Never used one for a SIG but I have one that I use on duty with my 1911 (plainclothes/"casual" duty). It only has two screws, not counting the ones that hold the belt loop on, and neither are adjustable. One holds the locking mechanism in place and the other looks like it should allow the holster to be tightened against the gun but the piece that it screws through is solid plastic and it will not give. I spoke to Safariland about it when I first got the holster and they said that I should be able to tighten that one but it doesn't budge. I've tried the holster with several different 1911s and, while the gun is not snug in the holster, the ALS does not allow it to come out unless you release it and use a straight up draw. I've yanked and twisted and wrenched on it and have yet to get a gun to release. Even if you defeat the ALS from the front or rear unless you pull the gun up straight it doesn't want to come out. In spite of all that if you practice with it you can work up to a wicked fast draw and with the 1911 my thumb releases the ALS and is perfectly positioned to release the safety. I really like it and it's a great security holster for my needs.