New Bushie 11.5 inch upper. Took it out to the range today and got it one paper. Out of the box it was shooting about 6 inches left @ 50 meters, and about 4 inches high. I did the necessary adjustments, and the sights look like this. Is there a problem? To zero, the rear sight had to be moved ALMOST all the way over....

Thats not very much really, you arent even to the first large index mark yet. Plus it's a detachable carry handle.
A good mallet whack to the front sight base should help that out .

Which way?
[IMG]http://img26.photobucket.com/albums/v77/jsinz/DSC01832.jpg[/IMG][;D]

So that pic is the zeroed setting? That's bad, you're allowed (max) 11.6MOA off when zeroed at 100, you're at 12MOA if you're 6" at 50 yds.

If it was hitting left you'll want to move the FS to the left to move the strike to the right. Front opposite, rear same. You moved the RS right to move strike to the right.

Do the adjustment on the range. Make sure to NOT hit the ears of the front sight. You rest the carry handle and side of the receiver against your thigh and tap the FSB. Try it then shoot it, repeat. Baby steps.


How does the FSP look for elevation?

Still hitting a bit to the left, about an inch. I'll be back at it tomorrow.

[IMG]http://img26.photobucket.com/albums/v77/jsinz/DSC01837.jpg[/IMG]
It's backed out quite a bit...

Nice, was thinking it would be two rotations. Looks like the RSB on your carry handle is thicker than those used on the M4, hard to tell tho with no reference. El error might just be the general mismatch between wrong FSBs, carry handles and uppers. There is an excessive (tho yours looks passable if not "spec") elevation thread in the Troubleshooting FAQ if you want more info. Flipping to the 0-2 ap will lower the strike too.

Thanks for the help Tweak.

The RSB is "supposed" to be a Bushie unit, has the splintered "A" then an "A" on the upper left side, but I bought it used from a member here, so who knows who really made it. At any rate, my other AR (RRA) also impacts high with it, and the FSB is backed out just as much. Funny thing is, the ARMS BUIS I have on my other one shoots the same POI as the carry handle. Who knows. The elevation problem I can deal with, it's the windage thing that bugs me. I must be compulsive or something, that rear peep sitting to the side just bugs me.

I'll hit the range tomorrow with your (and Tangeant's, thanks!) suggestion and see if that helps.

Not talking about the carry handle, just the steel part that holds the aperture. The ones intended for carry handles have thinner bottom portions than standard A2 RSBs. Some carry handles come with the thicker RSBs. Is the "A" (not the Anchor Harvey mark) stamped into the carry handle or is it raised?

If the BUIS shoots to the same El the error is probably in the FSB height or the height of the upper. The upper should be ~1.72" from the bottom of the upper to the bottom of the cross slots in the rail. I'm probably now repeating info that is in the FAQ.

I like my ap as centered as possible, no more than 2-3 clicks. When they sit to one side it slows down my target aquisition.

Jeez, is there anything you don't know about AR's?[hail2]

The "A's", both of 'em, are raised, not stamped. The height did mic measure out to 1.720, interestingly enough, my RRA upper mic'ed out to 1.730. That accounts for the extra amount of backing out I had to do with the front sight on it. Hmmm.

FYI, the height of this particular RSB (part with index marks) is about .205, although a real accurate measurement is hard to get without disassembling the sight.

From CL of bore to top of the FSB at the "UP" marked flat you're looking for 2.285" +/- 0.010" for a [b]non flattop[/b] FSB. "F" marked FSBs are in the 2.35" range.


[bk]

Quick fix on the elevation adjustment is to just go with a taller front sight post, instead of having to break out a Mic, and the calculator. Granted it fun to play rocket scientist, just not before my afternoon nap.  Plus, a new front sight post is way cheaper than a new Rear sight housing.

DPMS offers taller front sight posts, and with a drill and a file, you can spin file it down to look less like a fence pole against the target.

You must have a paper copy of their catalog? I can't navigate their website for crap. I found a NM one and tritium sights, that's it. Man, I remember now why I don't have any DPMS parts.[:)]

[URL]http://www.bushmaster.com/shopping/scopes/9349056-m.asp[/URL]

Bushmaster has them too.

Ahh, a navigable site. Thanks.


Both FSP's of mine are about .070. With a .040, I'll be shooting hairs off an gnats ass eh?

There's an old saying about barrel torque. 'If it shoots to the right, the barrel's too tight'. I had the same problem on an OLY and the barrel was incorrectly torqued from the factory.

I paid a small mint for the upper, what most folks would pay for a whole AR. Mostly for the warranty. I am considering send it back. Took it to the range today and smacked it a lot, never got it right.

Was shooting at 25 yards and still hittin left. I'd guess it averaged about two inches with the rear sight at mechanical zero.

I think it would just bug the crap out of me with the rear sight being way over to the right.

Id send it back.

The amount of barrel torque has nothing to do with sight alignment.

ETA,

AZ,

There's a WARRANTY? Send it back, it's obvious you've never toured the Troubleshooting forum. [:D]

Never had any luck with rubber "mallets", always used rawhide.

Never seen a barrel rotate back into it's incorrect alignment. If that could happen they could rotate off of correct alignment too.

Send it back.
DO NOT WHACK the FSB it with a mallet!
I made that mistake with my upper. It's a less than temporary solution and it will start to walk and you run the risk of looseing the barrel nut or shearing the indexing pin!

Have too! Every thread there is a "Hey, my thingamajigger is broke", which has a plethora of answers (not unlike this one [:D]) then you chime in with a hotlink to another thread dealing with the same issue, which may contain another hotlink to another thread with a possible answer. [:D]

That's proof right there. [LOLabove]

Note sent to Bushmaster with a link to this thread requesting a call tag.

This isn't Troubleshooting?[>:/]

[white]OOPS[/white]

Nevermind.

I like to make them work for the answers in the vain hope they'll learn something on the way. I think it's called "tough love."

is that a pube on the rear sight aperture?

Oh, I did learn some things. Trust me.

I just dont have the tools needed to pull the barrel, forearms, etc. Yes, I know I should, but I don't, and at this time, can't afford to buy them either. For the record, the Troubleshooting forum is a very good thing, I have yet to see any other sight approach the amount of info in there.

BM is sending a UPS label so they can look at it.

I sleep with my rifle. [:I]

While this would be true if we know for a fact that it's only an allignment problem, but we have no way to know if it's also torqued down way too tightly. That rear sight is all the way over, something else is wrong.

I've sent 2 back for that same reason.

Anyone else having trouble translating this? It's easy to get the short barrels cockeyed due to their short sight radius. The amount of torque has nothing to do with how the alignment pin fits the aligment pin slot. This is one of the hazards of not installing barrels the "Army way."

forgive me for interupting...
but honestly your carry handle looks exactly like the three  I just bought a the gunshow for 15.00 each, chinese stuff.
I found that all three fit on the pict. rail lopsided, I hade to take a dremil and remove some of the material on the side that is permantly attached to the carry handle to get them to sit straight, I had an identical problem with all three, after correcting all three they zero and rezoro in exactly the middle position.
I can try to get a pic of the fix, but it may take awhile

what i mean by the fix is this.

the "dovetail grabber" on the carry handle isnt deep enough to engage the edge of the rail, when you tighten the nut side it sits off to the side just slightly,f I have to deepen the grove in the "perminate side" so that it would sit flat on the rail(upper).

I bet your bushmaster carry handle is a chinese like mine,  (by the way they work great now, I cut one for a stand alone sight and it even works great.)

check to see if the rear of the carry handle is sitting flush and if the elevation/windage bridge is flush to the carry handle.

I know that was probably confuseing ,
Tweek the all knowing could have said all that in two words or less.
Hunter
p.s. take a pic of it from the rear so I can see the way it sits on the upper.

I would never insinuate that AZ-K9 bought a "junk" part. In this case I believe the lineage of the parts is fully known to him.

ETA [:)]

Did I mention that this carry handle zeros perfectly and co-witnesses with an Aimpoint on my other AR? [:D]
[IMG]http://img26.photobucket.com/albums/v77/jsinz/DSC01845.jpg[/IMG]
[IMG]http://img26.photobucket.com/albums/v77/jsinz/DSC01846.jpg[/IMG]
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[IMG]http://img26.photobucket.com/albums/v77/jsinz/DSC01848.jpg[/IMG]

EHunter-The Splintered "A" stands for Anchor Harvey Forgings. A prime commercial/gov't contractor. Therefore,It IS NOT a Chicom knockoff.

Translate this, maybe the barrel extension is too tight as well. If that happens the allignment pin will appear to line up correctly, but the front sight will not line up.

Barrel production 101.

Barrel blank is profiled, and then reamed.  
The barrel extension is torque in place (175lbs).
The barrel extension pin is drilled and placed, then the gas port is drilled using the extension pin index, and the front sight is set using the same index.

When a barrel is installed on an upper, the barrel extension pin is indexed in the upper socket slot. Tightening the barrel nut greater than 80lbs will damage the upper receiver threads. As long as the torque of the barrel nut wrench is directed to the upper receiver, and not threw the barrel (such as using a barrel vise clamp, nor failing to grease the bearing edge of the receiver extension), the barrel will not slip index/bend the pin in the upper socket.

Quoted:
"is that a pube on the rear sight aperture?"

I guess he thought he would whack the sight with his WHAT THE FUCK?

LOL

Where I worked the alignment pin hole was already drilled when we received the barrel extensions. Made it interesting when one of the occasional ones with a mislocated pin hole made it onto a barrel. Had a couple make it all the way to assembly where, oddly, they failed to feed.[:)] Hard for rounds to feed when the feed ramps are 90 degrees out.

Where can I buy a $15.00 Chinese detachable Carry Handle???

Sounds like a really cheap BUIS solution!

The indexing pin slot in the upper is wider than the pin its self in every upper I have ever assembled/disassembled. You can torgue a Brl enough that the indexing pin will not be perfectly cetered, it will be pressed against one side of the slot. I've done it, Bushmaster does it OFTEN.

I am only a beginner AR-builder, but I second IronBalaclava's motion.  Whacking the FSB with a mallet is dumb.  Adjusting the fit of the index pin in the slot is permanent and the right way to go.  JMHO, YMMV, etc.

C_M

I whacked, and nothing happened. [:D]


Still waiting on Bushmaster to send the UPS label........

You have just given the best example of why drifting the barrel in the upper with a leather mallet works. If you try to pull the barrel and retighten it, you will get the same results as before. Shimming the pin in is what I used to do, but this would take hours, and a few tries to get it right which included several live firings to account for barrel harmonics.  

By using a leather mallet, this correction of barrel index takes about three minutes during final live fire sighting. As for shims/verses the present gap between the pin/slot when leather drifting, if the barrel takes a hard enough hit to slip the new sighted index with the gaps, then shims/receiver would have been dented also, which would require a re-work to re-correct the index. It just boils down to whether you want to take another three hours (if you have the talent/tools) or just slipping the barrel back to were it belongs with the mallet again (three minutes/5 rounds at any shooting range).

The one thing that neither Tweak nor myself has ever said, was that you can correct a bad barrel that is either bent or that the front sight was not indexed with the receiver extension pin with the leather mallet (more than a few degrees between the two). The rule has always been that the rifle has to be able to be sighted in with the rear sight first (rear sight less than maxed out to one side of the housing). This allows the pin/barrel to either drift to the needed location if there is a gap, or the pin will slightly indent the side of the slot, and not mis-index the feed ramps in the upper.

P.S. Just installed a Shaw barrel in a DPMS upper (old DCM upper using a front adjustable sight) that has been re-barreled three times last night.  The pin to slot had zero gaps, in fact the pin had to be seated the last 1/8” with the barrel nut. If I need to re-index the barrel in the upper to center out the rear sight on live firing, I will need to either remove metal from the slot, or just leather mallet drift the barrel and let the extension pin indent/enlarge the slot the needed few degrees.  The sights laser out with the bore at install, just need to adjust for barrel harmonics under live fire.
Since the mallet is already in my shooting bag for tomorrow, guess which way I going to resolve any problem?

Only to slightly hijack the tread, which my guess is that I'm going to catch hell for,

Speaking of them, since the AW ban is going to sunset, is their game plan to drop the price on the 9mm upper kits (current design), or are they planning on changing the design to have a last round hold open and new mags that work with the system. I have been holding off on another 9mm (the whole Colt mags with last round hold open mags @ $100 a pop, verses the Sten mag savings with no last round hold open).

P.S. If this post goes to three pages with Point/Counter points, I'm bringing up the religion, and the influences it has on the whole re-barreling, verses the just using the mallet, so you have been for warned (may ever quote a few Popes, granted it may be out of text).[:P]

[shrug] The guys I stay in contact with there are friends, we don't talk biznatch. [:)]

Update: Just got back from shooting, two clicks to the left off the center mark, three clicks down from flush on the front post to zero the rifle. No barrel rework/indexing requried.

Thanks goes out to J&T for the barrel, and DPMS for a upper receiver that has lasted me threw several barrel changes.