decrease weight?

[brendanjev]

I was told 3 sets of 8-12 reps for size. I get through the first 2 sets fine, but by the third i have muscle failure by 6 reps. Should I move down in weight?

[Casper]

Yes but you have more issues besides not getting through that 3rd set. Check out some routines other guys are doing on this site. More calories = Size.

[OldGuy]

I'll disagree with moving down in weight. You'll eventually be able to move the weight in the last set for the right amount of reps so keep at it. You might want to increase the amount of time between the 2nd and 3rd sets. More rest and you will be able to get a few more reps.