve cores in case someone here has a need. These were chosen to meet the high pressure needs in our HW90 guns. They are USA made Dill 302-DN. They open at 80psi and are rated 2000psi. They are meant to be used in high pressure struts and the like. Easy to install -- plug and play in the HW90. My original core was leaking, brand new. No problems since screwing this one in. These are a simple gift to you who also own an HW90. Just PM me should you want one with your shipping address and I'll let you know when it ships. Charles how do I get one?