I am about to start reloading for my 7mmSTW. Does anyone have a preference in brass, and if so, why? Thanks!

I have three 7mm STW rifles and shoot both brands of brass in them. I really don't see any significant difference between them except maybe the Win brass is slightly lighter and therefore maybe 1 gr more capacity. One of my rifles is a 1000yd bechrest rifle and I use Win brass in it because I tend to push the limits a bit more to get the best downrange performance. The Win brass seems to be a little harder and the primer pockets hold up better when shoot the hotter loads. If you keep your loads There is no significant difference in accuracy between the two. I don't think you can go wrong with either.

Pretty much what David said, just stay away from A-square 7 STW brass. I bought a bunch of it back in the day (before Win and Rem got on the bandwagon) and it's very soft brass. - Dan

Winchester has been the best in my 7 STW in a Wby Accumark-Imr7828-83gr-fed 215 primers-3530av.fps 139gr hornady. Have tried Rem-8mm mag necked down and then 7 stw in Rem-brass and the primer pockets were loose on the 3rd reloading and streached badly. Have had best luck with win-brass. On 4th reloading and only trimed once. Max load in the Layne Simpson data for that 139 and the 140gr bullets.