According to the book "Black Rifle II", the M4 ramps were designed to make M855 more reliable in the M4s.  The M4s had more problems with that round because of the different bullet ogive and because they cycle faster.   They said because the carbine cycles faster the thinner heavier M855 bullet did not have enough time to rise high enough to enter one or the other feed ramps on the barrel extension, and the bullet noses were stubbing on the upper receiver under the barrel extension causing failures to feed.  They never really figured out the exact cause of this but believed that its a combination of the higher cyclic rate, shorter buffer, the plastic collapsible stock, higher bolt velocities and the different balance characteristics and the sharper thinner bullet ogive of the M855.

As a non enginneer I would say that stronger mag springs would help too.  All my 20 rounders have Wolff +10% springs and all but 2 of my 30 rounders have the same stronger +10%Wolff springs.

I have a slower cycling semi auto M4gery carbine using a PRI fatboy gas tube, LMT buffer, and 99% time I use the much cheaper and better performing out of a carbine 55gr XM193 or Q3131A and have never had failure to feed in over 5K.

Quoted: I SUPPOSE I SHOULD BE HEARTENED TO SEE THAT M4 FEED RAMPS ARE NO LONGER REFERRED TO AS A "MARKETING GIMMICK". AS POINTED OUT ABOVE, "BLACK RIFLE II" CLEARLY DOCUMENTS THE HISTORY OF M4 FEED RAMPS. IT IS A FACT THAT THE M4 FEED RAMPS ENHANCE RELIABILITY IN THE M4. THEY ALSO DO IN OTHER PLATFORMS. THE SPR USES RECEIVERS AND BARREL EXTENSIONS WITH M4 FEED RAMPS. WES GRANT M.S.T.N.

Yes,
Wes in the book they do explain they used the ramps in the SPR also because of the different ogive of the 77gr rounds.   What I found interesting is that they stated that the 73gr Bergers actually performed better than anything but at the time of testing the Berger plant was in the process of moving.  Meaning I guess they couldn't supply enough for full testing.  Not that the 77gr are bad by any stretch.

bigbore
Thanks great thread I learned alot.

Quoted: Quoted: actually, no, it does not. dremel makes chainsaw sharpening bits that have the exact conture of the M4 ramp. Sure, it will not be a "Colt M4" feed ramp but it will be identicle in every form other than the small amount of anodizing that will be removed. they are sold in a series so a person can grind out the material and then polish it. it's pretty easy. i'm not saying it's right or wrong, just that cutting the ramps is a simple task. installing a new barrel extension on the other hand, that's a major pain in the ass! OK, so you remove the material, that goes no where; you still dont have any feed ramps. Im order to have "feed ramps" they need to ramp up to something. If you dont have an M4 barrel extension, you have nothing to "ramp" to. The ramps cut into the barrel extension, are a completely different angle on the M4.

JTAC ramped the bbl ext on my RRA bbl to flush with the extended ramp cuts in my LMT upper.
Fit is perfect and smooth. No finish lost at all.

~ s0ulzer0

Quoted: BIGBORE - WHY, I DO BELIEVE IT IS YOU WHO ON THIS FORUM IN THE PAST REFERRED TO M4 FEED RAMPS AS A "MARKETING GIMMICK", BACK BEFORE YOU HAD UPPERS WITH THEM YOURSELF. WHEN I DID. WES

I don't want to add to any flame wars but bigbore has, in the past on at least one occasion, referred to M4 feed ramps as a marketing gimmick.  While I don't think they are absolutely necessary, they are not a gimmick either.  I just call it added insurance and peace of mind.

Quoted: Quoted: Quoted: actually, no, it does not. dremel makes chainsaw sharpening bits that have the exact conture of the M4 ramp. Sure, it will not be a "Colt M4" feed ramp but it will be identicle in every form other than the small amount of anodizing that will be removed. they are sold in a series so a person can grind out the material and then polish it. it's pretty easy. i'm not saying it's right or wrong, just that cutting the ramps is a simple task. installing a new barrel extension on the other hand, that's a major pain in the ass! OK, so you remove the material, that goes no where; you still dont have any feed ramps. Im order to have "feed ramps" they need to ramp up to something. If you dont have an M4 barrel extension, you have nothing to "ramp" to. The ramps cut into the barrel extension, are a completely different angle on the M4. JTAC ramped the bbl ext on my RRA bbl to flush with the extended ramp cuts in my LMT upper. Fit is perfect and smooth. No finish lost at all. ~ s0ulzer0

I believe bigbore meant the  anodizing on the receiver being machined off when you try to match an M4 style barrel extension to a receiver without them.  I don't think the barrel extension has any interior finish to rub off at all.  Wouldn't the simple solution to the removed anodizing be to re-anodize the receiver?  

There was a test of rifles offered to the local PD here.  The PD requirement was to use soft point ammo and and maybe those cuts would have made a difference?  ANyways, the Armalites had FTFs and from what I heard the COLTs were the only ones that ate the SP ammo up.  All rifles were CAR styles.  I really don't care if an upper has those 'm4 feedramps' as I did not experience any feeding problems that were related to having those cuts..as I don't have or don't even know those cuts existed in my rifles.  I have used SP ammo on occasion in my Bushie CAR and had no probs.  I see the same thing ADCO sees....marketing BS about 'M4 cuts...enhanced bolt carriers...titanium firing pins...etc.'  all this stuff that really lends itself to just more $$$ to the seller and little advantage to the end user.  There are people who can slap together an AR and GUNSMITHS who can build an AR.

I have a new M4 upper for sale and someone wanted to buy it, but came back later and told me that "his department" won't allow him to use it unless it has M4 feedramps".  I believe that M4 feedramps as an enhancement at best, but what type of "department" would require them other than the militray?  Maybe he was military or maybe wifey put the keibash on the purchae.  Who knows??

First of all, I like to extend a "thanks" to bigbore, Wes, Denny, Tweak, and others who've shared their considerable experience with us here. It seems to me that in debating the necessity of the  M4 feeding system a few of points have been clarified.

If I may;

The M4 feed system, comprised of the proper M4 barrel extension and the properly cut and matched upper receiver cuts is not in any way detrimental to the functioning of a weapon. To the contrary, for professionals with FA M4's this system can only enhance the functioning of the weapon, which is vital when one's life may depend on the weapons' reliability. There's no downside to having a weapon like this, except where cost may be an issue (which a professional may question with, "what's your life worth?").

The M4 feed system is not necessary for reliable functioning in a properly built and maintained semi-auto M4gery when combined with good magazines. It certainly would not hurt the weapon in any way, and may add a bit of reliability when handloads of various construction are used. But under normal circumstances, with typical military ball ammo, reliability should not be a problem if the weapon is constructed using a barell with std. rifle extension and an upper w/o cuts.

After-market M4 "dremel" cuts may offer some degree of reliability in weapons that do not function properly, and as such may be a practical solution to a specific problem. Addressing the FTF problem through other methods (magazine problems) may be a more prudent approach, however one can't argue with success, if it is in fact, a durable solution to a problem.

After-market "dremel" cuts aren't a marketing gimmick to those who've used it to fix their FTF problems that couldn't be solved by other means. If one demands authenticity in a weapons build, then they could certainly argue that if it's not to spec, then it's a marketing gimmick (although those whose problems were solved with a "marketing gimmick" might argue otherwise).

After hearing all the arguements, I'm quite comfortable with my M4gery with the rifle barrel extension (Bushmaster) and the non-cut upper receiver (Eagle Arms). Although it has been 100% reliable with various types of ball ammo, I've always wondered if it is somehow deficient without the M4 cuts. I'll worry no longer.

Again, thank's for all the info.

tagged

Armalite SOF 16" factory upper
http://home.earthlink.net/~aubertine/images/SOF.jpg

Armalite  20" A4 factory upper, ramps in upper, standard barrel extension.
http://home.earthlink.net/~aubertine/images/A420.jpg

These are not dremel cuts.
Please no comments on the cleaning.

Have you had any feeding issues with this? It looks like it could be trouble with the tip of a round possibly hanging up on the protruding edge between the barrel extension and the upper.

That being said theory goes out the window if it runs correctly

Thanks for the pic, by the way!

No problems feeding.  It is my "loaner gun".  When we get a group together to shoot, someone new always wants to shoot an AR.  I hand them this 20" Hbar with a detachable carry handle sight and a 30 rounder of cheap stuff.  It never fails to get a smile.

Quoted: No problems feeding.  It is my "loaner gun".  When we get a group together to shoot, someone new always wants to shoot an AR.  I hand them this 20" Hbar with a detachable carry handle sight and a 30 rounder of cheap stuff.  It never fails to get a smile.

Excellent, thanks for the info.

So much for theory

Sorry to chime in; after looking at my 1991 Colt Lightweight Sporter, I found out it has the M4 feed ramps.  When did Colt begin doing this?  There is no "4" stamped in the receiver lugs (that I could find).  Thank you.

deleted

Thanks Tweak,  there is no "4" stamped anywhere that I could find in or on the receiver.  Barrel is marked C MP 5.56 NATO 1/7, and there is no "F" stamped onto the FSB.

The ramps look just like Aubertine's Armalite SOF 16" pic on page 3.

Any other ideas?  Thanks.

If your feed ramps are not cut by Colt or LMT, they are not M4 feed ramps because we are playing a game here called symantics.

It's true, the M16/AR series got by many, many years without this feature.  Older rifles will not suddenly cease to function if they do not have it.  We also got by without green followers, reinforcements around the back of the receiver/receiver extention, mag well fences, M1913 rails and a host of other features that we take for granted today.

If you have never, ever had a bullet plow into the upper reciever below the barrel extention and get pushed into the case,  or you never shoot non-ball ammunition, or you don't care if your weapon is as reliable as it can be, then M4 cuts may not be for you.  Where I come from, we call this progress... like chrome plating the chamber, it's an improvement, it works, and it's there for a reason.  I think the M4 feedramps are the biggest single improvement to the rifle since the chrome plated chamber.  Having spent more than a few years in the army, I can tell you that several times I have had bullets stuffed back into the case by the offending bit of upper receiver while shooting ramp-less M16A2's.

I understand that bushmaster doesn't want to infringe on colt's patent, so they won't do it.  I understand RRA doesn't want to use the word 'M4' with any features on their rifle, because colt will sue them... but if you have the little cuts in your upper receiver, and they are properly done, even if they were put there by some dremel wielding weasel, for god sakes man, we can call them M4 ramps if we want.  They will not start randomly rejecting bullets because they were not hand carved by Samuel Colt.

And for other folks reading this thread, wondering if you might like feed ramps cut into your upper, several reputable gunsmiths/machinists will do this for you for a reasonable fee ($30-$50), and the feed ramps will function, in every aspect, the same as a Colt or LMT rifle.  You can even do it yourself, if you posess the skill and tools.  If it's done right, it will add value and increase reliability (even if it's only with certain types of ammo).  

Whatever you do, just don't call your sub-standard , home-made ghetto-fabulous feed ramps 'M4' feed ramps.  At least not here.

Quoted: ... but if you have the little cuts in your upper receiver, and they are properly done, even if they were put there by some dremel wielding weasel, for god sakes man, we can call them M4 ramps if we want.  They will not start randomly rejecting bullets because they were not carved by Samuel Colt.

Damn funny!!

Lon(dremel weilding weasel)Moer

I look at the M4 feedramps as a product improvement. Given the wide variety of bullet weights and shapes that are available in .223/5.56 caliber and the various magazines, springs, followers and the wide range in the condition of the magazines, I think the M4 feedramps are a prudent measure that takes real world chaos into consideration. If I were king of the world, they would become standard.

thanks for the info

My Colt LW Sporter made in November 1991 also has the M4 feed ramps. The barrel extension is marked with a "4" at the 3 o'clock position. No "F" stamp on the front sight base. No "4" markings on the A2 upper. Upper has a "C" in a square above the front of the ejection port, along with what looks to be a "P" in a triangle above that.

Mick

Quoted: Thanks Tweak,  there is no "4" stamped anywhere that I could find in or on the receiver.  Barrel is marked C MP 5.56 NATO 1/7, and there is no "F" stamped onto the FSB. The ramps look just like Aubertine's Armalite SOF 16" pic on page 3. Any other ideas?  Thanks.

Thanks Mick, my LW has a low serial number so I am guessing it was just missed (concerning the "4" on the barrel extension.  By the way; is your LW slab sided like mine?

I learned quite a bit through this discussion.....as I just could not figure out what was wrong with my carbine.  I had the same problems discussed in other threads, rounds jamming up at 45 degree angles, and my bolt gouging at the sides.

Apparently, the upper I picked up at a Tucson gun show, it the barrel extensions had a "lip" that the rounds were hitting, prior to hitting the ramp.  I didnt' realize it, until I finally put it on a lower, and took it out to the range.

I used the dremmel method that several have mentioned done after rifle assembly, and that has cured all the FTF problems I had (hanging up on bolt release & cycling, within 1-2 rounds, with 6 USGI 30rd mags, and 1 40rd steel).

Runs 100%, and although I'm a little worried about the anodizing I removed, I'll just be sure to keep an eye on that whenever I go shooting.  I also polished the feedramps on the extension, and the dremel cuts on the receiver.

At least I know what to look for now, and to beware of dealers offering me "factory M4 feedramp barreled uppers", which is what I thought I had....which never really existed on my upper.

Here's some pics......sorry for the bad quality, the last ones are of the polishing I did.  Great way to save $60 on gunsmithing!

Kurt at KKF did ramps on my Bushmaster when I had it recontoured to light weight.  Runs like a champ now (of course it did before I sent it in).

I have magazines that will run with  Colt factory upper that has extend feed ramps but not with standard feed ramps in my Bushmaster.

Lesson:  Never know what magazines one has to use, nice to have an extra safty margin with the system.  It is the difference between weapon runing and weapon NOT running.  

Let's face it.  Manufacturers do not want to change the feed ramps because it costs $$$$$$.   It is one extra step in the making of uppers and one extra step in QC to ensure the barrel extension and upper lines up.  This means there is a potential of 5 problems to take care of just to add two little steps.  Same reason you don't get forged extension tube,  barrel parkerization under FSB, properly chamfered magwell and MPed barrel, becasue they alll cost $$$$.  These things are reflected in the price point.

Get back to the point, not everyone needs these features and so some people will accept the fact by paying less.  However,  you pay 90% of the price to get  90% of the features.  The rest of the 10% is critical for a 100% system  and it is reflected in the money saved.  Just becasue some people do not need these features does not mean these features are purposeless.  By paying 90% of the price, they agree to give up something.  When the weapon goes belly up, it is not the problem of the AR platform, it is the money saved.

I used to say to my friends, " A moment of cheapness results in a lifetime of suffering'  

Great Thread.

I've been meaning to post a follow-up on my Bushmaster Carbon-15 Type 97S Carbine, but this discussion has prompted me to get off my ass and write, so here goes.

I got the carbine a few months ago. Overall, it ran fine, but every 2-3 magazines, the round on the left part of the chamber would be stuck, nose-first, into the upper receiver wall just below the left feed ramp.

I called Bushmaster, and they told me to send it to their place out in AZ. I did that, and two weeks later, it returned with the feed ramps enlarged as shown in a picture I have - someone please provide me with a location to host the picture at, and I will do so shortly thereafter.

Guess that puts to rest the issue of whether or not Bushmaster will provide extended feed ramps on their products, at least the carbon fiber ones...

I admit the ramps aren't perfectly symmetrical and all that, but with a loaded magazine in place, the rounds are definitely pointed in the middle of their respective feed ramp.

Also, there's obviously no issue of cutting into the anodizing here, as the upper and lower are of carbon fiber-reinforced polymer.

Now, it feeds like a champ. Many hundreds of rounds though it with a variety of GI 20 and 30 round magazines, and not one hiccup. A real blast to shoot. Not thorough enough testing to bet my life on it, (not sure I ever would) but good enough for more range time and perhaps a 3 Gun IDPA Match.

Interesting side note. My Colt Match Target HBAR purchased new in 95 (I know, one year too late. Sigh.) has many thousands of rounds through it with never one problem. I looked at its feed ramps, and they are defintely NOT M4 style. However, I also noticed just under the left feed ramp on the top of the receiver portion several very minor but totally identifiable marks where obviously a bullet nose had hit and then bounced up into the chamber. I would like to take a small fine file and clean that one up too, but not sure about this "damaging the anodizing" issue. Comments?

Anyway, I'll be posting a more thorough report on the Bushy Carbon Fiber after some more range time and shooting, but right now, it's a great little piece that's a hell of a lot of fun to shoot. And the materials all seem to be first rate, FWIW.

Jeff_Gilbertson,

Email the pic to me and I will post it for you.

[email protected]

FWIW, I juts looked at my Colt Green Box 6520 Govt Carbine and it has the M4 feed ramps with the "4" stamped at the 3 o'clock position, no "F's" or anything else that I can see. I don't know when it was made but it was back in the green box days.

Bill

G35, Picture sent. Thanks.

Here is Jeff_Gilbertson's picture.

Jeff,

You weren't kidding when you said they were not symmetrical with ramps.....

Is it just the camera, or are they oblong in shape?  Does your AR run 100% with them?

So long as it works, that's all that matters...

tagged

It's become quite obvious that there is no hard and fast rule pertaining to the M4 ramps, especially where Colt is concerned (so what else is new?). Anybody who claims that there is a "standard" involved is only fooling himself. There are many cases in point contained in this thread. Here's mine:

I bought one of the early production Colt civvy M4's (MT6400c) NIB from Gulfstream Sports when they first came out. There is NO stamp above the gas tube hole on the upper. The rails on this upper are NOT numbered either. The FSB DOES have the letter F stamped into the left side of the crossbar. The barrel extension DOES have the number 4 stamped at 3 o'clock on its rear facing surface, and it DOES have the M4 feed ramps. The upper DOES have the M4 feed ramp cuts, but they are NOT anodized. I figure that it just must be an early production example, but have seen several much later production Colt M4's that lack the anodizing and the stamp over the gas tube hole.

I've never experienced a FTF over thousands of rounds, and there is no appreciable wear showing on the un-anodized ramp cuts. I tend to question the advantage of anodizing in this area anyway, as it seems all too easy to scratch the mil-spec "hard-coat anodizing" found on any manufacturers uppers or lowers.

I sure appreciate everyones input to this thread, as it looks like it might just explain the FTF's that I've very recently experienced on a new SPR upper (no M4 ramps or cuts) when trying a load that I've just developed using the 77gr. Nosler Custom Competition bullets. This upper seems to feed everything else without a hiccup, including my favorite 69gr. SMK load. I think that I'll have to CAREFULLY have a go at it with a file or a Dremel.

Personally, I would always prefer to have M4 cuts. My Armalite AR-10(T) didn't have M4 cuts and the gun ALWAYS jammed because of it (but only on one side)...magazine, ammo, etc. didn't matter. It did it no matter what. This incident pretty much ended the debate for me as to whether or not M4 ramps are just a "marketing gimmick". Now Armalite makes all their AR-10(T)'s (and probably others) with the M4 cuts (they replaced my upper with a M4 cut upper but the gun still had *other* problems...sigh)

The way I see, even if you're not using your rifle in a life or death situation, why NOT have the extra bit of reliablility? When I bought my SPR upper from JTAC, I decided to go with a LMT upper (which has M4 cuts built into it) and I made sure my barrel extension matched.

While it may be true that "you don't really need it", it's an improvement, why not take advantage of it? Hell, there are a handful of AR "improvements" that no paper target shooter "really" needs but if you can get it, why not? It's called PROGRESS. It's helps your AR be just that much more reliable. If everything else was the same, I would always take a upper with "afterthought" M4 cuts (not anodized) over one with no M4 cuts.

JM2C....