part0056

Here’s some info about the light .30-calibre machine gun that was used to sing Bo Diddley’s “Shave and a haircut, six bits,” up and down the MLR. My thoughts about it were and are: it was a special song when the “head space” was set correctly. The head space is the amount of space between the barrel and the “trunnion block” which was the connection to the barrel for the bolt-and-trigger assembly group. This space was for gas escape when the firing pin engaged the primer of the round; thus, if not set properly the gun would fire sluggishly or not at all. A gas-operated weapon. The magic instruction was, “When screwing in a new barrel tighten to finger tight, no more, no less, and then back off four full turns. Adjust after firing as needed from this basic setting.” A key component of the bolt-and-trigger assembly group was the driving rod and spring. The rod was a locking rod that held the trunun block-and-bolt group together. The spring was about 18 inches long when not compressed, and the rod was six inches and about a 1/4 inch diameter with a slot in the face end, like an open-face slot for a screw driver. The gunner had a sack or ammo can of tools one of which was like a screw driver for pushing in that driving rod and then GENTLY turning it one quarter turn to the right! If it slipped and failed to lock it would fly backwards about like a 22 calibre! You always set to one side of the rod when inserting it. A buddy missed the catch one day. Thank God it was daylight. We clawed around on hands and knees for an hour until we found it. We generally used the tip end of a Kaybar to depress the spring and driving rod. Care had to be taken as the knife point could slip. A quarter piece would have been great but who had a quarter? When the head-space was set correctly then that beautiful, well oiled gun sprang to life each time that trigger was touched or held down with a light squeeze. The “cover latch and plate” provided the protection over the ammo belt and secured it into place as the round was fed into the chamber. Care had to be taken to see that the belt of gun ammo was not twisted or kinked, which would then stop the gun from feeding and firing. The A Gunner (assistant gunner) was responsible for keeping the ammo clean and the belts fed properly. A fearful thing that all gunners dreaded was a cook-off round. This happened when the firing chamber became so hot it triggered a detonation of the round. This could seriously injure the gunner and ruin the gun. There were supposed to be two ammo carriers with each gun crew. The gunner selected the targets and fired until disabled. The gun would only fire when on “full cock,” which was the second pull-back of the bolt handle. The first pull-back set it on “half-cock,” which was a safety measure in preparation for firing, as it would not fire on half-cock. It also took less pull to yank the bolt handle back to full cock for firing after half-cock was reached. It was a chilling shudder that went through you when out on patrol in a pitch black night and you heard the “shunk-clink” of the bolt going back on a Chinese machine gun, knowing that he already had it on half-cock! It carried a special sound all of its own. For the gunner it was a reassuring sound of total authority as it was “locked and loaded,” ready to bring mayhem on whomever.

The barrel had a perforated steel jacket housing around it which helped provide air movement to help with the cooling when firing as well as it saved skin from eager hands grabbing a barrel when it was firing hot. On Outpost Dagmire I had a nearly direct hit from a 76-mm. that tore half that steel jacket away like a giant can opener! Every machine gun bunker on Vegas had a deep hole about a foot in diameter and twice as deep directly behind the gun. This was from Chinese gunners and snipers shooting straight through the aperture of the bunker after the gun crew. I have been in a gun bunker when the gunner used a bayonet on an M-1 rifle to depress the trigger of the machine gun due to the amount of fire coming through the aperture!

The machine gun is mounted on a steel tripod by a connecting mechanism called a “pendle latch” that connects the gun to the “T and E Mechanism” or Traversing and Elevation Mechanism. This enabled the gunner to preset targets by moving the barrel by mil clicks accurately engaging a target in the dark without being able to see it. These were used for establishing the “cone of fire” and “beaten path” or impact zone where all the slugs hit. This beaten path would then become a part of the machine gun pattern of defensive fire for that hill, each gun interlocking if at all possible. If not interlocking then riflemen and barmen filled in between to lay out a wall of fire for assaulting enemy. A good gunner could hold the fire to single shots. A gun took on a special life of its own when it was being fired in rhythm of short bursts of four to six rounds and then longer ones of twice that. This nursed the life of a barrel from becoming burnt out. When things got really bad a gunner would sometimes unlock the T & E and go “free gun,” swinging it manually just trying to keep them off his position. Barrels would sometimes get so hot they were red for most of the length and the gunners desperately had to keep punching a round though as they cooled down just to keep the barrel from closing in on itself! I have done that. It is a fear beyond description to watch your very life, or the thing that has the best chance of keeping you alive, slowly melt away, knowing there will not be time to change barrels! This was the story of our gunners on Vegas and all the other overrun positions. The gun even starts to sound like it is hurting! It loses that lethal, assured “chong” that it maintains when the trunun block is hammering home to strike the cap of the round in the gun belt and send it spiraling down those lands and grooves of the barrel with such haste to kill the enemy storming up through the flare lit night. Oh, how I felt for Woody and Mac and the others that first night on Vegas. The response of that ignition in a single round when fired from that linkage belt was so reassuring to me. I felt like I could fire it forever and it would never fail me.

Mortars are made up of four parts, the base plate, bipod, barrel, and sight. The 81-mm. various parts weigh between 28 and 35 pounds apiece with the exception of the much lighter sight. The 60-mm. pieces weigh between 12 and 17 pounds. The mortar is an indirect fire weapon. It is best utilized from a defilade position, behind a hill or in a gun pit where the gun teams are protected from enemy fire. There is considerable “hang time” after a round is fired, which leaves the gun crew vulnerable to enemy fire. The gun is sighted by a compass used by the gunner or by use of an “aiming circle” typical of the 81s. Fire is adjusted by a forward observer, FO, and through aiming stakes in line with the target. The mortar round is an aerial bomb with a nose which when striking the ground detonates the charge. In flight it is guided by fins, which give it a spiral, thus stability and accuracy. The barrel does not have lands and grooves to provide that accuracy. Around the center of the mortar round is a narrow plastic ring. This is called the gas ring, and it is also essential to perfect flight. As the mortar round passes down the tube of the barrel, a shotgun-like cap at the center of the fins hits a firing pin fixed into the bottom of the mortar tube, much like a rifle firing pin. Once the cap sparks, it ignites a circle of powder-filled “waivers,” increments, cotton bags filled with powder that are hooked around the mortar round fins by metal hooks. Instantly, the ignited powder bags and increments create a flux of gas, which creates pressure behind the round trapped in the barrel. The gas ring then expands creating an airtight seal. The mortar round with all that pressure behind it seeks the path of least resistance, and we know it as “outgoing” or “incoming!” The range of the mortar can be adjusted by two things, the angle of the barrel and the number of increments or powder bags. The barrel can be moved left and right or up and down with the T & E Mechanism like the machine gun. Other times the gunner will hold the barrel with a gloved hand, replacing the T & E Mechanism with himself, sight down the barrel and hold it steady as the assistant gunner drops the round in. A term “Danger Close” is when the round is fired with barrel nearly vertical to engage enemy troops closing in and the round is propelled generally by just the blasting cap or maybe one waiver increment. The general effective casualty radius for the 81 is 35 meters and for the 60 it is 20 meters. The illumination round is designed to break in half in mid-flight. A high candlepower flare ignites in the end of the round, and a tiny parachute pulls out from the other half of the round. The rounds also deliver the effective WP (willy peter) round.