Weihrauch HW 100 X Bull-Pup Owner’s Guide

The HW 100 X Bull-Pup is a compact PCP rifle built around a bullpup layout, where the action sits back inside the stock rather than in front of the grip. 

This guide covers filling the cylinder, loading and cocking the magazine, adjusting the trigger, and the maintenance habits worth building in from day one.

How Do I Fill The HW 100 X Bull-Pup With Air?

The cylinder has a quick fill port, so you can top it up while it’s still fitted to the rifle, connect your fill probe directly to that port. The cylinder can also be unscrewed and filled separately using the 250 bar adapter if that suits your setup better.

Either way, fill slowly, watching the manometer gauge as you go, and stop once you reach the maximum fill pressure. Always release any pressure left in the fill line before disconnecting, since trying to pull a pressurised fitting apart while it’s still under pressure can damage the seals.

What’s The Maximum Fill Pressure For The HW 100 X Bull-Pup?

The HW 100 X Bull-Pup takes a fill of up to 250 bar. Never exceed this, as Weihrauch is explicit that filling, using or storing the cylinder above this pressure risks personal injury.

That’s separate from the seal damage that comes from filling too quickly, which is why both matter, fill to the right pressure, and fill slowly.

How Do I Load The Magazine?

Load pellets into the magazine one at a time, seating each one flush in its chamber.

Slide the magazine into the receiver until the securing slide locks it into place, and always check it’s seated properly before cocking.

What Calibre Does The HW 100 X Bull-Pup Come In?

The HW 100 X Bull-Pup is manufactured in .177 (4.5mm), .20 (5.0mm) and .22 (5.5mm).

If you’re still planning on getting one, check with us on current stock before ordering, since not every calibre is always held.

Once filling and loading feel routine, the trigger is the next thing worth getting properly set up.

How Do I Adjust The Trigger On The HW 100 X Bull-Pup?

Because the trigger mechanism sits further back inside the stock on this model, you need to remove the stock to access it.

Start by checking the rifle is unloaded and decocked. To take the stock off, knock the pin behind the pistol grip out to the right, then unscrew the screw in front of the trigger guard and lift the pistol grip unit away. From there, undo the two stock screws and the stock comes off, giving you access to the trigger. Putting it back together is just the same steps in reverse.

With the stock off, there are two adjustment screws. Screw A sets the travel to the letoff point, turn it left if you can feel any creep as you take up the trigger, or right if the shot breaks with no felt resistance at all. Screw B sets the overall trigger weight, turning it right makes the pull heavier, left makes it lighter.

If the trigger unit itself ever gets fully detached from the frame rather than just accessed for these screws, it must go back in uncocked. Reinstalling it cocked can cause the trigger to malfunction.

It’s not a five minute job the first time you try it, so if you’re not confident stripping the stock down, it’s worth having your dealer handle any trigger adjustment for you rather than risking a misalignment.

What Do I Do If A Pellet Gets Stuck In The Barrel?

Whatever you do, don’t chamber a second pellet behind it. Put in an empty magazine, cock the rifle and fire towards a safe backstop, which sorts it out in most cases.

If it’s still lodged, take the magazine out, open the action, and work a cleaning rod in from the muzzle end to push the pellet back towards the breech, where it can be removed through the open action. If there’s more than one pellet jammed in there, leave it and get the rifle to a gunsmith rather than risking the rifling by forcing it further.

If you’re at all unsure which direction to push, stop and get a gunsmith to clear it instead of guessing.

Any Tips For Better Accuracy With The HW 100 X Bull-Pup?

A soft rest makes a real difference, a sandbag under the front stock works well, and never let the barrel bear weight against anything hard. Work the trigger through smoothly rather than jerking it, and keep your sight picture on target for a moment after the shot fires rather than lifting off straight away.

It’s also worth testing a few different pellets in your particular rifle, since accuracy can vary noticeably between brands, heavier, well made diabolo pellets tend to be the safer bet.

How Do I Clean And Store The HW 100 X Bull-Pup?

Always make sure the rifle is unloaded and decocked first. Wipe the exterior and stock down with a dry or lightly oiled cloth.

If it’s going to sit unused for a while, vent the air cylinder down first rather than leaving it under pressure, roughly every 20 fills or if it’s been sitting for four weeks or more, and store it somewhere dry and out of reach of children.

With the fill, load and trigger routines sorted, the Bull-Pup gives you the same PCP performance as a full length rifle in a noticeably shorter package, worth the extra bit of care around the trigger housing.