DIY BULLPUP!

Bullpup Conversion Kits

The editor highlights an intriguing step-by-step conversion.

I recently witnessed two conversions — both done without any help from me. Using only hex wrenches and a spanner, my sausage-fingered, technically bereft friend actually turned his HW100 into a fully functioning bullpup. Then another friend, whose loathing of the bullpup format had always put him firmly in the “doth protest too much” category, finally came out and admitted his liking for the current wave of foreshortened rifles — or at least for this particular one.

It was satisfying to see, and I almost resisted the urge to say “I told you so,” but sadly, having any class at all has never been one of my strong points.

THE BAR BULLPUP CONVERSION KIT

The product at the centre of these conversions is exactly that — a conversion kit. It costs £299, is supplied exclusively in the UK by Blackpool Air Rifles, and it’s remarkable in its simplicity and effectiveness.

A clever man in Ukraine who goes by the name Craftsman Vit is the producer. His company makes kits that allow almost anyone to turn a standard rifle into a bullpup in around 10 minutes — or very close to it. No fuss, no special tools, no drilling, and no modification of any component. If you can remove your rifle’s stock, you can do this BAR conversion.

As this issue goes to press, conversion kits are available for the Air Arms S510, Hatsan AT44-10 and BT65, Benjamin Marauder, and Weihrauch HW100 and HW100K. More kits are being developed — check the BAR website for updates.

WHAT’S IN THE KIT

I used the HW100 version for this test and, like the others, the kit includes:

• a walnut bullpup stock with an integrated trigger guard,
• a replacement barrel clamp / scope rail and stock screw,
• an extended trigger linkage,
• plus a shim, washer, and nut.

At first glance I thought the walnut stock had rosewood tips at the fore-end and the base of the grip — but that contrast actually comes from a durable staining process, not added timber. The grip panels feature an overlapping scale pattern with wave forms at each end, and the drop-down pistol grip carries finger grooves on its front face. It’s a pleasing piece of furniture.

Now let’s use the BAR conversion kit to turn a standard Weihrauch HW100 into a bullpup.

STEP-BY-STEP CONVERSION

1. Make sure the rifle is unloaded. Remove the HW100’s scope and stock screw, then separate the action and stock. Also remove the charging port plug and silencer.
2. Slide the replacement barrel clamp / scope rail carefully over the barrel and air reservoir, with the trigger linkage to the rear, until the forward clamp sits over the raised section of the air reservoir. Line it up perfectly and lightly tighten the two hex-head grub screws.
3. Insert the provided metal shim between the rear clamp and the air reservoir, then lightly tighten the grub screws.
4. Fit the threaded trigger fixture at the end of the extended trigger linkage over the trigger blade, place the supplied washer over the threads, and screw on the nut using finger pressure only.
5. Place the action into the stock and check the replacement scope rail is perfectly vertical and the trigger blade correctly positioned. When satisfied, lift the action out, tighten all fittings securely — but don’t over-tighten.
6. Finally, fit the bullpup stock using the extended screw provided, and replace the scope, silencer, and charging inlet. That’s it — your rifle is fully converted.

BEFORE YOU START SHOOTING

Depending on your build and shooting stance, you may need to adjust the height of your scope. I used an MTC Connect scope, which has virtually no eye relief and required a reach-back mount. However, I also tried standard scopes in medium and high mounts and they fit perfectly.

The whole point of a bullpup is improved ergonomics, balance, and pointability — so don’t compromise by having your head out of position. Take your time to get everything comfortable and natural. This is essential to get the best from any rifle — especially a bullpup.

A COUPLE OF ESSENTIAL EXTRAS

BAR supplies two optional extras for their bullpup kits — although one of them is, in truth, essential. If you’re going to invest in a kit, add the extra £9.95 for the synthetic cheekpiece.

This simple slide-on component transforms the connection between stock and face. It fits the HW100’s existing scope mounting rails and is secured by a pair of grub screws. Get one — you’ll be glad you did.

The second extra is the biathlon cocking handle. These are 3D-printed for BAR, cost £24.95, and are worth every penny. The vertical handle “finds” your fingers as you sweep back to re-cock the rifle. It’s a simple grub-screw fitting that takes seconds and works flawlessly.

TALKING TRIGGER FUNCTION

Bullpup trigger systems have always been challenging due to their “remote” nature, where the trigger blade must activate the actual trigger via a linkage. If that link isn’t well-designed, the trigger feel can quickly turn notchy, spongy, or downright harsh — a disaster for accuracy. So I always pay special attention to trigger performance.

TRIGGER PERFORMANCE

Honestly, when I first saw the extended linkage in the BAR kit, I had my doubts — but I was wrong. The BAR team knows what shooters want and they test everything to exacting standards. The HW100 bullpup’s trigger displays all the two-stage precision of the original rifle — no loss of sensitivity, feel, or control.

I did detect a tiny bit of resonance from the extended linkage during firing, but a micro-dab of grease at the linkage joint solved it completely. And yes — the HW100 trigger retains all its original adjustment options post-conversion.

ON THE RANGE

Unusually for a rifle test, the rifle itself isn’t on trial here — we all know what the Weihrauch HW100 can do for accuracy and consistency. This time, all attention is on the new handling dynamics of the BAR bullpup.

It’s a true bullpup — not just a converted rifle. It shoulders naturally, like it was designed this way at the factory. The balance point sits just behind the trigger, and with an all-up weight of 9.9 lbs and overall length of 31 inches (including silencer), it’s effortless to bring on aim and hold steady.

The geometry makes it feel lighter in the shoulder than it is in the hands — so you get the stability of a 9 lb rifle without the fatigue. Add that biathlon cocking handle, and it’s a winner. I’d recommend every HW100 owner fit one — bullpup or not.

VERDICT

If you’re a bullpup shooter, you’ll love this rifle. It’s stable, compact, easy to convert, and — let’s face it — good-looking, which counts more than most of us will admit.

An adjustable buttpad would be a welcome addition, and if BAR’s 3D printer has any spare capacity, that’s where it should go next. But in terms of handling and shooting, this conversion is an outright winner.

If you already own a compatible rifle, this £299 conversion kit is far cheaper than buying a top-end bullpup new. I’ve done the conversion, tested it, and it’s clear why Blackpool Air Rifles can’t keep up with demand.

If you’re thinking of joining the bullpup crowd — give the boys at BAR a call, and they’ll convert you.