Ah, OK, you must have an older SBE then.
I've never heard of a Mobilchoke not fitting a Mobilchoke gun. Briley must have screwed up on these chokes.
I pretty much use Beretta brand chokes in my guns. To be more specific: the stainless extended Victory Mobilchokes.
MidWest GunWorks sells them at a 20% discount, making them more affordable than the equivalent Briley chokes.
See:
http://www.midwestgunworks.com/page/...ke-tubes/JCMEV
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