[ARCHIVED THREAD] - Colt 604 Upper

Posted: 4/2/2009 8:08:07 PM EDT

Does a Colt 604 upper require the large hole lower or could a modern lower such as DPMS fit?

Thank you.

Posted: 4/2/2009 8:49:33 PM EDT

[#1]

They made adaptors and bushings that'll allow a regular pin to fit or a special pin made specifically for this.

Posted: 4/3/2009 6:42:13 PM EDT

[#2]

My 604 is small pin.

it is sitting on a RRA lower here but would work on any new lower. I think the sp1's were the large hole but I really don't know for sure.

Posted: 4/3/2009 6:47:58 PM EDT

[#3]

Quoted:
My 604 is small pin.

http://disciplesofdelmar.com/img/ar/retro/DSC_0809.jpg

it is sitting on a RRA lower here but would work on any new lower. I think the sp1's were the large hole but I really don't know for sure.

604 uppers are mil-spec holes at 0.250" front pivot pin diameter.

SP1s have holes for the front pivot pin diameter of 0.315". The rear hole is still 0.250" diameter, same as the 604.

Posted: 4/3/2009 6:49:23 PM EDT

[#4]

What was the reason they went to the larger pin?

Posted: 4/3/2009 6:51:17 PM EDT

[#5]

Gentlemen,

Thank you very much for this helpful information. It's exactly what I needed.

RemFan

Posted: 4/3/2009 7:14:48 PM EDT

[#6]

I think the SP1 is cool as hell

[ARCHIVED THREAD] - Colt 604 Upper

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[ARCHIVED THREAD] - Colt 604 Upper

[ARCHIVED THREAD] - Colt 604 Upper