I am try to figure out when the SU / T-34 series switch from rounded front fenders to bent fenders. At one time I thought Bent fenders were post war but I have heard this is not ture. Does anyone know when the changed happen? Also were SU-100 every made with round fenders?

It seems so :

This one belonged to the 208th Self-Propelled Gun Brigade (Hungary, March 1945)

Another one (Zeida area. 13th Army/1st Ukrainian Front, April 1945 ) :


More reference stuff here : http://www.armchairgeneral.com/rkkaww2/galleries.htm

HTH
Frenchy

T-34/85 tanks built in fall /winter 1944 from factories #112 & #183 had "bent" fenders. (from T-34 Myythical Weapon)
So I would think any SU s built at these factories after this time would have the same kind of fenders.

SUs were only built at UZTM after autumn 1943, when they converted the T-34 there line for that purpose. It's possible that because of that, rounded fenders continued to be installed on SUs after they had been replaced on tanks. The squared fenders appeared on some T-34-85s very late in 1944.

Cheers
Scott Fraser