# A military question. What can go wrong firing mortars? **URL:** \ **Category:** Factual Questions\ **Created:** [May 4, 2017, 5:13pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863 "2017-05-04T17:13:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 4, 2017, 5:13pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/1 "2017-05-04T17:13:14Z")
A photo has been released just as the mortar exploded (in the tube) and killed several soldiers. Mortars like this are common in war films dating back to WWII. I’ve been reading about the weapons company that supports the three rifle companies in a battalion. Mortars are one of the standard weapons they carry. > **[Weapons company](https://en.m.wikipedia.org/wiki/Weapons_company)** > > A weapons company, sometimes called a manoeuvre support company, is a company-sized military unit attached to an infantry battalion to support the rifle companies of the battalion. It usually possesses some combination of machine-guns, mortars, anti-tank missiles, anti-aircraft missiles, reconnaissance vehicles and, sometimes, assault pioneers (infantrymen specially trained in the assault role). > In the British Army, the manoeuvre support company possesses an Anti-Tank platoon armed with 8 Javeli... What are the risks with mortars. What can cause them to explode in the tube? Is it usually operator error? Are accidents with mortars common? This particular incident was a training exercise in Afghanistan. > **[Army combat photographer's last picture is of her own death](https://www.cbsnews.com/amp/news/us-army-specialist-hilda-clayton-takes-image-her-own-death-military-exercise/)** > > Army Spc. Hilda Clayton took a photo in the split-second between when a mortar tube accidentally exploded and the blast killed her > [@](#): > > A mortar tube accidentally explodes July 2, 2013, during an Afghan National Army (ANA) live-fire training exercise in Laghman Province, Afghanistan. The accident killed U.S. Army Spc. Hilda I. Clayton and four ANA soldiers. (This photo taken by one of the Afghan soldiers at the moment of the explosion.) ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [May 4, 2017, 5:31pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/2 "2017-05-04T17:31:38Z")
Military - dot -com has a [list](http://www.military.com/video/guns/mortars/top-10-mortar-fails/3595016149001) ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 4, 2017, 5:46pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/3 "2017-05-04T17:46:11Z")
Thank you Tranquilis I understand now that mortars can go wrong quite easily. ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [May 4, 2017, 6:24pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/4 "2017-05-04T18:24:38Z")
> [@Tranquilis](#): > > Military - dot -com has a [list](http://www.military.com/video/guns/mortars/top-10-mortar-fails/3595016149001) And I thought mortar crews had a relatively safe job on the front line. As you can tell, I have no idea about military matters. Shooting things, especially things that blow up, is never a safe occupation. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 4, 2017, 6:59pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/5 "2017-05-04T18:59:57Z")
[Early mortars were huge hunks of iron.](http://images.all-free-download.com/images/graphiclarge/gun_mortar_weapon_227471.jpg) Probably considerably safer using just black powder, but a jammed projectile could still turn into a big pipe bomb. Mortars are used for most aerial fireworks also, the projectile isn’t as heavy as a metal one but they do explode and the mortar itself can be a lot flimsier than the weapons. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [May 4, 2017, 7:37pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/6 "2017-05-04T19:37:43Z")
The main thing that goes wrong is the enemy now knows where you’re at … and starts shooting their mortars at you … ---
**Author:** ![Mr.Duality](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.duality/32/4098_2.png) [@Mr.Duality](https://boards.straightdope.com/u/Mr.Duality)\ **Post date:** [May 4, 2017, 7:46pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/7 "2017-05-04T19:46:52Z")
I was told that during the Korean War someone allowed a group of POWs to get too close to a US mortar position. One of the POWs launched himself at the mortar immediately after a round was dropped into the tube. The round exploded when it hit the POW. ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [May 4, 2017, 8:38pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/8 "2017-05-04T20:38:08Z")
> [@Mr.Duality](#): > > I was told that during the Korean War someone allowed a group of POWs to get too close to a US mortar position. One of the POWs launched himself at the mortar immediately after a round was dropped into the tube. The round exploded when it hit the POW. US mortar rounds of that era had what was called a bore riding safety pin, in addition to another safety you removed before firing. The bore riding pin would locked in place before the round was fired. When it hit the bottom of the tube and the propellant went off the acceleration would move a setback out of the way\*, and then the bore of the mortar would hold the pin in place (‘bore riding’) against a spring until it exited the bore, when the pin would fly out and the shell would be fully armed. Whether the pin would have time to fly out if somebody threw themselves right on the mortar’s muzzle? Maybe, but you know how it is with war stories. It was definitely possible though to set up a mortar too close to trees and have the round air burst over the friendly personal because it hit small branch on the way out. Modern mortar rounds generally have some more complicated forms of arming safety where the round isn’t fully armed out to some minimum range (of say 100 or more meters). \*in the final minutes of ‘Saving Private Ryan’ they were trying the trick of banging the mortar round very hard on the ground to get the setback to release the pin, then use the mortar round as a point detonating hand grenade. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [May 4, 2017, 8:45pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/9 "2017-05-04T20:45:12Z")
During my brief (three and a half months) peacetime mandatory conscription in the Swedish army some thirty years ago, I served in a mortar unit. We used [these](https://sv.wikipedia.org/wiki/Granatkastare_m/84). First thing, they’re just a steel tube made of rather thin (like about 7 mm) metal, so there’s not much between you and the round fired. Second, unlike the case with cannons, you do not have the opportunity to seek shelter behind the gun (or even better, behind a wall!) when they’re fired; you just have to crouch immediately beside it and hope to God it doesn’t explode. (Although the rounds we used were just for practice, and contained no HE, rather some smoke-releasing formula). And we were absolutely forbidden to use gloves (in winter time) when dropping the round into the mortar (it fires on drop, i.e. when it hits the bottom of the tube) for the danger of glove getting stuck to the round and following it down the muzzle… ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [May 4, 2017, 8:57pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/10 "2017-05-04T20:57:13Z")
Another deadly fault is double-loading. Two personnel are loading the mortar (higher rate of fire) from opposite sides of the tube. One round doesn’t fire immediately(bad primer, bore is fouled so insufficient impact on primer, build-up of propellant clips [older 60 and 81mm], wet propellant doesn’t ignite properly, slow burn [wet or deteriorated prop charge], crew gets out of synchronization); second crewman positions second over tube mouth and there’s real trouble. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 4, 2017, 9:06pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/11 "2017-05-04T21:06:00Z")
Double-loading may be what happened in this case. That was quite an explosion. ---
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [May 4, 2017, 9:26pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/12 "2017-05-04T21:26:14Z")
A few questions: 1. Why is the mortar fired by merely dropping a round into the tube? Isn’t that super dangerous? Why not have the round loaded, but not fired except by pulling a trigger? 2. Would a thicker mortar tube contain the explosion, or just make for bigger shrapnel? 3. If a glove gets stuck to the round in the tube, does it obstruct the round and cause it to only get out of the tube a short distance? ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [May 4, 2017, 9:57pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/13 "2017-05-04T21:57:08Z")
> [@Velocity](#): > > A few questions: > > 1. Why is the mortar fired by merely dropping a round into the tube? Isn’t that super dangerous? Why not have the round loaded, but not fired except by pulling a trigger? Some light mortars have triggers, and can set to either use the trigger or not. But considering the experience of muzzle loading individual arms, where IIRC one musket was found at Gettysburg loaded with 20-something rounds, a trigger isn’t going to necessarily insure safety from multiple loading. It might exacerbate that risk, though for hazards like the glove thing I guess it might help. Some mortars have also had mechanical anti-double loading devices on the muzzle, some Soviets ones did even back in WWII. And like most things preventing double loading (or a second round’s propellant detonating the first one’s explosive filler anyway) can now also be done more elegantly electronically. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 4, 2017, 10:24pm UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/14 "2017-05-04T22:24:06Z")
I’ve been reading about mortars. They can adjust the range by adding cheese charges. Rings that fit on the tail. [https://goo.gl/images/IC1Ur5](https://goo.gl/images/IC1Ur5) Here’s a small mortar with cheese charges added. [https://goo.gl/images/dSi63k](https://goo.gl/images/dSi63k) ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [May 5, 2017, 12:16am UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/15 "2017-05-05T00:16:05Z")
> [@aceplace57](#): > > I’ve been reading about mortars. > > They can adjust the range by adding cheese charges. Rings that fit on the tail. > [https://goo.gl/images/IC1Ur5](https://goo.gl/images/IC1Ur5) > > Here’s a small mortar with cheese charges added. > [https://goo.gl/images/dSi63k](https://goo.gl/images/dSi63k) Yeah, I remember those, but in our case they were not rings, more like packages like the individual bubbles in bubble-wrap, stuck between the wings of the shell. As I remember it, there was room for eight of them. At the command “charge five” we were supposed to remove all but five of them, and then wait for command to load the projectile into the barrel. (We did have a good bit of fun with the surplus powder!) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 5, 2017, 12:25am UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/16 "2017-05-05T00:25:14Z")
> [@Velocity](#): > > A few questions: > > 1. Why is the mortar fired by merely dropping a round into the tube? Isn’t that super dangerous? Why not have the round loaded, but not fired except by pulling a trigger? > > 2. Would a thicker mortar tube contain the explosion, or just make for bigger shrapnel? > > 3. If a glove gets stuck to the round in the tube, does it obstruct the round and cause it to only get out of the tube a short distance? 1. The whole point of a mortar is to have a relatively lightweight piece of equipment with a high rate of fire. Adding a trigger doesn’t help prevent malfunctions & slows down the process. 2. By the time you got it thick enough to contain a warhead burst it’d fail the “lightweight” part of its mission. 3. Any obstruction in any firearm from derringer to a 16" battleship gun tends to prevent the projectile from accelerating as planned. So the firing charge builds up excess pressure behind the partly jammed projectile which then bursts the tube or blows out the breech. To be sure, any weapon hurling explosives is more dangerous than playing with an eggbeater. But by and large, mortars are real safe precisely because they’re so simple. Don’t use damaged or dirty or expired ammo, keep it clean per procedures and you can send a lot of hurt a decent way downrange with one. ETA: Ref cheese charges. At least on US 81s, those aren’t additive; they’re subtractive. Each shell was shipped with a full set. You’d remove the ones you didn’t want to use from each shell before the drop. And yes, at the end of a firing day you’d have a pile of cellophane-wrapped “cheese slices” that were fun to dispose of. ---
**Author:** ![MichaelEmouse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/michaelemouse/32/101_2.png) [@MichaelEmouse](https://boards.straightdope.com/u/MichaelEmouse)\ **Post date:** [May 5, 2017, 1:53am UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/17 "2017-05-05T01:53:40Z")
> [@Tranquilis](#): > > Military - dot -com has a [list](http://www.military.com/video/guns/mortars/top-10-mortar-fails/3595016149001) Allah failed to akbar on a few of these. Lesson learned: If someone on your side both handles explosives and needs cosmic reassurance, give them a wide berth. Some mortars do use remote triggers which can be as simple as pulling a cord. Any idea why that option is there for some mortars but not others? What’s the CEP on average infantry-carried mortars? Even if simplicity is what they’re optimized for, have there been recent advances which add worthwhile complexity? Anything beyond the usual GPS/laser guidance? ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [May 5, 2017, 2:00am UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/18 "2017-05-05T02:00:14Z")
And to answer another question that hasn’t been asked yet - Yes, there are breech loading mortars. Link to Soviet 240mm mortar. Damn near a foot in diameter. And yes it did have a nuclear shell. > **[240 mm mortar M240](https://en.wikipedia.org/wiki/240_mm_mortar_M240)** > > The Soviet 240 mm mortar M240 is a 240 millimeter (9.4 in) breech loading smoothbore heavy mortar that fires a 130 kilogram (290 lb) projectile. > The mortar consists of a smooth-bored barrel with a breech and a breech-block frame, a frame with shock absorbers, mount with training and equilibrating mechanisms, a two-wheel traveling carriage with the suspension, a boom for changing from the firing to the traveling configuration, a baseplate and a towing bar with a lunette. The sights are carried ... Many armies in WWI had large caliber breech loading mortars to attack fortifications with high angle piercing shells. [240 mm trench mortar - Wikipedia](https://en.wikipedia.org/wiki/240_mm_Trench_Mortar) ---
**Author:** ![westhou](https://avatars.discourse-cdn.com/v4/letter/w/f1d935/32.png) [@westhou](https://boards.straightdope.com/u/westhou)\ **Post date:** [May 5, 2017, 2:38am UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/19 "2017-05-05T02:38:48Z")
I was Section SGT of 4.2" (107mm) Mortar Platoon in VN. We fired more than 100 rounds per week and only had one mishap with equipment and ammo. There are three types of propellant used in combination. There are sacks of gunpowder, bout the size of a coaster and thin C4 charges looks white cheese and about 3 inches square and i/4 lb shape charges of C4. You adjust the charges and the elevation to determine the range. When you have a fire mission there are 100s of these c4 charges laying around the mortar on the ground. The only mishap that we had( and there were only a few frag injuries because of it) was a short round. The charges ignited before the round bottomed out on the firing pin. We had been firing flares all night along with some HE. (High Explosive) in support of a Special Forces operation about 500 meters from us. The hot tube apparently ignited the charges, the round came out prematurely and was actually tumbling end over end. The tumbling apparently threw the safety pin out and the round hit the ground about 30 meters down range and exploded. We also had a Navy direct fire mortar that had a trigger, It was pretty much just point and shoot, it used standard 81 MM rounds like the Army’s smaller mortars. I only remember it being fired in anger at a real target two times. Small arms infantry in Vietnam were MOS 11B, mortarmen were 11C and both were used interchangeably. often in the same day. One cool? thing. our mortars were made by AMF, who at the time were mostly known for making bowling equipment and I think the owned Harly Davidson at one time ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [May 5, 2017, 6:35am UTC](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863/20 "2017-05-05T06:35:46Z")
M36A1 propellant charge for 4.2" mortar rounds. The “sacks of gunpowder” contain M9 flake propellant. The “C4” are actually M8 sheet propellant. They look and feel waxy a little like C4 but are very different. Nitrocellulose based. From the Army Data Sheets for Artillery TM-43-0001-28 (pdf - big but fun to have handy) [https://ia800300.us.archive.org/27/items/milmanual-tm-43-0001-28-army-ammunition-data-sheets/tm\_43-0001-28\_army\_ammunition\_data\_sheets.pdf](https://ia800300.us.archive.org/27/items/milmanual-tm-43-0001-28-army-ammunition-data-sheets/tm_43-0001-28_army_ammunition_data_sheets.pdf) A full charge consists of 36 increments of M8 sheet propellant and a doughnut-shaped bag of M9 flake propellant arranged in the following order: one bag charge, three 5 increment bundles, five single increments, two 1/2 increments, and three 5 increment bundles. This full charge is assembled on the cartridge as issued. Individual increments or bundles may be removed as required for fire adjustment as indicated in the appropriate firing charts, but the bag charge will not be removed at any time. [Next page](https://boards.straightdope.com/t/a-military-question-what-can-go-wrong-firing-mortars/785863.md?page=2)