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unclesam
12-10-2006, 02:12 PM
Well here is something that is just too interesting not to share.

Has anyone ever heard of a full auto airgun?Apparently this is not a toy, and they are giving the plans away for free.Maybe someone like Launchpad or junkyard blacksmith could do a build. ;D

http://www.instructables.com/id/F93HKE2RLQES9J51EX/

unclesam
12-11-2006, 02:10 PM
heres a pic of the prototype.

http://www.thehomegunsmith.com/pics/caselman-mg.jpg

LaunchPad
12-22-2006, 01:26 PM
sounds interesting. I'll look into it but it won't be a quick turn around with all the other pokers i have in the fire. :)

LaunchPad
12-30-2006, 02:12 PM
ok, i've been studying the plans. They leave a lot to be desired. So today i started putting them into a 3D CAD program (Solidworks) to sort out a lot of missing details and see if this is actually a reasonable use of my time.
(I am stuck indoors due to the Colorado Holiday Blizzard so looking to keep busy)

I already have a few ideas for improvements over the original design- perhaps a few of these can be worked into my project list ??? (multiples take a whole lot less time than building individually- maybe sell a few to pay off mine??)


However,

If you guys don't want to see this thread disappear or for me to keep updating it- it will have to become sticky.

Reasons is: i am military and frequently get called for some "issue" that takes me away for bits of time. some long, some short. A simple 4 month deployment without a computer connection will see this thread disappear once it goes over 60 days old and no new posts.

billy_goat_gruff
01-01-2007, 02:36 PM
I'm not much a fan of auto anything but will help keep the thread alive.

I'm more a fan of the Girandoni system which was semi-auto. Here is a photo of the book on making that system...
http://www.bryanandac.com/images/EngBook.jpg

There is also a manual on construction of air canes. The books are imported according to the company at the website, and last time I asked about buying one from the guys at the website they said they were out. Cost too much for what they were selling them for... I let it drop at that point...

Back to auto, saw a website once that had an auto feeder for .177. It looked like the pump symbol in a schematic. Memory says the air entered at a 90 to the barrel, picked the bb's up and carried them to the barrel exit. Might not work too good with heavier balls, or with softer metal such as lead ball.

There is a 100 shot bb auto at the fairs in this area. Looks like a Thompson on the outside. Don't have a clue as to how the trigger mechanism works, but it does spit out bb's as long as the trigger is held, well, till the 100 rounds are expended.

unclesam
01-08-2007, 04:14 PM
We will help keep the thread alive Launchpad .

LaunchPad
01-09-2007, 08:58 PM
thanks you guys rock.

We have a nother big storm heading our way this weekend. Ifi cannot get out to the shop but still have electricity i may have enough drawn digitally to post images of the workings.

I'd rather get caught up on things in the shop though. :)

billy_goat_gruff
01-17-2007, 04:28 PM
Okay, so the Garandoni isn't semi-auto... It doesn't automatically feed the next ball in. :P

The other auto bb gun I was thinking of...
http://www.burntlatke.com/bb.html

Wonder if shotgun pellets would work... probably not at 40 psi. Oh, well.

billy_goat_gruff
02-02-2007, 07:57 PM
LaunchPad, wouldn't you rather make a pneumatic one of these? We could send them down to the border after putting some good solar cells on them to power the pump...* ;)
http://www.defensereview.com/modules.php?name=News&file=article&sid=704

Okay, this is just a poorly disguised bump... would like to hear any updates if you have any tho.

Was also thinking of paintball full-auto mechanisms... what are your thoughts on using those as a basis of design (other than they are patented probably...)

Till next time...

lost1
02-02-2007, 08:01 PM
::) ::) I am sorry to ask such a dumb question, but, what would you use one for?

billy_goat_gruff
02-02-2007, 08:17 PM
Vanity mostly... "Lookie here what I got!!!"

Kinda like the .600 Nitro pistol that some gunsmith built as a display piece, and some crazy guy actually fired. The video is on this page, bloody face and all...
http://stephenbodio.blogspot.com/2006/02/600-nitro.html

Hmmm... you do have a point there. Maybe some things are better left in fantasy land... :)

unclesam
02-02-2007, 08:32 PM
I'm not too sure how well one based on a paintball gun design would perform, as this airgun was intentionally designed to have performance similar to a modern firearm.

billy_goat_gruff
02-04-2007, 12:29 PM
unclesam, did they happen to say which modern firearm?

My understanding (which is always being improved, mind you) is that the modern firearm that airguns can be compared with are pistols, or maybe a .22 rifle.

Here is what I know (or think I know: )

Max velocity - ~1080 fps (speed of sound in compressed air)
The springers get 1200 fps by heating the air greatly through compression and changing the speed of sound velocity thereby. To change it otherwise, one has to use a different gas that has a much higher speed of sound velocity, such as helium or hydrogen. Some powder powered pistons (springers) compressing hydrogen can get into the 5-6,000 fps range. Compressing helium or hydrogen is a bit beyond garage abilities...

Longer barrel equals more velocity assuming the compressed gas is still compressed as the projectile exits the muzzle. Going through a nozzle cools the gas, btw, but a reduction is necessary to keep the projectile from getting into the firing valve so see above. That also means that the air lines inside the gun shouldn't be too much smaller than the projectile/bore for good efficiency.

Airguns amaze me. If enough gas can be compressed then 14 foot long 2x4s can be sent down range at 100 mph (~150 fps) or better...

I've often wondered what it would take for an airgun to send an arrow (with special air seal at the nock and maybe a centralizer on the shaft) down range at 600 fps. Wouldn't want a ten foot barrel, or pressures above what standard pipe found at Home Depot could handle though so never put pencil to paper. One guy had a page up about 10 years ago that used a welding rod (if memory served) coming out of a 3/4 inch copper pipe that went through 4 inches of wood at 75 yards. Yeah, I believed him cause he builds big bore airguns now that cost several hundreds or thousands of $.

Anyway, for performance about equal to centerfire modern rifles then an airgun is probably going to take something other than air. And some quirky designing to deal with the other than air part would be necessary.

Let me know what I missed there. Otherwise, seems like beefing up paintball mechanisms to handle higher pressures should work.

Take care out there
gruff

torenghout
05-26-2007, 10:03 PM
As a teen I made a bb gun machine gun out of K&S brass tube a bicycle pump and a 5ab fire extinguisher,+ wood frame. the rate of fire was a function of high/low pressure as the bb exited the barrel[ the suden low pressure drop a new bb into the chamber, after that the high pressure retarded the next from entering.

at 100 psi I got about 300-350 fps not very good but multiple hits made up for it. it would rip a pop can in half.

as far as maximum velocity nasa used helium at high presue to drive a large piston tha drove a small piston to get 20,000 fps for micrometeor simulation.

MadTripper
08-25-2007, 12:44 PM
Any additional information on this topic? I'd hate to see it die. I personally think the thompson looking bb guns at the local fairs would be fun to have. Something even more powerful is just a bonus.

Tripper