Rifle feed ramps to M4

[redshooter]

Can anyone comment on how difficult it would be to open up the rifle feed ramps on my barrel ext. to match M4 feed ramps. I'm looking to replace my upper receiver and the vast majority of stripped uppers have M4 ramps. I've found a reasonably priced upper with rifle ramps, but I'd really like a "slick side" upper, and they all look like they have M4 feed ramps.

 

[gnmontey]

I swapped my CQ311 over to a M4 receiver just to have adjustable sights. The mismatch didn't cause me any grief.

The strange part was the fact that the smith who swapped it for me, didn't mention the mismatch. Perhaps he didn't know any better?

M

 

[redshooter]

So Google says I can use diamond files, or my die grinder, but I prefer files as it's less likely I'll remove too much metal. I know I've asked before, but that was about changing the barrel ext., and if I recall it wasn't worth the effort. There are other reasons for getting an upper receiver with M4 ramps, I'll wear out the barrel eventually, and although rifle upper and M4 etx. don't seem to be a no no, I'm assuming they changed the ramps for a reason.

So unless someone tells me the barrel ext. is case hardened or has some other surface treatment that removing material can effect I'll be doing some filing (it's a Colt HBAR barrel).

I don't think I'm going to take a chance on M4 rec/rifle ext.. One of the example I read about had the guy pushing the projectiles back in the case and having big pressure spikes...by his first question on another forum he obviously didn't understand why he was popping primers.