To this day I still have to meet someone that has put 110% effort in the gym, in their diet and supplement regimen and not achieved a respectable physique. Now, having said that, not all of us can look like the heroes we admire due to different genetics and muscle shape, but we can certainly get bigger and more defined.
To the right you will see a picture of myself so that you can take a look at it. While I am not a threat to become a Mr. Olympia contender anytime soon, that physique you see there was accomplished without the use of steroids. Granted, I started bodybuilding back when I was 15 years old, so I used all of my naturally produced steroid hormones that the body makes during puberty to build most of that mass in conjunction with very dedicated training and dieting efforts.
Since you are 50 years old, I would suggest that you visit your doctor, get a physical and also check your hormonal levels. If your testosterone levels are low, then maybe you can discuss with him your options to bring them back up to normal high levels in order for you to be able to make good progress. In this case, typically your doctor prescribes you low dosages of testosterone along with an anti-estrogen in order to bring your hormonal levels back up. In this case, steroids are being used as hormonal replacement therapy so don't feel like you are cheating. If your testosterone levels are normal then nothing can stop you from making good gains so training, diet, supplementation and rest are the only variables that you need to concern yourself with.
As far as Arnold, Larry, Draper, and Casey, the size of those physiques was built from tons of hardcore training and massive amounts of food. As you rightfully said, typically a gallon of milk (at least) was involved along with tons of eggs and pounds of meat. While I cannot speak for these champions, from my understanding, back in the 60's and 70's many competitors would start a low dose cycle of steroids (they were legal and easily accessible back then) 8-12 weeks prior to a bodybuilding contest in order to be able to train harder and longer under the strict caloric restriction required to gain muscle definition. The steroids were basically used to protect as much muscle as possible from the extreme training and dieting circumstances. These guys would train for 3 hours in the morning and 3 hour at night when preparing for a bodybuilding show, if you can believe that! Today with supplements like Branched Chain Amino Acids, L-Glutamine, Essential Oils, and Creatine, in conjunction with better designed training protocols, we can protect muscle mass quite well during a dieting phase without having to resort to steroids. We even have over the counter anti-estrogen supplements like 6-OXO that help men boost their testosterone levels during a dieting phase.
Believe me, steroids are not the magic bullet that many would like you to believe they are. You will not turn into an Arnold Schwarzenegger, Dave Draper or any other bodybuilding celebrity just by using them. I've never seen a great physique being achieved by the simple action of just plugging a syringe or just taking a bunch of pills. The right bodybuilding mindset, the training, the diet and the consistency of following these factors day in and day out for many years is what will get you the respectable physique that you are looking for.
By the way, in that picture you see to the right my arms measured a good 17.5 inches and I am only 5'5" so it is indeed possible to get 18 inch arms (or close enough) without drugs.
Best of luck!
About The Author
Hugo Rivera, About.com's Bodybuilding Guide and ISSA Certified Fitness Trainer, is a nationally-known best-selling author of over 8 books on bodybuilding, weight loss and fitness, including "The Body Sculpting Bible for Men", "The Body Sculpting Bible for Women", "The Hardgainer's Bodybuilding Handbook", and his successful, self published e-book, "Body Re-Engineering". Hugo is also a national level NPC natural bodybuilding champion. Click here for more information on Hugo Rivera.