I was visiting the GS Custom bullet website and it says:

"You will find anomalies in our line of bullets such as the fact that we make two distinctly different 7 mm bullet sizes. If, for example you research the CIP specifications, you will find that 7 mm Remington Magnum and 7 x 57 are not the same size bore or groove. "

I find it hard to doubt the word of the projectile specialists at GS Custom but I've never heard of they're being two different 7mm bore sizes. Is anyone else aware of this and if so how much difference is there?

Regards

RJW

I don't know anything about CIP, but in this country, the 7mm Remington Magnum, the 7X57mm Mauser, the 7X64, the .280 Remington, the 7mm Weatherby as well as every other type and kind of 7mm/.280 rifle, EXCEPT FOR THE .280 ROSS, ALL USE .284" diameter bullets!! It is my understanding that some European made 7X57's are a little large, with some grooves going as big as .286", but not US made ones! The .280 Ross is a .288". So there's something wrong here!!

/

eldeguello & ALF

Thanks very much for your replies. I have a Rigby 275 (7x57) that was made around 1930. I've always used standard .284 cal bullets and it shoots fine. However, since this is of European make I think I'd better have the bore slugged to find out exactly what bore size I do have.

Regards

RJW

On 6.5mm bullets I have miked, I have found the following differences in their measured diameters:

RWS 93gr .26250
Speer 120gr .26300
Sierra 120gr .2642

Montero.

RJW, If you find that your bore is indeed 7.25mm instead of 7.2136mm, what will you do next?? If as you say, .284" bullets are shooting well in your .275 Rigby, are you going to change bullet sizes? This is .28543307" vs .284". Wow!! What a difference!! I shoot .308" bullets in a .303 British and a 7.65mm Argentine Mauser with MOA accuracy!! "If it ain't broke, don't fix it!!"