I agree with cynic, that you do need to mix up your exercises occasionally. Another way to increase your bench is to determine where the weakest part on your bench press is... Is it the lockout ?? Is it midway thru the lift .. is it at the bottom of the lift ?? Where ever it is, do some exercises to strengthen that part of your lift and it may help you get thru this "sticking point"
First, 275 after 5 months of training is pretty good. I bet there are a lot of people here who wish they could push 275! I agree with all of the above. A plateau may be a result of overtraining, or just a temporary lag in one or more areas while thye catch up to your stronger areas. The problem could be chest, triceps, shoulder joint, elbow joint, connective tissue, satabalizing muscles, etc. Try doing something different for a while, higher reps, more rest, different exercises, etc. Do you do other body parts as hard as chest (back/legs/lower back/abs/...)? How much can you squat, deadlift, bent row, how many pullups can you do?
This may not help you push through your plateau, and is more a sidenote, but is there any reason you arent doing deadlifts?
well wit 300lbs its the bottom lifts. if i get a spot to the halfway mark i can get it up. how do i work on the bottom lift?
Well, I am not sure how to exactly tell you to go abouts working on just 1/2 of a bench, but I know I throw some "burnouts" into my chest routineevery couple weeks. after I am finished with my workout I load it up with 135 and do 7 full lifts, 7 lifts from chest to about half way up, 7 lifts from half way up to fully extended, and then 7 more full ones that usually end up only being one or two...hahaha.....
Might work?