I believe you are correct.
Here is my example with the less often seen round wire catch.
Infanterie Sturmabzeichen in Silber, B.H. Mayer/Schickle
Searching for anything relating to, Anton Boos, 934 Stamm. Kp. Pz. Erz. Abt. 7, 3 Kompanie, Panzer-Regiment 2, 16th Panzer-Division (My father)
a very nice example.
I agree with the others...a very nice BH Mayer/O. Schickle Design ISA.
As to the actual maker of this variant, there are basically two theories with conceivable arguments on both sides...yet solid proof has yet to surface.
Because of this, the collecting community has taken to referencing both possible makers and refer to this one as the BH Mayer/O. Schickle Design.
Best Regards, fischer