With the barrel m-4 ramped and the receiver not, this puts a hell of a ledge between the two.

Granted that feeding shouldn't be an issue, you may have accuracy shortcomings cause by the step (read instead of the bullet being fully guided up the ramp, it falls off the ledge slammig into the next ramp and can cause the bullet to be knocked off eccentric alignment with the bore/case line during loading.

i built one for a friend that had his this way


rra dremeled feed ramps on upper and barrel which matched each other perfectly since the ramps were done with the upper assembled.


but we needed to replace the upper reciever so since the ramps were dremeled we could not get an upper that matched the ramps unless we did it ourselves so we decided on using a non-ramped upper. the ramps were not as aggressive or true as factory done ones but they were extended,


half a$$ed bbl ramps with rifle upper reciever, no problems at all.


the only problem i would have thought to have was the bullet slamming against the bbl. ext and shoving it into the casing, but since the ramps are beveled it just slid home.

Why not spring for a new upper receiver w/ ramp cuts for $95 ?

You can always sell the un-ramped receiver you have now on the EE and recoup 2/3 of the price of the new one.

Quoted: i would venture to say that the twist of the bore would correct this as the bullet traveled down the barrel, but barrel life could be affected somewhat.

So close, yet so far away,

The accuracy of a bullet in regards to the bore is that the bullet needs to cleanly imbed into the rifling, and glide down the bore/rifling in complete contact for a consistent spin/engagement.  Items like a long jump to lands (read bullet traveling without rotation then hitting the lands), or the projectile not parallel with the bore during engagement causes less than stellar consistent engagement/ unified travel down the bore, which leads to deviations of shot strings (back to barrel harmonics and the exit point of the bullets out the muzzle during barrel whip), hence variations of accuracy regarding shot string groups.  

P.S. Not trying to bust you balls, you just have to remember that at one time I chased the Holy Grail in bench shooting (read groups less than .1 MOA). In regards to the AR service rifle, my thoughts could be way over the top, but if the rifle is taken to the edge (read match type shooting), then these concepts become more valid.

Added: A WECSOG'er doing a little magic with a dremil tool regarding adding feed ramps to a upper,
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