The steps shown here, while specific to the Rowan Engineering unit for the Weihrauch HW 100, are fairly typical of the type of work you’ll need to carry out on your own gun should you want to fit a new blade.
Fitting one is a simple enough job as long as you take it slowly and keep a note of where everything goes. It’s a great idea to take a series of photos with your phone before you start, and whenever you remove or add a particular part. However, if you are not absolutely sure that you have the experience to carry out the job safely, take your rifle to a gun shop, where it can be done by an experienced gunsmith. If you do want to go ahead, here’s how to fit the Rowan blade. Rowan’s own instructions can also be found online.
Gather the tools you’ll need. The trigger blade comes with a 2mm Allen key, in addition to which you’ll need somewhere to work on the rifle, tools to remove the action from the stock, a pin punch and mallet, a pair of tweezers, some masking tape and a small block of soft wood or pencil erasers.
Make sure the gun is unloaded and uncocked, then remove the action from the stock.
Note the location of this small spring and unhook it with your tweezers. Remember to take photos of the orientation of the various components you’re working on as you go. Don’t put any more tension on the spring than is absolutely necessary to unhook it.
Punch out the pin holding in the original Weihrauch unit. Tape round the pin with masking tape to stop any unnecessary damage should your punch slip. Brace the rear of the trigger unit with your wooden block or pencil rubbers.
Remove the original blade, mounting lever and screw. You’ll need to reuse this screw when installing the replacement blade.
The Rowan blade can be fitted in two positions: upper and lower. The default position is upper, but if you want it in the lower you can unscrew it from the post, flip it round and reattach it the other way.
Attach the Rowan blade to the mounting lever. The blade can be adjusted for reach and angled to make it connect better with the pad of your finger. These adjustments can be made now, but it makes more sense to fine-tune the blade when the rifle is back in its stock.
Fit the new blade and mounting lever. Line up the holes, then insert the pin from the same side you punched it out. You probably won’t need to hammer the pin back in: just press it firmly home.
Reattach the spring. It doesn’t matter from which side you hook it, but you do need to make sure it’s the right way up. Again, take care not to stretch the spring any more than you have to.
Test the new trigger by dry-firing in a safe direction. Even if no other adjustments have been made, the trigger will certainly behave differently and may even feel lighter than before.