You know, there is always this tendency to pat people on the head and say "you have to practice." And it's true. Without lots of practice, you cannot do well. Dry fire, get to range, organize your practice sessions, get coaching, etc. The fundamentals are key; I'm having a little trouble getting a clean trigger release in slowfire this year, and it's costing me about 20 points per 2700 so far. So I don't claim to be the best shot around, or know all the answers.
Regardless, equipment is very important in bullseye pistol. You can not shoot good scores in an outdoor 2700 without good equipment. Nope, sorry, it cannot be done. That 10 ring is 3 1/3 inches. If your gun is shooting 4, 5, or six inch groups, you are going to have a lot of trouble putting together a good slow fire score. And how are you going to be able to call your shots? "Hey, I thought that shot was good. How come there is a hole down in the 7 ring?" Calling your shots, correcting errors, and re-enforcing things done right is fundamental. But you can't do it if your gun will not shoot to call.
A vital consideration is gun fit. Yes, gun fit. Some people have short stocky builds, and forearms the size of telephone poles. They can shoot a heavy gun well. Some of us have longer, rangier builds and don't manage a heavy gun as well. Some people have big hands and need long triggers. Some people have small hands, and with a long trigger, the trigger pull will seem like 10 lb. instead of 3 1/2. Can't see the front sights anymore? Well, do what you like; I'd put a dot sight on rather than screwing around with trick prescriptions. Got a creepy, 5 lb. trigger pull? Go ahead, be a man and keep it that way. The rest of us will go for a smooth 3 1/2 lb. pull on our .45s.
And by the way, I have listened to some of the top shooters in the country, and also some coaches, and they will tell you equipment is important. I've never seen anyone improve very fast with lousy equipment. The people I've seen improve fast have -- surprise -- good equipment. Go back to some of the excellent articles in the Gil Hebard book and read carefully. You will note that several of these articles say "you need good equipment."
I have never seen anybody shoot a master score with a .45 that wasn't properly accurized, didn't have a trigger job, etc. And that is a little expensive. I'm not saying it can't be done, just that none of the master shooters I know choose to try it. Going a step further I have seen good shooters absolutely held back by their equipment. I know one guy that had a new .45 built and watched his scores move up fifty [that's 50] points in the 2700. From 2550s to around 2600. He later replaced the slightly shot out barrel on his old 41 last year and picked up a few more points. We knew the barrel was shot out because we could see it putting 4 inch groups on the target at 50 yards from the machine rest. So we popped the barrel from my 41 on it and watched about two inches fall off the group. Equipment is important. In this shooter's case, part of the problem was old guns that literally had worn out barrels. But he got very frustrated sometimes when shooting slowfire and the shots were not to call. This frustration, and lack of confidence in your equipment, is devastating to a shooter. Did I just miss, or did the damn gun throw it out?
Ranting aside, I want to stress you don't have to spend an incredible amount of money on your equipment. A Ruger with a trigger job and stocks that fit your hand may work quite nicely, for example. I've seen 880 broken with a Browning Buckmark. But I've also seen sharpshooters and marksmen competing with equipment that would cost me 30 points per 900 aggregate. Some of them are not serious, and don't really mind.
I always suggest to people interested in bullseye they start with a .22 and see if they like the sport before investing in a .45. I also think I made better progress just working with a .22 for a year or so than I would have trying to shoot both a .22 and a .45.
I don't want folks to feel that they have to spend a fortune to participate in this sport, or that practice [and sometimes natural gifts] do not separate competitors. But equipment is important, and people who say otherwise do not win matches.