I noticed the green mountain barrels cut differently when I did a .338/405 winchester wildcat on a high wall last year.  The steel cut very smoothly, but didn't create a chip, rather it cut a continuous wire that ran very hot, the wire came out deeply blued.  The chamber cut very smoothly, but slow and very fine cuttings.  That barrel was what they describe as 41V50 steel.

I chambered a .257 barrel from them also last year, but didn't notice anything different about it.  It drawfiled and finished like a dream.  The .22 lr barrels I have done haven't been hard either.  I've done a few .45 barrels, but don't remember anything different.   

I notice a wide range of performance difference in cutting barrel steel from different manufacturers.  The times I have tapered Douglas barrels, I have realized why their rough turned barrels look like they do.  Their steel seems to cut much less smoothly than some other makers steel does.  If you use a flat cutter, it chatters.  A pointed cutter does well, but leaves a rough finish, and a lot of tear-outs.

I haven't cut enough barrels to do a good comparison, but there is a marked difference between makers.

dave