I wore Belleville 790 flight boots in Iraq in 2003 and 2004, and they were great for military purposes. They were a comfortable boot and a massive step up from what I had been issued. That said, understand that the 700 series boots are two decades old in design. They’re a military combat boot, and they’re designed to last a long time, protect from punctures, stop water, and provide ankle support, all while adhering to military uniform regulations. That doesn’t translate into a boot that provides all day comfort while bumming around on a shooting range for a day or two or three.
This is probably more information than you wanted, but the two major factors with long term foot comfort are a good midsole, and proper insoles. An EVA midsole is beneficial because it provides shock reduction and cushioning. What a lot of people don’t know is that EVA midsoles leech out acetate as they age and you wear it. The constant compression of it as you walk/run causes this. EVA is ethylene-vinyl acetate, which is a polymer closed-cell foam. As EVA leeches acetate, it stiffens and loses it’s “spring”, which results in the foam not absorbing shock and losing the comfort that it affords when its new. After about 2 years, the EVA has hardened enough that it’s basically worthless. Part of the reason you feet may hurt is because of the age of the boots.
The insole is also important, and a lot of traditional boot insoles do not provide adequate arch support. When you have poor arch support, the pressure from standing and walking is concentrated on the balls and heels of the feet instead of more effectively distributing the weight throughout. Depending on the age of your insoles, they’ve probably broken down enough to make this problem worse.
Salomon boots are fantastic, and they are built with the best foot support I’ve found. I’ve owned 6 pairs over the years, and I continue to come back to them. I’ve owned a lot of other boots, and Salomons are among the best for durability and long-term comfort. That being said, most modern hiking boots offer great support. Go to an REI or any larger shoe store that has a lot of hiking boots and try out brands until you find something you like.
Another factor to consider is that with training courses, you’re carrying extra weight on your body. You have to compensate for that weight, and that gets directed into your feet. I don’t know what kit you were wearing, but it’s a contributing factor. Another factor is the surface you were training on. Harder surfaces are harder on the feet. These are important to keep in mind, as it’s not always the footwear that are the problem. You can be on your feet all day long with the right shoes, but eventually your feet are going to hurt regardless. The knees are naturally going to hurt also because they are part of your shock absorption system. I’m guessing the problem is that your boots are shot.