Ammo instruction page

Line launching cartridge

37mm and 40mm

Invented by GROG

By GROG Copyright 2003 3LC Productions Inc


Here are the parts of the 40mm line launching round. From left, One of Brassman's plastic wads with penny, one felt wad, the projo with steel eyehook, kevlar line and D ring and 2 endcaps, and 40mm "greenie" casing.


Here's what it looks like assembled and ready to go. Simply remove the tape, uncoil the line, insert the D ring down the launcher barrel, close the launcher, and hook the D ring to your launch line. The projo can be painted bright orange to aid in visibility. (This is an experimental round, so not finish painted.


This is going to be an instructional page for several methods of making a line throwing 37mm and/or 40mm round. These rounds have various uses. One such use would be to throw a line to someone in distress from a vehicle or helicopter. Some circumstances in which you would want to use such a round would be attempting rescue of stranded individuals in floods or on mountain sides, otherwise inaccessible to normal rescue procedures. The 37/40mm series of launchers can be used in such instances to propel a thinner line to the target, then a stronger rope should be used for the rescue. Another use would be for launching antenna line through thick jungle or tree canopy, to aid in radio signal reception and transmissions. I recommend the use of smokeless blank 38 short colt or 38 special in the launching of these projos. Reason being, the potential use in, around, or near water or bad weather. Black powder is not a good propellant to use around water, as it absorbs moisture and could cause round failure. I have tested the following rounds with positive results. I will start with the most successful design I have come up with.

The first design uses the following items and can be used in 40mm launchers:

1. One 40mm aluminum casing (5" length) that is available from Brassman Brass, and is manufactured by MK Ballistic Systems

2. Two plastic end caps available from my home page.

3. One piece of aluminum 37mm casing tubing approx 4-6" long.

4. One piece of wooden dowel that fits into the 37mm tubing above.

5. One steel eye screw.

6. Orange paint.

7. Kevlar or other type of strong thin line (approx 2' length).

8. One "D" snap ring that will fit down your launcher barrel.

9. 200' length of Kevlar or other type of strong medium line (for launch line).

10. 200' length of strong rope for rescue line with larger "D" ring attached to holding end.

11. 1 thick felt and 1 plastic wad (available from Brassman) for interior of casing.

Here's how the round is made:

     Reload the 40mm casing by first knocking out the primer plug. Replace the primer in the plug, and using a small cardboard wad, seal the internal venthole with the cardboard wad, and measure out 5 grains of Bullseye Pistol Powder. Using a small thin piece of kevlar line or similar, use it to tightly insert the primer plug back in the casing. (The line is placed beside the plug, then the plug is tapped into place). The casing is now ready for the wads and projo. Using one of Brassman's plastic wads, I cut one side so it's flat, then tape a penny to the bottom, centered over the wad. (This will save your plastic disc from being melted by the lift charge). Then load in the 1/2" thick felt wad. On to the projo:

     To construct the projo you will need to use gorilla glue (no other glue!) and glue one of the the flat end caps into one end of the 37mm aluminum tubing. (Score the interior of the tubing with a wire brush so the glue will stick). Let harden overnight. Then measure and cut your wooden dowel so that when inserted into the aluminum tubing it leaves enough room for the top endcap to be placed on the end and glued. Next, do just that. Glue the top endcap in place. The basic projo is done. I put mine in a vise overnight to keep the gorilla glue from pushing the endcaps off. When hard, you will need to drill a very small pilot hole into one of the flat end caps, to insert the steel eye hook. Do so. (Use a larger stronger eyehook). I then painted the whole projo bright orange, to aid in visibility. (Easier to find after launch!) That is basically the projo section. Next, you will attach the short thin piece of Kevlar line to the eye hook using a modified hangman's noose knot. Make a loop in the other end of the line and knot it twice (About 1" apart). Attach the "D" ring to this loop. Slide the line to the nosecone and using a small piece of masking tape, tape it into position so it comes off the projo towards the front. When using 40mm casings, it is easier to load the projo into the casing, as it fits right inside. (You may wrap a few turns of electrical tape to make the projo snug. You need to do this to aid in launching. If you try a launch and get poor distance, tighten the projo up, and it will help).  Once the round is finished, it can be loaded into a launcher "D" ring first, then the launcher is closed and the "D" ring is snapped onto the medium line, that is coiled in front of you, ready for launch. Make sure the other end of the line is attached to something (NOT you or your launcher) so when you launch it, one piece remains with you while the other is propelled with the projo. When aiming, make sure you aim well over your intended target. Be cautious of electrical lines and rotor blades!!! Rotor wash will effect the trajectory of your round. If you intend to use this round on a semi regular basis, practice using it from the vehicles you will be employing for rescue purposes, so you can adjust your aim accordingly. Once fired, attach the strong rescue line to the large "D" ring on the end of the medium line, and, making sure the other end of the rope is securely attached, pass the rescue rope to the target via the medium line.

Here's a diagram of the round:



This is the best type of round for multiple applications.

37MM Line Launching Round

Invented by GROG

The 37mm round can be used in the same applications as the 40mm round. It is made in much the same manner, however a different type of casing is used, and an extra end cap and bolt is used. Here's a photo of the finished 37mm round:


Notice the stepped rim casing, can be used in either 37mm or 40mm launchers. Also, the two endcaps put together with a nut and bolt to assemble the round. The projo end may be painted bright orange to aid in recovery. Also, holes may be drilled in the projo body, and a small mini chem light inserted to make an illuminated projo!

Here's a photo of the parts:


Notice the two endcaps with bolt. Easy to assemble round! Use a wire brush to score the inside of the old casing, then gorilla glue all parts into it.

That's pretty much it for the line launching projos! They work very well, and can be used in a number of rescue and communications applications. The reloading video I'm workin on will show both of these rounds in use! GROG