FALaholic #: 263
Join Date: Jul 2000
Location: Eastern Washington State
Posted August 06, 2003 06:15
Things that will need to be corrected/oddities on ALL Century receivers (as of July, 03 batch):
1.) Know in advance that ALL CAI receivers are basically metric pattern, type 3 (sort of). The inch ones are metric with an inch magwell/front mag catch cut, top cover tab cuts, and folding charging handle cut. The ejector blocks are metric, relieved for inch BHO. What this means is that your inch mag catch will not fit unless you thin the "catch" part so that it will fit through the ejector block and grind down the leg that would normally ride against the mag catch pivot screw. You will also need to use a metric pivot screw. FWIW the inch BHO will work. You could also just use a metric mag catch, which fits fine.
2.) The counterbore into which the carry handle retainer portion of the gas tube nut is supposed to fit will be both undersized AND not centered to the threaded portion of the gas tube nut hole. Will need to be Dremeled to open up so that the gas nut will screw all the way in and retain the carry handle. You should do this before you install barrel as you will need to (CAREFULLY) come in through the front, threaded hole. (Be careful not to ding the gas nut threads) Use the gas nut as a guide.
3.) The gas piston hole will be undersized AND off center to the gas tube hole. Once again, needs Dremeling (easy).
4.) The counterbore for the head of the mag catch pivot screw will not be centered with the threaded portion of the hole. You will need to open it up so that the pivot screw will screw all the way in. (BTW this counterbore is too deep, the screw will screw in too far compared to normal. Not really a problem, just odd).
5.) Four out of five of these that I have done needed the mag catch pivot hole through the ejector block and receiver line drilled as the middle ejector block hole doesn't line up properly with everything else.
6.) The magwell will fit very tight on inch mags. The reason for this is that they forgot to take into account that inch mags are slightly longer, front to back, than metric due to the larger front catch. I have been relieving both the front of the magwell as well as the ejector block faces to loosen this up. (It doesn't take much material removal, so don't over do it or they will be too loose)
7.) The feed ramp geometry on these is what has been called "unibrow" by some; i.e. it doesn't have two separate distinct feed grooves. I have never had feed problems due to this, however if it REALLY disturbs you, a Dremel sanding drum is almost the exact size required to make the dual grooves. You would be best to get another receiver to use as a guide if you are going to do this.
8.) SOME of these that I had have needed the feed lips/rails polished a little FROM UNDERNEATH to allow the mag to fully seat and to facilitate proper feeding of rounds. You will be able to tell by looking to see if there is any casting flash left on these. If there is, polish it smooth.
9.) The receiver lock up catch may or may not be too big and need shortening. If it does, it wont need much, so file/Dremel carefully. In contrast, EVERY Entreprise receiver that I have ever seen had a lock up catch that is WAY too big/long.
10.) Some people have bitched about barrel timing, but so far all of mine have timed up about as good as any other manufacturer, so I cant comment.
11.) The locking shoulder hole will need to be polished or CAREFULLY line drilled, as it will be undersized.
If you look, you will note that many of the issues are related in some way to the CAI home made ejector block. On my next one, I am planning to throw away the CAI ejector block and install an OEM to see if it fixes the problems. All in all, these are not for the first time builder, but with a little effort, they will work fine. I wish they knocked off $10 and just sold them in the white, since you end up reparking them after you're done grinding on everything.
Harlan at FAC
Posted August 06, 2003 06:26
Does your review apply to the Century metric receiver?
Posted August 06, 2003 08:16
Harlan - Yes, this in general also applies to the Metric versions. As noted (and I'm sure you are aware already), the "inch" is really a modified metric. In general, the metric results in a much better finished product, as the magwell, mag catch, ejector block problems are non-relevant or less severe. The flip side, that I didn't bring up, is that the barrel timing IS a bigger issue on the metric version, as you don't have the luxury of picking a proper size breeching washer. Metric barrels that I have tried always timed too soon, i.e. about 10:00 (which is still better than late, say 1:00 like I got on an IMBEL, once).
To be honest, what I was really hoping to do was not to scare anyone, just to point out the few little tweaks required with these. I got a note from Harlan saying that the newer metric versions (which I haven't seen yet) were NOT unibrow, which would make them all the better deal. These really are not a bad deal, but for a first timer, they might be a little more of a challenge than just a run of the mill IMBEL, most of which could be built up blindfolded (although like I said earlier, I have seen some WAY out of spec IMBELs, too).
I'm by no means an expert like Gunplumber etc., either. I just have had the good (or bad) fortune to have built quite a few FALs now for myself and friends down here in sunny south Texas. (You find out just how many friends you have once you buy a set of FAL building tools!!)
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