There are a good many things that serious competitors can do to tighten up groups. Most involve fixing the shooter (#1 the most important failure point) then the gun (#2) and then the ammo (a very distant #3)
Jerry Miculek has some very good tips on his website
http://www.shootingusa.com/PRO_TIPS/...y_miculek.html as does Doug Koenig
http://www.dougkoenig.com/ http://findarticles.com/p/articles/m...8/ai_110457299 among other champion shooters. Books abound in the software and other publications sections of gun related retailers' websites.
Obviously serious competitors spend serious money on serious custom guns and serious time practicing. A teacher is a lot more valuable than most shooters seem to think. Almost everyone can benefit from having another pair of eyes to watch what you are doing wrong and right.
There are some things you can do to tune up loads and also to improve the function of factory guns. How much time and money you are willing to spend is up to you. Tuning your powder to your bullet and vice versa will shave some MOA off. Some aftermarket recoil springs, guides etc. can be changed on a factory gun to tune it to the load and the shooter. All will have some slight effect and require experimentation on your part. People shooting bowling pins or CAS at the local club may not find all this to be cost effective both in terms of money and of time.
Certainly I could be wrong. but guessing from the fact that the post was on this site in this particular category of the forum, the poster is looking for some extra advantage to be gained from special loads, techniques and the likeas so many, many people who post such questions on such sites are. I would answer that there is a great secret and it applies equally to rifle shotgun and handgun competition shooting. It will do more for any shooter young or old, experienced, or tyro. It is this: fix #1 first.