Odin Works upper not fitting on Larue Lower

[eugevita]

So this is a first for me. I own a Larue Ultimate Upper AR (Larue upper and lower) and recently tried to put my odin works slick upper on the Larue lower. I had been planning to use the odin works upper as a second upper for that lower. Unfortunately to my surprise the odin works upper would not properly mate up with the Larue Lower. It felt like the Larue take down pins were almost too large for the holes in the odin upper. I lubed up both holes with hoppes #9 and was generally only able to get the rear take down pin in the rear hole but could not get the front pin in despite much effort and frustration. I was only once able to get the front pin in but then I couldn't get the rear pin in (in fact, I was only able to get the front pin inserted one time).

Is this odin slick upper and Larue lower combo just not meant to be together? Appreciate any advice from those who have had this sort of issue before. The odin upper fits on every other lower I own and the Larue lower fits all my other uppers.

Thanks!

 

[Powder_Burns]

Tolerance stacking; the specs on your odin upper and larue lower are just off enough the holes aren’t lining up properly but work with any other combination of receivers you own. I don’t think its your pins if you dont have that issue with any other uppers. If you have some calipers, measure the recoil lug dimensions and the distance from the pivot pin to takedown pin on your odin and compre those measurements to your larue. I suspect you will find some different numbers.

 

[Animal357]

There is a company that makes both oversize and undersize pins for this exact reason, but I can't think of the name.

 

[Powder_Burns]

KNS?

 

[eugevita]

Tolerance stacking; the specs on your odin upper and larue lower are just off enough the holes aren’t lining up properly but work with any other combination of receivers you own. I don’t think its your pins if you dont have that issue with any other uppers. If you have some calipers, measure the recoil lug dimensions and the distance from the pivot pin to takedown pin on your odin and compre those measurements to your larue. I suspect you will find some different numbers.

This sounds quite likely. I will measure the distance between the two pins as very possible that you are correct. What do you mean by measure the recoil lug dimensions? Are you referring to the pin dimensions? Thank you for the advice!

 

[eugevita]

KNS?

Guessing these are the ones you are referring to?

Pretty interesting, though I am reluctant to change pins on the Larue lower as I would like to keep the OEM tolerances between the Larue lower and the Larue upper which is the host for a ballistic advantage 6 ARC barrel which I expect to shoot out to 1000+

 

[Powder_Burns]

The recoil lug is the square piece of the upper your takedown pin goes through. See if it may be longer than the larue one.

 

[1moaoff]

If you donate to the fundraiser and have new holes punched and add oversize pins all will be good with the world including your build

 

[eugevita]

The recoil lug is the square piece of the upper your takedown pin goes through. See if it may be longer than the larue one.

will do, thanks!

 

[eugevita]

If you donate to the fundraiser and have new holes punched and add oversize pins all will be good with the world including your build

What fundraiser? I am confused by your response...also not really interested in any permanent alterations

 

[6.5SH]

What fundraiser? I am confused by your response...also not really interested in any permanent alterations

ALERT!! Fundraiser: Shooter with spinal cord injury

Here we go. For those of you who have been around a while, you know this is something we do. For those of you who are newer, this is something we do. We all as a group give a hand to someone in need. Story is this. Group of kids were traveling in a car and an intoxicated driver crossed the...

www.snipershide.com

As to your fitment issues, mix and match on billet can be a problem.
Have you tried the pivot pin only while the rear lug is out of the lower? I saw you did the opposite with take down pin only.

 

[Slick66]

So this is a first for me. I own a Larue Ultimate Upper AR (Larue upper and lower) and recently tried to put my odin works slick upper on the Larue lower. I had been planning to use the odin works upper as a second upper for that lower. Unfortunately to my surprise the odin works upper would not properly mate up with the Larue Lower. It felt like the Larue take down pins were almost too large for the holes in the odin upper. I lubed up both holes with hoppes #9 and was generally only able to get the rear take down pin in the rear hole but could not get the front pin in despite much effort and frustration. I was only once able to get the front pin in but then I couldn't get the rear pin in (in fact, I was only able to get the front pin inserted one time).

Is this odin slick upper and Larue lower combo just not meant to be together? Appreciate any advice from those who have had this sort of issue before. The odin upper fits on every other lower I own and the Larue lower fits all my other uppers.

Thanks!

Tolerance stacking; the specs on your odin upper and larue lower are just off enough the holes aren’t lining up properly but work with any other combination of receivers you own. I don’t think its your pins if you dont have that issue with any other uppers. If you have some calipers, measure the recoil lug dimensions and the distance from the pivot pin to takedown pin on your odin and compre those measurements to your larue. I suspect you will find some different numbers.

Not just tolerance stacking, but also what some folks might be willing to push out the door in these crazy times. Not saying this is odin's issue, don't know anything about them.

Unless the OP has the tools and experience to measure quite a few dimensions within a couple thou, I would return the upper and try again.

 

[Powder_Burns]

Wouldn’t surprise me, I have an odin works handguard and the rail height is a few thousandths higher than the receiver its mated to.

 

[eugevita]

ALERT!! Fundraiser: Shooter with spinal cord injury

Here we go. For those of you who have been around a while, you know this is something we do. For those of you who are newer, this is something we do. We all as a group give a hand to someone in need. Story is this. Group of kids were traveling in a car and an intoxicated driver crossed the...

www.snipershide.com

As to your fitment issues, mix and match on billet can be a problem.
Have you tried the pivot pin only while the rear lug is out of the lower? I saw you did the opposite with take down pin only.

yes I tried that, was only able to get the pivot pin in one time and when I did I could not get the rear pin in.

 

[6.5SH]

yes I tried that, was only able to get the pivot pin in one time and when I did I could not get the rear pin in.

If the pivot pin goes in, watch where the rear lug contacts the lower.
I had a similar issue with a DD Mk18 upper on a LaRue lower. The shape of the DD lug was flat and square on the back the inside contour on the LaRue lower is round. The LaRue upper rear lug has a pretty severe bevel on the edges.
I ended up hitting the rear corner edges on the DD lug with a swiss pattern file (it didn't take much) and it fits like a vault door now.

Your upper may or may not be the same issue, but is something to look at and compare since you have a LaRue upper as well.

 

[Slick66]

So you can assemble the upper and lower, but you can’t get both pins in? Are the holes concentric?

 

[KineticPerformance]

There is a company that makes both oversize and undersize pins for this exact reason, but I can't think of the name.

JP Enterprises

 

[357Max]

Check the Odin upper. The front pivot pin hole should be perfectly round. The rear take down pin hole in the upper should not be a round hole.
This is how mil spec accounts for tolerance stacking. Rear upper hole is oblong allowing for increased pin spacing variances.