Case dimensions 20mm m61 Vulcan & 25mm Bushmaster???

sneaky pete · August 23, 2009, 06:21 PM

old Sneaky Pete here: I know that this is a bit far out in "left Field" but does anyone know wheere I can get the Case dimentions for the above 2 rounds??? particularly the Head diameters. I'd appreciate it. THANX--SNEAKY

Starvingboy · August 24, 2009, 05:18 PM

Umm. Yep. I still have the 20mm info. Whacha got in trade?

Just kidding. If you're building a DD, give me some detail though. I've a Pipe-dream project about that size. Give me a few minutes to figure out how to post the picture to this forum.

Starvingboy · August 24, 2009, 05:25 PM

Awe crap. I think it's the specs for .50bmg. You're welcome to it anyway, I can email it to you. Posting it is not working for some reason. None of my 2min search achieved anything. I have a couple of rounds I can measure, if that will do you any good.

sneaky pete · August 24, 2009, 08:49 PM

old Sneaky Pete here: Actually my request is rather mundane. I have a hiking staff I cut from a Malaluka sappling and I want to use an empty casing on the bottom end to keep the wood from getting all buggered up-so I would cut the top of the case just below the shoulder and rubber cement the staff inside the case. I saw in a "Cheeper-Than Dirt catalog that they have dummy shells of each so if I knew the case dimentions I could buy the correct size.. I hope that I don't sound too weird--but then what can you expect from an old retired S/F, M/sgt. THANX--SNEAKY

wncchester · August 24, 2009, 09:22 PM

"...rubber cement the staff inside the case.."

If you do make it, bet you would be happier with epoxy.

ballardw · August 26, 2009, 01:53 AM

Sneaky Pete

Having done some similar projects you might consider visiting your local hardware store and getting copper end caps. There's not as much bearing surface for glue but that can be fixed with a small drill and a couple of brads if worried about the cap coming off.

Of course if this is a style thing, go for it.

**Mal H** · August 26, 2009, 09:19 AM

Sneaky Pete, I have a demo board with the various stages of manufacture of the old Oerlikon 20mm round. The inside diameter of the case is 17mm (7/8ths inch), but it tapers down to roughly 11mm at the flash hole with a gentle radius (see the closeup image).

Hope that helps for the 20, but I have no hard info for the 25mm case. Obviously it is going to a little less than an inch in diameter, I would guesstimate it to be around 22mm.

sneaky pete · August 26, 2009, 11:50 AM

old Sneaky back: MalH--Thanx for the info on the old Oerlikon round. There must have some changes over the years. I found a site and it gave me the case head diameter of 29.1MM for the m61 Vulcan--m791 ammo. So if i subtract 3mm( 1.5 per side wall)=26mm+/- above the webb which will work. THANX--SNEAKY

**Mal H** · August 26, 2009, 12:10 PM

Are you positive about that? M791 ammo can be 25mm as well. Do you have a link for the site?

SL1 · August 26, 2009, 01:11 PM

Quote:

"I have a hiking staff I cut from a Malaluka sappling and I want to use an empty casing on the bottom end to keep the wood from getting all buggered up..."

Darn! I read this thread thinking somebody was going to wildcat that case for a .17 caliber bullet. I think if you used something REALLY slow, like a nitro-molasses based propellant, you might achieve orbital velocity

.

SL1

sneaky pete · August 26, 2009, 03:11 PM

"OLD" Sneaky back: Mel H you were correct that m791 roun was for the 25mm Bushmaster and it's case head diameter was 38MM which is way too big. That's what I get for eating too much chocolate. Cheeper than Dirt sells those m61 Vulcan "Dummy" rounds with no holes drilled--3/$15. so I don't know what I'll do with the other 2??? THANX--SNEAKY

OBTW!! I found the bushmaster site just by typing in my webtv's search egine m242 bushmaster 25MM ammo and then scrolled down till I found I site that I thought would work--S/P

mapsjanhere · August 26, 2009, 03:48 PM

BTW unless you can get your hand on some toughened epoxy, stay with the rubber cement to glue it in. Standard epoxy is way to brittle for this application, especially if you add in the swelling and shrinking of the wood with season, and the CTE mismatch.

SL1 · August 26, 2009, 05:50 PM

West Marine (and other places) sell a tough epoxy called "G-flex" that is hard, but does not crack. It comes in tubes or cans. You can drill a pilot hole in it after it is cured and screw in a sheet metal screw and it does not crack. And, it really sticks well.

For capping a piece of wood, I would first let it soak-up a penetrating epoxy to keep it from getting wet inside and rotting, later. Then I would file it down to the wood surface and bed it in the G-flex inside the brass case.

SL1

sneaky pete · August 26, 2009, 09:32 PM

old Sneaky back: Sorry about the sarcasm---BUT---What I'm going to use is actually called Dip-It, The stuff you dip plyers in to form a rubberised handles. I used it when I designed and made an adaptor for my Bushnell 20x60x80 spotting scope. to eliminate the vibrations caused by an un-ballanced tripod mounting location, made out of 1-1/4x1/8" aluminum stock. I dipped the end that the barrel of the scope rests on to eliminate scratching. If you care to get a copy of "The Varmint Hunter" magazine--April '09 issue page 169 you can see a pictures of the mounting bracket and read the article I wrote. The reason I'm using it to glue the staff inside the 20mm shell case is CUZ I have some of the stuff left over so I won't have to go out and buy anything. So now that settles the adhesive thing. THANX-SNEAKY

August 23, 2009, 06:21 PM	#1
sneaky pete Senior Member Join Date: November 24, 2004 Location: Florida Keys Posts: 510	Case dimensions 20mm m61 Vulcan & 25mm Bushmaster??? old Sneaky Pete here: I know that this is a bit far out in "left Field" but does anyone know wheere I can get the Case dimentions for the above 2 rounds??? particularly the Head diameters. I'd appreciate it. THANX--SNEAKY

August 26, 2009, 03:11 PM	#11
sneaky pete Senior Member Join Date: November 24, 2004 Location: Florida Keys Posts: 510	proably another brain f!!!* "OLD" Sneaky back: Mel H you were correct that m791 roun was for the 25mm Bushmaster and it's case head diameter was 38MM which is way too big. That's what I get for eating too much chocolate. Cheeper than Dirt sells those m61 Vulcan "Dummy" rounds with no holes drilled--3/$15. so I don't know what I'll do with the other 2??? THANX--SNEAKY OBTW!! I found the bushmaster site just by typing in my webtv's search egine m242 bushmaster 25MM ammo and then scrolled down till I found I site that I thought would work--S/P Last edited by sneaky pete; August 26, 2009 at 03:16 PM. Reason: aded an OBTW

August 26, 2009, 09:32 PM	#14
sneaky pete Senior Member Join Date: November 24, 2004 Location: Florida Keys Posts: 510	Lots of adhesive suggestions but NO case dimensions old Sneaky back: Sorry about the sarcasm---BUT---What I'm going to use is actually called Dip-It, The stuff you dip plyers in to form a rubberised handles. I used it when I designed and made an adaptor for my Bushnell 20x60x80 spotting scope. to eliminate the vibrations caused by an un-ballanced tripod mounting location, made out of 1-1/4x1/8" aluminum stock. I dipped the end that the barrel of the scope rests on to eliminate scratching. If you care to get a copy of "The Varmint Hunter" magazine--April '09 issue page 169 you can see a pictures of the mounting bracket and read the article I wrote. The reason I'm using it to glue the staff inside the 20mm shell case is CUZ I have some of the stuff left over so I won't have to go out and buy anything. So now that settles the adhesive thing. THANX-SNEAKY Last edited by sneaky pete; August 26, 2009 at 09:34 PM. Reason: sp.

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August 24, 2009, 05:18 PM	#2
Starvingboy Member Join Date: September 17, 2008 Posts: 74	Umm. Yep. I still have the 20mm info. Whacha got in trade? Just kidding. If you're building a DD, give me some detail though. I've a Pipe-dream project about that size. Give me a few minutes to figure out how to post the picture to this forum.

August 24, 2009, 05:25 PM	#3
Starvingboy Member Join Date: September 17, 2008 Posts: 74	Awe crap. I think it's the specs for .50bmg. You're welcome to it anyway, I can email it to you. Posting it is not working for some reason. None of my 2min search achieved anything. I have a couple of rounds I can measure, if that will do you any good.

August 24, 2009, 08:49 PM	#4
sneaky pete Senior Member Join Date: November 24, 2004 Location: Florida Keys Posts: 510	old Sneaky Pete here: Actually my request is rather mundane. I have a hiking staff I cut from a Malaluka sappling and I want to use an empty casing on the bottom end to keep the wood from getting all buggered up-so I would cut the top of the case just below the shoulder and rubber cement the staff inside the case. I saw in a "Cheeper-Than Dirt catalog that they have dummy shells of each so if I knew the case dimentions I could buy the correct size.. I hope that I don't sound too weird--but then what can you expect from an old retired S/F, M/sgt. THANX--SNEAKY

August 24, 2009, 09:22 PM	#5
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	"...rubber cement the staff inside the case.." If you do make it, bet you would be happier with epoxy.

August 26, 2009, 01:53 AM	#6
ballardw Senior Member Join Date: September 19, 2008 Posts: 1,411	Sneaky Pete Having done some similar projects you might consider visiting your local hardware store and getting copper end caps. There's not as much bearing surface for glue but that can be fixed with a small drill and a couple of brads if worried about the cap coming off. Of course if this is a style thing, go for it.

August 26, 2009, 11:50 AM	#8
sneaky pete Senior Member Join Date: November 24, 2004 Location: Florida Keys Posts: 510	old Sneaky back: MalH--Thanx for the info on the old Oerlikon round. There must have some changes over the years. I found a site and it gave me the case head diameter of 29.1MM for the m61 Vulcan--m791 ammo. So if i subtract 3mm( 1.5 per side wall)=26mm+/- above the webb which will work. THANX--SNEAKY

August 26, 2009, 12:10 PM	#9
Mal H Staff Join Date: March 20, 1999 Location: Somewhere in the woods of Northern Virginia Posts: 16,947	Are you positive about that? M791 ammo can be 25mm as well. Do you have a link for the site?

August 26, 2009, 03:48 PM	#12
mapsjanhere Senior Member Join Date: August 6, 2009 Location: Albuquerque Posts: 2,832	BTW unless you can get your hand on some toughened epoxy, stay with the rubber cement to glue it in. Standard epoxy is way to brittle for this application, especially if you add in the swelling and shrinking of the wood with season, and the CTE mismatch.

August 26, 2009, 05:50 PM	#13
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	West Marine (and other places) sell a tough epoxy called "G-flex" that is hard, but does not crack. It comes in tubes or cans. You can drill a pilot hole in it after it is cured and screw in a sheet metal screw and it does not crack. And, it really sticks well. For capping a piece of wood, I would first let it soak-up a penetrating epoxy to keep it from getting wet inside and rotting, later. Then I would file it down to the wood surface and bed it in the G-flex inside the brass case. SL1