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Posted: 4/2/2012 8:22:46 AM EDT
| Ok I saw a GmM16a1 supposed to be the real thing. Registered etc. Upper was marked L M, barrel marked mp 12 and flash hider 3 prong. According to the info above L M was a later made upper maybe early 70's. MP 12 were early barrels and 3 prong was last used in 67 I would have expected a c marked barrel and an unmarked upper or ribbed upper and a birdcage flash hider. Why is there no real good information on the GM? What are your thoughts on this. Looking at it closely makes me believe its legit. everything look perfect doesn't look like its a parts gun. Lets say is not legit then why would someone put a mp 12 barrel made in early 60s on a 70's manufactured upper unless L and M marked uppers were made way earlier than our info states. any thoughts? |
| The "MP 12" barrel is Colt. The "L M" upper receiver is supposedly a replacement part. Maybe when something happened to the original upper assembly or when it wore out, an NOS "MP 12" barrel was mated to the "L M" receiver and then mated to the GM lower receiver. |
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redbaby, do a search in this forum, search for "GM" and "Hydramatic" and you will find a bunch of threads that answer your questions as good as can be answered.
Production info on GM 603's is virtually non existent, all we really know is what has been shared with us from a few armorers who have had first hand experience handling seemingly original specimins. WpnsMan is very knowledgeable about this topic, as he is one of those armorers(at least I think he is an armorer) Anyhow, I've seen the registered Hydramatic you speak of. The upper and barrel are definitely not original to the lower. LM uppers were replacement uppers, and like you said, the MP 12 barrel is way too early, not to mention its made by Colt. GM uppers have no forge codes or proof marks, and may or may not have flashing on the carry handle. The barrels were marked MP C, and the FSB would have forging flash, drain hole, and may or may not have forge codes. Some have small numbers in circles on the bottom of the bayonet lug. Many of the small parts from contractors that supplied GM and H&R have these small "number in a circle" mark, generally 1 through 5. The forward assist and bolt catch are most notably marked this way. Most of the other small receiver parts were made in house and marked with a small number inside a G. H&R had their own in house mark. Check out these sites. Willyp's info is solid. http://www.google.com/url?sa=t&source=web&cd=1&ved=0CCMQFjAA&url=http%3A%2F%2Fimageevent.com%2Fwillyp%2Ffirearmsalbums%2Fuscoltarmalitem16ar15556%2Fresearchprojectsetc%2Fhrgmproductionm16a1s&ei=lzZ6T_rWAtKutwf95YD0Dg&usg=AFQjCNHWcyFbkeiaZ2K8ww1dYVnUopE9Hw http://imageevent.com/willyp/firearmsalbums/uscoltarmalitem16ar15556/researchprojectsetc/hrgmproductionm16a1s?z=9&c=4&n=1&m=-1&w=4&x=0&p=9 |
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