Anthony, this is just a guess of course but I suspect since Swenson had been hand building the single and ambi safties for some time and they were very time consuming, my thought is he was thrilled to have a stainless part. Remember there were darn few, if any, stainless parts when he brought out the production Swenson ambi. The time frame to build and install an ambi on one of his guns went from several long hours to a few minutes with his stainless production part.
There are lots of pictures of Swenson's guns and Heinie's guns for that matter, blued, with a stainless Swenson ambi. The cosmetics and attention to detail that we find common place today, was different 30 years ago. Chrome was a new thing and stainless was the FUTURE :grin:
On this Govenment model the ambi is on the original sales receipt. The NM guns I have seen had hand made single safeties and all were chromed. The two Swenson Government models I have here to rebuild both have hand built ambis and both were indeed chromed with the guns.
That is why I think Swenson used the stainless material, less work on fit and finish.