M4 feedramp question

[tju1973]

I know many people "have to have" M4 feed ramps on their ARs, that being said, are they even needed on full length ArRs? I carried an A2 in the FMF and never had a feeding issue...Are the ramps on M4s there to help with the short gas system, or why did they make them? As a Grunt that got out in 97, I never had the chance to see M4s...My AR does have M4 ramps, and they work fine, but are they really needed on my 18" full length gas system?

 

[sv51macross]

The Army developed the 'M4 feed-ramps' so that worn-to-hell magazine springs would still feed reliably under full-auto fire. The ramps are [IIRC] 17 degrees steeper than normal, that is all. For a semi-auto AR-15, or a M16 owner who keeps his/her mags in good shape, the ramps are completely unnecessary and according to LaRue Tactical, actually harm accuracy by stressing the cartridge as it's forced up the sharper ramp.

 

[kwelz]

Feedramps are made to better feed heavier and longer bullets.

 

[Wahoo95]

Not needed in 20" AR's....they were made to helo with the "M4" hence their name.

 

[Bartholomew Roberts]

The M4 has a faster cycling time than the M16A2. The cycle time difference can be measured in milliseconds; but apparently this is enough that some magazines that function in the A2, will not function in the M4. As part of an improvement to the M4, the feedramps were added to assist with this problem, which appeared primarily in full-auto and was exacerbated by suppressor use.

Since that time, a side benefit of the M4 feed ramps has been minor increases in reliability in the M4 when feeding long OAL 5.56mm rounds (like the Sierra 77gr) and help with feeding softpoint ammo used by law enforcement.

Since neither of my 16" carbines have them, I wouldn't consider them a necessity on a 20" rifle at all; but if I was building new, I would probably go ahead and upgrade.