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Ducati748r
03-23-2005, 1:41 PM
replace the upper receiver on a colt sporter..I want to change the upper receiver (fixed carrying handle) to a flattop upper. This would also include removing the barrel from the old upper and slapping it on the flattop. If it's too much of a pain can anyone recommend a good gunsmith around the bay area I can go to? Let me know folks. Thanks. http://calguns.net/groupee_common/emoticons/icon_razz.gif

Ducati748r
03-23-2005, 1:41 PM
replace the upper receiver on a colt sporter..I want to change the upper receiver (fixed carrying handle) to a flattop upper. This would also include removing the barrel from the old upper and slapping it on the flattop. If it's too much of a pain can anyone recommend a good gunsmith around the bay area I can go to? Let me know folks. Thanks. http://calguns.net/groupee_common/emoticons/icon_razz.gif

BigAL
03-23-2005, 2:15 PM
Assuming all your flat top receiver is missing is the barrel(ie it has the rear sight, forward assist, dustcover assembly,etc) the swap is simple. You need an AR-15 armorers wrench, a 1/16" punch, snap ring pliers, a receiver block to hold the upper in a vice, and some molybdenum disulfide grease. Go to this link for specific instructions and pictures. Go Here (http://ar15.com/forums/topic.html?b=3&f=4&t=226782) ans scroll down.

bwiese
03-23-2005, 2:17 PM
Hi, Ducati...

You could do this yourself if you bought a barrel wrench tool, had a good vise, AR upper receiver block, torque wrench, etc. Since you're prob a newbie at this, I'd prob avoid it as it'll cost you more for tools than the job cost, might scratch up something, etc. (I've built 5 ARs and still have yet to barrel an upper...)

Remember, it's perfectly legal to mail barreled AR uppers in/out of CA. They are not assault weapons, only the serialized lower receiver is.

Many AR vendors will swap barrels or receivers for you for little or even nothing if you purchase the relevant part(s) from them. I think Bushmaster & Armalite will do this as well as other smaller vendors (J&T Distributing, Legal Transfers, Rock River Arms, etc. - though I'd discourage your using ASA, Model 1, Sherluk services.)

Call your preferred vendor on the phone and find out. If all's well, just send your upper to 'em, insured (and request it be returned too!) and it shouldn't take too long.

Sorry, I don't really know any AR smith in Bay Area (at least that won't charge a fortune!).

Some notes: <UL TYPE=SQUARE>
<LI> Since you say you've got a true Colt barreled A2 upper you should NOT get a true Colt flattop upper receiver - Colt uses different front-sight/gas-block assemblies on their A2 and flattop rifles. (These flattop FS/GB assy's are marked with an 'F'.) You could end up w/an upper that can't be zeroed, or front sight post has to stand way up beyond front sight 'ears' to be zeroed. (And these Colt uppers require a Colt carry handle too, see below.) So get a Bushmaster, Armalite, etc. standard flattop upper.

<LI> do NOT buy a true Colt carry handle for your non-Colt upper. There's 0.040" difference in sight heights btwn Colt flattops and non-Colts and this heiight may be spread btwn Colt's thickness of their Picatinny rail and vertical height offset of carry handle rear sight assembly.

<LI> besides your new upper receiver itself, you'll need a forward bolt assist ("FBA") button, spring & roll-pin, an ejection port door, spring & pin. Maybe one other little part or two, not sure... Your vendor will tell you. Prob not worth the grief/time to take 'em off your old receiver - just put new ones on, they're all cheap small parts.

<LI> whoever you choose, emphasize they should NOT overtorque the barrel when mounting bbl. Bushmaster has sometimes done this on their production rifles and shears the barrel index pin on the bbl extension, resulting in a slightly canted front sight base. While this may be within mil specs (adjustable +/- 30 (?)windage clicks), it shouldn't have to happen.

<LI> make sure the smith uses some Molybdenum Disulfide (MoS2) - 'Moly Lube' lubricating paste on the inside of the rcvr bbl opening, and on the receiver/bbl nut threading. This is an anti-seize compound and lets your rifle be disassembled/repaired 10yrs later without threads corroding/fusing together due to heat, electrolysis, etc. (If your AR smith doesn't know about use of moly lube, he's not a good AR smith.) Ensure he does NOT use any graphite lubes, as graphite is corrosive to aluminum and its alloys.
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Since you're keeping the same barrel assembly (with bbl extension) headspace is not an issue and you of course can retain/use your old bolt.



Bill Wiese
San Jose

xsquid
03-24-2005, 10:45 AM
If this is only going to be a one time thing, I'd advice you just go find somebody to do it for you as it'll wind up being more expensive buying the tools you would need to properly re-barrel the upper than having it done. It is a simple thing though - I've done it a few times for myself and friends - haven't had any problems yet http://calguns.net/groupee_common/emoticons/icon_wink.gif