AR10 BS Thread

Greetings everyone.

I went to complete my lower yesterday, and got messed up. I got a rifle buffer kit, but carbine stock. I love the stock and want to use it. Question is, will a carbine buffer kit work on a AR10 with a 20 inch barrel? Please let me know.

Thanks.

 

Aero is 100% officially dead to me

 

Id like to try and fix it...

 

I'm for sure ordering a new barrel PA has barrel sale this weekend can get a criterion barrel for sub $300 and new bolt. That should resolve safety concerns along with reliability issues and give me a more accurate barrel. Wasn't super thrilled with 1.5-2 moa with 168gr Gold medal match out of the Aero anyway

I'm debating how petty I want to be. Considering spending money to have a good smith look it over and build a case too send a giant F you back to Aero

 

New barrel and headspaced bolt ordered

 

Barrel should ship today and be here next week.
Decided I'm going to take both to a good smith to install new barrel and perform inspection/measure the original aero/BA chamber and headspace just because and if indeed out of spec or imperfections gives me something to fight aero on.

 

Keep us posted

 

i wouldn’t necessarily consider it a scam. But then again I’ve never seen a barrel the “requires” a matching bolt. I’m sure they are out there though. The main benefit I saw with mine, and also my gunsmith/custom rifle builder, was with the Wilson Combat matched bolt/barrel: the lockup was very crisp and there’s no slop like you get without a matched bolt. It’s definitely not a necessity and I’ve spent many years using a hodgepodge of ar-15/ar-10’s without matched bolt/barrels and been fine. They were plenty accurate as is.

 

What is "slop"?

Also what is the process for "matching" an ar bolt to a barrel? Because they are reamed before the extension is installed.

And what would make an "unmatched" (?) Bolt sloppy?

I'm envisioning someone standing at a table with a box of bolts and agauge........? Or are they shorting all their chambers then screwing on extension based on some special bolts?

I truely would like to know what they do differently.

 

Quoting so I don’t miss anything.
What makes slop. Basically, think of legos, literally all of them from years past to a Lego now fits together. They are able to do so because there is a minimal amount of error or space built into the fitment pieces. If you take a standard Aero barrel and a criterion bolt, they fit together, but when you rotate the bolt into the barrel with a fired round or snap cap- there is a very slight amount of wiggle because by design, they should all work together. With a bolt that is specifically machine to match the barrel, it is as you say they are taking the very minimum off the face until it will lock up on a round. There is no wiggle on lockup.

Does this truly matter- it depends. At 1-700 yards, no. At 1000?- maybe. Beyond that- maybe.

I have shot my precision ar10 side by side with my buddies “thrown together” ar10 in 6.5cm. Mine was more accurate at 600 yards on a steel goat. I was able to take headshots and keep most rounds within a 5” circle. Some of that is me being a behind a lot of long guns for work. My buddies rounds were a 9” circle using the same ammo. I think he has a palmetto barrel and a random BCG.

For me, the 4” difference in impact at that range was worth the extra cash. But it was probably a $400 cost difference.

 

So a "matched" bolt means they match lugs. Got it. I thought it meant they"matched" for headspace.

I would need to see some sort of proof that one specific barrel and one specific bolt went through the entire reaming/extension machining-install procedure before i paid someone $400. Basically a blueprinted AR....

In my luddite mind which has 30+years of AR assembling experience, if the chamber is correct, i could care less about what was done to the bolt lugs. They wear anyway. I know some guys that lap lugs so wear is more evenly spread.... But that juice aint worth the squeeze to me in the AR platform.

I just think sometimes the internet goes a little bonkers with the fiddly stuff without really delving too deep into the physical-mechanical rationale.

 

Yeah, it’s very similar to lapping lugs on a bolt gun. I did get a chamber specs sheet with my Wilson barrel/bolt combo. I sprang for it mainly because I know that area is where accuracy is truly effected in an AR platform (and it was the color I wanted and a fast twist) Everything else can be sloppy as hell. I’ve used m16’s that were “shot out” and still made accurate 400-500 meter shots just to prove a point to students. But yes, a lot of overthought on the subject.

 

Anything mechanical or related to internal ballistics will show up at a 100y in proportion to range. If gun is half moa at 100y, that is 5 inches at 1000. If your target is 10 inches at 1000, and your gun is .5 moa, and you are a perfect shooter (lol) then your hit probability would be 50% in a perfect world.

Slop may or may not effect harmonics, when talking build to build.


That said, if you’re not in the mood to take the gamble, I would agree, matched bolt and barrel and proper alignment is the way to go including tuned barrel torque and a few other things.

 

Has anyone looked at how an AR (Armalite Rifle) platform actually works? From back to front you have the Carrier which is machined to a specific tolerance, this is the part that allows the bolt to rotate into firing position and conceptually hit a positive stop via the cross pin which is also machined to a particular tolerance. The bolt itself is machined to a specific tolerance so that when it is in it's forward locked position the bolt face is XYZ 0.000" from the shoulder of the chamber (the shoulder is where headspace comes from). The barrel itself is head spaced off of that dimension. The barrel extension is screwed onto the barrel to achieve the desired head space AND line up the gas port at 000*. Then we add the variables of barrel nut torque and set back. So when you put it all together there is "tolerance" built into the system to allow for dirty ammo, water, dust et al to be introduced and still work. OBTW the direct impingement system "Sh!t's where it eats" adding more garbage to the mix. The concept of a "matched bolt" is on its face silly as a "matched bolt" will have the tolerance of all the associated parts built into it. Otherwise if the tolerances stack not in your favor you will crush the shoulder and the gun will cease to function. To have any meaningful improvement in barrel accuracy (other than the barrel itself) you should concentrate on the mating surface between the upper and the barrel extension. Brownells sells an upper face truing tool. It refaces your mating surfaces to provide full contact so that you have ZERO tolerance between the two. After that it's down to your barrel, you and your ammo.

Cheers,

Doc

 

Doc, great point! That’s something I also did not remember. My rifle had the face trued as you suggested, my friends does not. I also know that it took some work to fit my barrel to upper, as it was pretty close tolerance.

I’ll check in with my buddy, but I remember him saying it wasn’t a tight fit and he used a glass/epoxy compound of sorts to take up the extra space when he torqued the barrel nut on. Great points all around, and nice to be able to have a civil discussion on the topic. It’s not the case on other forums.
If anyone is in Oregon, let’s organize a shoot of sorts. I should be getting my hunting rig back in the next couple weeks, so I’m tracking down 30 Nosler ammo as we speak.

 

Some uppers like an Aero enhanced upper I don’t see how that can be done. The barrel nut actually goes inside. The one I did assemble the barrel was, to me, a snug fit but required no heat.
Civil discussions are always nicer and folks like me actually read and pay attention. I much prefer a discussion like that to listening to some one bad mouth the equipment others may choose talking down to them. It is what I initially very much enjoyed about this thread as I don’t participate much on the truck threads anymore due to an elitist attitude given by many

Edit: ok I thought this was the AR15 thread but the statement is the same.

 

I humbly beg to differ about it being ridiculous.

While I’m sure the rest of the forum is assuming production type “matched,”
I’m talking literally krieger typed matched.

While I understand that is fairly easy to lap and you should get a lot of this with reliable manufactures, we are looking to keep headspace is at a minimum and for even & complete lug contact.

It can also provide less slop in lug clearance.

I mean, people will spend serious money on blue printing, bedding, etc a bolt gun, I don’t see how it’s anymore ridiculous to tighten up a gas gun… or more so than it is to choose a gas gun over a bolt gun for this intended accuracy.

 

I surprisingly have more cash in my AR10 than my custom built Model 70 bolt gun in 30 Nosler. But you are correct. My Wilson combat “matched” bolt to barrel is probably better than the set you get from Faxon. And in the ar10 case, the BSF or proof set is probably better than my Wilson.

 

I again refer you to how the AR platform is intended to operate. The bolt lugs on an AR are not designed to "lock into place" like a bolt gun where you can lap lugs and set head space off the bolt face. The reason the lugs are there are simply to prevent a catastrophic failure of the cartridge getting to the operator. If you have wear on the back side of your bolt lugs in an AR you are dangerously close to catastrophic failure. The bolt lugs on an AR hang in space and don't touch anything at battery. They are simply there to prevent the chamber from opening in the event of an over pressure BEFORE the gas impulse runs down the gas tube and connects to the BCG. Head space on an AR platform is a misnomer in that it is variable. Close from the bolt catch? Close from the charging handle? Close from normal operation? Each one of those events will result in a different chambering and by proxy a different head space. The bolt of an AR "floats" which allows it to absorb variances in cartridge dimensions. If you reload for the AR you must pay particular attention to the case base for "swiping" when you have circumferential rings around the base of the case you are getting dangerously close to maximum pressure because the bolt and BCG are opening before the cartridge case has had time to "snap back" from it's initial expansion to fill the chamber. The quality of your barrel and how the chamber, lead, lands and groves are cut will have exponentially more effect on your accuracy than how the BCG shoves a round into the tube.

Cheers,

Doc