10mm to 30mm Experimentals

[EODGUY]

The U.S. has experimented with about every caliber of ammunition between 10mm and 30mm over the years, not including the various "inch" designation experimentals. Photo 1 shows l-r 10x108mm high velocity, headstamped FA 61; 12.7x108mm APDS ,headstamped 88; 15x99 spotter, headstamped FA 60; 16x98mm Vega, HE, for the Vega aircraft gun; 20x158mm T5E2 case; 23x133mm Smith & Wesson Bushmaster candidate, only 1500 cases made; 23x139mm Amron made Bushmaster variation; 23x159mm unknown Bushmaster candidate case.
Photo 2 l-r 25x145mm AAI candidate Bushmaster TPT; 26x130mm Colt Industries Bushmaster candidate; 27x70mm US Air Force T142 Practice, aluminum case; 27.5x160 Aerojet Bushmaster candidate; 27.5x140 Aerojet Bushmaster first design case; 30mm semi-caseless.
Can anyone else fill in other metric calibers between 10 and 30mm the U.S. has played with over the years?

 

[Chris 42 RQ]

Very nice !

Very nice collection EODGUY with a few I have not seen before.

 

[SG500]

Can anyone else fill in other metric calibers between 10 and 30mm the U.S. has played with over the years?

Lovely rounds there EODGUY, as for filling you in on the other calibres, you guys did all sort of experiments so the list is as long as your arm:
Bofors 40/20
USN 40/20
Vigilante 37/20
All the hughes lockless variations
All the tround variations
Various telescoped and caseless rounds, 20 x 82, philco ford etc.
Various gyrojet up to 40mm
25mm aai
Gau 7 variations
25x173
27x96
27x99 caseless
27x142 amron
The list goes on and on..........its just finding the stuff.
Dave.

 

[EODGUY]

OK, I wasn't clear in my posting. I meant to add that there were multiple experiments in many of the calibers I posted, many of which I have in the collection, but what I was looking for were experiments in other calibers between 10 and 30mm. For example was there ever a 28mm US or a 13mm US case type, etc.? I am not aware of any, but the good thing about this hobby is there are a zillion things I don't know about yet!

 

[Hoeksel]

Is the 20 mm T5E2 a wartime experiment or post war?

 

[jonnyc]

Did you mention the .60 MG and I just missed it?

 

[kahu1]

I understand the T5E2 was a Barrel testing round.
I just missed out on one a couple of years ago,not likely to see too many about.

 

[clarkbr]

Hello All,
Do you have any information on the 10 x 108 High Velocity?
I would be interested in dimensions and it's history.
Thanks!
Brian

 

[Tony Williams]

Hello All,
Do you have any information on the 10 x 108 High Velocity?
I would be interested in dimensions and it's history.
Thanks!
Brian

This was the result of a USAF aircraft gun project in the late 1960s. While every other air force was using cannon (of 20-30mm calibre), the USAAF was obsessed with a highest possible bullet velocity to maximise the chances of scoring hits. So they developed the cartridge (of which there are several variations) from a .50 BMG case, necked-down and lengthened. The gun they intended for it was a six-barrel gatling type, the GAU-6, and it was intended to fire at up to 8,000 rpm, or 10,000 rpm in a proposed seven-barrel version. However, they never finished the linkless feed, so the belt-fed gun was limited to 4.500 rpm. They also never fired the 10 mm ammo in the gun - the ammo never worked well so the gun was initially built to shoot standard .50 cal ammo for test purposes.

 

[clarkbr]

Thank You Tony and a Merry Christmas to you,
Thank you for your information.
I just received my copy of "History of Modern Small Arms Ammunition Vol. 3" from Santa today.
I haven't checked to see if it is in there.
All the best,
Brian

 

[Big Al]

The 12.7 x 108 APDS is NOT experimental round. It was part of the clandestine war in Afghanistan against the Russians. It is an American factory round.