Colt A4 Upper Receiver

Tom_Swift

Tom_Swift

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Looking for one is there any retailer that sells just the Upper Receiver. I see lots of people with Colt stuff but haven't been able to find a retailer in any of the board sponsors. If not from Canada how much would it cost to import one for an upper build that I'd like to begin on.

Also what's the approx cost going to be of just the receiver I have a general idea but a firm price would be nice to know?
 
If you are looking for a A4 upper(doesn't have M4 feed ramps) they where discontinued as a factory part earlier this year. I had two of them and the like the idiot I am I sold them in a moment of weakness in the EE.:mad: Then went to reorder them from Brownell to find out they were discontinued.
 
Rebel Rouser said:
If you are looking for a A4 upper(doesn't have M4 feed ramps) they where discontinued as a factory part earlier this year. I had two of them and the like the idiot I am I sold them in a moment of weakness in the EE.:mad: Then went to reorder them from Brownell to find out they were discontinued.
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As I understand it the M4 feed ramps improve functionality and feeding issues? I'm a little confused maybe you could just clarify? If the having the M4 feed ramps improves the upper what upper am I looking for?
 
A4 is for the 20" barrel. The one with the M4 feed ramps is for the carbine. Also remember that a Colt upper will only match up to the M4 feedramps of a Colt barrel or Stag. Colt uses a more shallow cut feedramp. If you put them side by side of any other manufacture you would notice there is a big difference. The M4 feedramp are there to improve function in full auto fire. With the cyclic rate on M4A1 carbine reaching as high as 750-900 rounds per minute it there to improve feeding the round in the chamber. The other mod done to the M4A1 was the H2 buffer to slow the cyclic rate down.
 
Rebel Rouser said:
A4 is for the 20" barrel. The one with the M4 feed ramps is for the carbine. Also remember that a Colt upper will only match up to the M4 feedramps of a Colt barrel or Stag. Colt uses a more shallow cut feedramp. If you put them side by side of any other manufacture you would notice there is a big difference. The M4 feedramp are there to improve function in full auto fire. With the cyclic rate on M4A1 carbine reaching as high as 750-900 rounds per minute it there to improve feeding the round in the chamber. The other mod done to the M4A1 was the H2 buffer to slow the cyclic rate down.
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So the LE 6920 Upper Receiver will do? Is Colt and Stag the only barrels that will work or are there others? I'm wanting to build a 16" mid-length upper with a 9" rail.

Thanks for the help I'm learning a lot.
 
We use both Colt uppers and colt barrel extensions and have not had any problems with feeding.

I'm not sure I'd get all worked up about minor differences in feed ramps. We've seen uppers come through the shop with no feed ramps at all and they seem to work just fine.
 
Tom_Swift said:
So the LE 6920 Upper Receiver will do? Is Colt and Stag the only barrels that will work or are there others? I'm wanting to build a 16" mid-length upper with a 9" rail.

Thanks for the help I'm learning a lot.
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There is no point of getting a colt upper if you just slap a generic midlength barrel on it. Get a Stag, save yourself money.

The only difference is that - Colt has better QC in anodization.
 
Colt M4 feed ramp.
DSCN1392.jpg

LMT M4 feed ramp.
DSCN1386.jpg
 
Thanks for all the images and info guys I think I'm going to rethink the Colt cool aid I've been drinking and look at some other stuff out there. I was looking at STAG last night actually.

Cheers
 
Suputin said:
Go take a look at the resale value of lesser brand names vs Colt. You may save a few bucks on the purchase but you are gonna take a bath on the resale in the future.
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1: The Colt and the Stag were likely machined at the same place, (unless Diemaco marked).
2: Take a bath on a $189 upper receiver? How much does a used Colt marked flattop receiver sell for anyway?
 
dangertree said:
1: The Colt and the Stag were likely machined on the same machine, (unless Diemaco marked).
2: Take a bath on a $189 upper receiver? How much does a used Colt marked flattop receiver sell for anyway?
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The ones I ordered from Brownell where $189-$210 stripped(A4) and $225-$250 M4 marked ones. It also depends on what the dollar is trading. Walter is probably right, Stag is most likely making them for Colt. The last couple I had just had a "C" stamped on them.
 
Tom_Swift said:
As I understand it the M4 feed ramps improve functionality and feeding issues? I'm a little confused maybe you could just clarify? If the having the M4 feed ramps improves the upper what upper am I looking for?
Click to expand...

They do nothing on a semi-auto gun, and depending on who you believe, do nothing on a full auto either, particularly one with a heavier buffer and/or decent mag springs.

There is one school of thought that thinks Colt introduced them to help protect/extend their patent on the M4, and others who believe that on the early high-cyclic-rate carbines, increasing the feed angle might help prevent a misfeed if the cyclic rate of fire exceeded the mags springs ability to feed cartridges firm against the feed lips in time. No bad thing about inclusion if there, but of no advantage on a semi-auto for sure.

Also, unless the manufacturer of your barrel definitely used a Colt or CMT barrel extension, I would suggest a regular flattop receiver without the bevels cut.

Why? There are many different and unique styles of "Extended Feedramps" often referred to as "M4 Barrel Extensions" but are neither the same angle nor depth found on the Colt/CMT upper receiver or barrel extension. Now you're into an ugly setup.

Regular (non bevel cut) receivers will work 100% with any manufacturers barrel extension, regular or m4, normal or otherwise.

Cheers,
DT
 
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