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View Full Version : Couple of AR 15 questions (Upper change)


crimsondave
November 19, 2009, 10:40 AM
I have a Colt H-bar with carry handle. I want to purchase a new flat-top. I was thinking about the DPMS 24" stainless 1-8" twist.

1.) How do I know if my Colt is a "large pin colt?" Do I mesure the diameter of the back pin you push out to take it down?

2.) If I have a large pin Colt, what adapter(s) do I need, and where can I get it/them?

3.) If bought a different caliber upper, would anything on the lower need to be changed (other than magazines?)

I know this would likely be better posted on AR15.com, but that site gives me a headache.

flight954
November 19, 2009, 02:38 PM
If it's an older Colt chances are it is a large pin reciever. If I'm not mistaken Colt just started producing the small pin AR recievers. You could email Colt with the serial # and they could tell you. You could also look up Wildalaska on TFL, he's a Colt dealer and he's very knowledgable when it come to Colt AR's

Ridge_Runner_5
November 19, 2009, 10:17 PM
Unless you bought it this year, odds are its a large hole receiver, in which case you can buy a screw that will allow you to use a small hole upper receiver.

Changes to the lower depend on caliber. 9mm, .40S&W and .45 uppers require a magwell block, new magazines and sometimes a new hammer. Similar sized or smaller rifle rounds can use just different magazines. Larger calibers like .458SOCOM, .50Beowulf and .308, among others, will require a different lower receiver...

sailskidrive
November 19, 2009, 11:39 PM
Don't some of the small calibers, i.e. 9mm, require a different weight buffer? I want one of those AR57 uppers, they're not that expensive I've just been lazy about locating one.

~Sail

Ridge_Runner_5
November 20, 2009, 03:25 AM
Ah yeah, thats right, some of the pistol calibers might need a different buffer.

FWIW, if you get a dedicated .22lr rig, no need for the stock, so you can put a folding stock or just an endcap on it...

RockyMtnTactical
November 20, 2009, 05:18 AM
Post some pictures! ;)

crimsondave
November 20, 2009, 08:58 AM
It's a few years old, so I'm sure it's a large pin based on your input.

Thanks.

flight954
November 20, 2009, 09:36 AM
Don't some of the small calibers, i.e. 9mm, require a different weight buffer? I want one of those AR57 uppers, they're not that expensive I've just been lazy about locating one.


The smaller calibers require a heavier buffer. You can get them at blackrifleworks.com The AR57 uppers come with the buffer. The best price I found on those uppers is blackheart international