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I need a measurement!

1622 Views 14 Replies 8 Participants Last post by  robscastle
My next project looks like it will be turning a wooden bullet for a 30mm cartridge from an A-10 Thunderbolt. I have been asked to make the bullet for a spent cartridge. I have a complete "dummy" round but I need to determine the inside diameter of the opening where the shell casing interfaces with the bullet. I refuse to tear mine apart and the person, for whom I am making it, refuses to let it out of their sight. I was told it it "about an inch". That just isn't accurate enough. If any LJ member has a spent 30 mm GAU-8 shell casing and could post the dimension, or point me to a website, I would appreciate it.

Thanks for any assistance!
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This may help. There are quite a few specs, but it didn't take the time to verify if the one you want is included.
I think that might just be what I was looking for!
Lew 30 MM should be just that size if you ask me.

a 45 calibar should be .450 thou. 308 should be .308 thou.
Those specs do show a case mouth inside diameter (1.168" +0.004/-0), but for the best fit, you're really going to have to measure the actual case the bullet is going into. Individual specimens vary - it might be unfired, or it might be fired and resized, or fired and not resized (loose), and every one of those cannons has seven barrels, which means seven chambers, no two exactly alike, and the case mouth naturally stretches out when the bullet is seated because it's a press fit, and the spec may be without a bullet, etc., etc.
Lew I'd make a plug with a "V" to insert into the case. ask him to insert it into the case and mark around the rim of the case with a sharp knife and then give it back to you.

Then just a little smaller because.
Or turn V-grooves into the shank (like threads) so if it's oversized it can be sanded down more easily.
Sounds like I should turn a cone shape. Send it to them and have them fit/mark the cone at the transition and then use that as the pattern.

Thanks for all of the ideas, I really appreciate it!
Ask PASs or Nate Meadows your question, its something that I would think either of them may have experience with and can provide the correct answer, or if not I am tipping they will have a contact to find out.
Lew 30 MM should be just that size if you ask me.

a 45 calibar should be .450 thou. 308 should be .308 thou.

- Karson
Life should be that simple, but… unfortunately, it ain't ;-( 45 caliber can be anywhere for .450 to .463 +++?? . .308 is a little better but still has variations.

Definitely check the inside diameter of the case. If you turn a very light taper, hopefully you will get an impression on the wood that will give you a little more accurate measurement than the line above the case mouth. Making your wooden bullet with a slight taper will give you a little more margin. Good luck.
There are quite a few specs do show a case mouth inside diameter,this may help
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Well, I am relieved to see you are getting some help. I first saw A-10's in the early '80's, flying out of Eielson AFB….....sometimes those things seem to hover and I would think I was passing them by…

Being a good friend, I was trying to come up with some scenarios, thinking that the weapons freaks wouldn't be here in droves. Of course they are here in droves. I don't even own a gun, and I still think in terms of weapons!!.............

The Unproject

1) I determined that the A-10's still do fly here in Alaska, as recently as August. Apparently they are used in the Red Flag war games on a regular basis. Wonder if I could join in the fun and games, and get close enough to purloin a casing or ten….......

2) I could sneak onto the base at Elmendorf or have my good buddy, (retired EOD), see if there are any A 10's around, "could you give me one of the spent cartridges, maybe a dented one?", I think they recycle the cartridges.

3) Or I could ask if they would like my aging Honda van for target practice… exchange for a bunch of the cases. That would be an excuse to get a new car…........

4) .........perhaps suggest a politician or two to use for a moving target, they would most certainly die, but could go out with a smile having finally done something useful in life…...(-:

5) My son-in-law is a civilian working at Eielson AFB in the interior. He is one of the guys that runs the heating and generating facilities there, and perhaps he could wrangle a cartridge case or two, perhaps trading moose meat or smoked salmon to one of the Chair Force people there…..........

Then I would have my excuse to run out and buy a lathe to make the bullet… would be necessary, because after measuring one, the rest would need to have a purpose…...right?

So, Lew, just let me know…...if I need to implement any of the above schemes. Might try them all, just to see what works best….......(-:
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Thanks for all of the schemes! The politician one is extremely attractive but the aircraft may need to go back and reload- as targets are plentiful!! ;^)

I am hoping the folks will give me a little closer dimension. If not, the link "bucket" supplied will get me close. I'll turn the end tapered and maybe need to sand a bit.

You are so right about the A-10's ability to "hover" I swear they come with sky hooks!
Definitely Sky Hooks….........

.....and the politician one, I will scheme and dream about a little longer….......

Have a good one…........
How to live a long and happy life.

Never get on the opposite team to the A-10s

Totally irrevelant to the topic but I needed to say it…. sorry!

JB you are a bit of a scallywag!!
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