survivalshop Posted September 20, 2016 Report Share Posted September 20, 2016 (edited) I had a factory Colt Carbine come to me the other day with a Iron sight issue , rear sight ( Magpul MBUS )was all the way to the left for impact on target to be close to center , but not . here is some of what I found & what I did . The front sight tower is just a hair off . I centered the Laser with measurements of the Rail center , as best as I could , Laser was aligned using two measured marks on top of Rail front & back , Laser line can be seen from rail , down the Barrel on top of Gas Tube & up the A2 Sight Tower . I'll post some photo's when I can get them smaller or off my PhotoBucket , which , I haven't figured a way to get the photos on here & not just the link . The front sight tower was off a little & the Gas Tube where it should have been close to center in the Upper Receiver Channel , was way off , to one side . I use a Jewelers Screw Driver for a Gage on both sides of the Gas Tub & it should fit between the Gas Tube & the side of the Channel on both sides , I could not get it even in on the left side looking down into Upper Receiver & could flop it around on the other side , so I knew something was out of center . Disassembled Barrel components & removed the Barrel Nut & all nice & tight with fitment of Barrel in Upper Receiver & Extension Pin was tight & "0" play in it . Surprised how easy all came off , no Rockset or Loctite of any kind , very light grease on Barrel nut threads . Reinstalled Barrel / Nut ,Aligned Gas Tube Passage in Nut & checked alignment of Gas Tube in Upper Receiver Channel , perfect with Taper Pins in Sight tower , just pushed in , after seating Taper Pins , the gap or alignment of Gas Tube in Channel was only slightly off on the same side , but no where near where it was & it would fit in , so after reassembling rifle & setting up the Laser for checking alignment , the Laser was dead center on front sight post , Perfect. I believe the Barrel Nut was not indexed correctly for the Gas Tube to pass through with out putting undo tension on the front sight tower , so when the Taper Pins were seated from the Factory , the torque on the Tower from the misaligned Barrel Nut/ Gas Tube , permitted the Tower to seat or center correctly . Will know more when I test fire it this week , but it won't be because something is out of kilter . Edited September 20, 2016 by survivalshop Quote Link to comment Share on other sites More sharing options...
sketch Posted September 20, 2016 Report Share Posted September 20, 2016 Thats Crazy, ss what year is this rifle? Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 20, 2016 Author Report Share Posted September 20, 2016 I'll have to ask the owner to be sure , but it looked like 11/13 on the Barrel , i'm not familiar with Colt markings ,so don't know if that means anything. Quote Link to comment Share on other sites More sharing options...
sketch Posted September 21, 2016 Report Share Posted September 21, 2016 I know a guy in that similar timline? But sure he has no similar problems? Laser is good idea! Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 21, 2016 Author Report Share Posted September 21, 2016 It was time consuming to set up though , I have a photo of after adj. the Barrel Nut , I have to down load it . I'm shooting it today to see if it made a difference or its his eye's or ammo . I have some Fed mil spec 5.56 to shoot & my hand loads . Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 21, 2016 Author Report Share Posted September 21, 2016 (edited) Shot the rifle today , but it still shoots to the right . The alignment did help , at least the rear peep is not maxed to the left & the grouping is centered . I was wondering , since I really don't have much experience with the 1-7 twist , I know its for shooting the heavier bullets , would a 62 gr. loads ammo shoot better or shoot closer to the center of the target ,then the four 55 gr. loads I used today , two 5.56 loads ( factory ), one S&B 223 ( factory ) & one of my Hand loads , all 55 gr. all printed right, almost a foot , off a sand bag rest at 20 yards. After the sight was adj. to the left , @ 100 it was the same , but for me me & my old eyes , it could have been me but was consistent with the shorter range . I just can't believe seven grains would make the barrel shoot more to the left , This one has me puzzled , beginning to think the Barrel is $hit . Edited September 21, 2016 by survivalshop Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 21, 2016 Report Share Posted September 21, 2016 (edited) 62gr green tip, was it? That's a completely different round, brother. It's the whole reason that M16 twist rates went from 1:9" to 1:7", from the M16A1 to the M16A2. EDIT - ***Tracers had an impact on twist rate change, too...*** Edited September 21, 2016 by 98Z5V Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 21, 2016 Author Report Share Posted September 21, 2016 So your saying I should try some 62 gr. loads , I have some Hand loads & some green tips. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 21, 2016 Report Share Posted September 21, 2016 (edited) Fire up those green tips and see if you have a point-of-impact change, same point-of-aim. It won't be the same as the 55s. Edited September 21, 2016 by 98Z5V Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 21, 2016 Report Share Posted September 21, 2016 I went through this in 1991, through a "US Army NCO Professional Development Course." All the instructors were talking schit about the weapons qual portion, saying "we wouldn't qualify the same that we do at our home unit." They proceeded to ask every student what they usually qualify at, at home. Fukkin Expert, arsholes! Always! They bet me I wouldn't... I started asking questions, and they didn't have answers, but the only thing they would say is "We run it REAL here!" Alright, fuksticks... These dipshits were running M16A2 rifles and left-over 55gr mil ammo. No poop, it's gonna be off a little, over a 300m 40-round pop-up range. I still shot 40/40, Expert. They were puzzled... Afterwards, they got an education on ballistics, and a pretty intense After Action Review on how fukked up their weapons qualification portion of the course was, based on pure weapons idiocy of the entire cadre, the lack of the proper ammunition for the given weapons system, and pure cadre-cockiness. Not long afterwards, from reviews from people I kept in touch with, they were shooting the fukking green tip through the A2s for the weapons qual. Fukkin bastards, and their schit-talking... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 21, 2016 Report Share Posted September 21, 2016 (edited) For the record, most students DID qualify lower than they did at their home stations. BECAUSE of two issues... #1, the cadre were fucking idiots, and didn't realize how much of an impact a 55gr round has versus a 62gr round, over 300 meters - AND, we zero'd on the M16A1 Zero Target!... They just wanted to talk smack, and thought they were the only ones in the career field that ran an "honest range..." and #2, most students don't know schit about ballistics over a given range. Ammo is ammo, right?... It was a combination of a triple-Fukup. My AAR was not kind to the cadre... Edited September 21, 2016 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Sisco Posted September 21, 2016 Report Share Posted September 21, 2016 Ballistics 101. Bet it would have been fun to hear you set them straight. I bought an AR-15 A2 H-Bar in 92 when it was clear that the Ban was coming, and that information was well known in the civilian marksmen community by then, amazing they didn't still didn't have a clue. I remember back then you couldn't get the 62 gr. SS109's or M-855's. I ended up getting 2,000 IMI Israeli equivalent bullets from Natchez and handloading my own. Only way a civilian could get it back then. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 21, 2016 Report Share Posted September 21, 2016 The SS109 projectile is definitely different, and the best thing for it is the 1:7: twist. Quote Link to comment Share on other sites More sharing options...
blue109 Posted September 21, 2016 Report Share Posted September 21, 2016 Lol I remember guys not even firing at the 300y engagement and saving the bullet for a closer miss. You can still get sharpshooter without them ? Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 21, 2016 Author Report Share Posted September 21, 2016 (edited) 1 hour ago, 98Z5V said: The SS109 projectile is definitely different, and the best thing for it is the 1:7: twist. I would think the SS 109 would fly different because of the Steel penetrator , not the same as full lead core . I have shot many M16's & AR's with 1-14, 1-12 & 1-9 & I have a 24" 1-10 & never had an issue with 52 gr. match 55 gr. match & FMJ & 69 match , loads with Iron sights . That 1-7 seems unforgiving in bullet weight choices . , I think I have the same twist rate on my Piston build & my wife Carbine , now I have to look & I have Irons on my wife now , so I guess Ill take it with me to the range with this Colt . Edited September 21, 2016 by survivalshop Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 21, 2016 Report Share Posted September 21, 2016 At one point I had 4 or 5 extra Colt barrels. I still have one left, a 16" carbine, pencil contour. It too is 1:7 and hates the 55gr stuff. I was very tempted to cut it to 10.3" and use it for strictly for heavies. There's a guy in SoCal who will cut pencil barrels and build a new shoulder for the barrel threads. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 21, 2016 Report Share Posted September 21, 2016 41 minutes ago, survivalshop said: I would think the SS 109 would fly different because of the Steel penetrator , It does fly different, just because of that penetrator. The guy's barrel you're working on is a 1:7"... Shoot some green tips through it after the work now, before making a determination on it's perfrmance of shooting it with 55s... Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 21, 2016 Report Share Posted September 21, 2016 If he's been dumping 55gr pills at a high RoF, just for shits and giggles, he could've burnt the rifling. Those NATO 55gr rounds will burn a barrel with tight threads if you're not minding the barrel heat. That's a shiit ton of friction, pressure and heat. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 22, 2016 Author Report Share Posted September 22, 2016 25 minutes ago, Robocop1051 said: If he's been dumping 55gr pills at a high RoF, just for shits and giggles, he could've burnt the rifling. Those NATO 55gr rounds will burn a barrel with tight threads if you're not minding the barrel heat. That's a shiit ton of friction, pressure and heat. He's not that type to dump Mags , but i have no problem doing his rifle for him My wife's Carbine , has a 1-8 Wilson Combat barrel , but my Piston gun has a new 1-7 . It has a scope on it with QR Warne rings , so I will put some BUIS on it & do a shoot out with the Colt . Learn something new every day around here . Here's a good one for you Robo , a group of LE had a Glock Armorers course next range over , I parked next to one of the guys & asked what was going on & he told me they were just issued Glocks & they were all getting used to them . I said , I thought those Austrian hand cannons never quit working , so why the Armorers course , he got a good laugh out of it & I'm sure that went around those guys shooting . Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted September 22, 2016 Report Share Posted September 22, 2016 4 hours ago, 98Z5V said: Fire up those green tips and see if you have a point-of-impact change, same point-of-aim. It won't be the same as the 55s. The difference in switching from 55s to 62s on our Pinky was over a foot at 100 yards between POA and POI. Pretty amazing. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 22, 2016 Author Report Share Posted September 22, 2016 (edited) At 100 yards , I can understand that , but to have the sight windage all the way over at 20 yards , doesn't leave any room for any down range adj. . I've just never seen almost a foot off at that short of distance , sure with different bullet weights , you expect to see some adj. needed between them , but man ,almost 1' is a really big & something I'm not used to . Like I said, these 1-7 twist rate is new to me & I already don't like it , it could be just this BBL. too . More testing , I'm going to get a 1-9 to compare , hell , I might have one in there some where . Edited September 22, 2016 by survivalshop Quote Link to comment Share on other sites More sharing options...
blue109 Posted September 22, 2016 Report Share Posted September 22, 2016 (edited) My SPR is 1:8 and its a laser with 45g varmint stuff...and 77g otm. It's not a fan of 55-62 and the groups open up quite a bit with some mild poi shift. I know plenty of people with 1:7s that shoot 55s decent. 55 is still the most common plinking ammo purchased so if 1:7 didn't shoot it, 1:7 barrels wouldn't be so common on factory guns. Barrels like what they like, but I really doubt twist rate is the issue with that colt. Edited September 22, 2016 by blue109 Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted September 22, 2016 Report Share Posted September 22, 2016 (edited) 12 hours ago, planeflyer21 said: The difference in switching from 55s to 62s on our Pinky was over a foot at 100 yards between POA and POI. Pretty amazing. I should add that the 55s were some of the seriously underpowered Wolf/Tula crap too. The 62s are green tips. Edited September 22, 2016 by planeflyer21 Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 22, 2016 Author Report Share Posted September 22, 2016 This Barrel really doesn't group bad , at all , just way to the right & it does center with the rear peep sight all the way left . I know I have had some 1-9, 20" barrels that would do almost the same , but not to this extreme , where the sight is all the way to the left , they would be half way between center & left go the sight travel, you still had plenty of adj. left to use . Not so with this rifle or Barrel . The Gas tube is centered in the Channel , at least now . Quote Link to comment Share on other sites More sharing options...
blue109 Posted September 22, 2016 Report Share Posted September 22, 2016 (edited) If the ammo doesn't make a difference... Maybe try a different rear sight to eliminate that possibility? and maybe try mounting the rear sight further forward to eliminate the possibility that the rail is slightly out of spec. Mount an optic to see if it behaves the same. Just start eliminating things. Edited September 22, 2016 by blue109 Quote Link to comment Share on other sites More sharing options...
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