Ok, I am building an upper.  I am using an FN USGI barrel.  Chrome-lined, 1/7 twist, 20 inches long, you know the same specs as what is on an M16A2 because that is what it is.  I am going to send it down to Kurt@KKF to get it shortened to 18", threaded, and then have the bayonet lug removed.  I see that Delton is selling flat top receivers with the M4 cuts in the EE.  I am going to get an enhanced LMT bolt & bolt carrier for this upper and eventually go for an FF RAS with an ACOG, but that is all far into the future.

Here is my question.  Should I wait and buy the M4 cut upper receiver so that I can have Kurt put M4 cuts into the barrel extension, or should I just forget about M4 feed ramps and send the barrel to Kurt for all the other work and use a RRA flat top?

I have searched and read about M4 cuts.  They were done after cold weather testing for the M4 with blunter nosed bullets, is that correct?  Is there any harm of having these cuts done?  The only ammo I ever plan on using in this upper will be 55-62 FMJ and then some of the heavier bulleted rounds, 75-77 grain bullets.  Is it very well possible that if I got these M4 cuts done, I could shoot for a life time and never have a bullet tip hit the feed ramp in the upper receiver, always hitting on the barrel extention?  Thus negating the need for the M4 ramps?

I want to build this rifle so that I will never have a reliability problem after break in.

What are your opinions?

BTT

It doesn't really help when you don't post your reasons.  It seems like a dead poll, which is odd because all the ARF.comers love polls right?


Come on guys!  Let me hear what you have to say!

If you are buying an upper, might as well get one with the ramps since it is the same price.

I sent a complete upper back to DPMS for some work and they installed some feedramps in my upper. Works great!

You don't really have a poll choice that i can agree with.

M4 ramps can help with some guns with others it doesn't matter.  I am about to put them in a new RRA upper i just built even though it has had just one FTF in several hundred rounds since i built it, the reason?  why not?

Feed ramps may be cool, but are not worth removing metal from the receiver to me. All firearms can have feeding issues it would be best to address each one directly and not just try to compesate for them. Things like ammo selection, mags, springs ect. ect. can be delt with as needed. Just my thoughts others may differ.

I will probably have them cut for my M4, but it is a registered M16 rifle. Seems full-auto rifles are the main ones needing the cuts.

I went with the cuts because it gives me more flexibility as far as ammo selection.  If you only plan on shooting FMJ, I wouldn't worry about it.

True, full auto sets up harmonics in springs and various other things that would not be present in a semi auto rifle.



I do only plan on shooting 55 grain FMJ, 75-77 grain OTM, and possibly some V-MAX or some other poly-tipped bullets.  They don't look very blunt nosed to me.

Bradd_D, can you see any marks in the upper ramps where the bullet noses have actually used the upper ramp?  If, so, what bullet type were you using?

I am going to look at a Colt upper that has factory M4 feed ramps this weekend and compare it to a standard upper.  Then I will make up my mind.  You all better have left me some prety good answers by the time I get back on Monday.

I tried to shoot a 45 grains hollow point that looked like a star in one AR15 I have and it kept hanging up and shoving the bullet back into the casing. But with my other AR15 that has the M4 cuts it fed ok. so What you think.

I wish I could answer that.  I haven't built the rifle yet.  [;)]  I have the parts, but haven't made the time.

One thing you'll notice is that the ramp cuts in the upper are very small.  They simply augment the larger cuts in the barrel extension.  It's the combination that gives you the desired effect.  I just want the flexibility to shoot soft point or tactical ammo without worry.

When using the mag as a vert grip I have tipped it forward enough to cause cartriges to nose down into the lower reciever.  It looked like M4 cuts would have prevented this kind of stopage.

I think it's time to spend 10 minutes with a dremel tool and make your own feed ramps.  Did this on my DPMS, no problems.

They do prevent it. This could also take place in prone type positions. It also seems like a loaded 30rnd. mag fitting loosly in the well could tilt a little forward due to the curve.

I think this is reason enough to go with the ramps. My .02