So, the gun you want to prop up against the glock isn't actually a true production model at all.
You may want to check out the P210 Legend. And that article is full of bull. They were not a small run. They made as many as they could make and sell. They made them up until the late 1980's. They weren't expensive either. Now the Legend is very expensive. But the original P210 was just not that popular among many shooters who didn't really like 9mm handguns at the time. It was before the modern 9mm cartridges became available. But just for the record there were 350,000 of the original P210's made. That's hardly a small run. Keep in mind that the 210 is back in production with an upgrade or two but the new guns are a limited production unlike the original. I don't know how many they will make but again, the original was NOT a limited production pistol.
And the 210 is just one example of what a Sig can do. The article pointed out that the P220 was the direct descendant of the 210 and I plainly said my 220 can do 2" groups at 50 yards but certainly not every time. It does shoot very accurate though and I doubt you will find any Glock that will match it's accuracy.
You can prop up Glocks all day. There's no way they are as accurate as Sigs. It's a well known fact. They weren't designed to be as accurate as Sigs. That doesn't make them bad guns. I clearly said I like them. So I'm not "putting them up" against Sigs. I'm just describing the differences in the guns and the facts as I know them.
If you doubt my conclusions try the ones on this web page
where the 21 is compared to the P220. He rated the accuracy of the Sig much higher but he rated the Glock as a better buy. Makes sense to me but I could shoot my Sig better than he shot his any day of the week. But then he didn't spend any time figuring out the best load or practicing from what I could tell. That's not much of a way to run a test IMO but that's pretty much how they all go. For a better test of accuracy he should have fired from a rest instead of off-hand but he didn't. Just for the record the Sig managed a 3.5" group at 25 yards while the Glock couldn't do better than 8". Both were fired off-hand.
There are plenty of other places on the net that agree with what I said about the Sig being more accurate. I suggest you use Google if you want to read them yourself.