HW55M Question

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    gmkmd
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    Just picked up an HW55M at a local gun shop.  This has the barrel latch on the left side.  One thing I noticed is that after you cock it, the only way the barrel stays up is if you employ the latch.  Is there not supposed to be a spring detent to hold the barrel up, with the latch providing the final locking in place, or is this not the case?

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    JohnL57
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    Lucky find! There is indeed a spring detent to hold the barrel up. Here is a photo-

    The spring detent is the silver piece-it slides back and forth under spring pressure to latch the barrel against the rather small lug visible below the transfer port. Mine makes a definite click and does hold the barrel up on closing when the gun is cocked.

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    AirNGasman
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    I believe it's adjustable.

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    JohnL57
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    The lever lock is adjustable-not sure about the spring detent. Mike Driskill from the Yellow forum seems to be pretty knowledgeable about the HW55, maybe he'll comment if he reads this post. 

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    JohnL57
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    I just took a more careful look at my HW55-it appears that the lever latch adjustment will also snug up the spring detent.

    Here's a link to an article on adjusting the latch-

    https://www.tapatalk.com/groups/americanvintageairguns/viewtopic.php?t=3961&p=24101

    And a picture of the adjusting screw-

    The screw is turned counterclockwise to tighten the lockup latch. From what I can observe the detent lug fits into the round hole in the silver bar and is sprung so that it moves back into the breech block as the silver bar passes over it, then springs back out into the round hole in the silver bar to hold the barrel up while the lever is latched. Hope that made sense!

    John

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    MDriskill
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    The notes above are correct on how the little auto-latch works. The recess in the pivoting bar also serves as the seat for the auto latch.

    The auto latch does wear over time. I have a couple of older 55’s where it works only barely or not at all. And even when working well, it doesn’t hold the barrel closed firmly enough to fire the gun. It’s just there as a convenience to help you out while you reach for the real lever.

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    MDriskill
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    JohnL57

    Lucky find! There is indeed a spring detent to hold the barrel up. Here is a photo-

    The spring detent is the silver piece-it slides back and forth under spring pressure to latch the barrel against the rather small lug visible below the transfer port. Mine makes a definite click and does hold the barrel up on closing when the gun is cocked.

    I think you fixed this in your subsequent posts, but just to be clear the BIG silver piece does not move when the barrel is closed. It’s the little gizmo under the transfer port that is the sprung auto latch. 

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    gmkmd
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    Wow, thanks so much for all your help.  I'll have a look at it tonight.  In the bigger scheme of things, I'm planning on doing a tune up on this gun because the power is very weak, so I'm thinking it needs new seals.  BUT; I've never worked on an air rifle before.  I've done plenty of other gun work, but not air guns.  I've been doing a lot of online research, and it seems fairly easy, though I do realize that there are some very important particulars to be aware of.  I ordered a spring compressor and various lubes, but I would love a good reference book about working on these.  Any suggestions?

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    MDriskill
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    If you can find a copy of Tom Gaylord’s “R1 Supermagnum” book, it’s an excellent general guide to taking apart a Weihrauch rifle. But it’s out of print and suffering from the usual preposterous online price inflation. Tom has also posted many excellent article about the HW 55 at his Pyramyd Air blog, definitely worth a look.

    https://www.pyramydair.com/blog/?s=Hw+55&btnGo=

    Here’s an excellent blog post on rebuilding the 55’s big brother, the HW 35. The 55 uses a similar threaded-on rear receiver section to the 35 and R1.

    https://anotherairgunblog.blogspot.com/search?q=Hw+55

    Both Jim Maccari and Vortek offer kits for the HW 55, which will include a spring, guide, and lubes. I’ve never used a Vortek but have had excellent luck with Maccari parts in the 55.

    The 55 used the very same receiver as the original HW 50 sporter (NOT the same as the gun now sold under that name). In the old days, the 55 was sold new with a target-shooting spring giving around 600 FPS, but a common upgrade was to use a 50 spring giving a boost of 80 or so FPS. Both Vortek and Maccari’s kits will give a power boost over stock.

    Unless it’s a very late production gun, it will have a leather piston seal. You can get conversion parts for plastic seals, but I’d keep the leather one if it’s in good shape. Depending on its age, the gun may have two, one, or none of the very thin breech shim washers shown in the HW 35 article. The leather breech seal is also a tricky animal to replace, but they hold up extremely well, I seldom have to fool with them.

    If you can tell me the gun’s approximate serial number, I can offer some more details. I am NOT an expert mechanic in general, but I do own, and have worked on, a stupid number of HW 55’s. PM me and we can chat by email if you prefer.

     

     

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    gmkmd
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    Thanks so much for all this information!  The serial number is 313205

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    MDriskill
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    Very cool. Manufactured in 1969, and likely imported by the original Air Rifle Headquarters in West Virginia. Would love to see some more photos!

    A few notes:

    Definitely a leather piston seal originally.

    Iffy on having breech shims. Those are nice to have, but hardly mandatory, make for smooth cocking and reduce wear to the finish on the sides of the breech block. But can be hard to get in there if not originally present. The HW shims are made in two diameters, you want the smaller one. May have to buy these from a dealer or importer.

    The sight rails on HW's made before 1978 or so are spaced wider apart (nominally 13mm) than on newer guns (11mm) – be aware when buying scope mounts. Take good care of the match sight, the older ones are harder to find!

     

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    gmkmd
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    Wow, 1969?  I didn’t realize it was that old. 

    My HW35 is 266356; do you know when that was made?

     

    I’m surprised to hear that the leather seals are actually more desirable (if they are in good condition).  How do you tell if they’re good, other than just looking at them? 

    What type of lubricant do you use on leather, that won’t deteriorate it?

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    MDriskill
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    Probably 1967 on your HW 35.

    Leather seals last basically forever with even the most basic maintenance, and like everything else on the HW 55 was carefully designed and fitted for maximum smoothness and accuracy; Weihrauch kept the leather seal on the 55 long after they had converted all their sporters to plastic. Plastic piston seals, in my opinion, have little inherent advantage in lower-powered guns like the 55, though many will disagree! Your 35 would originally have had leather too, by the way, HW changed the 35 to plastic in the 850000 serial range IIRC.

    The piston seal will be a cup shape with a hard rubber filler in the center, through which the seal’s attachment screw passes. If it looks good with no tears or divots and fits fairly snugly, it’s good.

    All that being said, I’ve converted a couple of older 55’s with trashed seals to plastic, and that works fine too. The HW 55 uses the same 25mm seal as the HW 30/R7 design. I think JG Airguns sells those, maybe also Vortek or Maccari, haven’t looked in a while!

    When doing a rebuild, I like to use 25-weight pure silicone oil (a good source is the shock absorber oil made for radio-control model cars). Soak the seal in silicone overnight, then dry up the excess (stand the piston on a paper towel for a few hours) and put some moly grease on the outside of the seal. Note, silicone is the best leather-to-metal lube, but TERRIBLE for metal-to-metal contact – soaking up the excess is important to keep it from migrating.

    A leather seal will need a drop or two of oil once or twice a year. For that I use the old Beeman Chamber Oil (a stiff mixture of silicone + some neatsfoot oil I think) or Beeman Ultra Lube (same with some moly powder added), applied with a needle through the transfer port.

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