MIM in 1911 Well Covered, How About AR15?


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grendelbane
September 17, 2004, 10:55 PM
The discussion concerning MIM parts in 1911 type pistols has been both spirited and extensive. Lots of good information and speculation from several people who I won't take time to name. You know who they are.

What is the situation with the AR-15 and its various clones? What parts are made with MIM technology? Have their been any issues with these parts.

The 1911 and the AR15 have quite a bit in common. Both are military designs. Both were at the leading edge of the technology curve when they were introduced. Both have been cloned, copied, modified, hot-rodded, rechambered, used and abused.

Both were originally produced with forgings. Both are now also produced with castings. The 1911 actually used polymer parts before the AR-15.

The reason I ask is that my Colt Sporter Lightweight doubled on me. I bought large pin parts at the gun show last weekend. (At a nice premium, thanks Colt!). The hammer looks like MIM, as it has been described by Tuner. The trigger displays a mild seam line, indicating it was cast.

I will have to cut the hammer to 9mm dimensions. I have done this before on a Bushmaster. I don't think this will cause any issues.

On the bright side, I cleaned out an old desk drawer recently, and found a plastic bag with several 1911 parts I had forgotten about, including two extractors! Memory barely seems to indicate that I must have acquired these in the mid-80's, so I am going to assume that they are older than that, and not MIM. It makes me feel old before my time to have old parts that are considered superior to new parts.:)

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grendelbane
September 24, 2004, 10:15 PM
Well, it has been a week since I asked my question! No answers yet.

Apparently no one has any opinions on this subject?

I have not been able to make it to the range yet with my Colt 9mm. Perhaps I will tomorrow.

The Ar-15 kind of reminds me of the 1911, what with its barrel length, and caliber variations.

Glock makes nothing to compare to the AR-15. What would Gaston's rifle look like if he were to decide to compete against the AR-15?

1911Tuner
September 25, 2004, 05:42 AM
Howdy grendelbane,

I haven't looked at the guts in a new AR-15 in years, but I'd say that the MIM is there. Everybody's using it these days...even my beloved Smith & Wesson revolvers have MIM lockwork now...so the chances are high that Colt has gone with the stuff in their little black rifles. Take the hammer out and look for the telltale MIM sprue mark. It'll be an indentation...round, square, rectangular...somewhere on the hammer, and probably at several places.

I'll move this one over to Rifle Country to see if anybody over there knows the answer.

Luck!

Tuner

AZ Jeff
September 25, 2004, 06:46 PM
I cannot say with certainty about the newest AR-15's, but there were a number of trigger group parts on the AR that were made from investment casting from the beginning.

The following parts were cast (and may still be, for all I know):
Trigger
Hammer
Safety selector
Bolt stop/release

All of the above, of course, get secondary machining after casting.

The upper and lower receivers are drop forged aluminum. Some reproductions use cast aluminum receivers, but the Colt stuff and all military guns have forged aluminum for the recievers.

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