Chamber issue on Compass Lake built Aero M5

[PrimoLuvr]

Good morning all.
This will be a bit lengthy. Please be patient as I'm looking for some advice.
I purchased a Compass Lake built Aero M5E1 308 rifle this winter, the rifle was built in 2019. Here is a post about it:

AR10 feeding issue

I recently purchased a 'used' Aero AR10, built by Compass Lake. Looking at the barrel through the borescope leads me to believe the gun was only fired by CLE after assembly. The rifle was built in 2019, 1 of 3 for a single customer. The rifle is a joy to shoot. I've only 82 rounds through...

www.snipershide.com

The seller said that it had at most 10-20 rounds through it. When I bore scoped the barrel there was no carbon fouling and only a little copper build up, and the throat still had reamer marks on the rifling. From this I believe the barrel was only test fired by CLE and not the original owner. What was disappointing though was the reamer was clearly not centered on the bore when the chamber was cut. I could clearly see the freebore section on the upper half of the chamber, the lower half still had the rifling extending all the way to the case mouth. This didn't look good at all but decided to break-in the barrel and start load development, you never know it may just shoot... Unfortunately, and as expected, the rifle has not produced consistent accuracy. I've got a couple loads which showed promise, shooting 1/2 MOA @ 100 with a single 5 shot group, but then opening up to 1.5 MOA on the next.
Not wanting to take the time to go into loads, load development or shooting technique I want to focus on what to do with this rifle. Here are my questions:

Is the Aero M5E upper, rifle also has an Aero lower, capable of producing 1/2 MOA (or close to it) with a quality barrel?

Or should I sell this and have a new rifle built on a Seekins, Larue, or some other brand receiver that prevents the handguard from attaching to the barrel nut and allow a thermal fit barrel?

The goal is to engage targets out to 800 yards, accurately. Thanks for taking the time to read and respond...

 

[sinister]

The target does not lie. Yank the barrel, take the loss, get a new barrel done correctly..

Or not -- and accept your downrange performance and results.

Cut-rifled Kriegers are generally much better than mass-produced "Consumer-grade" tubes.

 

[PrimoLuvr]

The target does not lie. Yank the barrel, take the loss, get a new barrel done correctly..

Or not -- and accept your downrange performance and results.

Cut-rifled Kriegers are generally much better than mass-produced "Consumer-grade" tubes.

I definitely am not accepting the results so far. The barrel on this gun now is a 10 twist Krieger, which is why the chambering job was so disappointing... If I keep this rifle it'll get another Krieger or a Bartlein, probably a little slower twist.

 

[powdahound76]

So, it has a CLE chambered Krieger barrel?

Have you contacted CLE?

Seems like the best place to start.

 

[MarshallDodge]

So, it has a CLE chambered Krieger barrel?

Have you contacted CLE?

Seems like the best place to start.

Agreed. Call CLE and give them a chance to fix it.

 

[PrimoLuvr]

I kinda thought the same thing. But, the rifle was built in 2019, I'm the 2nd owner, and they don't do retail work any longer. I don't think they'll touch it.

 

[smoothy8500]

I've got a couple loads which showed promise, shooting 1/2 MOA @ 100 with a single 5 shot group, but then opening up to 1.5 MOA on the next.
Not wanting to take the time to go into loads, load development or shooting technique......

Not saying it's the issue here, but a large frame 308 AR is a little bit harder to drive accurately/consistently and is more dependent on shooting technique.

 

[BCP]

I could clearly see the freebore section on the upper half of the chamber, the lower half still had the rifling extending all the way to the case mouth.

A gunsmith might be able to fix that with a finish reamer w/o screwing up headspace

It could also be shooter technique, i've a hard time believing it would shoot a really good group and then go wonky, then shoot another good group

And of course call compass lake and see what they say (probably piss off but maybe you'll get lucky)

 

[Ex E6]

Either live with it or get a quality barrel ,everybody's got an opinion on best barrel producers ,so you don't need mine .

Fyi : I've got a Ballistics barrel and it's .320" MOA in 6.5 CM ,so sometimes one gets lucky . As I recently stacked #20 hunting loads into .404" at 278 Yd. .

 

[PrimoLuvr]

Thanks for the replies guys.
Re-reaming the chamber centered on the bore will cause other issues IMO. It'll make the chamber at the shoulder, neck, etc oblong.
I'm confident in my shooting ability, nothing during dry fire indicates an issue. The all too often errant shots just aren't on call...
I re-formatted the initial post so my questions were separated. If you all could dive into those it would be appreciated. Here they are below:

Is the Aero M5E upper, rifle also has an Aero lower, capable of producing 1/2 MOA (or close to it) with a quality barrel?

Or should I sell this and have a new rifle built on a Seekins, Larue, or some other brand receiver that prevents the handguard from attaching to the barrel nut and allow a thermal fit barrel?

 

[smoothy8500]

Is the Aero M5E upper, rifle also has an Aero lower, capable of producing 1/2 MOA (or close to it) with a quality barrel?

Yes.

10 rounds at 200yd, 1-1/2" group
Criterion midweight 308 20" barrel Aero upper/lower

 

[powdahound76]

Again.

Call CLE first

Anything else before this is just silliness


Then, if no good answer from CLE, see about reaching out to other smiths known for AR barrel work about fixing it vs ditching what is likely an $800-900 barrel.
They can answer your questions and guide you.

 

[nn8734]

I've got a couple loads which showed promise, shooting 1/2 MOA @ 100 with a single 5 shot group, but then opening up to 1.5 MOA on the next.

Lol, you are the lead suspect in the variability in your shot groups, not anything else. I get the same variability with my KAC Mk11 Mod 0 with some groups .5-.75 MOA and others looking like they were shot with a Benelli M4 12 gauge. The cause has been and likely always will be, me.

And this is with my hand load which is a dup of M118 LR in terms of components used, relevant cartridge dimensions and MV.

Whether 1.5 MOA will meet your needs depends on

a) target size, esp at 800m
b) your wind reading abilities
c) your load development skills
d) your ability to drive the rifle consistently correctly

I was once chasing a wandering zero problem with this same rifle and realized after two range sessions, I was the source of that wandering zero (was death-gripping the grip thereby imparting variations in my NPOA which was causing the POI to wander...May or may not apply to you but I'd rule out yourself first before looking at the rifle, barrel, etc (assuming you haven't satisfactorily done this already).

If so, see @powdahound76's post above.

 

[BCP]

Lol, you are the lead suspect in the variability in your shot groups, not anything else.

Whenever I have a troublesome rifle I put it in a lead sled and use factory ammo like varmint loads federal match etc. Sometimes you are fighting a rifle that shoots 1.5MOA on a good day, other times you have a rifle that shoots great and are just fucking things up.

 

[Cascade Hemi]

Post pictures of the inside of the barrel.

 

[PrimoLuvr]

Post pictures of the inside of the barrel.

Top pic is top of barrel, bottom is bottom. I've put 461 rounds through this barrel.

 

[nn8734]

Whenever I have a troublesome rifle I put it in a lead sled and use factory ammo like varmint loads federal match etc. Sometimes you are fighting a rifle that shoots 1.5MOA on a good day, other times you have a rifle that shoots great and are just fucking things up.

I'm planning on building a test fixture, similar to the ones the USMC PWS as well as others use to actually T/E loads - takes me completely out of the equation and can see each iteration's raw, unadulterated performance.

IMHO, that's the way all loads should actually be tested for precision potential, effectiveness, etc...SD/ES can be collected at that time as well..

 

[stanley_white]

What is the size of the best group you have ever shot?

-Stan

 

[PrimoLuvr]

I'm planning on building a test fixture, similar to the ones the USMC and PWS as well as others use to actually T/E loads - takes me completely out of the equation and can see each iteration's raw, unadulterated performance.

IMHO, that's the way all loads should actually be tested for precision potential, effectiveness, etc...SD/ES can be collected at that time as well..

I used to use a Ransom Rest to test my handguns and loads for bullseye competition and agree with that in principle. But, after I was able to start calling shots it was easy to tell when it was me or the gun/load... that's the case with this rifle, I'm on call.

 

[PrimoLuvr]

What is the size of the best group you have ever shot?

-Stan

Great question. In this rifle the best 3 shot during load development was in the .2s, best 5 shot was in the .5s. But that same load would also open up to 1.5" or more.