37mm reloading.
Materials:
I suggest going to a local photography store, and picking up a bag of their used/empty film cannisters. Black with grey lids. You will require 1 canister, and 2 lids per shell.
These are a perfect fit for your 37mm aluminium hull cases.
Get some Federal 209 shotshell primers
Get some FFFg blackpowder.
Get some 1" flat washers.
Get some white flour.
Get some blue or red roofers marking chalk.
Process:
1. Clean out the shells, use a punch to knock out the old primer from the inside out. (I think a 3/16" punch worked on mine)
2. Insert new primers, I used a vise to slowly press them into the cases.
3. Measure between 45-60 grains of FFFg blackpowder (I usually went with 55 gn) and pour into the case.
4. Take the "extra" grey 35mm film canister lid and push it in on top of the powder, with the inside down. (so the smooth side is facing up towards the mouth of the shell.) This seals in your powder, and acts as wadding.
5. Take your 35mm film canister, put in 2-3 large flat washers to provide some weight. Fill full with white flour, then tamp it down, and add a teaspoon of roofers chalk on top. Place the lid on the canister. This is your completed projectile.
6. Place the canister into the shell with the grey lid facing up. It will be a snug fit, so ease it in smoothly so that the lid doesn't pop off the canister.
7. Take the the range and fire.
Expected results:
About 25% of these will have the canister fail partway down the range resulting in a big poof of flour and chalk in mid-air. COOL.
About 70% will go between 100-150 meters, and will burst on impact, giving a clear mark (chalk and flour) as to where you hit.
About 5% will land gently enough that they will not burst.
After firing, you will be able to go downrange and recover most of the flat washers for re-use.
You will also be able to recover most of the grey lids for re-use.
A couple of notes on firing the Cobray.
1. Check that your firing pin is cocked before loading the launcher. If it is not, you may end up inadvertently firing as you snap the breech shut. (This happened to me once.)
2. When test-firing new loads, do not place your hand on the handguard portion of the launcher. When firing under-slung on an AR-15, I kept one hand on the rifle's pistol grip, and used the other hand to fire the Cobray.
A suggestion.
Consider finding (or making) a stand-alone launcher for your Cobray. I ended up making MUCH more use of mine when I had it stand-alone and not on a restricted AR-15.
Here was mine. I sold it a while back. Good fun though.
NS
