Colt vs. LMT bolt design differences?

koalorka

koalorka

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Today I decided to get into the Christmas spirit by taking apart and cleaning my AR's, plus I have a few BCM Crane extractor kit upgrades I was meaning to install in my carbines. Now, having them laid out disassembled in front of me I noticed some slight differences, particularly between my Colt M16 and LMT FA bolt:



The Colt (bottom) seems to have a raised surface extending behind the bolt lugs with an additional cut just aft of each lug on that surface. Does anyone know the purpose of these? My guess would be to make unlocking smoother by providing "relief" cuts to ease the lug disengagement process.
 
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Just different manufacture process..the m16 bolt would be stronger with the increased meat and chamfers on the edges..The lmt has a few 90's on it and a skinnier throat,actually not a great design with that slot cut in there..why would they even do that?
 
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Bolt shear happens at the based of the lug. Putting more meat below the point of shear stress failure is not going to do jack.
 
The only recent bolt modification that seems to make sense are the ones where the lug opposite to the extractor is shorter....instead of being 'hammered' due to the uneven pressure applied, it allows the force to be evenly distributed to the other lugs...
Just not sure how critical this is?!:confused:
 
foxbat said:
The only recent bolt modification that seems to make sense are the ones where the lug opposite to the extractor is shorter....instead of being 'hammered' due to the uneven pressure applied, it allows the force to be evenly distributed to the other lugs...
Just not sure how critical this is?!:confused:
Click to expand...

Armalite does this now, and it works pretty well. I've used Colt, LMT and Armalite bolts in carbines, and despite the extra visible wear on the lugs, Colt preforms excellent. Surprisingly the Armalite bolt seems to be better than the LMT bolt, because it didn't crack and my LMT did.
 
stag-bolt.jpg


Saw the question for the Stag bolt, had a pic. ;)

It's covered in preservative, thus the crap looking finish.

FWIW.
 
Thanks Walt. The Stag(CMT?) and Colt bolts look very similar, but not quite the same. From these pics I'd say CMT does not = Colt, but this is a very, very small sample. Maybe I'll pull out some of my LMT and Colt bolts for some pics later...
 
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