Polishing m4 feed ramps?

[Rambozo]

I've never polished my feed ramps, though I have filed them in on uppers that don't have the M4 ramps. Doing that obviously removes the anodizing, though I have noticed no ill effect. It absolutely has increased reliability though. some grendel magazines don't have the relief cuts forward of the feed lips, which can cause the cartridges to nosedive more. Adding the ramps helps there. I also use the SS CMMG followers in my 5.45 mags. the benefit there is that they are simply bent sheet steel. That allows you to adjust them to fit the mag however you like. In my case, I have them adjusted in a way that the cartridges strip from the mag straight forward, without any popup. They just run smoother that way, but they also require the M4 ramps, else they would simply just nose dive and fail to feed.

I guess the short of it is, if nothing else, I would advise at least cutting ramps in the upper if you don't already have them.

[FirstTenor]

nice polishing job. I'll have to try it.

[rasp65]

The ramps can also be polished with emery paper 600 grit and crocus cloth wrapped around a 1/4" dowel. It may not be as fast but all you really need to do is get everything smooth.The smoother the feed ramps the less amount of friction the cartridge works against on it way into the chamber. Another area to cleanup is the sharp points on the 10 o'clock lugs, this will prevent the 2 marks on the case neck when it is extracted.

[Opus Dei]

what polishing compound are recommended?

I've always used a Dremel tool with the felt bit and rouge. The bit is compliant enough to conform to the shape of the ramp. It can sling some rouge around, so it's best to plug the breech. Just stop every few seconds and wipe the area clean; you'll see the shine after a few passes.

[LRRPF52]

The ramps can also be polished with emery paper 600 grit and crocus cloth wrapped around a 1/4" dowel. It may not be as fast but all you really need to do is get everything smooth.The smoother the feed ramps the less amount of friction the cartridge works against on it way into the chamber. Another area to cleanup is the sharp points on the 10 o'clock lugs, this will prevent the 2 marks on the case neck when it is extracted.

Do you mean the lugs at 2 o'clock and 3 o'clock? I think the vampire bites in the AR are from the top inner edge of the 3 o'clock lug, and the bottom inner edge of the 2 o'clock lug in the barrel extension. I have heard of guys taking the edge slightly off those, but that is usually done before threading the barrel into the barrel extension, when the extension is stand alone.

As the spent case is extracted from the chamber, as soon as the neck clears the breech, the ejector tension forces it to the right and upwards, with the rim pivoting off the extractor lip until it can clear the ejection port.

[txgunner00]

Do you mean the lugs at 2 o'clock and 3 o'clock? I think the vampire bites in the AR are from the top inner edge of the 3 o'clock lug, and the bottom inner edge of the 2 o'clock lug in the barrel extension. I have heard of guys taking the edge slightly off those, but that is usually done before threading the barrel into the barrel extension, when the extension is stand alone.

As the spent case is extracted from the chamber, as soon as the neck clears the breech, the ejector tension forces it to the right and upwards, with the rim pivoting off the extractor lip until it can clear the ejection port.

Agreed. That's how I got rid of my vampire, along with some garlic and a crucifix.

[rasp65]

Do you mean the lugs at 2 o'clock and 3 o'clock?

Yes that is exactly what I meant. I don't know what I was thinking all I have is a digital clock.