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Posted: 12/23/2015 7:48:21 AM EDT
I bought this as an LMT bcg. Said to be older. Can anyone confirm or decipher who may have made this from the markings and characteristics? Thanks for the help.
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The bolt is marked "E 1" Identical to mine? No 1 on mine. Just E on the bolt and E on the carrier. I don't know if Anderson makes these or not, but I can tell you with 100 percent certainty that ours were made by the same company, and mine was purchased from Anderson and labeled as being "their bcg" |
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You already have the answer, but for others who might be in the same position.
Every LMT bolt I've seen has a small groove machine behind the locking lugs to eliminate the inside square corners. LMT uses the proper fasteners. Those are simple head head bolts. They have thinner walls and use a larger size hex wrench than the proper ones. They tend to also be weaker. The newer LMT gas keys are MIM. There will be a small circle usually on the top where the injection was. |
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Quoted:
You already have the answer, but for others who might be in the same position. Every LMT bolt I've seen has a small groove machine behind the locking lugs to eliminate the inside square corners. LMT uses the proper fasteners. Those are simple head head bolts. They have thinner walls and use a larger size hex wrench than the proper ones. They tend to also be weaker. The newer LMT gas keys are MIM. There will be a small circle usually on the top where the injection was. The key in the picture is almost certainly MIM - there's a mold line clearly visible. MIM is not a "bad" manufacturing method for gas keys. |
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UNTIL they fail... <a href="http://s135.photobucket.com/user/PursuitSS/media/AR15%20Failures/ef093eda.jpg.html" target="_blank">http://i135.photobucket.com/albums/q125/PursuitSS/AR15%20Failures/ef093eda.jpg</a> Quoted:
Quoted:
Quoted:
You already have the answer, but for others who might be in the same position. Every LMT bolt I've seen has a small groove machine behind the locking lugs to eliminate the inside square corners. LMT uses the proper fasteners. Those are simple head head bolts. They have thinner walls and use a larger size hex wrench than the proper ones. They tend to also be weaker. The newer LMT gas keys are MIM. There will be a small circle usually on the top where the injection was. The key in the picture is almost certainly MIM - there's a mold line clearly visible. MIM is not a "bad" manufacturing method for gas keys. UNTIL they fail... <a href="http://s135.photobucket.com/user/PursuitSS/media/AR15%20Failures/ef093eda.jpg.html" target="_blank">http://i135.photobucket.com/albums/q125/PursuitSS/AR15%20Failures/ef093eda.jpg</a> Yes indeed. Maybe "not 'horrible'" would have been a better turn of phrase. There are probably several different ways to cast an MIM carrier key - your picture shows one, while the OP's picture shows another. Your part seems to have been made as minimally as possible, and may only have been finish-bored for the inside of the key, while the OP's is cast with the mold flash down the middle of the whole thing from a left/right mold design, and appears to have been finished throughout the tube portion of the part; that suggests a more robust part overall. Until I saw your part, I would have thought that the left/right mold structure in the OP's picture would have been the most logical (and thus most common) way to do it. I don't understand why your part was made that way from a casting design point of view. And with that said, I am not endorsing use of MIM for any stressed part. I've seen MIM slide stops on 1911s break, and even MIM mainspring housings have problems (though PLASTIC ones seem to do fine...). In the AR world, bolt catches and selectors seem to be the more likely MIM parts - but I would NOT use either because the bolt catch is stressed (when it catches the bolt) and a selector is way too critical to safe (and legal) operation to risk just to save a couple of bucks. Carrier keys? I'd have said they were "less stressed" in general until I saw your picture. Now, it's more like an indication to have a spare key on hand for when it fails... |
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