Potato Mortars

Anyone ever made one here? Got any advice for a budding (no pun intended) potato mortar man?

For some reason I got talking about these with the RSM, now it has got him very interested.
Therefore I've been 'asked' to produce one in the near future.

Have seen various sites on the internet, but was wondering who has first hand experience...?


A mate of mine (ex-RCT) now works on the lorries was telling me one
of his co-workers (ex 3 Para mortars strangely enough) had made an orange gun.
Not the colour, this fecking thing apparently fires Jaffas nearly 1000yds using
hairspray type arerosols as propellant.

He went out with the bloke to do a test fire somewhere in North Wales & he was saying this
mad bar steward was aiming at sheep across a small valley & getting good groupings at
good distances. He could hardly speak on the phone as he was laughing so hard trying to
describe things.

Am still trying to track any manufacturing instructions to attempt a self build.
Will post here if i can 'obtain' them. The inventor is jealously guarding his idea
at present.

Start with a tiny amount of fuel. Too much and it won't work.
My mate owns a car breakers yard abd has been making giant spud guns from plastic down pipe for years. I actually witnessed a Spud ( Barn Piercing ) round go through an Asbestos shed at 80 metres! I can get the Spec of him for you?

1 x Monkey (not RMP) metal tube for driving in angle iron pickets (not royal anglians)
1 x Thunderflash with handle cut off
1 x Issue ball of green string (compo cans also fit)

Test fit ball of string / can in monkey
aim mortar tube (monkey)
light and drop thunderflash down monkey
drop ball of string down monkey

Ahhhh the joys of sapperhood
Pretty simple stuff

Plastic drainpipe. Choose caliber. Tennis ball size is good as it leaves fantastic welts if used in direct fire mode with said tennis balls as they tend to flatten out a bit on impact. Experiment with barrel length for range + accuracy.

Piezo bit off lighter for ignition of fuel with metal conductor inside ignition chamber. We used a nail.

Ignition chamber where the hairspray or similar propelent is introduced (we reinforced this with light steel but can be just plastic)

Hand held or whole hog baseplate-and-bipod your call.

All in all a good healthy project to get your teeth in to.

Hours of fun and games. HUNT THE GIMP! :D
Gundolph said:

1 x Monkey (not RMP) metal tube for driving in angle iron pickets (not royal anglians)
1 x Thunderflash with handle cut off
1 x Issue ball of green string (compo cans also fit)

Test fit ball of string / can in monkey
aim mortar tube (monkey)
light and drop thunderflash down monkey
drop ball of string down monkey

Ahhhh the joys of sapperhood
Swap the string for a smoke grenade and you have a real 'mortar', so much so that one lad I know was using it during and ex got RTUd for using live rounds!!!! Looked good though!

We have a REME Armourer who has one as well. We were firing it in Dartmoor over the summer, and got some good ranges and hits on sheep from it.
the reme boys in falklands had created a gas powered tube using cabbages wrapped in masking tape(!) funniest thing ever, seeing a spanner monkey calling out the shots as they landed, reporting one dropped penguin at a range of 150m. Priceless!
Indoor training device for aforementioned Potato Morttar...........the Map Tube LAW 66!!

1. Take 1 x issue map tube (not the big one), 1 x can of lighter fuel, a lighter and a selection of either a table tennis ball/shuttle cock/golf ball.

2. Sgts Mess bar during dinner night/exchange drinks/happy hour.

3. Select a No1 and No 2.

4. Remove end caps to map tube.

5. Designate one end as the breech/chamber and the other as the muzzle - do NOT forget which is which.

6. Squirt a liberal amount of fuel into the designated chamber.

7. Agitate the device = shake the feckin' thing about. This allows the fuel to become a potent vapour.

8. No 1 adopts a recognised LAW 66 firing position and selects target. Note: this should be the most humourless git in the bar.

9. No 2 loads projectile of choice into muzzle.

10. No 2 operates the lighter and gingerly waves it around the chamber.

11. Assembled company alternately carry out defecation drills and pointing/laughing at Humourless Git, who should now be semi-comotose on the floor of the bar.

Note: ITDU will not acknowledge any stoppage drills for this equipment. It has yet to be adopted for Land service.
You can make a real simple just by going to B&Q.

You need about 4 foot of tubing from a sink, the trap that fits underneath that catches stuff that goes down the plug hole, an electric BBQ lighter and a can of hair spray.

Attach the tubing to the plug hole end of the trap, insert the BBQ lighter into the hole on the side where the waste water would go out, I used some cork, glue and tape to hold it in and get a seal.

Get a potato and cut out a nice chunk using the end of the barrel so it fits nice and snug, push it down about 3/4 of the way with a broom handle.

Take the bottom off the trap, spray in hairspray for about 2 to 3 seconds and seal the trap as quick as possible, click the lighter and the poptato should come flying out the end.

We managed to get it to go about 30 meters with your average size trap, so the bigger it is the further it should go.

Great fun for a tenner.
I believe that technically these are regarded in law as being firearms, so there is the potential for it all to get a bit tricky.

'It's all fun and games till someone loses an eye'

That said, for purely academic purposes I would add that if using plastic drain pipe select ABS rather than PVC, since the former will not shatter whilst the latter may do :wink:
Jeremy Clarkson showed how to build one on the show 'Inventions that changed the world', I can't actually remember now, but if anybody can remember the show then there is your answer.
RAF Mess Cannons have always been of a larger bore - at times using cabbages as rounds.

Old catering size metal tins, bodge tape and imagination. Some friends were putting measured squirts of lighter fuel in, shaking it a number of times for the fuel-air mix, then using an old piezo-electric lighter to ignite.

Even funnier with beer as an extra for all participants! Cabbages for miles.
Re the baffles, if you halve the size of the aperture you double the pressure aproximately. The best way to achieve this is to cut out circles in the bottom of each can aprox. half the diameter of the can, in the middle of it. This however can lead to duct tape failure and an interview with the RMO without coffee, explaining why the better part of your hand is no longer flesh, merely bone and tin shrapnel.
The much easier version is to remove half of the base of the can , leaving a semicircle still intact. Whilst sticking together ensure baffles are rotated at 1600mil or 3200mil to the previous. The top 2-3 cans in say a 6 can mortar should be left open in order to load the projectile. Damp tissue paper can be used as a very succesful forward means of obturation to help increase pressure inside, however a good rammer is required to ensure a tight seal round the edge of the projectile.
To allow the propellant to be inserted a small hole should be made just above the base of the mortar on the side. I would suggest the use of plenty of the strongest commercial DUCK tape you can find to fasten the cans together, if you don't have an LAD with a welding expert, as this will provide the best results.


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