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Posted: 10/12/2005 2:53:20 PM EDT
Is there any reason a small-hole upper can;t be drilled out to fit a Colt large hole receiver to avoid the use of conversion pins?
Link Posted: 10/12/2005 3:21:13 PM EDT
[#1]
The front lug is longer on a large hole upper.
Link Posted: 10/12/2005 3:37:56 PM EDT
[#2]
So in other words it can't be done, right?  I have to hold out for an actual large hole upper?
Link Posted: 10/12/2005 3:43:48 PM EDT
[#3]
use off set pins
Link Posted: 10/12/2005 4:27:40 PM EDT
[#4]

Quoted:
So in other words it can't be done, right?  I have to hold out for an actual large hole upper?



With enough desire anything is possible...  there was a company years ago that used to add onto the lug of the upper and welded it closed.... then they redrilled it....  I have not seen that done since about 1997 or so but there was someone that did it way back then...

Now that lowers are so cheap and there is no ban affecting most of us in the states there is really no reason for people here to do it anymore...  Is there a reason you have to do this in Canada?

Back in the day I had a Colt R6600 AR-15A2 Green Label and I loved that rifle but I hated the big screw pivot... I looked hard and long for a solution and I just went to a mil-spec lower (Bushmaster) and sold the R6600.  Later I owned quite a few small pivot Colts that could be convered to the push pin...

Good Luck!
Link Posted: 10/12/2005 4:35:43 PM EDT
[#5]
Well in Canada, AR lowers are SUBSTANTIALLY more expensive than in the USA.  Also, uppers are about double the US price.  

Problem with using an offset pin is that you have to remove the offset pin before the rear pin, right?  So then I would not be able to pivot hte receiver open for cleaning without risking dammage to the receiver, no?
Link Posted: 10/12/2005 4:41:35 PM EDT
[#6]
Colt A2 large pin uppers can be had reasonable in the EE.

If you want a FT large pin upper you have 2 choices that I am aware of.

1: Watch for a Colt LP - FT upper to pop up in the EE - Have mucho  $$$.

2: Daniel Defense

Danny
Link Posted: 10/12/2005 4:44:54 PM EDT
[#7]
There are also large pivot flattops from the early Colt R6700s plus Armalite made a few large pivot flattop uppers back in about 1985-1986....  You don't see them often as the guys with the really big bucks tied up in large pivot M-16s will pay a healthy price for one but they do show up every so often...

I didn't know DD still made them...  that is your best choice!
Link Posted: 10/13/2005 2:46:39 AM EDT
[#8]

Quoted:
Colt A2 large pin uppers can be had reasonable in the EE.

If you want a FT large pin upper you have 2 choices that I am aware of.

1: Watch for a Colt LP - FT upper to pop up in the EE - Have mucho  $$$.

2: Daniel Defense

Danny hr


I've already got an A2 upper - gun is a factory R6601 Colt Sporter Match HBAR.  Works great as-is, but the flat-top would give me more flexibility.  I could just get a goose-nack mount like the new MI to mount an Aimpoint or Eotech, but I've been told a replacement upper and BUIS is almost the same price.
Link Posted: 10/13/2005 11:00:15 AM EDT
[#9]
I've used the offset pin to adapt a small hole upper to a large hole lower before. I never had any problem using it as a pivot pin. I'm used to using the double headed Colt screws and it doesn't bother me at all. And I never treated the offset screw any differently.  
Link Posted: 10/13/2005 2:24:33 PM EDT
[#10]
It's a shame that you don't live in the U.S., as American Manufacturing converts large-hole LOWERS to small-hole specs. Mike welds up the pivot hole, redrills it with a Colt drilling jig, and refinishes the lower.
Link Posted: 10/13/2005 5:01:48 PM EDT
[#11]
That'd be cool.  Too bad is right!
Link Posted: 10/13/2005 5:12:15 PM EDT
[#12]
If they can do that to a lower it would seem they could go the other way and make you a flattop upper receiver?  Then again, I think you were already given a better and less expensive option above!

www.danieldefense.com/
Link Posted: 10/13/2005 5:49:54 PM EDT
[#13]

Quoted:
It's a shame that you don't live in the U.S., as American Manufacturing converts large-hole LOWERS to small-hole specs. Mike welds up the pivot hole, redrills it with a Colt drilling jig, and refinishes the lower.



I'll let you know if Mike will convert a small hole upper to large hole, been meaning to contact him about this for some time. I have a small hole slick side upper I want to convert to a large hole upper to go with my slab side SP1 RR for a no forward assist, no case deflector no magazine release fence build. I already have 2 large hole flattop uppers but want that slick/slab side build.
Link Posted: 10/14/2005 2:46:59 AM EDT
[#14]

Quoted:
I already have 2 large hole flattop uppers...



Lucky man! (grumble-grumble...)
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