What are the sources / options on flattop (A3) uppers with a large hole to work with my SP1?

Thinking would like a nice flattop 20" HBAR for the SP1 (color match would also be nice but can live with black vs gray).  Receiver will probably have to be stripped as do not see that many pre-ban HBARs.

Regards
John

For other reasons do not wish to use an offset pin.

www.danieldefense.com/products.htm

Daniel Defense...  I have no insight as to the quality but they do make them...

If I recall correctly some of the other posts on this upper, it has to be hand fitted to the lower as it's built oversized.

If this is not a problem for you, go for it.  The other alternative is to go with a standard small hole job, and use the adapter fromm CDNN [url]www.cdnninvestments.com[/url]. Do NOT use the piece of junk adapter sold by nearly everyone else. That one rotates w/the upper when you open the action, but doesn't rotate back when you close it, so you have to reposition it w/screwdrivers.  The CDNN piece rotates both ways, so once set, it stays set.

Man, I got all excited until I went to the CDNN website.

After looking at the picture, I think CDNNs offset pin is the same as those that came with Colt upper caliber conversion kits.

Unless I am mistaken, they will only work with large hole lower only if it is not slabside (like most of them are).  The metal around the front detent pin for the take down pin is what will keep it from rotating.  Otherwise the pins will be free to rotate like the aftermarket ones.  Most aftermarket receivers have this feature and are small hole already.  

Why Colt ever did the large hole thing is beyond me.  But they did switch it back, although they are not on models I want to buy, the exception being R6551 Sporter target models with normal fire control pins.

I have the same problem with my Sporter II and small hole M4 flattop upper.  Because of the rotation, sometimes the upper is tough to get open unless I use a brass punch and hammer on the rear takedown pin.

I have no idea what Colt uses on it's current big holes, but I have used the CDNN piece on a slab side SP1 for years with absolutely no problems.  It rotates w/the upper when you open the action, AND IT ROTATES BACK WHEN YOU CLOSE IT; unlike the other type.

Any number of AR15ers have bought this piece on my recommendation, and those of others, and NO ONE has ever reported results other than what I just wrote above.

If some one has bought one of these pieces, and it didn't work as I've described it, I'd appreciate a report.

And no, I don't work for CDNN [:D]

I've used the same pin from CDNN on my SP1, have had no problems.