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9/19/2017 7:27:10 PM
Posted: 3/30/2006 8:55:55 PM EDT
I have a HBAR that I'd like to convert to a flat top but unsure if it's possible. Can a normal uuper be drilled out to make it work?

If Colt makes one that will fit, where can I purchase one?

Any help would be appreciated.
Link Posted: 3/30/2006 9:25:17 PM EDT

Originally Posted By phylodog:
I have a HBAR that I'd like to convert to a flat top but unsure if it's possible. Can a normal uuper be drilled out to make it work?

If Colt makes one that will fit, where can I purchase one?

Any help would be appreciated.



iT IS POSSIBLE TO GET A LARGE HOLE FLAT TOP upper . but colt doesn't make them anymore . I bought a complete gun in 1992 20 inch barrel flat top upper large hole upper and lower , grey finish.

I don't know where to find one but they were made . best of luck !!
Link Posted: 3/30/2006 9:30:53 PM EDT
[Last Edit: 3/30/2006 9:31:19 PM EDT by Dace]
Link Posted: 3/30/2006 9:39:11 PM EDT
Colt still makes their guns with large hole uppers?
Link Posted: 3/31/2006 2:03:12 AM EDT
Colt has not made large pin receivers for nearly 10 years. You can get an offset pin that will allow you to place a small pin upper on your large pin lower. However, if you do want a large pin upper, I would call Specialized Armament Warehouse and see if Ken has any. Back in those days the flat top upper was not really in production much on commercial guns. THat was around 1994 when they stopped producing those uppers. It was also that time when the flat top came on line for the XM4/M4. To my knowlege Colt had made very few if any flat top uppers with feed ramps with a large pin. Hope this helps.
Link Posted: 3/31/2006 2:26:21 AM EDT
If it must be Colt, expect to hunt around a bit before you even find one, and then be prepared to spend $400 (upper only, no barrel) or more, even for a used piece. The one linked to above from Daniel Defense is probably your best choice.
Link Posted: 3/31/2006 12:40:11 PM EDT
Thanks for the help guys. It doesn't have to be a Colt as long as the quality is good. I really appreciate the information.

Phylodog
Link Posted: 3/31/2006 2:11:54 PM EDT
I believe that the only large-pivot flat top upper that Colt ever made was on the early R6700's. The later R6700's were small-pivot. Like Gus said, they are a rare item indeed.

You cannot drill an existing small pivot upper to large-pivot specs, as the centers of the two holes are not in the same place.

Your best bet will be the Daniel Defense upper linked to above.
Link Posted: 3/31/2006 2:35:11 PM EDT
Link Posted: 3/31/2006 3:03:38 PM EDT
I purchased a RRA complete upper for my Colt Match HBAR with large hole. I use the large hole front pin adapter and it works perfectly. Offset pin adapter is all of about 5 bucks. So far i have not had any issues with this set up. I have heard that some have problems breaking open there rifles with this pin, but mine breaks open just as easily as the Colt upper. And i am exremely happy with the RRA upper 16"
Link Posted: 3/31/2006 3:05:11 PM EDT
There are adapter pivot pins that let you put a large pin upper on a small pin lower and a small pin upper on a large pin lower.

Bushmaster sells both types.

Is that what you're asking?

I wouldn't bother drilling out the upper unless you REALLY need to be able to pop the upper off the lower on a regular basis.
Link Posted: 3/31/2006 3:23:35 PM EDT
a friend of mine take the large pin lower and installs an AL plug and them redrills them to .250. the plug is glued in with a special epoxy. the epoxy is strong enough that it holds even when drilling
Link Posted: 3/31/2006 7:13:53 PM EDT
saw a like new (never fired or pulled frmo the box Colt . It was 1/9 habar 16" 4 stamped on the flat top an was colt grey. It had a a2 birdcage no bayolug and had that big hunk of steel in the lower reciver. Was a two screwdriver lower w a flattop upper. IMHOP the dealer was asking a "new" price for the rifle.

There around if you want them just have to look.
Link Posted: 4/1/2006 11:58:42 PM EDT

Originally Posted By Gregory_K:
There around if you want them just have to look.


I couldn't have said it better myself!

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