AR lapping/bedding test thread.

[jelenko]

Correct, this is just parts slapped together. No lap no bed.


55 grain sierra match king.

But, Sierra doesn't make a 55 match king - are they blitz kings?
No big deal, just wondering given the group.

 

[Mastershot]

Going to lap and bed my 6mm fat rat this week. She is on the bench right now waiting for this to be done.

 

[LVLAaron]

But, Sierra doesn't make a 55 match king - are they blitz kings?
No big deal, just wondering given the group.

You're right. They're 52 grain. I wrote 55 on the bag years ago when I loaded these.

 

[LVLAaron]

 

[jelenko]

I'm watching this with interest.

Is that all you're going to lap the face? I've been thinking [and doing] that ~ 80+ % of the face should have the anodizing at least being to show wear.

 

[LVLAaron]

I lap it almost all the way bare. That photo was just to illustrate what’s going on.

 

[Ledd Slinger]

View attachment 1554346

Yeah she’s shouldering up a little crooked for sure

 

[LVLAaron]

This one really wasn't that bad. I had one before that, after straightening, moved the bullet impact 6 MOA to the right.

 

[Hal]

Any pictures of the lapping,straightens bedding process?

Hal

 

[LVLAaron]

My hands were dirty so I didn't want to get my phone out for pictures... but I use a tool like below with some compound on it. I've cleaned up the lapping face on the lathe a couple times, because it wears.


The bedding part = coat the tenon in loctite or JB and jam it in and lock it down.

 

[VA_XTC_Shooter]

My hands were dirty so I didn't want to get my phone out for pictures... but I use a tool like below with some compound on it. I've cleaned up the lapping face on the lathe a couple times, because it wears.


The bedding part = coat the tenon in loctite or JB and jam it in and lock it down.

Why not just face the upper in the lathe? I have the Midwest URR, I chuck it in the 4 jaw and dial it in. Then slide the upper on and go.

 

[LVLAaron]

I already have the lapping tool and it works fine.

What secures the upper onto that URR mandrel?

 

[Mastershot]

Going to lap and bed my 6mm fat rat this week. She is on the bench right now waiting for this to be done.

Got mine done yesterday. Bedding was red locktight, I missed that pictures of the lapping and red locktight.

 

[Bat Rastard]

My hands were dirty so I didn't want to get my phone out for pictures... but I use a tool like below with some compound on it. I've cleaned up the lapping face on the lathe a couple times, because it wears.


The bedding part = coat the tenon in loctite or JB and jam it in and lock it down.







View attachment 1554826

Bedding with loc-tite, will it be removable?

 

[Rocketvapor]

Bedding with JB?

 

[jelenko]

Bedding with loc-tite, will it be removable?

With red, it's going to take heat.
The bedding works just as well with a low/medium strength product. Still requires some but not as much heat to disassemble.
Henckel does make a sleeve retaining product - I haven't tried it.

I think the key is simply to bed the extension to the upper to keep it from wiggling. The barrel nut does all the retaining that's needed.

 

[LVLAaron]

I'm gonna be "that guy" that says to always refer to loctite by it's number, and not it's color. There are several of each color, and they're different! There are probably 6 different "green" loctite products.


@Rocketvapor - Yeah, If I know I have a good barrel, I'll just glue it in. It's permanent, but uppers are cheap and 223 barrels last forever.

 

[VA_XTC_Shooter]

I already have the lapping tool and it works fine.

What secures the upper onto that URR mandrel?

Obviously, I can't guarantee for every upper, but mine slid on and the raised fin held it in place. Very light cuts, I didn't see any movement whatsoever and the receiver came out square. Checked with machinist square and surface plate afterwards, could no longer see any light.

I did it more out of curiosity and was surprised.

With that said, just clamp it. The receiver will tighten down around the mandrel.

 

[Twdmar]

With red, it's going to take heat.
The bedding works just as well with a low/medium strength product. Still requires some but not as much heat to disassemble.
Henckel does make a sleeve retaining product - I haven't tried it.

I think the key is simply to bed the extension to the upper to keep it from wiggling. The barrel nut does all the retaining that's needed.

One of the illinois highpower guys says he whacks them out with a dowel and hammer through the receiver and he says it works with all the different loctites.

 

[Mastershot]

I have always used red loctite on my AR barrels, getting the barrel off takes a little work with a heat gun.