Pyrotechnic Plunger Project

Building A ‘Bomb’ From Stair Railing
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The end result is the perfect complement to Will’s vintage PIAT launcher.
Being made of wood and toilet parts, it’s about as inert as you can get.

Did you know a deftly wielded Projector, Infantry, Anti-Tank (PIAT) bomb — a not-well-regarded British anti-tank weapon — actually saved the D-Day invasion?

The British 6th Airborne Division and other units landed in Normandy behind the beachhead early in the morning of June 6, 1944 to capture area bridges in order to stall German reinforcements. Everything went relatively well until the brits heard the clank of tanks approaching.

Taking his PIAT gun and two remaining rounds of ammo, SGT Thomas “Wagger” Thornton blew up the lead Panzer in a choke point and prevented the follow-on armor from reaching the bridges so tenuously held by the lightly armed paratroopers. SGT Thornton’s fortitude and coolness under fire effectively stopped the German armored counterattack from reaching the invasion beaches. It is not hyperbole to say this one shot by this one man from this one gun potentially saved the D-Day invasion.

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The PIAT was actually a spigot mortar. This spring-driven rod
has a firing pin on the end that shoves up into the projectile.

The Weapon

At 34 lbs., the PIAT was a truly monstrous thing. The PIAT was actually a spigot mortar. It used a powerful spring to launch a 2.2-lb. projectile assisted by a propellant charge in the base of the round. The maximum effective range of the gun was listed as 115 yards against point targets and 350 yards against the area sort. Tommies who used the gun in combat claimed it was only really good out to about 50. In combat, one in four rounds failed to detonate. However, for all its faults, the PIAT accounted for more German tanks destroyed during the Normandy invasion than did Allied fighter bombers.

Literally, nobody on the planet needs a PIAT gun. You can’t shoot it, and the thing is as heavy as a late-night philosophy discussion in a freshman college dorm at Berkeley. However, after reading Stephen Ambrose’s telling of the story in his superb book Pegasus Bridge, I just had to have one. I eventually found a nice example on GunBroker.com.

PIAT guns on this side of the pond are rare, but de-milled PIAT ammunition is unobtanium. I poked around for literally decades looking for a PIAT round to go with the cool British anti-tank weapon in my collection, and always came up dry. The British actually call these things PIAT “bombs.” Then, while on a long-anticipated vacation to the UK with my wife, I walked into an antiquities shop in London and heard angels singing.

There behind the glass counter was a WWII-vintage deactivated PIAT bomb at a decent price. However, the moment the proprietor heard my American accent, he told me to put my credit card away. He explained that it was literally impossible to get deactivated ordnance through customs to the States. I briefly considered trying to sneak it onto the plane home, but my long-suffering bride intervened. Spending the next 20 years in a British prison lacked appeal.

When the exigencies of life and the ignorance of the uninitiated conspire to prevent me from adding a PIAT bomb to my personal militaria collection, I saw no other alternative than to retire to my workshop and craft my own.

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With the top of the round complete, it was time to build the fins.
You can roughly cut the sheet metal bits with tin snips.

The warhead for Will’s PIAT round began life as a
wooden stair baluster from Home Depot.

Technical Details

The heart of my homebuilt PIAT bomb is a wooden stair rail baluster from Home Depot. This thing set me back maybe four bucks and was already kind of round. I used a stick of PVC scrap for the body and crafted the fins and stabilizing ring out of scrap roof flashing riveted in place. The fuse started out as a broken toilet bowl plunger.

I have made wooden models in my workshop for decades. They always start out as a diagram downloaded from the Internet. Translating the diagram into a physical object takes a little basic math.

I start by establishing a single cardinal dimension for my final product. In this case, it was the diameter of the warhead. I then carefully measure the same dimension on my diagram and divide the real number by the diagram number. This gave me a unique ratio I could jot down on my diagram or my workbench. With this as a basis, I can measure anything I want on the diagram, multiply it by this ratio, and determine how big to make the component. Using this same basic idea, I have crafted literally countless boats, ships and airplanes out of white pine lumber. As the geometry of the PIAT bomb is fairly uniform and predictable, this becomes a pretty straightforward chore.

To craft the warhead I removed the mounting screw from the baluster, chucked it up in the lathe and shaped it by hand. Once the warhead was roughly the right shape, I polished it up on the lathe with sandpaper and set it aside.

I measured out the fuse in the same manner and turned it down from the broken dowel that had previously been the handle to a toilet bowl plunger. This wood was fairly soft and easy to work. Once this was complete, I carefully drilled a hole in the base of the fuse and the top of the warhead. By gluing a small length of dowel in place, I joined these two components, rotating them until the geometry seemed right.

I turned the base of the warhead to be a slip fit for the inside of the PVC pipe and secured it in place with a sheet metal screw. I ground the head of the screw down with a bench grinder so it didn’t look so lame. Then it was time for the fins.

Roofing flashing is an underappreciated hobby material. My kids and I built two complete sets of Lorica Segmentata or Roman Legionnaire’s armor out of the stuff as homeschool projects when they were young. The metal is fairly soft and easy to bend using a vise and hammer but do take care. Those edges can be razor-sharp. You can cut it with tin snips or a cutoff wheel on a table saw after marking the desired shape with a Sharpie.

The original PIAT bombs had four fins. I used three, so it wouldn’t get so cluttered. I used a protractor to draw a compass rose of sorts on my workbench, with each leg separated by 120 degrees. Then by carefully setting the PVC pipe in the middle, I could mark off the location where each fin should be. I used a center punch to site the holes for my drill press and secured everything in place with pop rivets.

Don’t let the pop rivets intimidate you. A cheap rivet tool costs $4.99 from Harbor Freight and will last you a lifetime. I sized everything via trial and error. If something doesn’t fit, just throw it away and make another. Roofing flashing is just dirt cheap.

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The warhead for Will’s PIAT round began life as a wooden stair baluster (above) from Home Depot. The finished round (below) ready for painting looks undeniably crude.

Ruminations

I picked a Mk IV HEAT round and painted the bomb accordingly. I first painted the whole thing blue, masking off the stripe, and then painted the whole thing yellow. You then mask off the larger stripe and paint the whole rig olive drab. The spray paint came from Walmart.

My first OD coat went on when it was below freezing outside and subsequently cracked. This disappointed me at first. However, a further coat of OD sealed everything up nicely, and the cracks underneath make the round look old. As such, it is a perfect mate to my vintage PIAT gun. Half an hour touching everything up with water-based acrylic brush paint from Walmart finished out the project.

An afternoon spent in my horribly cluttered workshop conjuring a makeshift PIAT bomb out of literal garbage was inimitably satisfying — and I didn’t have to see the inside of a British jail!

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