SCAR 17S Canted Barrel ...and my fix...ETA - pics up

[Evil_Ed]

Hi all, been lurking for a while...


A week or so ago I picked up a nice new black 17S...been reading here, saw the 'canted' thread(s), and gave mine a look. Sure enough, the barrel as it exited the receiver was 'off', noticably. As in I could stick a pen in the gap on one side, and maybe I'd be able to fit a cut index card or two on the left side. It was really that bad.

Following the threads here, I removed the barrel assembly to take a quick look, figuring the remove/reseat solution would work. Well...I noticed that it was canted even worse when I removed it from the rifle.

Then I inspected how the whole thing was set up, what was attached to what, etc...and realized that it's %100 possible that the barrel is straight relative to the trunion/extension, and that it's the lower rail, and it's receiver mounting points, that are off. That lower rail is on there really snug, and if it's pushing the whole thing to one side...well, that'd explain it.

I took a framing square as it was the only true straight edge I had laying around, and lined it up against the extension, and verified...the barrel was straight but the rail was not. I guess their jig for attaching the lower rail might be in need if some straightening

Anyway - Using a T25 bit, I took out the torx screw connecting the lower rail to the extension, jiggled the lower rail for a bit (it was still attached)...it lined up just fine with some careful moving around. Screwed that bit back in, torqued the barrel assembly back into the receiver per the directions...and now it's as straight as can be.

Sorry, I don't have pictures, but if you remove your barrel assembly you'll see what I mean as to what's connected to where.

Thought this might help someone down the road...

[101ABN327]

Outstanding observation and correction tip! Solution seekers are very welcome here.

101

[Ocalus]

I tried that with no luck. It seems it has to do with the seating of the barrel against the receiver on mine. I'll post pics once I get them uploaded. Doesn't particularly bother me but is still annoying loose stitch in the overall picture. I'll find out if mine is particularly affected in POI once my Eotech EXPS3-0 and AAC 51T miter gets here.

Pics will have to wait.. too much shadow from the rifle to make out enough detail. Guess it really comes back to the fact that this really isn't an issue. Really wish opticsplanet would hurry up and notify me when my eotech has shipped.

Tried said technique one last time since pics turned out bad, and to my surpise it was a bit better this time. so much so that I am thankful for your advice.

[SONYtec]

Welcome!!!


Nice work, and posting the info!!!

[djv38]

Very good first post

[Thermallator]

Good post - made it a sticky.

-TH

[Evil_Ed]

Good post - made it a sticky.

-TH

Wow, I didn't expect that

After I did my fix above, I mechanically zeroed the front and rear sights (the rear was all the way to the right and the front was quite a ways to the left, out of the box). Centered them both up visually against the markings.

I finally got to the range on Sunday. It was just about dead-on at 50 yards, but a little low (of all the things). One click of the front sight to the left and two clicks of the front post down (to bring the POI up) and it was printing in the X once I did my part.

Unfortunately I misread the manual and sighted in at 50, when I should have sighted in at 25 I'll have to do that next range trip..

I'll have to get pics of the procedure, it's really very simple. Hopefully it helps more than me. I'll see if I can take some when I get home from work today.

[SONYtec]

Yes, pictures.

[Evil_Ed]

Ok -

When I first took the barrel off, no kidding or joking - this is exactily what it looked like:





As you can see...that's jacked.

Using a driver with a T25 head on it, I loosened the screw (4-5 turns or so, no need to unscrew it all the way if you don't want to) on the bottom REAR of the rail, and gently wiggled it up and down until it reached roughly this stage:



At this stage it's still attached to the receiver extension but it is NOT going to influence the barrel when it's mounted; it'll move side-to-side as well as up-and-down. Not quite free-floating, but close enough for gov't work

At this point, the easiest way to straighten it out - remount the barrel and torque it down, including the front points...and THEN tighten that rear rail screw back in tightly. That way it'll basically zero the rail for you, while leaving the barrel perfectly straight in the receiver.

At least, that's what I did, and it worked for me. I mis-typed in my earlier post...I thought I had centered the front post before sighting it in; I had actually over-cranked it one click to the right! So, when I had to adjust the front back one click to the left...I was actually centering it!

I didn't "torque" the rail screw to a specific in/lb or other setting; it seemed like it was just tightened until tight plus an extra crank, so that's what I did manually.

That rail screw, btw, has what looks like some kind of a thread locker on it (as does the slot in the receiver extension where the rail fits into). It'll take a little bit of strength to pop the screw loose, then it'll come out. You won't harm it by unscrewing it. It's not staked or otherwise fastened; it's just in there with some loc-tite like substance.

HTH!

[SONYtec]

WOW!!!

Nice follow up, and photo's.