I have a Colt HBAR match AR in A2 form, I want to take this same rifle and put a new flat top reciver on it and put a low pro gas block. I want to keep the 20 inch barrel (nice heavy 1-7. Do I have to run a colt upper of will any work. The front sight is pinned on (I think) can it be removed? Can I put a new flash suppresor on it. will the 20 inch barrel work with new uppers. The rifle is about 10 years old. would it be better to buy a new upper like I want? Oh yeah because I know someone will say it, I won't be doing this work as I do not have the smithing experience. If all this has been asked before sorry. Thanks
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My Colt AR rebuild
- Thread starter gishooter
- Start date
Colt uppers and lowers come in two flavors - large pin and small pin. You can get converter pins to mix & match both types, but it is more convenient to get an upper of the same type as your lower.
Is your lower small pivot pin or large pin?
I think the pivot pin sizes are large pin (.312) small pin (.250).
Is your lower small pivot pin or large pin?
I think the pivot pin sizes are large pin (.312) small pin (.250).
The easiest way to tell is this:
Are the front (pivot) and rear (takedown) pins the same diameter? If so, you can use any quality upper, such as those from Fulton Armory. If not, you probably have the two-screw pivot pin. Replace that large pin with an "offset adaptor pivot pin" (just a few bucks) and again you can use any quality upper.
I'm not going to be bashful here, you can read all about it in a couple of books I wrote (now on sale at 25% off 'till the end of January).
Regards,
Walt
Are the front (pivot) and rear (takedown) pins the same diameter? If so, you can use any quality upper, such as those from Fulton Armory. If not, you probably have the two-screw pivot pin. Replace that large pin with an "offset adaptor pivot pin" (just a few bucks) and again you can use any quality upper.
I'm not going to be bashful here, you can read all about it in a couple of books I wrote (now on sale at 25% off 'till the end of January).
Regards,
Walt
If you are going to do this and have a large hole pivot pin, Daniels Defense has an upper receiver with a large hole pivot http://http://www.danieldefense.com/?page=shop/detail&product_id=19. For what it's worth, I am thinking of doing the exact same thing to mine.