In the workshop

One of the most popular rifles in the excellent Weihrauch stable is the HW99S – a break-barrel designed with the weight- conscious in mind. It bears all the quality hallmarks that have made this German brand so popular in the UK, but has shed a few pounds in order to attract those who find Weihrauch’s traditional models a little on the heavy side. At just 3.2kg, it’s become very popular with young guns, women… and those shooters not built like doormen.

The rifle that’s come into my workshop is down for a V-Mach tuning kit, and the owner has also asked me to rectify an issue he has with the gun’s cocking linkage dragging unnecessarily along the cylinder; it’s a problem I’ve seen before and easy to remedy. Indeed, the HW99S is a fairly easy rifle to strip, requiring minimal tools, and nothing more than general DIY ability. You will need to grind down a hex wrench to help remove the trigger block from the action, however.

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Unscrew the front and rear trigger guard screws and the large screw on the underbelly of the forend, and lift the stock free from the action to be put out of harm’s way while you work on the action. To completely remove the one-piece trigger unit from its housing [1], tap out the front pin – and provided they haven’t already made a hasty exit, extract the safety catch bar and small tensioning spring from within their end block.

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On the HW99S, the trigger sits in a block that’s locked into the action with four square plates, two either side of the trigger [2]. These have to be removed using a small hexagon wrench (Allen key) that’s had its short arm shortened even more on a grinder – or you can cut it of with a hacksaw [3]. This is so that it will fit inside the slot in the trigger block.

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To get the first plate out, put the shortened hex wrench into the hole fromt he inside of the trigger block and then push against it witha  large, flat-blade screwdriver to allow the plate to simply push out [4]. WIth the locking plates removed from one side of the action, you can then push a parallel punch through the hole and tap out the plates ont he opposite side [5].

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However, before you take the last plate out, here’s a workshop tip. Because the trigger housing block is under tension of the mainspring, it could – once all four plates are removed – rotate enough to unhook itself from the retaining lug and shoot out. To avoid a potentially dangerous accident like this, screw the front trigger guard bolt back in a few turns [6]. That way, if the housing should rotate, it won’t be able to break free as the bolt will be holding things in place.

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With the trigger unit and all four locking platest removed, place the action into a spring compressor or sash cramp and adjust so that it’s ready to take up the tension. Like other guns I’ve stripped in my column, the HW99S benefits from a suitably-sized insert in the end, to help release the trigger housing. I use a BSA pistol seal, which happens to be a perfect fit [7].

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Remove the ‘holding’ bolt you’d previously put in and then take up a little tension on the compressor. This will allow you to rotate the inner trigger housing so that the lug unhooks from the cut-out slot in the cylinder [8].

You can then carry on undoing the compressor until the mainspring’s tension is fully released. The whole action can then be removed and the trigger housing block, mainspring and its guide can be removed from the cylinder.

Next, the barrel and cocking linkage needs to be disassembled from the cylinder. With a large, flat-blade screwdriver, remove the barrel axis lock nut and the spring washer (arrowed) that’s on the right hand side of the action [9]. 108Then, tap open the barrel and unscrew and remove the axis bolt. This also has a spring washer, but it often sticks inside the axis bolt hole – so check before you lose it.

With the axis bolt removed, the barrel will slide out of the breech jaws, along with the metal shim washers that sit between the jaws and breech block [10]. I tend to make a note of which way round they’re fitted so that I can replicate it on reassembly – being under high load, they tend to ‘form’ into shape. Do this by placing them back onto the breech block and either re-fitting the axis bolt while the barrel’s being stored out of the way [11]… or by passing through a cable zip-tie.

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Once the barrel and breech block assembly is slid out of the jaws, you can also pull the cocking arm linkage toward the cut-out at the front of the cocking slot and then lift it completely free from the cylinder.

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Put a screwdriver into the cocking slot and gently ease back the piston until it can be extracted from inside the cylinder [12]. The HW99S is now stripped and ready to be degreased. Next month, I’ll cover polishing, lubrication and reassembly – including how to solve that dragging cocking linkage problem.

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4 comments on “In the workshop
  1. rubydog says:

    HI, were is part 2of 99s stripdown?

  2. PT says:

    Hi, Did you just give up? Where’s part 2 please

  3. The Editor says:

    You will need to check in to the June 2013 issue of Airgun Shooter, a digital copy of which is available from http://www.pocketmags.com. Search “Airgun Shooter”, and then download the June 2013 edition.

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