I bought a new Glock 17 Gen 5 on-line and I'm having it sent to a FFL in Ellicott City. I haven't purchased a new handgun in a while and didn't realize you need an inter barrel lock. My FFL transfer dealer doesn't have any. I've looked on-line (dealers, Amazon, etc) and I can't locate one. Does anyone know where I can buy one to fit the Glock?