Pulling G's while shooting is perfectly normal as most airplanes are turning in a fight and you must learn the proper technique for shooting this way. Shots are divided into two different types based on how the target is moving relative to you. When you're saddled up on him and there is little relative motion between your two aircraft (low track crossing angle) you can position and hold your pipper in front of the target for lead. This is a tracking shot. If you're not saddled up and have high relative motion between your two aircraft (a high track crossing angle) you can set yourself up for a momentary opportunity to fire as the target passes in front of you. That's a snap shot.
In a tracking shot you need to be in the proper position behind the target, in range, and stable in relationship to him with the proper lead as you fire. In a snap shot the technique is to anticipate where the target is going to be when you get in range and fire a stream of rounds in front of him to let him fly into it. While an unloaded shot is easier you need to know how to do a proper tracking shot under G as the target may never give you the opportunity to fire an unloaded shot. The steady-state nature of a tracking shot is what gives you an excellent kill opportunity and is the best of all possible shots.
While technically your rounds "disperse" more while pulling G's it's irrelevant as we only care about where the rounds go relative to the target. Yes, with both planes turning the rounds do not go to the exact same place in the sky, they are dispersed along the plane of your turn. If someone is looking at the fight from above it'll appear that your rounds are spreading out like a fan but this sort of dispersion isn't important and is really irrelevant since your target isn't standing still. From your position in the cockpit, it'll appear that your bullets are dropping away under your nose. The only thing that is relevant is where your rounds go relative to the target and this apparent bullet drop is why you need to pull lead. In a good tracking shot with the correct lead you can put every round into the target so there is no dispersion relative to him (except for the normal dispersion of the guns themselves.)
Tracking shots are limited by the amount of lead you need to pull and the nose of your aircraft. The more inside of your target's turn circle you are, the greater the turn rate and distance, and the slower your rounds (i.e., a 30mm vs 50cal) the more lead you need to pull, the higher the G you'll need (more loaded), and the more likely it is that the target will be hidden under your nose. In truth, the real answer isn't to shoot "unloaded" but "less loaded". The harder you're turning the more lead you'll need and the more difficult the shot so, quite obviously, you want to set up a shot that requires less G and less lead. It's easy to tell someone to shoot "less loaded" but how do you set this up?
There are several things you can do to optimize your shot and the best choice can sometimes be dictated by the airplane you're flying. If you have closure on the target you can just wait until you get closer as the shorter range will result in shorter bullet time of flight (BTOF) and less apparent bullet drop and less lead required. You can reposition yourself closer to the target's turn circle (i.e., move from well inside of the target's turn circle to either on or even slightly outside of it) by lagging him. You can lag him either by easing up a bit on your turn for just a moment, doing a slight high yo-yo, or doing a quick lag roll. Once you do this you can begin to pull lead again to set up the shot with less lead and G required. Which technique you use depends on the overall geometry and where you are in your performance envelope. Easing your turn for a moment means you'll need to momentarily pull even harder to re-establish your turn with lead. You may not have enough G available to do this. Both a high yo-yo and lag roll will increase your nose-to-tail distance so you want to be careful not to position yourself out of range unless you know you have the faster aircraft or more E. A lag role is a great option in the 190 and 109. Both have relatively poor over the nose visibility but roll well so it's a quick and easy maneuver to reposition yourself. On the other hand this is definently not the maneuver you want to try with slow rolling planes like the Typhoon. You can also offset your turn to the inside and below his with a slight low-yo-yo so you can see him down the side of your nose and shoot as your turn circles intersect. This works particularly well with the Spit and Pony (and to a degree the 109)which have great visibility down the side of their noses due to the in-line engines. A consideration here is if you have enough G available to get your nose inside of his turn enough for the yo-yo and also that the low yo-yo will decrease your nose-to-tail which can be a factor if you're already very close. Another option is to pull more lead than needed then quickly unload and fire in front of him in what really amounts to a snap shot. Unfortunately, this means you'll lose sight of your target for a moment as you pull the extra lead and then have to predict where he'll show up again. This is a shot that I use extensively in vertical scissors where the target's path is pretty predictable.
There are many other techniques for air-to-air gunnery and it's one of the most interesting aspects of air combat. Don't worry about "unloaded" vs "loaded" shots, just remember that "less loaded" is what you're after. Also, most of the time, a little bit of prior planning can avoid situations where you need to pull lots and lots of lead. Most new pilots tend to see the enemy, roll to put him on their lift vector, and then pull directly toward him. This means that when they arrive they'll have high track crossing angle and won't really be positioned for a good shot. If, instead, you plan ahead and rather than pulling directly at the target you pull to a position behind him you are much more likely to be in an optimum shooting position with less track crossing angle when you arrive.
