German 77mm Bi-Metal case makers mark

[Falcon]

Today I picked up a slightly trench-arted German 77x230R Bi-Metal case. It is stamped with the makers mark shown in the attachment.

The other markings are: 276, 15, Sp61.

What factory does that maker's mark represent?

Thanks in advance for any help.

 

[Krt7.92]

That's the symbol for Rheinmetall, Borsig.

greetz,
Kurt

 

[Falcon]

Thanks Krt7,92.

On the wikipedia it says Rhinemetall had several factories, which one was likely to have made my shell case in 1915?

 

[Der_Feldgraue]

In 1915 there was Rheinmetall only. Here you will recognize the company logo:

http://images.google.de/imgres?imgu...ages?q=rheinmetall+firmenlogo&hl=de&sa=N&um=1