Hey,
My AR is shooting 20moa right at 25yds.
I have a micrometer, is there a way to look for sight cant of the FSB?
Barrel is new. There are no hurricanes here.
a canted FSB wouldnât cause a 20MOA⊠if you canât get POI within 20" of POA then you might have a FSB issue, but youâd be able to see a cant like that.
what do you mean by MOA? extreme spread? 5 or 10 shot groups with holes 5" apart at 25m?
what kind of barrel and ammo?
ETA: totally didnât read the original post right⊠i see now you said shooting 20MOA to the right
whatâs the weapon? what sights you got on it? does the FSB LOOK canted? what kind of barrel/muzzle device? check for damaged crown/burrs on the crown?
I gotta ask do you know how to adjust the sights?
20MOA to the right.
The group sizes are about 3-4MOA.
This is with Hornady FMJBT âtrainingâ 55gr .223 steel case. Laqured, which is why I donât shoot rapid fire with it.
16" midlength 1:9 armalite barrel. Just had the FSB swapped for an F-marked by ADCO. Standard irons and flat top carry handle. A2 FH. No apparent crown damage.
I donât use rods or brushes, I use boresnakes and weed-wacker line with patches on it.
EDIT: Yes. Turn the rear sight drum to the bottom. Center both the front post level with the âshelfâ and windage on the rear. Turn up to the âZâ mark. At 25yds at the 6/3 mark any adjustment for elevation is done with the front post and windage is self-explanatory.
EDIT2: I tried some UMC .223 55gr and it did the same thing. I have some M855 and M193 but that can wait. I already know it can do 3moa on M193 without too much difficulty and M855 is easy 4moa. This is all done prone with a loop sling â I donât use benches.
EDIT3: it does not look canted. I experimented with cant on my 10/22 a while back and you have to get some 20Âș of cant before things look dirty. I have not had a single FTF or FTE with this carbine, I did have a IMI .223 55gr (shoots 3moa at 300ydsâŠgood stuff) that had a damaged shoulder that stovepiped, aside from that nothing. At least 120 rounds have gone down the barrel now.
Shot 2moa with a M261 GI .22 bolt kit too. I oughta get one of those things.
so you obviously have windage shoved up against the housing and still not zerod, right?
if your windage is all the way over and youâre still 20" off, if itâs the FSB youâll be able to see the cant. wouldnât be the first time ADCO put on a crooked FSB- they do so many its bound to happen from time to time. but unless itâs visible, i think thereâs something else going on.
Well I counted the clicks back from zero (as in, centered on the windage graduations) and itâs ~20 clicks over. I have half-minute clicks if I recall right, they could be 1moa clicks â right now Iâm to concerned with the 20moa right to run a âboxâ â 10 clicks up, fire a group, 10 clicks right, fire a group, 10 clicks down, fire a group, 10 clicks left and fire a group.
I do need to know how much MOA do I get per click on mine, from a table itâs about 1.75MOA for the front and 3/4 for the rear or something like that. A box will tell exactly what it is.
With the windage cranked over, it shoot fine. But no rifle should be cranked that far over except an Indian or Chinese AK47-copy-reject.
It cycles and locks back the bolt fine, so I know the gas port is lined up. If the original FSB shot the same way but not cranked so far over, then why would the F-marked swap be so far over and still cycle?
It has to be something. I put on a post on the ADCO section of ARFcom and see what they say.
If its a rail mounted sight loctite them down. Also zero the elevation first and when thats on then zero the windage. Then fine tune.
Thanks, aye on the ele/windy thing. Elevation was fine.
It is a standard F-marked FSB, I have no rails except an MI FSB light mount. And that was already ruled out since it shot the same with it or without it.
Sling pressure was found to do nothing immediantely conclusive. And then sling pressure doesnât cause windage stress.
The only similar story that I had any involvement with had a bend in the barrell. It was barely noticeable until we took the handguards of the rifle.
So what shall I do next?
contact adco and have them T&E it for you?
Must be right.
It was fine beforehand. Click or two on the windage and it was fine.
Either the FSB or the barrel is twisted farther than it needs to be on the upper. The âportsâ on the FH look as they were before it left, and the feed ramps look the same. So it must be the FSB.
You canât see it from the rear, but from the front and playing with a micrometer on various parts itâs canted by about 10 degrees to the left, looking down the barrel as you would shoot it.
That was my thoughtâŠ
Maybe itâs one of those new super secret, shoot-around-the-corner barrels that somehow escaped from R&D.
And he did on another forum, and they have stepped up to look at it.
ADCO will take care of this guy. I have read some posts from the ADCO crowd on TOS and they care about the work that they do, not just the money they are payed. Good people.
New H&K invention?
It is canted. The barrel doesnât need to be removed for an FSB swap. Since it was shooting fine before, that means the index on the barrel and upper hasnât moved. So that means the FSB is borked.
And it is. About 5 degrees to the left.
EDIT: whatâs âTOSâ?
âThe Other Siteâ, aka (b)arf.com