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Posted: 10/29/2003 5:15:29 PM EDT
I saw the other post about which ar's have the M4 feed ramps and was woundering what the advantage to them was?

Thanks in advance for the info.
Link Posted: 10/29/2003 5:54:00 PM EDT
[#1]
As a fresh round is stripped from the magazine and fed it into the chamber the extended feed ramps make the round less likely to hang up and jam. The other advantage is that an extended feed ramp is less likely to deform a softtip hunting round.

That being said my older Colts have standard feedramps and feed ammo just fine, although they [b]will[/b] deform certain softtip rounds. I haven't tried any softtip rounds in my Colt M4 with extended ramps yet, so I don't know how much of an improvement it will actually be.

Some folks have made their own extended feed ramps with a small file. Supposedly it only takes a few minutes and is pretty easy to do.
Link Posted: 10/30/2003 6:33:48 AM EDT
[#2]
Quoted:
I saw the other post about which ar's have the M4 feed ramps and was woundering what the advantage to them was?
quote]

I came across an article that said that the M4 feed ramps were introduced due to chronic failure to feeds during full auto fire.  The high speed stripping cycle was apparently causing some bullets to dive below the ramp.  They found that by starting the ramp at a lower point, they could pick up a higher percentage of the rounds, and feeding reliability was improved.  Mind you, I believe I found this statement online, where all info is subject to, ahh, further scrutiny.
If true, this puts the ramps in the same category as heavy buffers and pigtail gas tubes, that is, to offset the bolt velocity issues endemic in tapping the gas closer to the chamber.
Link Posted: 10/30/2003 12:39:17 PM EDT
[#3]
Fast carbine bolt cycle (full auto or not does not matter)

Weak mag spring

Bolt strips bullet before magazine can get bullet all the way up

bullet lodges less than .1 inch low and jams under the feed ramps

Solution, make feed ramps lower and longer


This type of malfunction is very rare.
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