Browsing sources for a locking block for an alloy 220. Mostly consistent info BUT found a vendor with one locking block for steel frames and a different one for alloy. I am fairly new to Sigs so I confuse easily. Anyone know if the blocks actually differ?

Not sure of the difference between the two (as far as the 45 ACP locking insert is concerned), but if you are shopping at Numrich, they do have a 30 day return policy if the part isn't to your liking. I've ordered three of a possible part and was able to return the other two that didn't fit with no questions asked.

Take out that locking bloke at your peril!!Then spend 2 hours trying to get the damn thing back in!!