Swiss 6.45x48 GP80 case dimensions?


#1

Jean Huon’s book on military rifle cartridges states that the Swiss 6.45x48 GP80 has a case diameter of 10.82mm. Yet I have an example in my collection (headstamp 5 T 81 T) which has a case diameter of 11.9mm.

Were there two different versions? If so, which was the definitive one?


#2

Tony,
I don’t believe there were two versions and my specimens measure closer to yours than Huon’s so I’d suggest it’s an error in his book.

I have three rounds which measure as follows;

Ball (no hdsp) 11.85mm
Ball (T 7 T 80) 11.86mm
Tracer (T 5 T 81) 11.87mm


#3

Where exactly on the case are you measuring?


#4

The rim.


#5

OK, just to confirm, before I measure mine…
Rim diameter is actually on the rim, Case/Head diameter is just above the extraction groove.
Perhaps this difference in terminology illustrates the difference in measures the two of you have gotten?


#6

I measured across the rim also.


#7

Here are mine. They also don’t tally with Huon:
Tracer: rim 11.86; head 11.82mm (5 T 81 T)
Blank: rim 11.88; head 11.81mm (no h/s)
Ball: rim 11.86; head 11.77mm (7 T 80 T)
Proof: rim 11.90; head 11.85mm (12 77)


#8

It must be error, I think all Swiss versions 5,6-6,45 x 48 have ~11.9 mm base.


#9

Thank you all, gentlemen, that seems to settle it.

I understand from another source that 6.45mm is the actual bullet diameter, rather than the bore diameter which is more usual in military ammunition, which makes this round very close in dimensions to the old .250-3000 Savage.


#10

What I know, 6.45x48 bullet is about 6.6 mm.


#11

Can you tell me your source for this? I received this comment on my own forum:

[quote]Swiss authors Christian Reinhart and Michael am Rhyn in their book Automatwaffen II (Dietikon-Zürich 1983) give the rim diameter for the 6.45 mm x 48 GP80 as well as the 5.56 mm x 48 Eiger as 11.9 mm.
Bullet weight for the 6.45 mm (real diameter) was 6.3 g and muzzle velocity 900 m/s from the [experimental] rifle…

Reinhart/am Rhyn explicitly say bullet diameter 6.45 mm (p. 180). They correctly list 7.8 mm for the GP11 and 12.96 mm for the .50BMG. So I think this value is quite reliable.
[/quote]


#12

Self measured one cartridge from my collection (6.61) and all measured specimens in ECDV are also 6.54-6.65 mm.


#13

Thanks, that’s helpful.