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9/22/2017 12:11:25 AM
Posted: 11/18/2003 12:31:23 PM EDT
i just installed a new mid length FF ras and it seems to flex quite a bit more than i expected it to. too much to put optics on it. how much flex is there usually? am i not installing it properly? just curious.
Link Posted: 11/18/2003 12:42:08 PM EDT
What brand of FF RAS KAC M-4? If so there should not be much under normal conditions. Now if you are abnormaly trying to flex it i.e. pushing on the barrel and the RAS at the same time then you will see some flex. Otherwise you may not have the locking nut fully torqued down. IPSC_GUY sends
Link Posted: 11/18/2003 2:13:39 PM EDT
[Last Edit: 11/18/2003 8:56:23 PM EDT by Green0]
Link Posted: 11/18/2003 3:47:53 PM EDT
it's a kac ff ras. i didn't think it was "abnormal" by pushing on the barrel and ras. i also didn't think it would flex enough for me to see it. oh well, now i know i should limit what i put on the rail.
Link Posted: 11/18/2003 6:51:11 PM EDT
i'm not sure but maybe you guys have airsoft versions. i have 2 KAC FF RAS units, one is carbine and the other is a long. there is absolutly NO flex at all. i can see the barrel flex if i put my index finger on the barrel and my thumb on the RAS and squeeze. i tried to get my RAS to flex and its impossible. i have had my paq4 on there for months and i had used a bipod for scope shooting and a pistol grip with no movement of the laser. but i guess stranger things have happened. maybe there is a rift in the space-time continum near your location???[:\]
Link Posted: 11/18/2003 6:56:10 PM EDT
at first i thought it was the barrel flexing. it may be the barrel flexing and not the ras, but i thought a stainless 16" HBAR barrel would be more stiff than the ras. anyway, something is flexing, barrel or ras, and it bothers me. i just wondered if other people had flex in their setup also.
Link Posted: 11/18/2003 7:12:27 PM EDT
Link Posted: 11/18/2003 8:42:11 PM EDT
[Last Edit: 11/18/2003 8:58:15 PM EDT by Green0]
Well I have to retract my former statement, I was told by a KAC employee to torque just barely past hand tight and then tonight as I was installing the gas tube from MSTN (which by the way arrived this morning as scheduled), I had a thought, "Maybe that KAC employee was full of shit." Oh and My FF RAS's are all KAC, I bought one from MSTN and one from C4I GRANT and the other from Impact guns. (I don't reccomend Impact [HUGE BACKORDERS] but MSTN and C4I GRANT are excellent dealers.) SO I put it in my vise and tightened the nut with a strap wrench to about 30-40 ft lbs and now there is almost no play- not nearly as much discernable flex- I think it is still a little more than a SIR but not much more at all. (even with the pinch method it was about .050in.) I doubt it will flex at all under normal shooting pressure. [b]Well Now I better tighten all of them. Because I think play was about three times what it is now before I re-torqued it. I have a question too, I just built all these FF RAS guns and I haven't really shot them much, is loctite neccassary or does the nut not come loose?[/b]
Link Posted: 11/18/2003 10:09:44 PM EDT
Originally Posted By GDITheman:.....it seems to flex quite a bit more than i expected it .....
View Quote
I have three KAC FF RASs on my ARs , same a close friend of mine , also I've had the chance to handle a lot of "speed boyz" hardware KAC FF RASs outfitted and listen their feedbacks , no one of those FF RASs flex , the POI never shift . PP out
Link Posted: 11/19/2003 5:18:35 AM EDT
[Last Edit: 11/19/2003 5:27:14 AM EDT by GDITheman]
i'll use a strap wrench and tighten it up some more. i did notice that it flexed less after i tightened it up a bit.
Link Posted: 11/19/2003 12:02:52 PM EDT
GreenO, no lock tight on mine needed. i too used a strap wrench and snugged it up tight. i did put a drop of oil on the threads though. i think i remember seeing that recomendation in the installation instructions.
Link Posted: 11/19/2003 12:16:17 PM EDT
Link Posted: 11/19/2003 1:52:40 PM EDT
No need for locktite here. I actally put moly paste on my threads so the foreend could be removed later when the URX as available as a stand alone unit. GreenO, are you saying you tightened the barrel nut or the retaining cap? My barrel nut is VERY tight. I had the choice of just a hair past hand tight and REAL tight to line up the gas tube after my 3 tighten/untighten series and went for the next hole. My retaining cap is just average tight.
Link Posted: 11/19/2003 3:55:41 PM EDT
[Last Edit: 11/19/2003 3:59:35 PM EDT by mongo001]
I've got a question related to this topic. My M4 setup has a KAC M4 RAS and an ARMS 38-EX-MOD (thanks MSTN) connecting the upper receiver rail with the top rail of the RAS, in effect floating the barrel. The more I thought of this, the more I thought I may have inadvertently placed a stress on the barrel via the forward handguard cap. Opinions? Would it be wise to open up the hole on the forward cap a smidge to relieve any potential stress,just in case? I know, go to a KAC FF, when funds allow I will. Thanks.
Link Posted: 11/19/2003 5:53:45 PM EDT
Link Posted: 11/19/2003 8:21:58 PM EDT
"GreenO, are you saying you tightened the barrel nut or the retaining cap? My barrel nut is VERY tight. I had the choice of just a hair past hand tight and REAL tight to line up the gas tube after my 3 tighten/untighten series and went for the next hole. My retaining cap is just average tight. " The FF handguard retainer cap/ring whatever, I always have the same choice- barely tighten the barrel nut or tighten the piss out of it, So I always torque my barrel nuts to about(my guess) 60ft lbs or more, as I am not comfortable with the next looser notch.. My strap wrench is just one of those stupid POS rubber strap and steel handle things, brand new it was $12.95, it is the smallest one I could find (the only one that woud work) at Walmart and Ace Hardware, I didn't want to drive to Sears or Snap on They are in Milwaukee. The point- It will only torque to about 30ft lbs before the rubber strap starts slipping. At this point it is very firm but there still is a little flex if you check it. I'm OK with it, I might at most put an IR laser on it. No optics are going out there so it shouldn't be a problem.
Link Posted: 11/20/2003 5:07:17 AM EDT
i retightened the ff ras nut last night and it took some flex out, but the wrench i have will over torque the ras nut so much i can unscrew the barrel nut. my point is that tight is good, but i think you can over tighten it if you're not careful. i was worried i might break the gas tube by over torqing the ras nut and unscrewing the barrel nut.
Link Posted: 11/20/2003 9:09:43 AM EDT
Well I guess you know how firm the RAS gets and how much play torque on the collar can eliminate. How much play is still in your RAS, with a moderate pressure pinch between the barrel and forend. Last night I noticed that there is a slight movement in mine when I set it down on a Bi-pod (maybe .03in or so in relation to the barrel.) I wonder what that would equate to at 100yds with an IR laser attached to the forend. That would be impossible with my wrench, It will go to about 30ft lbs prior to slippage. and my barrel nut is torqued to about 60. Common sense, if you torqued with a 1 ft wrench, don't tighten the FF RAS nut with a 1 ft strap wrench and you won't have problems. (the priniple of the lever)
Link Posted: 11/20/2003 9:34:01 AM EDT
If you are putting that much ass on your Handguard Nut (the part that holds the FF RAS iteself to the weapon), and are still getting flex, it is very possible, or rather very likely, that you do not have the RAS properly seated on the two alignment/index pins that go in the barrel nut. You would be surprised how often this is the reason for flex, and how often people swear they have it right... Hope this helps, Clint
Link Posted: 11/20/2003 3:05:49 PM EDT
the flex was significantly reduced. maybe i have a bit more flex since it's a mid length ras and has more leverage since it's longer than the m4 ras. it appears to be seated on the pins properly. thanks for the discussion on this.
Link Posted: 11/20/2003 4:48:37 PM EDT
If I didn't have it indexed on the pins properly the RAS would be about 1/10 of an inch from fully assembled, that is a deffinite no. Mine is a rifle length too, and believe me the KAC RAS could be a little more rigid, I think the very minute ammount of flex in the system comes from the joint where it is attached to the rear collar part. It's firm but it could be better. (If it were as firm as the barrel nut you could pinch for all you are worth and you would see no movement.) [b]That's probably why KAC built the URX, they know there is a way to make it better and more rigid.[/b]
Link Posted: 11/20/2003 6:58:46 PM EDT
Link Posted: 12/7/2003 11:14:45 AM EDT
Thanks MSTN for the reply. I'll leave it as is. One thought on all the strap wrench issues I've read about. What if you were to sacrifice, let's say a ARMS #5 or something similiar (which has alot of clamping area on the rail) and welded a handle to it. Seems this would make an ideal "wrench" for tightening a railed free float tube. God forbid anyone sacrifice an ARMS #5 mount so any suggestions on a acceptable device to sacrifice for this proposed tool would be welcome. I intend on buidling one and trying it out some day soon on my next FF project upper.
Link Posted: 12/7/2003 11:24:07 AM EDT
Link Posted: 12/11/2003 9:20:49 AM EDT
I will gladly e-mail our (KAC) instruction sheet for proper torguing of the FF RAS varients. Proper torgue (using the 3-time torque method) is 300 to 350 INCH lbs. Let me also state that if your UR and barrel nut are mil-spec, then our FF RAS handguard nut and RAS forend does not move, flex, or bend if properly assembled, particualarly complete with the two barrel nut pins at 3 and 9 o'clock. This can only be tested if the rear of the ur is secured in a vice and weight's are added to the end of the top RAS rail. Movement (if any) can be detected with a side rail mounted laser shining against an oposite wall or using a dial indicator. Been there, done that, and our FF RAS don't move. If you want to see something flex, just push on your barrel a little with the ur secured the same way, it flexes like a spring.
Link Posted: 12/11/2003 9:26:59 AM EDT
coldblue, maybe it was the barrel flexing and not the ff rail. i didn't expect flex from the barrel like that. thanks for the input.
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