I spent much of the day at Ammo Brothers in Cerritos CA today, doing my part to support National Ammo Day.
While there I played with bunches of guns. In one of the display cases they had a new S&W Sigma, 9mm.
A few months back I was discussing the Sigmas in a post here on FTF and mentioned one of the issues with the Sigmas back when they were first introduced (1990's) was the fact that the frame bulged when the trigger was squeezed. Some members said they have Sigmas and the frames do not bulge. I figured they had fixed the problem at S&W when they came out with the "new and improved" Sigma.
But the one I played with at Ammo Brothers today bulged when I dry fired it.
The place that they bulge is on the right side of the frame near the slide, maybe an inch behind the ejection port.
If you own a Sigma and want to check this, just make sure it is unloaded and look straight down at the top of the slide while SLOWY dry firing. You will see that as the trigger is squeezed, the frame will bulge on the right side. It is only about 1mm, but it does bulge.
Anyone else notice this?