You are probably correct on dating. I show on my list two in the SN 649xxx range which shipped in 1935 and none quite that high which shipped in 1934. But at that time, one cannot reliably know the shipping date without a letter as gun sales were very slow during the Depression. The silver medallion round top service grips are correct for the 1930s but you might not be able to find a nice pair in the $100-$150 range. You might get lucky on eBay, but good ones don't show up every day.