I need a 5.56 reamer to run down the chamber. I would be willing to rent it if neccessary. My DPMS is very tight and the shell gets stuck every now and then so I want to take it up to mil. spec.

If your chamber is chrome plated then no reamer will touch it as the chrome will be harder than the reamer material.

I suggest you just use some type of cloth and polishing rouge chucked into a power drill and run it for a while.

DUH! I have a DPMS in .223 they don't usually come in crome, they do come in crome moly such as mine. I want to make it a 5.56 due to the sticking brass problem and I believe this will fix this problem. Does anyone have a reamer?

mpearcex,

The only difference between a .223 Rem and a 5.56mm chamber is in the angle of the leade in the throat.  Running a chambering reamer in a finished barrel is overkill and will likely make the headspace longer.  There is only 84/10,000ths of an inch difference between minimum and maximum headspace in the AR15.  You may have less room to play with.  

You may also want to consider that any warranty would be voided by amateur chamber cutting, and that your problem might be nothing more than indifferent cleaning and lubrication or ammunition selection.

You might try the chamber polish method... fine emory paper on a patch rod in a dril, followed by a mop with jb bore paste in a drill...

What FALARAK said. Reaming's not gonna' do it.