M4 Feed ramp or ?

[Mity2]

I'm looking in to stripped upper right now, and while I'm pretty sure I'm gonna go with either Anvil arms(I have Anvil arms lower, and pretty happy with it), or WhiteOak Armament upper, I cant figure out the difference between Upper with M4 feed ramp, and without.

I'm building either rifle or SPR(likely SPR), like one below


Whats the difference between those 2 upper in term of AR builder, and term of barrel choice?
Only info I can find in this matter is this
"You will need to be sure you match your barrel extension type and the upper receiver type. If the barrel has ramps then you want a receiver with ramps. If it does not have ramps you want a receiver without ramps. If you mix and match these parts you WILL have serious feeding problems. The only exception is that you can use a ramped barrel in a non-ramped receiver and it will function acceptably. Any other mismatch will not work"

So what should I get for my SPR build?
Thanks

[Mabuz]

Not an AR expert, but I'll take a stab at it from what I've learned so far.

I think regular uppers have no "feed" groves cut into them, just the barrel extension has grooves in it to feed ammo.

The M4 feedramps have deeper groves cut in the barrel extension that are extended into the upper receiver. If you don't have a matched barrel extension, you very well may have serious feeding issues, which defeats the extra cost of the M4 ramps in your upper.

FWIW, I've been told you can have 3 successful combinations of upper/barrel extension, and 1 failure:

Good: M4 upper/M4 extension
regular upper/regular extension
regular upper/M4 extension

Bad: M4 upper, regular extension

Check out this thread that shows an upper with M4 feed ramps for a visual: http://www.ar15.com/forums/topic.html?b=3&f=4&t=381786

In the second post, at the bottom of the receiver, you can see two little notches which are the M4 feed ramps.

ar15.com has lots of good info, just browse through the AR section. I'm just starting my first build, and have learned a lot from that site.





Edit: See post #7 (and the rest of this thread) for good comparison/discussion - http://www.pafoa.org/forum/rifles-42...pros-cons.html (M4 feedramps - pros and cons?)

[Xringshooter]

Mity, You can also go to www.M4carbine.net and get a lot of info about it. If it were me I'd match the upper and the extension just to be sure.

[stevieb92]

Originally Posted by Mity2

I'm looking in to stripped upper right now, and while I'm pretty sure I'm gonna go with either Anvil arms(I have Anvil arms lower, and pretty happy with it), or WhiteOak Armament upper, I cant figure out the difference between Upper with M4 feed ramp, and without.

I'm building either rifle or SPR(likely SPR), like one below


Whats the difference between those 2 upper in term of AR builder, and term of barrel choice?
Only info I can find in this matter is this
"You will need to be sure you match your barrel extension type and the upper receiver type. If the barrel has ramps then you want a receiver with ramps. If it does not have ramps you want a receiver without ramps. If you mix and match these parts you WILL have serious feeding problems. The only exception is that you can use a ramped barrel in a non-ramped receiver and it will function acceptably. Any other mismatch will not work"

So what should I get for my SPR build?
Thanks

I have both the Anvil Arms Lower and Upper (with M4 feed ramps) and am really happy with the result so far. You can see close up pics of the feed ramps buried in this thread...

http://www.pafoa.org/forum/rifles-42...uild-pics.html (Stevieb92's "PAFOA" AR-15 build pics...)

I found that barrels without M4 feed ramps were a little more difficult to find. However, I was looking for something specific. I went with a White Oak Armament barrel.

Its killing me to go shoot this thing!!!

ETA: Page 2 has the M4 feed ramp pics.

[Lycanthrope]

It really doesn't matter until you get into the 16" range with a gun that cycles VERY fast.

The whole H buffer thing was to slow the bolt down so the carrier does not outrun the magazine spring......if it does....the carrier wants to strip a round before the mag spring has fully pushed the next round up into full position. Maintain your rifle and it's a non issue.

I have both and they all run 100% in semi auto variants. Now....Del Ton and others offer M4 ramps for about $25 and that's a nice upgrade for the risk of bad mag springs.

http://www.ar15barrels.com/gfx/feedramps.jpg

Not totally necessary to make an AR run.......not worth high dollar.....nice to have on a full out AR you intend to abuse.

Lycanreallyyourchoicethrope

[Mity2]

Well, its only like $15~25 more to have M4 feed ramp. So I'll go with it.
Now, I'm looking at some barrels at midwayusa's site, and none of them states if any of them are M4 feed ramp or not.
So is that mean that M4 ramps are part of barrel extention or part of barrel?


Sorry for noob questions. But I am still AR build noob....

[Lycanthrope]

Everyone's a noob once.....

Anyhow the ramps are cut into the barrel extension.....and the upper must be cut to match. Yes, you can mix and match to a degree shown in the pic, but it's not recommended. Barrel extensions are usually coming with the barrel and headspace is already set.

Most barrels are not coming with M4 ramps so you need to ask. Plenty of good companies utilize them, though and Midway can likely get them. They may have both in stock. Call and ask.

Lycanexnoobthrope

[ham385]

Originally Posted by Mity2

Well, its only like $15~25 more to have M4 feed ramp. So I'll go with it.
Now, I'm looking at some barrels at midwayusa's site, and none of them states if any of them are M4 feed ramp or not.
So is that mean that M4 ramps are part of barrel extention or part of barrel?


Sorry for noob questions. But I am still AR build noob....

I think you're putting the cart before the horse. You should pick the barrel that you want, then get an upper that matches.

This, of course, is just my opinion, but the barrel is probably the most important part of the weapon, and the most expensive, so why not build the weapon around it instead of the other way around.

[Mity2]

Originally Posted by ham385

I think you're putting the cart before the horse. You should pick the barrel that you want, then get an upper that matches.

This, of course, is just my opinion, but the barrel is probably the most important part of the weapon, and the most expensive, so why not build the weapon around it instead of the other way around.

While this is very true, and was my original plan, my fiance told me she'll buy me a stripped upper, so I wasn't going to argue...

Main things I wanted to know is that which configuration barrel is easier to find, since its going to be buy barrel around upper, instead of way you and I(and most I presume) would go for..