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Old June 12, 2012, 05:45 PM   #1
Knuck39
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Question: What calibre is this?

I was given a Thompson Contender by an Aunt. It was her 1st husband and he has long passed. Anyway, it has a customer barrel on it and it comes with 100 rounds of loaded ammo. The bottom of each case has "TWO 7" written on it. Bullet diameter is. 308, case length is 1.740, base diameter is. 372, rim diameter is. 372 and overall length is 2.577. It looks to be some kind of wildcat but I would like to know which one.
Thank you.
Jon.
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Old June 12, 2012, 06:37 PM   #2
jaguarxk120
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From what you have said the cartridge sounds like a 300 Whisper. If you do a search for the 300 Whisper you have more than enough information on the caliber.
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Old June 12, 2012, 09:03 PM   #3
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not a chance. That is way longer than a .300 whisper. The case is longer by almost a half an inch.... I think your best bet is probably to take it to a competent gun shop or gun smith for help identifying it, rather than depend on the errornet....

Edit- or at the very least, post some pics...

Last edited by dacaur; June 12, 2012 at 09:09 PM.
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Old June 12, 2012, 10:17 PM   #4
Sport45
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Welcome to The Firing Line!

Is there anything stamped on the barrel of the gun?
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Old June 12, 2012, 11:25 PM   #5
WWWJD
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Those dimensions aren't matching anything in Lymans... or anywhere else I've looked. Pics would be great.. and a full set of cartridge dimensions.
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Old June 13, 2012, 04:27 AM   #6
Knuck39
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I'll get some photos to you guys ASAP . Nothing stamped on barrel of gun unfortunately.
I really appreciate the help.
Take care.
Jon

Last edited by Brian Pfleuger; June 13, 2012 at 08:27 AM. Reason: Fix pictures
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Old June 13, 2012, 04:53 AM   #7
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dcaur is correct--300 whisper case is 1.355 (though some manuals have it listed at 1.400)

If your measurements are correct I suspect it is a one off wildcat but surprised the gunsmith did not stamp or etch in the caliber.

JMHO

Gary
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Old June 13, 2012, 06:52 AM   #8
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There were too many http//'sin your picture link. The headstamp indicated military surplus TW 70 brass that has been reformed into something else, but I'm not sure what.

To answer your original question, it is a 30 caliber.
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Old June 13, 2012, 06:59 AM   #9
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Wildcat

What calibre? You already know that....as you stated the diameter at .308.
The cartridge itself looks like a .30 TCU. The more common 7mm TCU has a case length of 1.749" and a rim diameter of 0.378". Head diameter of 0.3764"

Pete
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Old June 13, 2012, 07:07 AM   #10
Mike Irwin
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My guess? And I'd bet hard money on it?

7mm TCU.

Case dimensions are VERY close to what you're reporting. Given the head size and rim diameter it's based on the 5.56/.223 case.

http://www.google.com/imgres?imgurl=...ed=0CBcQ9QEwAg
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Old June 13, 2012, 07:08 AM   #11
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Whoops, I missed the part about it being .308.

Dark Angel is, I believe, correct.

The TWO 7 is actually the military headstamp, and is correctly read as

TW

and 70

TW is Twin Cities Ordnance Plant, and 70 is 1970, the year the round was originally manufactured.
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Old June 13, 2012, 07:10 AM   #12
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Looks like a .223 Remington/5.56 NATO necked-up to .30 caliber.

Maybe a "Loud Whisper"?

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Old June 13, 2012, 07:26 AM   #13
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Darkgael is right it's a 30 TCU, there were several cartridges base off of the full length 223 case, and a 30 caliber was one of them.
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Old June 13, 2012, 07:48 AM   #14
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30 TCU

30 TCU
7mmTCU
30 Herrett
357 Herrett

All were rounds being developed (played with) to enable best accuracy with least recoil and enough energy to topple Rams at 200 meters in IHMSA competitions.
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Old June 13, 2012, 08:19 AM   #15
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I recall an old gunzine article about the .30 Apache, which was just a .30-.223 owned by a guy named Joe Apache. It amazed everybody by holding headspace, shooting accurately and knocking down RIFLE silhouettes.
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Old June 13, 2012, 02:50 PM   #16
SL1
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Maybe TCU, but Maybe NOT

The cartridge is definitely a .223 remington necked to .308. The 30 TCU was such a widcat that was sort of standardized after a while. But, there were others early-on that might have had the shoulder in a slightly different place or at a different angle, or with a different body taper on the case.

With an old custom barrel that was not stamped as "30 TCU", there is a significant chance that the chamber is not going to match the standardized dimensions exactly.

So, before ordering 30 TCU dies and finding that they don't work well, I suggest that you ask that wonderful aunt of yours if she can find the dies that her first husband used to load those 100 rounds. If so, you are in business. But, if not, at least you have 100 rounds of ammo that you know fit the gun. You can CAREFULLY measure those to determine if the standard 30 TCU dimensions are close enough to the what you actually have. If not close enough, then you will need custom dies.

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Old June 13, 2012, 04:05 PM   #17
Knuck39
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I really appreciate all your help. Thank you so much.
This is a fantastic site.
Take care.
Jon
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