Looking for Info in Vintage Scopechief

[jonh172]

I have a Bushnell Triple tested Scopechief 3x and am wondering what one of the underside markings mean.

It has;

3x20.5
BK
JAPAN

The “3x20.5” is magnification and lens size and “Japan” is where it is made but what does the “BK” stand for?

Thanks in advance for any info!

Jon

 

[Rwilco]

Generally speaking, the early Japanese scopes are of lower quality than the US made scopes.

This guy really breaks down the vintage scopes.

https://youtu.be/Il888wRHDLA

A great resource:

https://www.vintagegunscopes.com/

Canadian resource:

https://www.facebook.com/tracescoperepair/

 

[jonh172]

Thanks RWilco, lots of good info there.

But I’m just looking for what the BK stamp means on the underneath.

 

[Suther]

Perhaps it is indicating the type of prisms used in the optic?

https://binocularsguides.com/bak-4-vs-bk-7-prism-which-is-the-best/

 

[jonh172]

Looks pretty reasonable thanks!!