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View Full Version : Adding M4 feedramps to A1/C7 upper



Circle_10
01-12-16, 16:37
I've been thinking about doing sort of an "Early Diemaco C8 carbine" clone build with a C7 style upper receiver. I was planning on using a Daniel Defense 14.5 pencil barrel, because like the C8 they are CHF, lightweight profile, and .750 at the FSB (And also because quality carbine pencil barrels with .625 gas blocks seem to be in short supply...or else I'd just build a 723 clone....) . However the DD 14.5 are ideally meant to mate up with M4 style upper receiver feedramps. While this gun is a more of novelty build than a "serious use" AR, I intend to use good parts and want it to run as well as my other ARs. So I'm thinking I ought to have M4 ramps in the gun because based on what I've read: Rifle receiver+M4 barrel = "OK" but not ideal.
Can anyone suggest someone who can add correct M4 style feedramps to an A1 upper and then properly re-anodize the ramps? Any ideas how much the whole process might cost? There's no way in hell I'm going to even attempt to do this myself.

Renegade04
01-12-16, 17:18
I've been thinking about doing sort of an "Early Diemaco C8 carbine" clone build with a C7 style upper receiver. I was planning on using a Daniel Defense 14.5 pencil barrel, because like the C8 they are CHF, lightweight profile, and .750 at the FSB (And also because quality carbine pencil barrels with .625 gas blocks seem to be in short supply...or else I'd just build a 723 clone....) . However the DD 14.5 are ideally meant to mate up with M4 style upper receiver feedramps. While this gun is a more of novelty build than a "serious use" AR, I intend to use good parts and want it to run as well as my other ARs. So I'm thinking I ought to have M4 ramps in the gun because based on what I've read: Rifle receiver+M4 barrel = "OK" but not ideal.
Can anyone suggest someone who can add correct M4 style feedramps to an A1 upper and then properly re-anodize the ramps? Any ideas how much the whole process might cost? There's no way in hell I'm going to even attempt to do this myself.

Here is something that will help you.

http://i557.photobucket.com/albums/ss19/gatorhunt2201/AR15%20stuff/feedramps2-1.jpg

I will attest that a rifle upper and a barrel with the M4 feedramps works just fine. No need to alter the upper.

Circle_10
01-12-16, 18:00
I've seen that pic, it is a good reference. I think my question would be why rifle receiver+M4 barrel is just "ok" rather than "good", unless the point is that in a carbine-gas gun M4 ramps are just considered an improvement over no ramps period rather than there being some particular shortcoming with the rifle receiver+M4 barrel combo itself.


I will attest that a rifle upper and a barrel with the M4 feedramps works just fine. No need to alter the upper.

That's good to hear.

Renegade04
01-12-16, 18:39
I've seen that pic, it is a good reference. I think my question would be why rifle receiver+M4 barrel is just "ok" rather than "good", unless the point is that in a carbine-gas gun M4 ramps are just considered an improvement over no ramps period rather than there being some particular shortcoming with the rifle receiver+M4 barrel combo itself.



That's good to hear.

You have to realize that several upper receivers (A2) with no feedramps were outfitted with newer barrels with M4 feedramps on the barrel extension. There were some carbine uppers that were built using re-purposed A2 rifle upper receivers. Additionally, there were some C7 and A2 uppers that had slightly cut ramps to match up with the barrels with extended carbine feedramps (not to be confused with M4 feedramps). This was done in the mid-late 1980s. It was not until later on that the flat-top receivers started getting feedramps to match the M4 feedramps on the barrel extensions. This is why you can use a barrel with an extension with M4 feedramps with a receiver that does not have feedramps, but you cannot use a receiver with M4 feedramps with a barrel with an extension with rifle feedramps.

I have a 723 build (w/ C7 upper) and a 727 build (A2 upper) that use 14.5" Colt M4 barrels. They both function very well with no feed or extraction issues.

http://i100.photobucket.com/albums/m8/jamesrea_2006/Weapons%202014/Retro%20ARs/Model%20723/008_zpsubodx0nf.jpg (http://s100.photobucket.com/user/jamesrea_2006/media/Weapons%202014/Retro%20ARs/Model%20723/008_zpsubodx0nf.jpg.html)

http://i100.photobucket.com/albums/m8/jamesrea_2006/Weapons%202014/Retro%20ARs/Model%20727/016_zpscdedsdrs.jpg (http://s100.photobucket.com/user/jamesrea_2006/media/Weapons%202014/Retro%20ARs/Model%20727/016_zpscdedsdrs.jpg.html)

Circle_10
01-13-16, 07:43
That's interesting. I had just assumed that the "M4" ramps on the barrel extension and those in the upper were developed and put into production concurrently and that factory guns would always have both. Nice builds too!

mack7.62
01-13-16, 08:03
I would only add the feed ramps to the receiver if I had feeding issues, which you should not have.

the_1iviper
01-13-16, 17:19
I would only add the feed ramps to the receiver if I had feeding issues, which you should not have.

/\ this

or you could source out a colt c7 upper , it should have ramps cut into it already.

Renegade04
01-13-16, 18:34
/\ this

or you could source out a colt c7 upper , it should have ramps cut into it already.

Some C7 (A1E1) uppers did not have feedramps.

the_1iviper
01-13-16, 19:20
C7 (A1E1) uppers did not have feedramps.

colt A1E1 733 uppers didn't have extended carbine feedramps ?

Renegade04
01-14-16, 07:32
colt A1E1 733 uppers didn't have extended carbine feedramps ?

I will have to retract my statement and correct myself by saying that some of the 700 Series carbines (727 and 733) did have extended carbine feedramps. Soon after working on carbine versions of the M16A2, Colt found that M855 fed low due to various reasons. To maintain reliable feeding, the feeding ramps in the barrel extension were lowered into the upper receiver. The extended 700 series Carbine feed ramps are shallower than the feed ramps used on the M4/M4A1 (date app 1988-1992) and are commonly found on 727 and 733 Carbines/Commandos. Standard rifle feed ramps (on barrel extensions) were used on 600 series Carbines and can be found on 700 series Carbines as late as 1990.

scottryan
01-14-16, 22:27
I will have to retract my statement and correct myself by saying that some of the 700 Series carbines (727 and 733) did have extended carbine feedramps. Soon after working on carbine versions of the M16A2, Colt found that M855 fed low due to various reasons. To maintain reliable feeding, the feeding ramps in the barrel extension were lowered into the upper receiver. The extended 700 series Carbine feed ramps are shallower than the feed ramps used on the M4/M4A1 (date app 1988-1992) and are commonly found on 727 and 733 Carbines/Commandos. Standard rifle feed ramps (on barrel extensions) were used on 600 series Carbines and can be found on 700 series Carbines as late as 1990.


That is not complete information.

Any carbine made after 1994 has full size M4 ramps. There were 723 made as late as 1997 and 733s made as late at 2000.

There was also a run of 6320s made in the early 2000s that have full size M4 feeramps.

Renegade04
01-15-16, 07:04
That is not complete information.

Any carbine made after 1994 has full size M4 ramps. There were 723 made as late as 1997 and 733s made as late at 2000.

There was also a run of 6320s made in the early 2000s that have full size M4 feeramps.

I would like to know where you came up with that info on those dates, especially on the 723. It is inconsistent with what I have read from credible sources.

scottryan
01-15-16, 14:01
I would like to know where you came up with that info on those dates, especially on the 723. It is inconsistent with what I have read from credible sources.



Because I have a 723 sitting in front of me with a 1997 barrel date with a charcoal black upper and a 733 with a 2000 barrel date and C A forge code black upper. Neither of them have F marked front sight bases.

They also made 727 carbines up to 2001.

Example of a late 1990s 733 is seen here

http://autoweapons.com/photosv/npostm16a2comm.html

Renegade04
01-15-16, 17:03
Because I have a 723 sitting in front of me with a 1997 barrel date with a charcoal black upper and a 733 with a 2000 barrel date and C A forge code black upper. Neither of them have F marked front sight bases.

They also made 727 carbines up to 2001.

Example of a late 1990s 733 is seen here

http://autoweapons.com/photosv/npostm16a2comm.html

How about pics of the 723 and 733 and pics of the receivers, not the barrels, showing M4 feedramps.

Circle_10
01-15-16, 20:45
Out of curiosity, anyone know when the Diemaco/Colt Canada guns started being made with the M4 style feedramps? Based on what I've read thus far the old carry handle C8 carbines (Which is what I'll be trying to approximate with this build.) didn't have them but the current Colt Canada C8SFWs etc do.

the_1iviper
01-16-16, 03:41
Out of curiosity, anyone know when the Diemaco/Colt Canada guns started being made with the M4 style feedramps? Based on what I've read thus far the old carry handle C8 carbines (Which is what I'll be trying to approximate with this build.) didn't have them but the current Colt Canada C8SFWs etc do.

i don't believe m4 ramps showed up in the c8 until the dutch army requested them in a contract with colt canada when they upgraded the carbines back a few years , maybe 5 or 6 years now.

Circle_10
01-16-16, 18:00
Thanks.

How about the barrel dimensions on either an early C8 or a 1980s era 723? I got my DD lightweight CHF barrel today and it tapers from .670 down to .650 behind the gas port, .750 at the FSB point and then seems to taper gradually from about .625 down to about .580 just behind the flare at the muzzle end. Obviously the gas block is too thick to be a good fit for a 723 but aside from that how close is it to the dimensions of a Colt "pencil" barrel? The DD seems a touch heavier. Is this light enough to work for an early C8?