I also thought it was a crock... The place that you use for the nitride treatment has the "increased velocity" claim as a benefit on their website.
On the Stevens, did you add a longer LOP butt stock to it? It looks longer than normal to me.
I do believe a slight increase in velocity may well be a side benefit of the improved bore surface resulting from the Black Nitride treatment. But, “hundreds of feet per second?” Though I didn’t actually check, I really don’t think my .30-30 cast bullet load, doing 1700 fps before treatment, was suddenly doing 1900+ fps after treatment. I suppose there could be some extremely high intensity cartridges for which a couple hundred fps would represent but a small percentage increase.
The pictured stock is what came on my Stevens Favorite Model of 1915 .22LR.
