I like these, very nice. My one issue is that the M14 has a great deal of recoil and you wouldn't be able to hold it even with the foregrip unless your off hand is stranger than your main, which I doubt. I love the look of it though, looks mean!
I don't know your resources, age, or priorities, but if you are inspired enough you could start sketching these yourself, learn the anatomy of a gun and so forth. With that you could attend a school for firearms development and design and make a career out of it. Just a thought.