The cutoff for RV in any of the categorial seats will vary highly. I had joined RV in 2014 through Lateral entry in computer science and the cutoff then was 274 for 3B, but lately the cutoff has went down below 200.
If you have studied in rural areas or either you’ve studied kannada, the chances are high that you get seats even with lesser ranking. GMR or GMK has cutoff’s around 400.