Author Topic: Back up iron sights loose on picatinny rail  (Read 2055 times)

Offline ag2

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Back up iron sights loose on picatinny rail
« on: September 14, 2012, 02:45:44 PM »
I've got a Bushmaster AR-15 xm15-e2s.  This is a flattop with no iron sights.  So I replaced the gas block with a picatinny rail gas block and put on flip up back up iron sights. (BUIS)  I recently purchased these iron sights at a local gun show.  But there's no markings on these iron sights, so I do not know the manufacturer, but they look VERY similar to Yankee Hill.

Here's the problem:  the rear sight doesn't fasten down snugly on the picatinny rail.  It still wiggles a bit. 

I've removed the rear sight for close examination.  The allen bolt retracts a cleat on the opposite side of the sight and rail.  As I tighten the allen bolt, this cleat retracts to clamp onto the picatinny rail.  The cleat to which the bolt is threaded is designed to be attached in one direction (I have flipped it over and checked to be sure.)

The problem is that the base of this rear sight appears to be slightly too wide which prevents the cleat to fasten snugly to the picatinny rail.
The base of this rear sight wiggles ever so slightly when mounted to the picatinny rail.

Is this normal?  Is it supposed to go on a riser?  Is a riser 1 or 2 mm wider?
Mild-mannered beans, bullion, band aids, bullets prepper cautiously watching history repeat itself.

Offline SheepdogSurvival

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Re: Back up iron sights loose on picatinny rail
« Reply #1 on: September 14, 2012, 04:58:43 PM »
Mostly likely you have airsoft/Chinese nock-off sight that is out of spec. Either that or your upper is (which I highly doubt).

My advice is to only buy HIGH quality sights/optic mounts parts from a trusted manufacturer. If you have an outstanding firearm and cheap sights or rings you are really screwing yourself, it's almost worse than having just a cheap beater gun since you perceive that you have more capability than you actually do.

my 2cents..
"If ye love wealth greater than liberty, the tranquility of servitude greater than the animating contest for freedom, go home from us in peace. We seek not your counsel, nor your arms. Crouch down and lick the hand that feeds you; May your chains set lightly upon you, and may posterity forget that ye were our countrymen."
- SAMUEL ADAMS

Offline ag2

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Re: Back up iron sights loose on picatinny rail
« Reply #2 on: September 14, 2012, 11:34:45 PM »
Mostly likely you have airsoft/Chinese nock-off sight that is out of spec. Either that or your upper is (which I highly doubt).

My advice is to only buy HIGH quality sights/optic mounts parts from a trusted manufacturer. If you have an outstanding firearm and cheap sights or rings you are really screwing yourself, it's almost worse than having just a cheap beater gun since you perceive that you have more capability than you actually do.

my 2cents..

D@mn.  Lesson learned.  Better now than later.  I thought the airsoft crap was made of plastic and I naively thought that a purchase from the PE gun show in Loveland would be quality.  Boston taught me better than that.
Thanks
Mild-mannered beans, bullion, band aids, bullets prepper cautiously watching history repeat itself.

Offline nelson96

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Re: Back up iron sights loose on picatinny rail
« Reply #3 on: September 15, 2012, 12:17:24 AM »
I would agree with sheepdog, this isn't an area you want to scimp.  Go with a trusted manufacturer that supports "battle" quality gear. . . .   Your rifle, no matter how cheap or expensive, is only as good as the sights and/or optics you put on it. 

For a BUIS, I've had very good luck with Troy.
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One hundred thousand generations of people lived and ate as hunter-gatherers, and only two generations have grown up on highly processed fast foods. . .  It's not too late

Offline endurance

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Re: Back up iron sights loose on picatinny rail
« Reply #4 on: September 15, 2012, 09:14:17 AM »
Not that I'd recommend anything but doing it right, but if you have to make what you have work you might try using a piece if innertube as a spacer.  While I haven't used it in this application, innertube is my spacer of choice in many applications (primarily because I always have holey bike thee around).
"There are things that you don't question when your home always smells like baking bread."  From The Hunger Games

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Offline Bradbn4

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Re: Back up iron sights loose on picatinny rail
« Reply #5 on: September 15, 2012, 09:26:44 AM »
While there are good plastic backup sights available like http://store.magpul.com/prod_detail_list/44

But without markings - well, I like endurance's suggestion of using a rubber pad to snug down the sights without damaging the rail system.  This would be a nice stop gap method to keep the sights snugly attached until you can work out a solution.  I have also seen some very light weight foam sheets that could also be used.
 
If you are looking for metal backup sights - http://troyind.com/back-up-iron-sights/fixed/rear-fixed-black-fde
Brad(bn4) - In Colorado

Offline Jungle_Jim

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Re: Back up iron sights loose on picatinny rail
« Reply #6 on: September 15, 2012, 09:46:39 AM »
I only use Troy. Here is a little hint. Thanksgiving week Troy will have a huge sale. 30% off last year on all sights :). You might wait until then and make a big score on great sights.

Offline nelson96

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Re: Back up iron sights loose on picatinny rail
« Reply #7 on: September 15, 2012, 10:25:00 AM »
For optic mounts, I purchase nothing but LaRue.  I love their QD mounts.
“There are few things more pathetic than those who have lost their curiosity and sense of adventure, and who no longer care to learn.”
 ~ Gordon B. Hinckley

One hundred thousand generations of people lived and ate as hunter-gatherers, and only two generations have grown up on highly processed fast foods. . .  It's not too late

Offline ag2

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Re: Back up iron sights loose on picatinny rail
« Reply #8 on: September 16, 2012, 09:34:33 PM »
As long as we are throwing out hints, Rock River usually has a 20% of end of year clearance sale in December.

Maybe we should start a sale/bargain topic/thread???
Mild-mannered beans, bullion, band aids, bullets prepper cautiously watching history repeat itself.

Offline nelson96

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Re: Back up iron sights loose on picatinny rail
« Reply #9 on: September 16, 2012, 09:41:11 PM »
As long as we are throwing out hints, Rock River usually has a 20% of end of year clearance sale in December.

My brother-in-law took advantage of this on a very nice rifle last year.  I was jealous, since I didn't have the funds to invest at the time.
“There are few things more pathetic than those who have lost their curiosity and sense of adventure, and who no longer care to learn.”
 ~ Gordon B. Hinckley

One hundred thousand generations of people lived and ate as hunter-gatherers, and only two generations have grown up on highly processed fast foods. . .  It's not too late