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1/8/2011 7:26:56 PM EDT
I recently purchased a A1 type upper for a A1 semi build.I need some help as I am not AR knowledgeable. I need to know what I need to finish the upper. Thanks for your help.          

1/8/2011 7:35:22 PM EDT
[#1]
I know there is no bolt , bolt carrier, and charging handle, anything else?
1/8/2011 7:52:43 PM EDT
[#2]
Quoted:
I know there is no bolt , bolt carrier, and charging handle, anything else?


Looks like that's all you need for the upper. Any bolt carrier will work too, i.e. you can use the common carriers with the forward assist notches or hunt for a carrier without them. You have a later version of the Model 604 (birdcage flash suppressor) so a notched carrier is most likely what Colt used in it.

Save your pennies and get a Nodak Spud lower too. They are the proper style and very high quality.

And welcome aboard.
1/8/2011 8:00:47 PM EDT
[#3]
Quoted:
Quoted:
I know there is no bolt , bolt carrier, and charging handle, anything else?


Looks like that's all you need for the upper. Any bolt carrier will work too, i.e. you can use the common carriers with the forward assist notches or hunt for a carrier without them. You have a later version of the Model 604 (birdcage flash suppressor) so a notched carrier is most likely what Colt used in it.

Save your pennies and get a Nodak Spud lower too. They are the proper style and very high quality.

And welcome aboard.

+1 for everything said here.
1/8/2011 8:03:03 PM EDT
[#4]
so full and semi bolt and carriers are the same?
1/8/2011 8:16:48 PM EDT
[#5]
Yes. And you can use the full auto carrier in a semi auto gun too. There's been debate about the legality of this but a few years ago Colt started shipping their semi auto rifles with full auto bolt carriers. That settled the question for me and I used a full auto carrier in both of my retro rebuilds. Unfortunately I don't have pics currently uploaded.
1/19/2011 12:51:51 PM EDT
[#6]
I havent got the upper in yet but it is a SP1 upper with the screw pin. Now can I use a 601 Nodak reciever? It requires the left side of the upper to have a countersunk front pivot hole? Does a SP1 upper have this?  Thanks Mike


We have manufactured original style front pins for the NDS-601 lower receivers.
The detent ball snaps into the countersink on the left side of the front pin boss of your upper receiver.

NDS-31 (pin for NDS-601)
1/19/2011 6:46:02 PM EDT
[#7]
You'd have to use an (some) adapter bushing(s) for your SP1 receiver to work with a NoDak 601 lower receiver.
1/19/2011 7:15:17 PM EDT
[#8]
my question is, does a sp1 upper have a countersunk hole on the left side?
1/19/2011 7:31:44 PM EDT
[#9]
I don't think the SP1 uppers ever had the counter bored front lug. They all used a nonstandard, oversized double headed screw as a pivot pin. Unfortunately they were also drilled with the center offset from where the pivot pin would be centered. So to use and SP1 upper on a lower with a standard pivot pin you'll need an adapter. It'll be an offset bushing installed in the upper and you'll then use the standard sized pin in the lower.
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