Call Ellie at Samson Manufacturing. They make the OEM sights on the SIG Sauer AR type rifles and pistols. They are really nice people to deal with and they stand behind their products 110%.
I recently had a SIG Sauer 516P pistol come in direct from a distributor for a customer. The front sight was installed on the firearm and the front sight was missing the locking piece that keeps the sight in the up position. After two days of trying to reach SIG (if you think the wait time at S&W is long, try SIG Sauer), I called Samson.
I offered to purchase a new sight and then to attempt to deal with SIG Sauer on the original that was missing the vital part.
Ellie transferred me to the owner, who would not hear of it. He insisted that he be allowed to send me a brand new sight. He had Ellie send me a pre-paid shipping label to return the sight that had been on the firearm. They shipped the new sight immediately without waiting for me to return the original.
The new sight arrived. It was installed, and the old returned. I offered again to pay for everything on the theory that it was SIG's warranty issue, not Samson's. They would not hear of it. I think that speaks highly of the company and the people who run it.
By the way, just to give you an idea of the quality control at Samson, this happened just after the new year, and the Return Authorization number I was given was still a 2013 number, and it was number 1. When I pointed that out, they changed the Return Authorization number to a 2014 number, still number 1. They may be a small company, but they make good stuff, and they stand behind their stuff, even under circumstances that would indicate it was "not their issue" to correct.
As far as I am concerned, Samson makes good stuff and their products are at the top of my list for after market sights for AR type rifles.