One way. In the code posted below, all the variables will be prefixed with "Dwg" and then a number assigned as to where they are in the list.
(setq Lst '("O_SR01.DWG" "O_SR02.DWG" "O_SR03.DWG" "O_SR04.DWG" "O_SR05.DWG" "O_SR06.DWG"
"O_SR07.dwg" "O_SR08.DWG" "O_SR09.DWG" "O_SR10.DWG" "O_SR11.DWG" "O_SR12.DWG"
"O_SR13.DWG" "O_SR14.DWG" "O_SR15.DWG" "O_SR16.DWG" "O_SR17.DWG" "O_SRB1.DWG"
"O_SRM1.DWG" "O_SRM2.DWG" "O_SRM3.DWG" "O_SRM4.DWG" "O_SRSB.DWG"))
(setq cnt 1)
(foreach i Lst
(set (read (strcat "Dwg" (itoa cnt))) i)
(setq cnt (1+ cnt))
)