To add a contribution to answer the original poster's questions:
Missouri Boot and Shoe hand-make each pair of footwear here in the United States and have the original purchaser provide dimensions of their feet (and calves if the purchaser is buying boots) as well as tracings of both feet, so their products tend to fit straight out of the box and require minimal breaking-in. Some other suppliers source their products off-shore and those items often run on the small, and therefore tight, side, and are very much an out-of-the-box sort of thing; they'll either fit properly or they won't. To compound the issue, the size stated on the box may or not accurately reflect adherence to any known American shoe size, a sad truth that doesn't make buying by mail any easier. The initial purchase price of MB&S footwear is frequently a bit higher than that of their competitors, albeit not by that much once their quality is factored in, but they last forever with even modest care and are appropriately historically accurate. (That's not any sort of paid endorsement, by the way, but rather the result of several decades of experimenting with reproduction period footwear, and is only my opinion.)
Try following the advice offered by several others and substantially loosen the laces when you put your brogans on, and make sure they fit correctly when they're on your feet. It could just be that they're too small and you may need a different size. Aside from that, it's not unknown for a new pair of properly made shoes or boots to run a little tight in the heel to minimize slippage; boots in particular have to slip some in the heel but can sometimes be a bit too tight in that area when first acquired. An easy solution to the problem is to sprinkle a small amount, a pinch or two will do it, of talcum powder into each shoe or boot at the heel. It serves as a dry lubricant, only needs to be done once, is accomplished with a material widely available during the Victorian era, and will substantially ease the process of putting on or removing footwear until the leather has a chance to mold to the feet. I was taught that particular trick by an old Turtle (a pre-Second World War rodeo cowboy) back in the late 1960s and have tried it myself. It's worked for me, although your own mileage may vary.
I hope these comments are of some use.
Best,
phil