Question: What calibre is this?

Knuck39 · June 12, 2012, 05:45 PM

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.

jaguarxk120 · June 12, 2012, 06:37 PM

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.

dacaur · June 12, 2012, 09:03 PM

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...

Sport45 · June 12, 2012, 10:17 PM

Welcome to The Firing Line!

Is there anything stamped on the barrel of the gun?

WWWJD · June 12, 2012, 11:25 PM

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.

Knuck39 · June 13, 2012, 04:27 AM

I'll get some photos to you guys ASAP . Nothing stamped on barrel of gun unfortunately.
I really appreciate the help.
Take care.
Jon

Whisper 300 · June 13, 2012, 04:53 AM

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

Sport45 · June 13, 2012, 06:52 AM

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.

darkgael · June 13, 2012, 06:59 AM

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

**Mike Irwin** · June 13, 2012, 07:07 AM

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

**Mike Irwin** · June 13, 2012, 07:08 AM

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.

SL1 · June 13, 2012, 07:10 AM

Looks like a .223 Remington/5.56 NATO necked-up to .30 caliber.

Maybe a "Loud Whisper"?

SL1

jaguarxk120 · June 13, 2012, 07:26 AM

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.

oldmanFCSA · June 13, 2012, 07:48 AM

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.

Jim Watson · June 13, 2012, 08:19 AM

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.

SL1 · June 13, 2012, 02:50 PM

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.

SL1

Knuck39 · June 13, 2012, 04:05 PM

I really appreciate all your help. Thank you so much.
This is a fantastic site.
Take care.
Jon

June 12, 2012, 05:45 PM	#1
Knuck39 Junior Member Join Date: June 12, 2012 Posts: 6	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.

June 12, 2012, 09:03 PM	#3
dacaur Senior Member Join Date: March 16, 2010 Posts: 733	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.

June 12, 2012, 10:17 PM	#4
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	Welcome to The Firing Line! Is there anything stamped on the barrel of the gun? __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

June 12, 2012, 11:25 PM	#5
WWWJD Senior Member Join Date: February 9, 2011 Location: Central KY Posts: 552	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. __________________ *~Mark* NRA Endowment FTW

June 13, 2012, 04:27 AM	#6
Knuck39 Junior Member Join Date: June 12, 2012 Posts: 6	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

June 12, 2012, 06:37 PM	#2
jaguarxk120 Senior Member Join Date: February 28, 2008 Location: Michigan Posts: 2,620	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.

June 13, 2012, 04:53 AM	#7
Whisper 300 Senior Member Join Date: December 29, 2006 Posts: 155	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

June 13, 2012, 06:52 AM	#8
Sport45 Senior Member Join Date: May 25, 1999 Location: Too close to Houston Posts: 4,196	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. __________________ Proud member of the NRA and Texas State Rifle Association. Registered and active voter.

June 13, 2012, 06:59 AM	#9
darkgael Senior Member Join Date: February 9, 2006 Location: Homes in Brooklyn, NY and in Pennsylvania. Posts: 5,473	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 __________________ “Auto racing, bull fighting, and mountain climbing are the only real sports ... all others are games.” Ernest Hemingway ... NRA Life Member

June 13, 2012, 07:07 AM	#10
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,390	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 __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

June 13, 2012, 07:08 AM	#11
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,390	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. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

June 13, 2012, 07:10 AM	#12
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Looks like a .223 Remington/5.56 NATO necked-up to .30 caliber. Maybe a "Loud Whisper"? SL1

June 13, 2012, 07:26 AM	#13
jaguarxk120 Senior Member Join Date: February 28, 2008 Location: Michigan Posts: 2,620	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.

June 13, 2012, 07:48 AM	#14
oldmanFCSA Senior Member Join Date: November 8, 2010 Location: WISCONSIN Posts: 283	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. __________________ OldmanFCSA = "Oldman" at www.fcsa.org FCSA Member, SCSA Member, NRA Member, & AMA Member "Oldage & Treachery will overcome Youth & Skill"

June 13, 2012, 08:19 AM	#15
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,543	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.

June 13, 2012, 02:50 PM	#16
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	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. SL1

June 13, 2012, 04:05 PM	#17
Knuck39 Junior Member Join Date: June 12, 2012 Posts: 6	I really appreciate all your help. Thank you so much. This is a fantastic site. Take care. Jon