Does anyone have any knowledge about cleaning the small gap that is between the feed ramp and the barrel?

I will only be able to clean it in the field so no chemicals other than CLP will be available, and no tools except for the basic bore punch, small brush, and chamber brush will be available unless I am able to purchase or make another tool.

I just got out of Marine Corps. basic and realized cleaning that particular spot will be an issue, especially concidering I will be infantry.

Thanks

That gap should not be accumulating anything of note. If it is, it is too big or you have a non-M4 feed ramp barrel and a  M4 ramp barrel extension or some other poorly advised setup.

do you mean behind the locking lugs?

I use those long wooden q-tips to get in there. or you can get a long nose hemostate to hold a just the head of a q-tip to get around in there.

Or you could go to the vendors at the top of this page and search in the "cleaning supplies" area and get some chamber stars to clean behind the locking lugs

What did they teach you in boot camp?