I will always choose to train without a chest rig when possible. However, there are times when a chest rig is a must in order to have enough magazines on hand. I prefer to run a reload or two on my belt but sometimes chest rigs are just unavoidable. So, if you have to wear a chest rig, you might as well have one that really works for you and give some thought as to how you wear it.
High or Low
Many people wear chest rigs so low that I wonder if it would be more accurate to call them gut rigs. It is true that the lower the chest rig is, the faster and easier you will be able to access magazines but that is not the only consideration with a chest rig. You must also account for a few ergonomic considerations.
When you shoot a rifle from the prone position, there is a natural space between your upper chest and the ground since you are up on your elbows. If you wear your chest rig too low, it will be wedged under your stomach which can be uncomfortable. If you can move it higher on your chest, it will slip up into the natural space between your chest and the ground, allowing you to get lower and stay comfortable.
A higher chest rig is also less likely to interfere with items on your belt like reloads and your handgun. I can’t tell you how many times I have seen people training with chest rig straps covering their handgun. They would never be able to access it if they needed it. Simply moving the chest rig higher will prevent interfering with items on the belt and interfering with the draw stroke.
Making Low Work
If you do have to wear your chest rig lower, there are some things that you will address. First, make sure that you keep it clear of items on your belt. This may mean that you have to use a drop holster to keep your handgun clear of straps (there are considerations for how to wear these as well). You may also need to figure out a way to lower any reloads that you keep on your belt as well
Second, keep your chest rig as thin as possible. You do not want a lot of bulk down around your stomach line where you will have lay on it in the prone and where it will block your draw stroke. If you do need to place something bulky on your chest rig, make sure it isn’t over your handgun.
I prefer to place my chest rig as high as I can while still being able to access the magazines and without interfering with shouldering a rifle. This may make magazine access slightly slower for some (magazine management can help mitigate this) but overall it is a better solution.