M4 Feedramp upgrade?

This is a discussion on M4 Feedramp upgrade? within the MP Rifles forums, part of the Smith & Wesson MP Forum category; So with all this talk about the newest M&P's getting M4 feedramps, any chance of SW upgrading our older rifles for us early adopters? Who ...


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Old July 1st, 2008, 09:10 PM   #1
 
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So with all this talk about the newest M&P's getting M4 feedramps, any chance of SW upgrading our older rifles for us early adopters?



Who volunteers to be the first to call them and see what they say? "Buy a new rifle?" Probably.
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Old July 2nd, 2008, 05:56 AM   #2
 
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Quote:
Originally Posted by Krik' post='151090' date='Jul 1 2008, 11:10 PM
So with all this talk about the newest M&P's getting M4 feedramps, any chance of SW upgrading our older rifles for us early adopters?
Are you serious? The M4 feedramp cuts need to be on both the barrel extension and upper receiver. Do you think they should replace both of those?



It would be less money to just buy a new upper and you could make it a 1:7 twist barrel with a midlength gas system to boot for the total upgrade. I am considering doing exactly that:

http://www.gandrtactical.com/cgi-bin/comme...category%3DNRIF
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Old July 2nd, 2008, 02:34 PM   #3
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Quote:
Originally Posted by Krik' post='151090' date='Jul 2 2008, 05:10 AM
So with all this talk about the newest M&P's getting M4 feedramps, any chance of SW upgrading our older rifles for us early adopters?



Who volunteers to be the first to call them and see what they say? "Buy a new rifle?" Probably.




No chance. To be honest, on a semi-auto gun in a 1/9 twist I would not worry about it. On 1/7 twist weapons, I view it a must have as I shoot 75/77gr ammo.





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Old July 6th, 2008, 10:50 AM   #4
 
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Quote:
Originally Posted by Austin12Gauge' post='151129' date='Jul 2 2008, 08:56 AM
Are you serious? The M4 feedramp cuts need to be on both the barrel extension and upper receiver. Do you think they should replace both of those?



It would be less money to just buy a new upper and you could make it a 1:7 twist barrel with a midlength gas system to boot for the total upgrade. I am considering doing exactly that:

http://www.gandrtactical.com/cgi-bin/comme...category%3DNRIF


Let me get this right.. This is an M-4 type rifle and S&W just now are adding feed ramps?

The terms lunacy and incompetent come to mind. M-4's have feed ramps, am I correct? Am I missing something? You would think they would be there from the git'go.



If this is true what a let down...but at least they got their heads out of their asses.
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Old July 6th, 2008, 12:21 PM   #5
 
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Originally Posted by Puffy' post='151995' date='Jul 6 2008, 12:50 PM
Let me get this right.. This is an M-4 type rifle and S&W just now are adding feed ramps?

The terms lunacy and incompetent come to mind. M-4's have feed ramps, am I correct?
The M&P15 is not an M4 - none of the commercially available AR15s that we civilians can buy are. But with the exception of a semi-automatic FCG, some of the commercially available ARs come very close with the Colt 6920 being considered the closest civilian build to a M4 carbine. LMT and Noveske are very close also and some might even say the Noveske is superior.



If you look at The Chart you will see that top tier do have M4 feedramps and the lower tier do not. In the middle teir, some do and some don't. The top tier also have 4150 barrel steel (Noveske uses M249 MG barrel steel), 1:7 twist barrels and M16 bolt carriers.



The bottom tier are less expensive and you get what you pay for. They use less expensive parts and frequently the build quality is sloppy.



The middle tier, which includes the M&P15, are getting closer all the time, partly due to the pressure generated by The Chart. For example, the M&P just went to the M4 feedramps, which, as Grant said, isn't necessary with a 1:9 twist barrel and lighter bullets. But it will get S&W another X on The Chart.

And newer builders like ADS and Charles Dailey did a great job of balancing features, build quality and price from the get go.
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Old July 7th, 2008, 08:00 AM   #6
 
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Unless you're using old worn out magazines, you don't need feed ramps. The military still has some 'expired' mags with weak springs etc. which is why they 'need' feed ramps.



My guess is that S&W is putting them on as a selling point. "Hey look, we've now got feed ramps"!! If your M&P 15 won't feed, try a diff. mag. If it still won't feed, send it back for repair.



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Old July 9th, 2008, 04:05 PM   #7
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Quote:
Originally Posted by Puffy' post='151995' date='Jul 6 2008, 05:50 PM
Let me get this right.. This is an M-4 type rifle and S&W just now are adding feed ramps?

The terms lunacy and incompetent come to mind. M-4's have feed ramps, am I correct? Am I missing something? You would think they would be there from the git'go.



If this is true what a let down...but at least they got their heads out of their asses.
The majority of the AR makers out there do not use M4 barrel extensions and M4 upper receivers. The ones that do, just started a short time ago.





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Old July 9th, 2008, 09:20 PM   #8
 
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So if I want to run some 77gr. Hornady TAP ammo out of my MP15, I'm SOL?
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Old July 10th, 2008, 07:30 AM   #9
 
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Quote:
Originally Posted by Krik' post='152665' date='Jul 9 2008, 11:20 PM
So if I want to run some 77gr. Hornady TAP ammo out of my MP15, I'm SOL?
No, you are not. The bigger problem is the 1:9 twist rate of your barrel, which may or may not stabalize the heavier bullets.
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Old July 10th, 2008, 11:27 AM   #10
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Originally Posted by Krik' post='152665' date='Jul 10 2008, 04:20 AM
So if I want to run some 77gr. Hornady TAP ammo out of my MP15, I'm SOL?


You can be. It would have more to do with the twist rate than anthing. 75gr is really the max you shoot shoot.





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Old July 10th, 2008, 12:58 PM   #11
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Back on track with M4 feedramps:



Understanding that stabilizing heavier bullets is dependent upon twist rate, do bullet weights come into play with regard to feeding? With regards specifically to the M4 feedramps, is there any mechanical difference between the way an AR feeds 77 gr rounds versus 55 (or even 45 gr) rounds? I can't see how bullet weight matters unless there is a difference in the cartridge's overall length.



I have a MT6400C and it has no problem feeding M855 (62gr green tip) but my friend's new M&P15A wouldn't feed the stuff and sure enough, there was green paint on his receiver where there were feed ramp extensions on my rifle. The M855 was 1/25,000ths longer than a .223 Rem UMC cartridge on a caliper which seemed to support my theory that it's OAL and not weight attibuting to the FTF in his M&P15A. Both guns were running both 55 gr and the M855 out of new USGI and PMAGs. Still, his would not cycle the M855.
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Old July 10th, 2008, 02:03 PM   #12
 
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AR Technical Discussion FAQ/Knowledge Base Threads

M4 Feedramps

http://m4carbine.net/showthread.php?t=193
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Old July 10th, 2008, 02:10 PM   #13
 
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I am curious what all the hype is about feed ramps? First I dont have a problem shooting up to 70 grains in my AR and according to this site it is'nt in the right tier to have a feed ramp. So given this once you get above 80 grains I believe, as I dont have a manual in front of me, if you load the heavier bullets to the correct length your not going to feed them from a magazine anyways you would single load them. If you did you would take up to much of the powder colum and would be counter productive. Also on twist rate it can be possible to shoot up to 75 grainers out of a 1-9 twist but as stated above it is rare, I realize that most want the 1-7 that the military uses wich I guess is fine if you want to still stay on the lighter side of the heavier bullets. For instance if you wanted to shoot 90 grainers for competition you might be able to get away with it with a 1-7 but more than likely you are going to want a 1-6.5 twist or even 1-6. In fact some have concluded that a 1-8 is by far ideal from the lightest up to 77 and 80 grain bullets, I would have to find it again but the Army has even questioned if the 1-7 is'nt to fast.
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Old July 10th, 2008, 03:54 PM   #14
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This thread keeps getting turned [pun intended] into twist rate and bullet weight compatibilities. I understood this to be about M4 feedramps finally being put on the M&P15s. I think my experience w/ my MT6400C (with M4 ramps) - running the same ammo that a M&P15A (without them) wouldn't run - supports the hype around why you'd want them. fwiw, this was my first attempt to cycle anything other than 55 gr ball through my MT6400C.



Thanks, A12G for the link and after re-reading that thread, I don't see anything regarding a) length of cartridge or b) bullet weight having any negative (or positive) influence on the NEED for M4 feedramps.



Gotm4 said:

"The ramps help with weak mags, fast cyclic rate guns and rounds with odd projectile ogives."



Perhaps Grant can explain but if you're running new mags in a factory AR (which I don't think would qualify as a fast cyclic rate) and using factory ammo (would M855 be considered a "normal" projectile ogive???), then why does one AR feed M855 and one not? Does it not have any bearing on the length of the cartridge hitting the inside wall of the receiver where M4 feedramp extensions should be?



-B
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Old July 10th, 2008, 05:56 PM   #15
 
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Quote:
Originally Posted by Boris' post='152807' date='Jul 10 2008, 05:54 PM
Perhaps Grant can explain but if you're running new mags in a factory AR (which I don't think would qualify as a fast cyclic rate) and using factory ammo (would M855 be considered a "normal" projectile ogive???), then why does one AR feed M855 and one not? Does it not have any bearing on the length of the cartridge hitting the inside wall of the receiver where M4 feedramp extensions should be?
I am looking at my 15A, which does not have M4 ramps, as I write this. I have the bolt locked open and the safety on so nobody need to get excited.



I put a loaded mag in to see where everthing lines up. The mag's forward top edge, which is below the top round, is on line with juncture where the top of the upper meets the bottom of the barrel extension. The top round sits well above the top of the upper receiver and the bullet point is horizontally on line with the the feedramp about 1/4 of the way up the ramp.



I simply can't see how a bullet tip would hit the top edge of the upper receiver, or do anything but go on up the ramp, unless the mag had serious issues and didn't line up the way mine is. Consider also that a longer bullet would be actually somewhat closer to the ramp.



And, BTW, since you read the M4 link above, I shoot soft points all the time as my current range does't allow FMJ. I have never had a feed problem and I don't see how it could the way I see everything is lined up in my gun.
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