[RonS]

When building a carbine, is it worth it to pay extra for M4 feed ramps?

It will be a LW 16" barrel with a carbine gas system.

 

[Alaskapopo]

When building a carbine, is it worth it to pay extra for M4 feed ramps?

It will be a LW 16" barrel with a carbine gas system.

Yes I think so. M4 feed ramps help the gun work well with 77 grain bullets and the various soft points.
Pat

 

[Gary G23]

All of mine have M4 feed ramps. My house guns are loaded with Hornady TAP 75gr and they feed fine.

 

[RonS]

Hadn't considered the longer bullets, I was thinking about timing in the carbine. Good point. Thx

 

[RMTactical]

M4 feedramps are nice to have, not essential. I would get them if you have the option.

 

[Kentak]

Hadn't considered the longer bullets, I was thinking about timing in the carbine. Good point. Thx

The overall length of the cartridge is the same, it's the weight of the bullet, I believe, that is the factor.

Some of the reading I have done indicated that the supposed reason for the feed ramp modification was, as you pointed out, timing. The concern was the shorter gas system increased cycle rate and could lead to a situation where the rounds weren't fully lifted to the mag lips as they were stripped out by the returning BCG. The bullet tip could catch on the edge of the receiver. The extended feed ramps help a "low" bullet tip make it into the chamber.

If you've got a mag full of 77 gr rounds, you've got considerably more mass that the spring has to lift into position, and that means it takes a little bit longer to do so. That's just physics. So, if you've got a fast cycling weapon, a mag spring on the weak side, and heavy bullets, yes, the M4 feed ramps could help.

Absolutely needed? Probably not if you're using a good quality magazine and standard 223 55 gr ammo instead of hotter 5.56 NATO ammo or heavy bullets. On the other hand, they don't *hurt* anything, so it could be considered a small investment in reliability insurance.

 

[Alaskapopo]

The overall length of the cartridge is the same, it's the weight of the bullet, I believe, that is the factor.

Some of the reading I have done indicated that the supposed reason for the feed ramp modification was, as you pointed out, timing. The concern was the shorter gas system increased cycle rate and could lead to a situation where the rounds weren't fully lifted to the mag lips as they were stripped out by the returning BCG. The bullet tip could catch on the edge of the receiver. The extended feed ramps help a "low" bullet tip make it into the chamber.

If you've got a mag full of 77 gr rounds, you've got considerably more mass that the spring has to lift into position, and that means it takes a little bit longer to do so. That's just physics. So, if you've got a fast cycling weapon, a mag spring on the weak side, and heavy bullets, yes, the M4 feed ramps could help.

Absolutely needed? Probably not if you're using a good quality magazine and standard 223 55 gr ammo instead of hotter 5.56 NATO ammo or heavy bullets. On the other hand, they don't *hurt* anything, so it could be considered a small investment in reliability insurance.

No its the length. 55 grain ball is loaded to a shorter overall than 77 grain match ammo. For example I load 77 grain match to 2.260 and ball to 2.250 or so.
Pat

 

[17445]

It's a nice option if you had it at the time of choosing.

 

[Chuck TX]

Yes I think so. M4 feed ramps help the gun work well with 77 grain bullets and the various soft points.
Pat

Pretty much this. You can get away with not having them, but if you have the option there's no reason to pass it up. Some loadings, especially soft points, can be problematic without the feed ramps.

 

[Kentak]

No its the length. 55 grain ball is loaded to a shorter overall than 77 grain match ammo. For example I load 77 grain match to 2.260 and ball to 2.250 or so.
Pat

No, it's the weight. If the round is properly positioned at the feed lips, how does that extra 0.01 inch affect the need for M4 feed ramps?

This round measures 2.248 in. The gap at the right jaw represents the difference to 2.26 in. Again, how does that relate to M4 feed ramps?

 

[blhar15]

If you have the choice between having them or not, I would defintely have them. Sure does not hurt.

 

[S. Kelly]

I'd opt for it. My latest Bushmaster (a separate upper put on a complte lower) doesn't have them but works like a swiss watch.

 

[1811guy]

Just get the feed ramps. There is nothing negative in getting them, and lots of positive - even if only marginally so.

 

[Alaskapopo]

No, it's the weight. If the round is properly positioned at the feed lips, how does that extra 0.01 inch affect the need for M4 feed ramps?

This round measures 2.248 in. The gap at the right jaw represents the difference to 2.26 in. Again, how does that relate to M4 feed ramps?

Its the length. Longer bullets can nose dive and fail to feed in non m4 feed ramped guns. The weight has nothing at all to do with it.
Pat

 

[Hoser]

No its the length. 55 grain ball is loaded to a shorter overall than 77 grain match ammo. For example I load 77 grain match to 2.260 and ball to 2.250 or so.

If you think that 0.01 makes enough difference of needing M4 feedramps and the gun running, your rifle has other issues.

To the OP, cant hurt, might help.

 

[Alaskapopo]

If you think that 0.01 makes enough difference of needing M4 feedramps and the gun running, your rifle has other issues.

To the OP, cant hurt, might help.

My rifles are fine. In the world of firearms and cartridges a differences of .1 (not .01 as you incorrectly stated) can make all the differences. Its a proven fact that M4 feed ramps help with feeding of longer rounds. Do a search on the net if you must to verify this.
Pat

 

[Kentak]

My rifles are fine. In the world of firearms and cartridges a differences of .1 (not .01 as you incorrectly stated) can make all the differences. Its a proven fact that M4 feed ramps help with feeding of longer rounds. Do a search on the net if you must to verify this.
Pat

What's 2.26 - 2.25? Those are your numbers, Pat.

Please explain what *causes* a round with a longer bullet to nosedive.

 

[Alaskapopo]

What's 2.26 - 2.25? Those are your numbers, Pat.

Please explain what *causes* a round with a longer bullet to nosedive.

Whoops you're right it is .01. Either way that is a huge differences when it comes to seating bullets. What causes nose dives is the longer bullets are closer to the feed ramp. The bolt pushes the bullet forward and down slightly when it first hits the back of the cartridge. With shorter bullets its not enough to make the bullet get stuck on guns without feed ramps. On longer bullets it can be.
Pat

 

[vafish]

....Do a search on the net if you must to verify this.
Pat

I did just that, typed "m4 feed ramps" into Google and the first thing to come up is a thread on M4Carbine.net that was started in 2006.

http://www.m4carbine.net/showthread.php?t=193

The industry experts in that thread seem to agree with Kentak that it is a cycling speed and weak mag spring issue and no one mentions overall length as an issue.

 

[Alaskapopo]

I did just that, typed "m4 feed ramps" into Google and the first thing to come up is a thread on M4Carbine.net that was started in 2006.

http://www.m4carbine.net/showthread.php?t=193

The industry experts in that thread seem to agree with Kentak that it is a cycling speed and weak mag spring issue and no one mentions overall length as an issue.

Actually we are both wrong. A post in that thread does mention size and weight but it says that light weight shot blunt bullets are the ones that need M4 feed ramps the most.


From your link.
1. Certain Ammo can be a problem without M4 feed ramps...
The Federal 50gr HP are fat, short bullets with big HP holes, that,
when observed feeding into the chamber by slowly hand releasing
the bolt/carrier, can snag on the feed ramp lip. The Black Hills 52gr
bullet is only 2gr heavier but is long and lean with a small HP hole
and did not come as close to the feed ramp lip, as such, not causing
the feeding problem. Therefore, HP ammo can be reliable without
M4 feed ramps, but short, fat ogive bullets need not apply.

2. The magazine can be the issue, but not the way you would think...
I noted that when the 10rnd Bushmaster magazine with the 'GI'
Green follower was used, I didnt have the same problem as when I
used a C-Products 30rnd mag with a MagPul 'enhanced' anti-tilt
follower. Again, when watching the bolt close in slow motion, I
observed that the follower tilting rearward just slightly is an
advantage to helping feed the 50gr HP. When the follower is
restricted from tipping, as in the MagPul, it drives the HP directly
toward the feed ramp lip. This is not to say the MagPul decreases
reliability, just that an anti-tilt follower may not be the best for
trying to feed wide tip ammo without M4 feed ramps.

So, yes, M4 feed ramps would be better, but only for using ammo the M4 was not really intended to fire, IE. lightweight HP. I will be doing further testing but I am only slightly disappointed that my upper does not have this feature since most of my shooting will be done with heavier weight bullets and mostly FMJ.

I have never had a problem with 77 grain ammo but then again my guns have M4 feed ramps on my carbines.