Reloading 40mm Chalk Rounds


Back when I ordered my M203, chalk rounds were about $5 shipped. When I got it, it took me a bit but I managed to buy a crate at $7 shipped. Still it is getting harder and harder to find these rounds. So, like many shooters shooting expensive ammo, I am going to reload.

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Chalk rounds are pretty simple. A blank, a case, a pusher, a cone, and chalk.

First, I have to punch out the old blank. On some of these cases, the blank came out easily. Others not so much. There is some sort of black sealant uses on these cases that made it kinda tough to get out.

At first I used a brass punch. After that failed, a few minutes on the lathe got me a stainless steel punch. The narrow diameter is about .01 smaller than a quarter inch. I started using a press to punch out the blanks.

Note the black sealant
Black sealant everywhere
Fired blank next to an unfired blank

Maybe I shouldn’t call this a blank. It might technically be an “impulse charge”, but that is semantics. I’ll keep these spent “impulse charges” as they can individually be reloaded. I bought mine from Gunbroker.

The replacement blanks can easily be pressed into the case. I didn’t bother with adding any new sealant for these reloads.

In the middle of reloading
The cones press on to the zinc pushers, the pushers can be pushed by hand into the case.

At the moment I am lacking cones. I am wondering if I 3d print if those would hold up to the firing.

Reloading the chalk rounds is very easy. Getting the components is the hardest part.


  1. Wish I was still in. When we did M203 qual there’d be dozens of those things left unbroken downrange. We’d police them up and just huck them in one of the 55gal barrels set up as targets. And the cases went straight into the dumpster, our ammo guys never took them back as “residue” and DRMO ultimately never wanted them.
    I’m sure 3D printing would work fine given the right resin. I know some of the 37mm guys find the right size of Easter eggs at the craft store to use. It might be worth looking into silicon molding too.
    Do you have to use some type of sealant or adhesive on the projectile to keep it seated in the case?

    • People would either laugh, cry, or get outraged if they knew about how much stuff we burned up, threw away, or buried so that we wouldn’t have to turn it back in.
      The zinc pusher fits the case snugly. While they are sealed in factory ammo, I’m not going to bother to seal mine.

  2. I know some people have found surplus cones on the market, some have used modified easter eggs, and others have 3d printed them. Are you on Grog’s forum by chance? That place is a wealth of knowledge for 37/40mm reloading and the 3 cd set of loading info is a fantastic resource for 37/40mm reloading. Exotic Firearms and have a ton of reloading supplies, and both could point you in the right direction for cones. I’m still stuck with my 37mm DD launcher and have had good luck with small easter eggs as well as some of the all plastic projectiles I have. Hopefully this year I can get a LMT 40mm though with the way my finances look it’ll probably be next year, but I’m glad I’ve had my 37mm launcher to practice on different load types.

    • I used to call LMT the best deal in M203s. Keep an eye out on DSA, when they were selling contract overrun M203s, they were much cheaper.
      IIRC I was on the old Grog forum. I’m, not on the new one. Last time I tried to join they were not allowing new members.

      • I just joined the new one a few weeks ago, I’m about nervous about a DSA anything after the issues they’ve had with FAL receivers. I know LMT isn’t going to put out a product consistently out of spec.

          • I’ve seen and heard of fewer problems from LMT than from DSA, DSA has put out a lot of bad FAL receivers, something that is supposed to be their specialty. That’s why surplus Imbel FAL receivers have jumped up to $650 a pop because there’s a way lower chance of them being wrong than DSA. Sadly, while DSA’s customer service has gotten a hell of a lot better than back in the day, there are still plenty of their rifles that get put out that don’t work. Jump on the FAL Files forum and you can see the pictures and videos of DSA’s issues, while I’ve been semi lucky with their products, they don’t exactly inspire the confidence as LMT does.

  3. I have a quantity of genuine blue plastic 40mm nosecones and other components that I would consider selling, if there is any interest among enthusiasts . . . .


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