Posted: 1/7/2009 7:00:53 PM EDT
| Just wondering why the new lowers have KT for a serial number prefix instead of CM? |
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A side note. I just picked up my 3rd RRA complete lower. The first two have the CM prefix and fit perfectly tight with RRA uppers. No detectable play between the two.
I can't say the same for the new one with the KT prefix. It isn't a complete rattle trap like some of the ARs out there, but the fit is not as good. Maybe it is just a coincidence. Does RRA perform their own machining on the lower receivers or buy them ready to use? |
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Out of curiosity, which of the lowers from the thread below does the "KT" marked RRA lower most closely resemble?
http://www.ar15.com/forums/topic.html?b=3&f=12&t=318113 I'm curious, as I just ordered a RRA lower instead of a few other available brands because they're machined very cleanly. No forge flash, no milling mismatch, holes are done right, curve below the receiver extension is cleaned up neatly and not hacked out, etc. Here's to hoping the change in serial doesn't mean they changed machine shops making their lowers. |
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Quoted:
I'll take a good look this weekend and note any differences that I see. From my memory, the quality of machining looks the same. It was just the loose fit between the new lower and my uppers that was noticeable. Oh, good. Thank you for taking a look and posting on it. Hopefully it's just that little bit of upper/lower play. IF the new KT-serial lower build tolerances are too sloppy, I'm going to have to track down a new lower for my NM Service Rifle build. |
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I have one of each. The CM lower was purchased stripped and currently has an RRA upper on it. Very tight.
The KT was bought as a compete two stage lower. It has an upper from BCM (keyhole) on it. It also does not have any play, either. The only difference my untrained eye noticed is the lettering is deeper on the KT lower. |
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Probably the quickest way to tell if RRA changed from CMT produced lowers ("CM" prefix on serials = CMT made? "KT"= ??) to someone else;
- Forge flash in the trigger well area (CMT cleans this out quite well) - curve from pistol grip to buttstock is smoothly rounded (CMT is generally smooth and rounded, to others obviously milled out flattened radius) Edit: Browsing around, I'm guesstimating the KT serial indicates Kaiser Defense. Machining is similar to CMT's clean work, mag-well is supposedly EDM'd, and anodizing is a pretty close match for the typical RRA coloration. http://www.ar15.com/forums/topic.html?b=3&f=118&t=405932&page=2 has some detail info on Kaiser lowers, as a point of comparison. |
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I couldn't see any real difference in the machining. No flash to speak of. Tried to take pics last night, but they came out lousy. Will try again.
The only noticeable difference besides the fit to the upper is the engraving. The font is slightly different and the word FIRE above the selector is where it should be. It looks misplaced on the two older ones. So, I'm guessing that they are machined, or at least engraved elsewhere. But the job is done well. Just too bad about the fit. Maybe it will be better when the upper that is actually going on it arrives. |