Hi everyone,
I started visiting this website to pick up some ideas for service rifle matches which I've been shooting in for a year and a half. Then I started reading the posts about carbines and now I've decided I "need" one.
I have a couple of questions that maybe you could help me with.  
1. Will a Colt SP1 lower and a preban upper fit together and if so are there any problems involved with this combination?
2. If I put an EO Tech sight on an upper with a flat top receiver and a regular front sight assembly will the front sight assembly block the view when looking through the EO Tech?
Thanks for your help.

By checking here: [url]www.biggerhammer.net[/url], you'll find some interesting faqs about ARs, like older Colt SP1s have larger pivot pins than new production uppers....

[img]http://www.biggerhammer.net/ar15/uppers/aruppercomparison.jpg[/img]



No the front site tower, while visible, will not obstruct your view, infact ya hardly notice it, if your using the EOTech properly, "with both eyes open".

Mike

True, but you can buy an offset conversion pin to match the late type upper to the SP1 lower.  There are two or three different types of conversion pins out there, but the ONLY one worth having is the piece from CDNN Sales.  The others will drive you crazy by slipping out of position every time you open the action, requiring you to reposition them with a screwdriver to get the top and bottom closed.

I say again--to mate a late or M16 type upper to an SP1 lower, get the conversion pin from CDNN [url]www.cdnninvestments.com[/url].  Do NOT buy any conversion pin from Bushmaster, DPMS, or anyone else.  What they sell will drive you nuts [;D]

Sham, thanks for the info on CDNN and their conversion pin.  I have one of the other conversion pins and it is a pain to use.

The CDNN conversion pin is the same as my Colt pin. It will actually tighten the upper to the lower if loose.