I have been dithering for a week now about the pros and cons of publishing this piece at all, but after some serious editing I have decided (obviously) to go ahead with it.
Explosive compounds are a field engineer's best friend at least that is my view of these wonders of chemistry. Not only does the use of explosives help with field engineering projects, they are also a force multiplier in a tactical environment. I will not be giving any specific formulas for the construction of field expedient explosive devises nor the methods of explosive manufacturing in this article, rather I will be speaking about the usage of explosive compounds in the defense of a wilderness retreat (Section 1), the types of explosives and the implementation of good explosive safety practices (Section 2).
The use of explosives in the defense of a wilderness retreat, this is an academic exercise for me, but for my fellow warriors who have not had the pleasure of explosives training will hopefully find some useful information contained in this breakdown.
Situation: A remote retreat compound situated in a mountain canyon is threatened by an unknown force after civilization collapses.
Geography and Transportation Routes: The compound is located one mile up canyon from the confluence of three canyons. There are four routes into the confluence area, and only one road into the target canyon. All routes are electronically monitored ten miles out from the confluence of the canyons on each route
SOP for Engagement: It is concluded that engagement will only occur if there is no other alternative but to engage.
Prepared Plan for Unwelcome Visitors: All routes that can handle vehicles are precambered for Road Cratering Charges 2 to 3 miles from the confluence of the canyons and the Cratering sites have over-watch technology active. Close in explosive defenses are served by command detonated claymore style directional AP mines.
1-1. Characteristics. To be suitable for use in military operations, explosives must have certain properties. Military explosivesâ
A) Should be inexpensive to manufacture and capable of being produced from readily available raw materials.
B) Must be relatively insensitive to shock or friction, yet be able to positively detonate by easily prepared initiators.
C) Must be capable of shattering and must have the potential energy (high energy output per unit volume) adequate for the purpose of demolitions.
D) Must be stable enough to retain usefulness for a reasonable time when stored in
temperatures between -80 and +165 degrees Fahrenheit.
E) Should be composed of high-density materials (weight per unit volume).
F) Should be suitable for use underwater or in damp climates.
G) Should be minimally toxic when stored, handled, and detonated.
1-2. Selection of Explosives. Select explosives that fit the particular purpose, based on their relative power. Consider all characteristics when selecting an explosive for a particular demolition project. See Technical Manual (TM) 9-1300-214 for detailed information on military explosives.
Types of explosives available to Combat Engineers:
1-5. Block Demolition Charges. Block demolition charges are prepackaged, high-explosive charges for general demolition operations, such as cutting, breaching, and cratering. They are composed of the high-explosive TNT, tetrytol, Composition-C series, and ammonium nitrate. Block charges are rectangular inform except for the 40-pound, ammonium-nitrate block demolition
charge, military dynamite, and the Â¼-pound-TNT block demolition charge, which are all cylindrical in form.
1-7. M112 Block Demolition Charge.
a. Characteristics. The M112 block demolition charge consists of 1.25 pounds of C4 packed in an olive-drab, Mylar-film container with a pressure-sensitive adhesive tape on one surface (Figure 1-2). The tape is protected by a peelable paper cover.
1-8. M118 Block Demolition Charge.
a. Characteristics. The M118 block demolition charge, or sheet explosive, is a block of four Â½-pound sheets of flexible explosive packed in a plastic envelope (Figure 1-3). Twenty Ml18 charges and a package of 80 M8 blasting-cap holders are packed in a wooden box. Each sheet of the explosive has a pressure-sensitive adhesive tape attached to one surface.
1-9. M186 Roll Demolition Charge.
a. Characteristics. The Ml86 roll demolition charge, shown in Figure 1-4, is identical to the Ml18 block demolition charge except that the sheet explosive is in roll form on a 50-foot, plastic spool. Each foot of the roll provides approximately a half pound of explosive. Included with each roll are 15 M8 blasting cap holders and a canvas bag with carrying strap.
1-10. Forty-Pound, Ammonium-Nitrate Block Demolition Charge
a. Characteristics. Figure 1-5 (page 1-8) shows the 40-pound, ammonium-nitrate block demolition charge or cratering charge. It is a watertight, cylindrical metal container with approximately 30 pounds of an ammonium-nitrate-based explosive and 10 pounds of TNT-based explosive booster in the center, next to the priming tunnels. The two priming tunnels are located to the outside of the container, midway between the ends. One tunnel serves as a cap well for priming the charge with an M6 electric or M7 nonelectric military blasting cap. The other tunnel
series as a priming path, with the detonating cord passing through the tunnel and knotted at the end. There is a cleat between the tunnels to secure the time blasting fuse, electrical firing wire, or detonating cord. There is a metal ring on the top of the container for lowering the charge into its hole.
Explosives Handling and Safety:
Do not attempt to conduct a demolitions mission if you are unsure of demolition
procedures; review references or obtain assistance. Prevent inexperienced personnel from handling explosives. Avoid dividing responsibility for demolition operations.
Use the minimum number of personnel necessary to accomplish the demolitions mission.
Take your time when working with explosives; make your actions deliberate.
Always post guards to prevent access inside the danger radius.
Always maintain control of the blasting machine or initiation source.
Use the minimum amount of explosives necessary to accomplish the mission while keeping sufficient explosives in reserve to handle any possible misfires.
Maintain accurate accountability of all explosives and accessories.
Always store blasting caps separately and at a safe distance from other explosives.
Ensure all personnel and equipment are accounted for prior to detonating a charge.
Ensure you give warnings before initiating demolitions; give the warning "Free in the hole!" three times.
Always guard firing points.
Assign a competent safety officer for every demolition mission.
Dual initiate all demolitions, regardless of whether they are single-or dual-primed.
Avoid using deteriorated or damaged explosives.
Do not dismantle or alter the contents of any explosive material.
Avoid mixing live and inert (dummy) explosives.
Do not use blasting caps underground.
Use detonating cord to prime underground charges.
6-2. Explosive Materials.
a. Blasting Caps. Both military and commercial blasting caps are extremely sensitive and can explode unless handled carefully. Blasting caps can detonate if exposed to extreme heat (cook off).
Military blasting caps are more powerful and often more sensitive than their commercial counterparts. When using commercial blasting caps to detonate military explosives, ensure they are powerful enough to detonate the explosives,
requirements for caps from different manufacturers vary, never mix caps from different manufacturers; mixing caps could result in rnisfires. When installing caps in explosives, never force them into an explosive or a cap well; use an appropriate tool for making or enlarging the cap well.
Ensure 1/8 to 1/4 inch of the cap is clearly visible at both ends when taping onto detonation cord. Do not connect blasting-cap initiation sets to ring or line mains or charges when nonessential personnel are on site. Never leave blasting caps unattended before or after attaching them to the charges or firing system.
Use only authorized equipment and procedures when crimping nonelectric blasting caps to time fuse or detonating cord. Maintain blasting caps in the appropriate cap box until needed. Never store blasting caps with explosives.
Never carry loose blasting caps in your pocket or place loose blasting caps in a container; secure them.
Do not blow into a nonelectric cap or attempt to remove any obstructions from the blasting cap well. Remove obstructions that will dislodge by using the wrist-to-wrist tap method.
Never insert anything but time fuse or detonation cord into a nonelectric blasting cap.
Do not twist time fuse or detonating cord while attempting to insert into a blasting cap.
Never attempt to crimp a blasting cap installed in an explosive. If the blasting cap has come loose from the time fuse or detonating cord, remove the blasting cap from the charge, recrimp the cap, and then reinstall the cap in the charge.
Avoid striking, pinching, and mashing nonelectric caps during crimping activities.
Use only the M2 crimpers for all crimping operations.
When using nonelectric caps to dual prime demolitions, cut the fuse to allow an interval of not less than 10 seconds between firings.
Do not remove the short-circuiting shunt unless testing or connecting the cap. The shunt prevents accidental initiation by static electricity. If the blasting cap has no shunt, twist the bare ends of the lead wires together at least three times (180-degree turns) to provide a proper shunt.
Use proper grounding procedures when static electricity is present, see paragraph 6-5b.
When transporting electric blasting caps near vehicles (including aircraft) equipped with a transmitter, protect the blasting caps by placing them in a metal can with a snug-fitting cover (Â½ inch or more of cover overlap). Do not remove blasting caps from their containers near an operating transmitter unless the hazard has been judged acceptable. Keep electric blasting caps at least 155 meters from energized power lines. If using electric blasting caps near power lines, temporarily cut the power to the lines during blasting operations. Always use at least the minimum current required to fire electric blasting caps. Always check circuit continuity of electric blasting caps before use. Cover connections between blasting cap leads and firing wires with insulating tape, not the cardboard spool. Remove firing wire loops and, if practical, bury blasting wires.
b. Time Fuse and Detonating Cord.
(1) Time Fuse.
Always conduct a test burn of at least three feet for each roll of time fuse. If you do not use the fuse within 24 hours of the test burn, perform another test burn before using the fuse. Use M2 crimpers to cut time fuse. If serviceable M2 crimpers are not available, use a sharp knife to cut fuse. Be sure to cut the fuse end squarely. Make the cut on a nonsparking surface, such as wood. A rough or jagged-cut fuse can cause a misfire. Avoid cutting the fuse until you are ready to insert it into the igniter and blasting cap. To avoid problems from moisture infiltration, never use the first or last 6 inches of time fuse from a new or partial roll. Avoid sharp bends, loops, and kinks in time fuse. Avoid stepping on the fuse. Any of these conditions or actions can break the powder train and result in a misfire.
(2) Detonating Cord.
Do not carry or hold detonating cord by placing it around your neck.
To avoid problems from moisture infiltration, never use the first or last 6 inches of
detonating cord from anew or partial roll.
Avoid sharp bends, loops, and kinks in detonating cord. Avoid stepping on the cord.
Any of these conditions or actions can change the path of detonation or cause the cord
to cut itself.
c. Plastic and Sheet Explosives. Always cut plastic and sheet explosives with a sharp knife on a nonsparking surface. Never use shears. Avoid handling explosives with your bare skin as much as possible.
d. Picric Acid. Picric acid degrades with time. Do not use picric acid if its container is rusted or corroded. A rusty or corroded container indicates the explosive is unstable.
WARNING Do not handle picric acid. Notify EOD for disposition.
e. Commercial Explosives. Commercial dynamite is sensitive to shock and friction and is not recommended for use in combat areas. Do not use old, commercial dynamite because it is extremely sensitive and very unstable. Follow the procedures in TM 9-1300-206 or the manufacturer's recommendations to destroy aged commercial dynamite. When commercial dynamite freezes, it becomes covered with crystals and is very unstable. Do not use frozen dynamite. Commercial dynamite containing nitroglycerin requires special handling and storage. Rotate commercial dynamite in storage to prevent the nitroglycerin from settling to the bottom of the explosive.
Sources for the above information:
FM 5-25 Explosives and Demolitions (1967)
FM 5-250 Explosives and Demolitions (1992)
FM 5-104 General Engineering
FM 5-31 Booby Traps