Accuracy fixed.

[DJudge]

Instead of starting a new thread, I will just add to this one. I went to the range again today with some hornady black ELD-M. I cant believe the difference that lapping the upper receiver and bedding the barrel has made to the accuracy. I was originally going to scrap the upper out of pure disappointment. Im glad this forum was here for me to learn off of and after a couple of easy fixes this gun is doing what I originally knew it would be capable of.


This is the target from before I lapped the upper and bedded the barrel and a target I shot today with the ELD-M after lapping and bedding the barrel. Thanks again for all the input. Couldnt have done it as easily without you guys.

Wow! Huge improvement! Hard to imagine that is the same gun.

[cst]

Which lapping tool us good? I have the wheeler and c ant trust how true it is

[just_john]

Wheeler is good unless it has been damaged on the rotating face in some manner.

[cst]

you guys spinning it by hand or using the drill?

[Bigs28]

I spun by hand with the upper verticle with wheeler 320 grit lapping compound. I bought my lapping tool here

http://pacifictoolandgauge.com/ar-tools/...results=13

[bj139]

Instead of starting a new thread, I will just add to this one. I went to the range again today with some hornady black ELD-M. I cant believe the difference that lapping the upper receiver and bedding the barrel has made to the accuracy. I was originally going to scrap the upper out of pure disappointment. Im glad this forum was here for me to learn off of and after a couple of easy fixes this gun is doing what I originally knew it would be capable of.


This is the target from before I lapped the upper and bedded the barrel and a target I shot today with the ELD-M after lapping and bedding the barrel. Thanks again for all the input. Couldnt have done it as easily without you guys.

Was the first target shot with factory ELD-M? It is not mentioned.

[Bigs28]

that particular first target was sst i think. I shot both sst and amax prior to lapping with terrible results. Since lapping i have shot sst and eld-m and they are both shooting very well

[bj139]

Wheeler is good unless it has been damaged on the rotating face in some manner.

The face on my Wheeler lapping tool was not true when I started lapping but it seemed to be good by the time I was finished as the tool and receiver wore together. The main body of the tool was good which is what really controls the accuracy of the tool. Maybe the irregular face was due to an uneven paint job.

[diddlyv]

I bought the brownell tool, also brownell lapping compound and used my drill at a low speed to lap. May have screwed up as I lapped with the receiver horizontal not vertical as i did not want any lapping compound to run down the tool and lap the inside of the receiver but what do I know. The Odin works 20 incher shot well

[bj139]

I did mine the same way and for the same reason as above. ^^^^^
There was no noticeable wear of the inside of the receiver.

[NugginFutz]

I bought the brownell tool, also brownell lapping compound and used my drill at a low speed to lap. May have screwed up as I lapped with the receiver horizontal not vertical as i did not want any lapping compound to run down the tool and lap the inside of the receiver but what do I know. The Odin works 20 incher shot well

While what LRPF52 said about vertical orientation of the upper while lapping has its merits, my lapping tool has a very good fit in all the uppers I've lapped. For that reason, I would have no qualms about mounting any future uppers in the traditional horizontal position. I get measurably straight surfaces and less chance of lapping compound invading the upper's interior. In the case of my tool, it has a definite recessed section which prevents the pilot section from coming anywhere near the receiver face and the lapping compound.

[82HALO]

I thought the same thing, so I put the receiver vertical facing down and went in from the bottom.

[dreadpirate]

I did the same thing to my AR Grendel; and polished the feed ramps as well. Will post range results.

[Klem]

I have never lapped or glue-bedded but am thinking about trying it. Here's a question for you...

How do you insert the barrel extension with glue on it without it ending up on the face of the receiver? I'm thinking if the barrel is a reasonable fit it will push the glue onto the face where you don't want it. And if you put less glue on the extension to avoid this surely you could end up with air gaps, so not enough support? Do you push it in most of the way and then clean the excess off the receiver face with a cotton bud, prior to the final seating?

[Bigs28]

I did mine verticle but basically just like this with a couple paper towels.

https://youtu.be/Wgw6MhO83Fg

Put the barrel in verticle, cleaned the dripping stuff and put on the barrel nut to hold in place for 24 hours.

[Bigs28]

Jump too 4:15 and watch from the on how i lapped.

https://youtu.be/HAL5DqNJd9s

[82HALO]

I put the locktite in the barrel extension and turned the the barrel as it slid into the receiver. I wiped any excess as the barrel went in, then locked it down with the barrel nut. Didn't touch it for 24 hrs,

[Klem]

I did mine verticle but basically just like this with a couple paper towels.

https://youtu.be/Wgw6MhO83Fg

Put the barrel in verticle, cleaned the dripping stuff and put on the barrel nut to hold in place for 24 hours.

OK thanks for that...I see after carefully lapping the face it now has Loktite on it. The paper towels in the video were only used to catch the excess and clean the threads, but not the face of the receiver.

The guy smears the Loktite on the outside of the barrel extension, so the excess gets pushed to the front of the receiver as the two parts come together. There has to be a thin film of glue now between the face and the shoulder of the barrel extension.

What if the Loktite was applied to the inside of the receiver only? The excess then gets pushed into the receiver and not on critical surface of the shoulder. Harder to clean the excess because you've got to get into the receiver but at least there's less chance it ends up on the carefully lapped receiver face.

[brian y]

I spun by hand with the upper verticle with wheeler 320 grit lapping compound. I bought my lapping tool here

http://pacifictoolandgauge.com/ar-tools/...results=13

That is the lapping tool I bought and I have 2 Aero uppers I picked up last year and this lapping tool jams when I tried to use it. It will only go in about 1-2 " and then sticks . I tried using it with slip 2000 but it will not go in and it will not turn even using a drill!!. I do not know what I am doing wrong so any help would be appreciated.

[just_john]

Klem, there is no issue with a little loctite on the face of the receiver. The point of lapping and loctiting is to facilitate a "single piece of metal" barrel thru receiver. If there is a little loctite on the face ( after cleaning off the excess), when the barrel nut is torqued down, it just helps to insure that there is no slack anywhere between the barrel and receiver. If there is any space or gap anywhere in this transitional area, there is opportunity for movement at ignition which creates an upredictable shot to shot variation. Just remember that if a little loctite is a good thing, a lot of it isn't!