Accuracy fixed.

[just_john]

+++++ above! LAP-IT! It pays!! As the uppers are made of aluminum a good valve grinding compound from your neighborhood auto parts store should work fine. Use it sparingly!

[bldsmith]

Lapping tool ordered. Thanks for the post.

[LRRPF52]

What media should be used?

I just use lapping compound from Brownell's.

I also make sure to orient the upper receiver vertically so I'm not biasing the weight of the lapping tool in the upper and therefore creating an angle on the receiver face.

[Chrazy-Chris]

I just use lapping compound from Brownell's.

I also make sure to orient the upper receiver vertically so I'm not biasing the weight of the lapping tool in the upper and therefore creating an angle on the receiver face.

If you happen to have the lapping compound that comes with the wheeler scope mounting kit (it's for lapping rings), that works well too. I use choke tube grease on the part of the tool that goes inside the receiver so that stays nice and tight without scratching anything up. The grease you're going to use for your barrel nut would probably work, too.

Good tip LRRPF52, I'm going to have to remember to put it in the vice that way next time.

[Ditcher]

Was talking to a friend at work about lapping the receiver and he told me it wasn't really necessary. Clearly it is! Very nice groups.

[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/1139-ar-15-upper-receiver-lapping-tool.html?search_query=Lapping&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.