MBUS Rear Sight Slop

mdhog · Jul 10, 2020

I have the standard Magpul MBUS rear sight mounted securely to a picatinny rail. When I flip it up I grab the whole assembly that's perpendicular to the rail and I can move it left/right about 1/32 of an inch. It's moving along that rod in the bottom left of this picture that would be parallel to the picatinny rail slots.

Is this slop, play, whatever you want to call it acceptable? I thought these things were supposed to be "quality". The aperature is attached to this complete upper assembly and can be either 1/32" to the left or the right on any given shot, that's going to affect the point of impact significantly at long distances.

outrider58 · Jul 10, 2020

No

I mean, not easily. Mine don't have any play other than the fact they are composite, which can flex, but no mechanical wiggling.

ETA There are fakes out there. I bought a set on Amazon once that were WAY out of spec. I told them they were probably fakes and returned them.

jamesp15 · Jul 10, 2020

Shouldnt be much if any "play" or "slop" in it. Is it a real magpul? (I only ask because there are a LOT of fakes out there on ebay and amazon and even seen some in stores.)

If you bought it local or on amazon I would try to exchange it. Or contact magpul they have pretty good customer service.

teratos · Jul 10, 2020

outrider58 said:
No

I mean, not easily. Mine don't have any play other than the fact they are composite, which can flex, but no mechanical wiggling.

What he said.

tallen702 · Jul 10, 2020

jamesp15 said:
Shouldnt be much if any "play" or "slop" in it. Is it a real magpul? (I only ask because there are a LOT of fakes out there on ebay and amazon and even seen some in stores.)

If you bought it local or on amazon I would try to exchange it. Or contact magpul they have pretty good customer service.

Agree. I've seen some VERY convincing fakes out there. You shouldn't have any slop in it when it's sitting on the rail and properly tightened.

omegared24 · Jul 10, 2020

outrider58 said:
No

I mean, not easily. Mine don't have any play other than the fact they are composite, which can flex, but no mechanical wiggling.

ETA There are fakes out there. I bought a set on Amazon once that were WAY out of spec. I told them they were probably fakes and returned them.

Yup and most likely the case. Believe it or not the real ones can take a beating.

TheOriginalMexicanBob · Jul 10, 2020

I agree about it being counterfeit...Magpul is good stuff but even good stuff can occasionally be bad. Where was it purchased from...Amazon, eBay or someplace known to have counterfeit selling vendors?

Blaster229 · Jul 10, 2020

When you "rest" the sight in the picatinny, you need to make sure you slide it forward. Then latch it.

mdhog · Jul 10, 2020

This came on my Ruger AR-15 so it "must" be real. Maybe not. I think the play is probably within the manufacturing tolernaces. Just not within mine. If you look at all the horizontal rods you can see there's gaps in the components, so all the assemblies are naturally going to move some. I'm not sure if a replacement would be any better. But thanks for the input anyways.

teratos · Jul 10, 2020

mdhog said:
This came on my Ruger AR-15 so it "must" be real. Maybe not. I think the play is probably within the manufacturing tolernaces. Just not within mine. If you look at all the horizontal rods you can see there's gaps in the components, so all the assemblies are naturally going to move some. I'm not sure if a replacement would be any better. But thanks for the input anyways.

“Play” cannot be in spec for a rifle sight. 1/32” play with a sight radius of 18” and distances in excess of 100 meters makes the sight useless.

outrider58 · Jul 10, 2020

Blaster229 said:
When you "rest" the sight in the picatinny, you need to make sure you slide it forward. Then latch it.

This

But ther should not be any play, once deployed.

3paul10 · Jul 10, 2020

I've never seen that.

outrider58 · Jul 10, 2020

3paul10 said:
I've never seen that.

What?

3paul10 · Jul 10, 2020

outrider58 said:
What?

Ive never seen slop in an MBUS....but, I've also never seen a clown whose nose I didnt want to knock off his clown face.....but hey, maybe I'll see one that doesn't bother me so much...never know..

MindTheGAP · Jul 10, 2020

mdhog said:
This came on my Ruger AR-15 so it "must" be real. Maybe not. I think the play is probably within the manufacturing tolernaces. Just not within mine. If you look at all the horizontal rods you can see there's gaps in the components, so all the assemblies are naturally going to move some. I'm not sure if a replacement would be any better. But thanks for the input anyways.

What you're describing is not at all standard / normal 'manufacturing tolerances' with Magpul's MBUS. I have what, 14 or 15 sets of them on various rifles / PCC's (and a couple Roni's), and not ONE has play in them, so a replacement should absolutely be better. Sounds like you got unlucky, but if you don't like the MBUS, buy the Magpul Pros. I have 3 sets of the pros and those are rock solid and have absolutely no play whatsoever (being that they're metal).

outrider58 · Jul 10, 2020

3paul10 said:
Ive never seen slop in an MBUS....but, I've also never seen a clown whose nose I didnt want to knock off his clown face.....but hey, maybe I'll see one that doesn't bother me so much...never know..

Okay. That's it! Come to my office, you non believer!

:spank:

3paul10 · Jul 10, 2020

outrider58 said:
Okay. That's it! Come to my office, you non believer!

I am in your office....RIGHT NOW!

outrider58 · Jul 10, 2020

3paul10 said:
I am in your office....RIGHT NOW!

C'mon in!

-Z/28- · Jul 10, 2020

mdhog said:
This came on my Ruger AR-15 so it "must" be real. Maybe not. I think the play is probably within the manufacturing tolernaces. Just not within mine. If you look at all the horizontal rods you can see there's gaps in the components, so all the assemblies are naturally going to move some. I'm not sure if a replacement would be any better. But thanks for the input anyways.

If it came from the factory with the sight then I would contact Ruger about it. They may warranty it if it's defective.

niftyvt · Jul 10, 2020

-Z/28- said:
If it came from the factory with the sight then I would contact Ruger about it. They may warranty it if it's defective.

And contact magpul. They are good people and I would think that they would take care of it.

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