I'll let you in on a little secret. It's for all you Goons ( including yours truly )that love SigArms and are considering an ICS version but are hesitant 'cuz of the mags.
A couple days ago I picked up a TM Sig Commando. It was supposed to be upgraded with fancy this and fancy that but it wasn't ( I won't go into it ).
Anyhow it came with a slew of 43 round fake bullet mags. Initially I offered it up to the ics magwell and it seemed tight so I accepted defeat.
Today I said to myself "I'm not gonna be beat by no ****ing toy gun" and I applied a bit more elbow grease and......Ha! Psyche!
All kidding aside, YES, they worked. Three of the bunch were stubborn so I applied some silicone oil (heavier, not spray but spray will work) to the BB retainer at the top of the mag. Loaded about 5 rounds in each mag, fired 'em all and no misery.
Try it out(gently at first) ICS is a virgin to these mags you know!
Now wipe the sweat from your brow and rejoice!
inomini patri, spiritos sancte. Praise the nailed up one!!!