Haenel 303 strip and rebuild.
An auction buy in .22, this rifle falls into the medium springer class. Outwardly it looked good with no obvious damage. It shot fairly well but was only producing c. 400fps on the chrono so a strip was in order. This guide explains the basics of the strip plus a few tips but does not cover replacing the piston and breech seals as mine were in excellent condition. You will need a spring compressor to keep control of the action. You will also need a ‘pronged tool’ to insert into the compression tube and around the trigger unit in order to take the strain off the system when removing the mainspring.
I am aware that the design of the 303 changed slightly during its lifetime so this guide may not cover all variants; it will however, cover most issues.
Remove the stock: two screws at the forend and two in the trigger guard. There is a trigger adjusting screw in the guard but you do not need to remove this. When removing the stock, note the disc sitting in the underside of the stock in the forend. This is to prevent the cocking arm rubbing on the wood. Do not lose it. Some variants have a spring under this disc. Mine did not. Note the spring fitted to the end of the safety bar; the cocking link nudges this spring to automatically set the safety on cocking.
With the action on the bench on its side, barrel to the left, note a plastic endcap housing the safety catch. Remove the pin through the end cap then turn the safety catch through 90 degrees and pull the end cap and safety away from the action. Turning the catch like this allows it to free from the safety setting bar that sits on top of the trigger housing.
In front of the trigger is a large disc with a bolt head on top. Remove the disc and lift the safety setting bar over the trigger. Do not lose the spacing washer. You will note a small flat plate in front of the trigger and under the safety bar. This plate forms part of the mainspring retention system. On my rifle this plate came away with the safety bar, leaving the mainspring retained only by the trigger pivot pin. So if it appears firmly fixed, do not remove it before placing the action in the compressor.
Place the action in the compressor and insert the pronged tool into the end of the cylinder. Tighten the compressor to just take the strain of the mainspring. Now remove the small plate and the pin that goes through the action and the trigger unit. Juggle the compressor setting until this pin can be removed easily and let your drift pass through the action to keep the trigger in place. With the pin removed, grip the trigger and its spring so as to prevent the spring pinging away and pull your drift out. The trigger plus spring will come free. Note that one end of the spring has a long leg that fits into a groove within the trigger sear. Release pressure on the compressor and the mainspring and guide can be removed.
The articulated cocking link will slip away from the slot in the piston without having to split the action at the breech. The piston can now be removed, examined and repaired as required.
This is a good time to examine the plastic pad held in the cocking arm; it prevents the arm rubbing on the underside of the action. It had worn down on my rifle and some rubbing was evident. The pad can be removed by simply levering it out. I made a new one but it would be possible to shim the old one so that the plastic surface was just above the cocking arm edge if needed.
The mainspring fitted was a replacement (22 cm long) and as the piston and breech seals looked fine, I assumed it had gone soft so prepared a replacement from a standard Meteor spring. Initially I cut it with two extra coils but this was a mistake as it became coil bound. I found that the 22cm length was the critical length ... any longer became coil bound.
Reassembly is a reversal of the process: add piston, spring and guide. With action in the compressor and using the pronged tool, compress the spring and guide until the slot in the guide that the small plate under the safety bar fits into lines up with the cut out in the action. Replace the small plate. The holes in the action cylinder that take the trigger pin will now be lined up with those in the guide sides. You can now refit the trigger. Initially I did this before fitting the trigger spring as it was easier to align the holes in the trigger mechanism with those in the action. Tip: use a small screwdriver to hold the sear in position in the trigger unit as you replace the unit in the action. I used a drift to fit the trigger first then tapped the pin through, knocking the drift out on the way. You then need to fit the trigger spring. Locate the leg on the spring in the groove on the sear and the spring on the peg on the trigger unit. Then compress the spring to fit the end over the small peg on the action. A bit fiddly.
Alternatively you can fit the spring into the trigger unit and then locate the end of the spring over the peg in the action as you lower the trigger into the action. You need to compress the spring as you do so, keeping a firm grip of it between thumb and finger. By looking through the holes in the action you can easily see when the trigger unit is correctly positioned to allow a drift to be inserted to secure the trigger in place. Then add the pin, knocking the drift out in the process. With the pin and plate securely holding the mainspring, you can remove the action from the compressor.
Add the safety bar over the trigger. Make sure the spacing washer is in place within the safety bar slot and add the disc/bolt. The safety bar should slide back and forth quite nicely. Take the safety catch and end plug and replace into the action, making sure the safety catch is at 90 degrees to allow the catch to enter into the cut out in the safety bar. Secure the end cap with the pin. You may need to rotate the end cap in order to align the holes to allow the pin to be inserted.
Replace action in the stock. I found it wise to keep the trigger pulled as the trigger guard and trigger adjuster was replaced; this keeps the trigger out of the way of the adjuster until the guard is fitted.
And now a tale about the mainspring. Having replaced the mainspring with one of identical length and specification I found no change in performance. Remember that my spring was c. 22 cm long and verging on coil bound. I began to cut the original spring back just to see what effect it would have. Having removed about three coils to give a length of c. 19cm I was delighted to see that performance increased by about 70fps to give me an output hovering on 8 ftlbs. I can only suppose that a previous owner had tried to increase performance by adding a longer mainspring; an action that backfired somewhat.
Cheers, Phil