The pics and load data y’all have posted makes me want one.

I googled them they seem kinda high.

I was going to build this for my RV85. Spotting charge small enough to stay away from being a DD in its own right.

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That probably the most impressive thing I have seen a Arfcomer draw up on CAD in a while. Good job.

Have you had a chance to make any yet?

What would be the charge weight?

And what brass are using in the base?

That design reminds me of another 26.5mm round with a percussion "detonator" and a simple safety...

The "26 mm Wurfgranate Patrone 326 Leuchtpistole"



Looks like a rimless version of the usual .38S&W blank, so, a 9x19mm. Charge weight on something like that would depend greatly on the finished projectile weight, intended range, etc., but likely no more than 3-5gr Bullseye or similar, much as 40mm, and 37mm, and many 26.5mm loads use... although the RV-85 would be capable of withstanding quite a bit stouter charge than most...

I drew this up 8 years ago on a whim.

No, i got hit by a drunk driver right after drawing it up 8 yrs ago and I'm still recovering.

You mean the payload charge weight? I don't remember off the top of my head. I could have to find the Solidworks models and open them up to get the measurements again.

At the time scott Pace had just come out with his reloadable high low pressure cases and was going to use them. He still sales then at reladableshells.com I believe.

I also considered an alternate of the design where as the firing pin was spring loaded and as soon as the round cleared the barrel and the fin unfolded the firing pin set off the cap and would light a smoke charge giving you a smoke round in flight.

I'm praying that you have a different user name elsewhere, and that this isn't that common a story for engineers.

Yeah its me. BTW I'm still on Grog's site as well.

I've been doing some work for recreating plastic parts for guns that are impossible to find these days and having them 3D printed.  Printing up this projectile would be easy and pretty cheap to boot. I have not gotten around to F1 my RV85 yet sue to the previously mentioned issues. But if the round was loaded with smoke then it would not make the RV85 a DD as far as I know (not a lawyer or ATF agent). It would hopefully just be an accurate smoke round. Replace the chalk with smoke compound and a fuse train instead of the bursting charge and it would set it off when it landed.

ETA - BTW I have looked and I can not find my original SW files on the design. I'm now thinking that I actually did the work while in the hospital and my lap top died losing a lot of info. It would not be that hard to redo it though.

Add a creep spring to the firing pin and it should work fine. Might have to add some weight the firing pin also.

Those that have F1 a RV85 whats your thoughts on doing a F1 on a 37mm launcher?

The cost of the RV85 is pretty high now $1.5K.

Was thinking that a 37mm with a F1 might be a fun 1.5 gauge or conical lead bullets. My only question is which 37mm launchers have the highest rated chamber PSI?

Looking on gun broker there are a number under $600 that look pretty sharp.

Really like the tac-M79.
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The federal gas guns look pretty neat as well.
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A whole lot of people have 37mm DDs, right along with 40mm DDs and 26.5mm DDs. There are some launchers stronger than others, with some simply not being worth paying $200 tax. The TAC-D, TAC-M79, TAC-79, and TAC-D pivot are all quite strong. The Spike's underbarrel launcher is also pretty good, but uses 1018 in place of 4140.

The older items, such as Defense Technology and Federal Laboratories, really vary a lot in strength, construction, chamber dimensions, etc. There's still no standard for 37mm chamber dimensions or case dimensions, so do your research before buying much of anything. No sense buying a great deal on cases if they won't fit the launcher you intend to buy, and so on.

ETA: I should have also addressed this.

This isn't a good idea, unless your idea of fun involves throwing the single, large bullet at a very low velocity (200FPS or so). You just won't be able to stand the recoil, even if you were able to push the bullet hard enough. Just like with the lack of chamber dimension standardization, there's no SAAMI-spec on pressure. It varies from model to model, manufacturer to manufacturer, it even varies over time as the different models undergo revisions. I've got a bunch of 37mm launchers, and some of them are visually similar only... even though the manufacturer is the same, and the model is the same.

Summarizing, a 37mm shotgun/slug gun is going to either be underwhelming (if safe, lower velocity loads are used), explode (if it's not strong enough to withstand a high velocity load), or drive itself clean through your shoulder (if it's strong enough to propel a 11.57oz/5061gr bullet to, say, 800+FPS, it's going to have recoil beyond fierce). You'd be happier with a different launcher and 40mm "Cannon" round, or a 12ga adapter in 37mm.

Yeah I figured a sold conical would be a no go. I was thinking more along the lines of a RN with a deep hollow cavity base. I guess like a mini ball. Even at that it still maybe to heavy. It would need to be lite as possible but still maintain that RN look.

Wonder if one could make a reloadeable steel 37mm case that would take much of the initial chamber pressure and reduce the case capacity. Where it would be easy reloading with trail boss of black powder. Just fill it up and glue the lead bullet on top. I think 800 FPS would be all id want. And that may kick too much.

What type of rounds do you fire out of your DD 37mm?

Reached out to the guys who make the tac series of launchers. He emailed me and said it would be best if I called and talked about it. I’m perfectly open to scratching that idea all together. So we will see where it goes.

Mainly wanting a fun DD Stamped and easy to load for and play with.

A giant Minié ball would be close to the weight of a sphere, so the same 5000gr or so worth of lead. You really don't want to fire any solid bullet of 37mm at 800fps, unless it's rubber or polymer, and even then you're looking at 520gr or so for 95A polyurethane. Depending on what you're firing it out of, you're looking at recoil energies similar to that you find with a .338LM rifle. There's a reason shoulder-fired ordnance doesn't have both high velocity and large bore, unless it's a recoilless type.

The chamber pressure isn't your only concern - there's something called bolt thrust, and frankly, 37mm and 40mm launchers just can't take huge amounts. The entire system from the ground up isn't made to take that sort of abuse. You could indeed design a case that's easy to reload, and safe with a given amount of a particular powder/bullet weight, but you're overthinking things. If you need a special case with a "sub-chamber" made of steel, you really don't want to be firing that out of a 37mm bore, off your shoulder.

I tend to mainly just use my 37mm launchers for signal flares on Independence Day. I've got 40mm for the fun stuff, and primarily I fire chalk rounds and 12ga through adapters.

Just talked to Ed at Ordnance Group. I sent him a email yesterday and he responded back with his cell number. He was very nice and pretty much said the same thing as you. He stated that some guys have F1 his launchers but he has no idea what they are firing or loading for them. He also said they have not done any formal PSI test on his launchers. Said they are not really intended for anything like I was wanting to do. He did say that guys have fired 3" magnum 12 ga out of them with no issues but he also said that they are not built to with stand that and failure maybe 1 shot away. He did say that a number of law enforcement agencies are using his launchers. Think he said thy were firing bean bag rounds.

Have you made any polymer bullets for your 37MM?

Also what 40MM options are out there. I am somewhat open to anything reasonably priced.

Unsurprising! It's the sort of question I've answered dozens of times... even though it's "firearms-like", signal launchers aren't guns and have very few standards across the industry. For 40mm launchers, they're generally made to take 40mm grenades and nothing else, so any other use is on the owner, not the manufacturer. Reloads, 12ga adapters, etc., may or may not work out for you, in the long run, but firing M781 all day long is just fine.

For my 40mm, yes, but the same principles apply. None of them are cheap, it either takes money to buy spheres of a given material or time to turn the raw stock , but my favorite tends to be the sort of thing I can just lop a length off, face to length, and chamfer. I've fired an awful lot of solid cylinders over the years, and they're fun for me. I also very much enjoy the usual M781.

For 40mm launcher options... pretty much only used rotary/break-action launchers, or M203s. Very few producers of 40mm launchers will sell them to anyone but an agency (direct) or the military. I also don't know what "reasonably priced" means, in your case - but please keep in mind that large bore DDs aren't budget friendly. It's part of why so few people own anything past a DD registered 37mm launcher. Even the 40mm launchers, which are just about the cheapest LBDD option there is, tend to be $5+ to fire with anything other than 12ga.

I have a Form1 20x102 cannon I built. I used Mike Riker's breech, a vulcan 20mm barrel, an M2 tripod and a bunch of redneck engineering to make it. There's a thread on it in this forum.

20mm reloading components are fairly easy to find and it costs me about $5/shot.

Entire gun weighs in around 200lbs (I haven't added fake armor to it yet). Breaks into 2 pieces now and fits in a truckbed (6ft gun).

We took it to TFAST this past weekend. Shot about 40 rounds through it (all the good brass I had, time to order more).

you need to be careful
fed labs launcher and high pressure do not mix

https://www.wcvb.com/article/large-projectile-launcher-explodes-in-swat-officers-hands-during-training/19684880

Edit.