Accuracy fixed.

[Bigs28]

So quick back story. Spent over a year collecting quality parts. Assembled them all about 2-3 months ago. Went to the range and accuracy sucked. 8" groups of complete randomness at 50 yards. I was extremely disappointed.

Several YouTube videos, lots of research here, and more tools ordered.

On Monday I took the upper apart. Hand lapped the upper receiver. Clearly was not even as the top left was the last to turn silver. Bedded the barrel with blue loctite, reassembled and went to the range today.

TAC DRIVER.

bullet inside of bullet. You could only truly identify 3 shots in my 4 shot groups. Again only at 50 yards but I'm using a cheap Nikon p223 3x32 scope. I'm ordering the vortex viper pst gen 2 2-10x32 after next week's overtime so then I will dial in at 100 yards.

So excited.

Thanks for everyone's help, advice, and guidance on this forum. This would have been much more difficult to have achieved without you guys.

[NugginFutz]

Glad you sorted out your issues. Also nice that you provided empirical evidence that lapping the upper to the barrel extension can and does (often) provide benefits.

Happy shooting!

[Steamburn]

Always lap!!!
My first build was a 30-06 built on an old Mauser action. I was under the guidance of a group of retired machinists from the Navy that had set up a gunsmithing shop as a hobby and were always glad to have an enthusiastic apprentice around.
They taught me how to fit a barrel to the action and once I thought I was done, I was asked to disassemble it, including the bolt parts. Next step was to spend quite a few hours applying valve grinding compound to the lugs after painting them with Prussian blue, back and forth until the lugs in the bolt matched the lugs in the action to perfection. Once everything was perfectly clean, I assembled it back again and checked for headspace once more. It ended up being a nice shooter. I still have that rifle.

[Chrazy-Chris]

Nice! I suspect that barrel nut was not tight enough the first time around - did it come off easily when you broke it down?

I just started lapping my uppers and I'm a big fan! It's a quick easy step and a fairly inexpensive tool.

[Bigs28]

The barrel nut was on pretty tight but once off there was allot of play between the barrel and upper receiver.

[Bigs28]

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.

[bj139]

I just thought I'd mention the difference between accuracy and precision.

Accuracy is hitting what you are aiming at (hitting bullseye).

Precision is repeat ability (group size).

[Bigs28]

Ok so lapping and bedding fixed the precision.

[VASCAR2]

Thanks for posting the update. Glad to see the forum was beneficial to you!

[S.Kargoh]

Should the blue loctite be green instead? For cylindrical sleeve mating of loose tolerances?


And also, do you decrease it and then put the loctite in? Because decreasing seems like it would be difficult due to the use of grease on the bbl nut?

[diddlyv]

the grease does not go between the receiver and barrel extension, it only goes on the treads and should never contact anything but those threads and the barrel nut. The blue loctite goes on the barrel extension and helps fill any slack between the barrel extension and the receiver. It is not applied to go between the shoulder of the barrel extension and the front of the receiver, that is what the lapping was all about

[rabiddawg]

Should the blue loctite be green instead? For cylindrical sleeve mating of loose tolerances?

And also, do you decrease it and then put the loctite in? Because decreasing seems like it would be difficult due to the use of grease on the bbl nut?

Did s sneaky write this?

[BluntForceTrauma]

Sweet. Good job troubleshooting and now have some fun!

[biodsl]

Always lap!!!

What media should be used?

[The Profit Joseph Sith]

Glad you sorted out your issues. Also nice that you provided empirical evidence that lapping the upper to the barrel extension can and does (often) provide benefits.

Happy shooting!

Seconded.. Thanks for posting.
I would use valve grinding compound because I already have some. The clover compound on Amazon comes in many different grit sizes. I'd reccomend NOT using TO fine of a grit you want some texture there for the "glue" to stick to. Maybe I'm wrong but typically you want surface texture. Something between 180-320 grit I'd think would be best.
But like a previous poster noted most of the bedding is between the stub and receiver. The I.D. and O.D. not around the extension collar and face if the receiver..

[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.