r/40_mm

CQB Ready

Haven’t seen any videos posted of this round. Wish the microphone did it justice. Happy 250th!!

Whats up guys, i just joined this group and i just finally ordered an LMT 40MM m203 receiver after a long time of missing the one i was issued in the marines(it may have been a colt 203). Anyway, i did some reading around in the group but inevitably im going to have some noob questions and hopefully someone can share some info with me. One of my questions is Can i shoot 37MM rounds out of my 40? Also will a 37mm barrel slide into my LMT 40MM receiver? Whats a good source for chalk rounds for training, and whats the coolest rounds i can buy short of HE or HEDP ? Id be interested in smokes and arial flash-bangs can i get those anywhere? (I have searched but honestly its not super clear and i want to be sure im going to the best place i can to get them which only someone with experience with 40mm stuff would know) This picture is of one of my M4s, with the 9” barrel i already had and its on a dummy receiver in this picture. I havent gotten my LMT yet should be here next week. Thanks!

Trying to dial in the right combination of components to load a bunch of deftec and ALS rounds back to factory spec.

Standard 25-30g foam batons are meant to go 315-345fps, extended range 400fps

Lots of things like vent hole size, and how much empty space is between the case and projectile affect muzzle velocity.

I’ve had great luck with the fiocchi blanks for getting standard velocity in just about any case with a small vent hole, 1/4 power boland for extended velocity in small vent cases.

Still need to try some fine tuning with various thickness burst disks and a good load for m212 cases.

Will work testing velocity for bean bags and rubber buckshot next.

Introducing the A.S.S. version 0.5. Its based on my previous sighting system; however, the mechanism has been redesigned from the ground up. Rather then using preset angles like all commercial sights, this base allows any angle from 0-25 degrees. Thats due to 3d printed ammo not having the same trajectories as commercial ammo. Over about 200 rounds I have found that 3d printed ammo shoots alot flatter then commercial stuff. If anyone has interest in making it, I'll be uploading the files on the sea under this username with a parts list from Mcmaster soon. As this is just a first revision, it's not the easiest or cheapest parts list. I will include .stls and .steps so people can remake it based on what they are able to source.

Well, they didn’t wait long to strike! They want me to pay a fine of $850 ($425 if I pay early!) The Beehives are not mentioned—just the inert M781 rounds! The regulation they cite me as being in violation of specifically states explosives and incendiary. Curious how inert fits into that…

Trying to recreate some of the “crushable OC/CS foam baton” rounds that law enforcement sometimes use.

Trimmed down foam golf ball to 40mm, used press and 30mm circle die punch to cut the middle out, filled with about 4g of talc powder before gluing the tip back on and gluing the whole thing to a plastic base.

It made a small but noticeable cloud on impact with the target. I’d like to find a more firm and brittle foam to try at some point which may perform better.

Transferrable mk19 and two China lakes. As well as a plethora of m203s and at least one m79

So whats the best method of removing these lifter charges. I mostly reload the aluminum def tech cases but recently came across a “few” of the CTS nylon ones. I assume a arbor press would work but is there any attachment thats made to push the lifter charge out?

Also where should I go to get lifter charges for these. The ones I buy for the def tech cases are different. Thank you.

Got a damaged case in a bulk by recently and just figured out what happened to it. Figured I’d make a post for anyone else to countering the issue in the future.

The case rim of 37mm is the same diameter as 40mm (thickness can vary) but the case walls are obviously narrower. This allows the 37mm case to tilt in the barrel enough to slip around/in front of the extractor in some launchers. Normally the extractor is positioned perfectly to catch the rim of 40mm when opened. When this happens the front face of the case extractor will ram into the back of the 37mm case rim and can bite a chunk out if you ram it closed like some cop seems to have done.

Have to open the launcher action, pull the extractor back/open as far as it will to and try to wiggle the case up/around the extractor.

Be careful loading 37mm dual use cases in 40mm, make sure the rim rests on the extractor properly when closing the launcher.

Pic 1: how it should look
Pic 2: how it should not look, care rim in front of extractor
Pic 3: side view of pic #2
Pic 4: pulling extractor rearward and trying to wiggle 37mm case out

The 2 extractor shaped chunks taken out of the rim are from someone slamming the launcher closed at picture #2