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7.62 nato????

7mm Comp

Jimiles said:
Tony,
I know it shares their 49mm(ish) caselength but I can't see how this green-tipped round (7mm FA-T1E3!) could possibly be a copy of the 7mm High-Velocity or the 7mm Second-Optimum as it's shoulder position is very different to both.
However, it is dimensionally identical to the 7mm Compromise in all aspects other than the slight reduction in caselength. This shortening wouldn't have any effect on it's ability to chamber in a weapon intended for the 7mm Compromise. I think it's got to be a US version of the Compromise.
Jim
Click to expand...

You may well be right Jim, as without having it in front of me it is difficult to tell from a photo. It depends where the difference is; if it is in the neck then it will affect free travel of the bullet, but if it is in the base to shoulder length then it will not chamber correctly as it headspaces on the shoulder.

Regards
TonyE
 
Hopefully this photo will illustrate the very clear similarity between the 7mm Compromise and the US 7mm FA-T1E3.

Pictured left to right;

7mm FA-T1E3 7mm Compromise 7mm High Velocity 7mm Second Optimum


7mmcartridges.jpg
 
&mm FAT

I can see what you mean now, the difference of 1.5mm is all in the neck. They must have used some 49mm cases to make those and necking them down from .30 gave another 0.5mm in length. The later ones like mine are a full 51mm.

I wonder what they were fired in, a test barrel or one of the US weapons rechambered? I suppose the difference in chambering would not make a lot of difference in a military round but it seems odd they used a wrong case length. Unless of course they got it wrong and thought the Compromise was the 7mm HV with a different shoulder position.

I am off to Bisley now to try out a new toy!

Regards
TonyE
 
TonyE said:
I can see what you mean now, the difference of 1.5mm is all in the neck. They must have used some 49mm cases to make those and necking them down from .30 gave another 0.5mm in length. The later ones like mine are a full 51mm.
Click to expand...

The 49mm cases were not made after 1950. Additionally, many of the dimensions, including shoulder angle, were different from the 51mm case. The mystery cartridges were very definitely made from shortened FAT1E3 cases. The amount shortened was determined by the location of the crimping groove on the Type B bullet.

Firing the short case in any of the existing US test weapons that were chambered for the FAT1E3 case would not pose any problems.

Ray
 
Rather than continue to speculate, I went to the guys who should know. I asked HWS about the FA 51 cartridges. They (Bill W and Frank H.) said the US loaded various British 280 bullets in the FAT1E3 case for tests in a Garand. The neck was shortened to accomodate the crimping groove as necessary. FA also sent FAT1E3 cases to England where they were presumably necked to 280 for tests concurrent with the development of their own types (Compromise, etc). Bill said that he has not seen any of the British loaded cases so can only presume that they were used for that purpose.

Ray
 
Last edited:
Jim

I completely forgot to ask for a name. I did send them an email with the photograph where I called it the 7mm/FAT1E3 and they didn't comment so that means:

1. I had the correct name
2. They didn't notice
3. There is no name

For now, I'll go with #1.

They (Bill and Frank) were at Bill's place working on HWS III and I would not think of asking them to stop work again. :tinysmile_twink_t:

Ray
 
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