Is there a lot of velocity lost with the 9" tube over the 12"?  I have never had a 37mm launcher before and wonder if the short one would limit the shells I can make and velocity/distance of the flares/bird bombs etc.

No, there is not a lot of velocity lost. The 40MM launching system is not like pistol, rifle, or shotgun. It uses a "high/low" pressure system. I posted that here before. Simply put, the power form the launch is imparted to the projectile on firing of the lift charge. You would not gain velocity by having 3 more inches of barrel to travel down. Actually, you would lose (very little) velocity as the friction of the projectile traveling down the barrel is taking energy away from the projectile, unlike pistol or rifle rounds, where the more powder that burns in the barrel, the greater the velocity. Hope you understand that....

In easy terms, when you fire a 40MM round, the maximum pressure is inside the high pressure chamber of the casing (25,000PSI) is let loose through vent holes in the sidewalls of the high pressure chamber, the pressure inside the casing drops to 3000 PSI, the projectile then leaves the casing and engages the rotating bands inside the launcher barrel. The projectile is then pushed down the barrel by this pressure, and since the pressure is not building, but getting smaller, the projectile is not going faster through a 12" barrel, as opposed to a 9" barrel.

Some woman will tell you that size does matter, but in 40MM, it does not. GROG

37mm you mean?  Unless you have a DD, I thought it had to be a 37mm.  Does the swing out limit the size of the round or will it take the same length as the 12"

Most 37MM these days uses the high/low system also, especially if you are using smokeless casings. The swing out should not limit the size of the casing. GROG

Cool, thank you.. I love this site, and learn something new every time I come here.  You sound like you have fun with your launcher.  What kind of rounds do you make/shoot the most?  I saw a video of fireworks, and smoke.

The rounds I make and shoot the most would be a cross of buck/flechette and star cluster and para flare, and perhaps ground smoke bursts as well as muzzle blasts. They are all easy to reload, and fun to shoot. I've been doing a lot of R&D lately with a few manufacturers of 37-40MM casings and launchers, so I do a lot of reloading. I prefer smokeless casings due to power, and ease of cleaning and reloading. I hate messing with black powder, but there are those die hard BP fans out there that make the stuff on their own and such, and they love their black powder casings. For me, I shoot launchers at least once or more a week, so cleaning them is an issue. I used to enjoy it, kicking back, cracking open a few cold ones, and watching FMJ, cleaning the 79.... but it does get old when you shoot as much as I do, and with black powder, you must clean your launcher and casings completely and very soon after firing, or you get rust and corrosion. I like the smokeless advantage, of being able to leave launcher and casing dirty until I have time to clean them well. Some smokeless casings I did testing on I loaded over 15 times with the only cleaning being a wipe of the primer pockets and pulling off old RTV.

Hope that helps, GROG

Can you suggest me good quality reload-able cases, smokeless.  Sounds like you have a DD, and realize I can't load crazy stuff.  Well unless SHTF, than I would like to know the cases I had could handle the loads like you have.

You're best bet would be to check out Grog's website, any and everything you want to know about launchers & ammo will be on there. You'll have to register first.

http://grog101.forumco.com/default.asp

If you are looking for casings that will fire buck and flechettes, and come in both 37 and 40mm, I recommend the "CANNON" rounds from Scot Pace at reloadableshells.com. I helped design these casings, and for the money, they are the best on the market for delivering their payload at high velocities. If you are looking for flare/cluster/smoke or other pyro launching casings, I would recommend the thicker walled casings that Scot makes, using the vent plugs, and copper or brass burst discs.

http://www.reloadableshells.com/37MM-Cannon-Round-Destructive-Device-Use-Only-37MM-Cannon-DestructiveDevice.htm

http://www.reloadableshells.com/37MM-XD-High-Performance-Screw-Apart-Shell-402155.htm

They come in 40MM also, and, although pricy, they are built to last for a very long time, and are so easily reloadable.... you will have a LOT of fun with these casings. There are a lot of casings on the market, but if you want a casing that you can defend your life with, or bet your life on.... these are my personal choice.

I have several DDs, M79, M203, registered B&D 37MM EX-D...

As Jay wrote above, drop by my site for reloading info, and reviews of these and more casings, launchers, and other 37/40mm related items. GROG

http://www.freewebs.com/grog/

Stupid comment on my part.  Removed

That's a bad hypothetical to be discussing (or doing)...on many levels.  Cue pictures of bloody stumps and police raids.

It's not worth it.  Don't go there.

I was worried it would be taken that way, and I was one who did reg'd his guns in CT.  No desire to break laws.  I just wanted to know if this is a toy or had the potential.  I would never stick one at the bottom of an AR for that reason.  I will remove my question.  sorry.

Hey Grog,I would like to register on your forum. When will you be turning registration back on?

Same here. any chance of opening registration?

I am interested in registering as well IIRC I filled it out but was not approved.

MAHA

Open for new members now. GROG

Thanks

MAHA

Hi guys, randomly catching up on the nfa section this morning and clicked on the DD subforum which I usually don't read. This thread caught my eye...

I've always had interest in these things but never realized apparently how many loading options there might be beyond smoke and training rounds. I've got all the other nfa toys my state allows but a DD is something I would love to add to the collection someday...

GROG, I've requested to register at your site in hopes to learn more and perhaps jump into this area someday myself! :)

registered...won't let me in....

Same here. Guessing I didn't get the email (I checked my junk folder too) or I'm too unfamiliar to be granted access. :(

Grog, I have registered a total of three times without any response from your site. I have checked the spam mail and received nothing, what is going wrong here?