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Posted: 11/30/2013 6:19:39 PM EDT
| Why Does Colt mill-off selector tabs on their semi only lower receivers? |
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The selector stops exist because the select-fire selector can rotate a full 360 degrees. The stops limit the travel of the selector to the 180 degree range of function.
On a semi-automatic variant, the selector is only cut to rotate 90 degrees, and cannot be turned any further, therefore making the selector stops redundant. Just like Colt removes the bayonet lugs from 11.5" barrels, they remove the selector stops because they're more or less of no use. ~Augee |
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The selector stops are needed for full auto lowers because the selectors dont have a stop, just detent holes and a channel all the way around... semi selectors only have two positions and have stops built in the selector itself.
Eta: beat by augee while multitasking. 
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Quoted:
The selector stops exist because the select-fire selector can rotate a full 360 degrees. The stops limit the travel of the selector to the 180 degree range of function. On a semi-automatic variant, the selector is only cut to rotate 90 degrees, and cannot be turned any further, therefore making the selector stops redundant. Just like Colt removes the bayonet lugs from 11.5" barrels, they remove the selector stops because they're more or less of no use. ~Augee As always, we know where to get the definitive answer to pretty much any questions regarding the AR. Augee, I gots to know. What is your background? Have you ever been on "Jeopardy"? |
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well then, why doesn't everyone else mill the stops off?
and rainbows are sunlight refracted through water vapor, sunsets are due to the rotation of the earth, posi-tracs (not a locker) have a clutch in the differential that engages and locks up the other axle when the right side start spinning. but i'll leave you with this. why do women say "its all right" when its definitely NOT? |
| Drugs kicked in now, need sleep, radiation tastes funny at 7 am every dayhttp://goo.gl/FD5Gqx |
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Quoted:Just like Colt removes the bayonet lugs from 11.5" barrels, they remove the selector stops because they're more or less of no use. Quoted:Just like Colt removes the bayonet lugs from 11.5" barrels, they remove the selector stops because they're more or less of no use. That's really cool, I didn't know did that too. It always irked me when I see Dissipators and SBRs with bayonet lugs 1" from the muzzle. Quoted:but i'll leave you with this.
why do women say "its all right" when its definitely NOT? To win. they do that to win all arguments by making you liik like a jerk. |
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Quoted:
well then, why doesn't everyone else mill the stops off? Probably the same reason no one else removes the bayonet lugs from 11.5" barrels, though in fairness, machining the whole "lump" off the forging is probably an easier machining process than the "half cut" that receivers with the selector stops require. Ironically, while Colt removes the bayonet lug from the 11.5" barrels, they retain it on CQBR barrels because that's the way Crane spec'ed it. In fact, for whatever inexplicable reason, the whole reason for the spec'ed length of the CQBR barrel, 10.3", is based on compatibility with the then-current M4QDSS in use by SOCOM - it's as short as you can go and still install the M4QDSS without removing the bayonet lug from the FSB. Why they didn't just cut the bayonet lug off and make it that much shorter, who knows - Crane was already cutting and re-threading barrels, you'd think hacking off the bayonet lug would've been no extra hassle - but there you have it. Now the 10.3" barrel is institutionally standardized despite the fact that the FSB has ben deleted in the Block II upgrades, eliminating the bayonet lug, and the M4 and NT4QDSS series is starting to get phased out (though they will likely remain in use for quite a while). In the meantime, the DD MK18 RISII was developed and has its length based on the CQBR's oddly specific barrel length. In twenty years, people will probably be asking "why 10.3 inches?!" Regarding the selector stops, the AR "aftermarket" was initially based on compatibility with select-fire parts, i.e. surplus uppers, ect., and during a time when FA conversions were legal, therefore it made sense to leave the selector stops. Incidentally, some lowers like the EA J-15 cast lowers had ninety degree selector stops, possibly because people were modifying full auto FCGs to fit semi-auto lowers, meaning that the selectors could still rotate 360 degrees. I'm just taking a guess at this, but I would guess that most likely the "origin" of the fully milled selector stops was because when the SP1 was first released to the market, Colt had to make quite a few modifications and take some lengths to get approval from the ATF by demonstrating that the SP1 was not "readily convertible" to full auto. This was the reason for many of the "unique" attributes of the SP1, including the "big hole" uppers without sear reliefs and cutting back the tail of the bolt carrier. More than likely, the milled selector stops were another little bit of "proof" that the lower was not compatible with full auto parts such as the selector. After that, it just became "what they do" and has carried on even today. And while at the time converting your semi-auto to full auto was fully legal on a Form 1, so was simply purchasing a select-fire rifle, which Colt was more than happy to sell anyone who wanted one on a Form 4 - in their eyes there was no reason to convert an SP1 to FA when you could just buy an M16A1. Of course as you and I all know, that's not what the market wanted - many, myself included still choose to Form 1 Colt lowers instead of buying factory SBRs for a variety of reasons, hence the various companies that did offer to convert SP1s to FA like Sendra, as well as the Lightning Link and DIAS that came along in the wake of the SP1's release. ~Augee |
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Quoted:
Drugs kicked in now, need sleep, radiation tastes funny at 7 am every dayhttp://goo.gl/FD5Gqx Wha'cha getting at there youngin? 
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