is the barrel the biggest factor in accuracy when it comes to building an upper? take two uppers for example built exactly the same way by two well known manufacturers, with all the musts like staked gas key and everything else. the only difference between them is one has a better quality barrel. will the one with the better barrel be more accurate if all else is the same.
what exactly can make things different between two uppers from two different manufacturers? im sure on does not have some form of hidden knowledge that allows them to build a better upper, maybe more experience than the other, but other than that if they are both using quality mil spec parts than they will both be the same? even if one discloses what type/brand of barrel they have and the other does not?
With all other things equal then yes, but obviously if you have a great barrel but something else is massively wrong then you won’t be getting sub moa groups.
Barrels are black magic.
Two identical barrels, made from the same steel, on the same machines, with the same heat treatment, will give different performance. One might prefer a different bullet weight or velocity than the other and produce different groups with different ammo.
Mechanical precision is a result of consistency. Barrel, action, and ammo are the key points. A great barrel won’t live up to its ability if you feed it garbage ammo. A mediocre barrel will generally be decent with good ammo.
It comes down to a cost benefit analysis. Great barrels are expensive, and the ones oriented to precision do not have long lives. Good “duty” barrels are more modest in cost and will generally last much longer. If you demand the highest levels of precision you will need to buy a great barrel and expensive ammo. For workable precision (1 to 2 MOA), you can go with a reasonable barrel and use expensive ammo when you need/want it and use bulk blaster ammo for sub-200 stuff without burning your barrel out as would happen by using an expensive barrel and bulk ammo.
Improper barrel nut torque, bad feed angle, excessive headspace, bad muzzle device, contact between HG and barrel, and bad barrel extension mounting can all adversely affect precision.
Spot on. My shooting buddies and I have several of the same guns and they all shoot a little different. This is not the result of the shooter, because we all trade guns (even if they are the same) and will give them a shot. Granted they are all close to each other, but they are all a little different.
Aren’t the headspace and barrel extension mounting all set by the factory? I don’t know of too many “home gunsmiths” that set barrel extensions to a barrel…
Your question seems kind of odd, you ask if barrels are the biggest factor in accuracy. Then in the body of your paragraph you ask if a “better barrel will shoot better if you remove all other variables.” Well of course it will, but that is a different question… basically- does a barrel affect accuracy, the answer is yes.
But what is the biggest factor on accuracy? I’m not a big group shooter, and if I can consitantly hit a IPSC at 300 I’m feeling good about myself. So take what I say with a grain of salt.
I have found that the biggest fator controlling accuracy (after the trigger nut) is ammo. I have taken XM193 vs match grade ammo and, with a chrome lined standard steel barrel, went from a little over 4 MOA to under 2 MOA (5x5 shot groups @ 100 yards.) I have done a similar test with a quality match type gun and went from a little under 4 MOA to a little under 1 MOA (which is my best shooting ever.) So we might surmise that a different gun (barrel) can squeeze an extra MOA out of quality ammo (with ALL the accuracy inproving do-dads,) while different ammo squeezes several MOA out of the same gun.
Based on my limited experience in trying to get good groups- I think the most important things that affect accuracy are…
the shooter
tha ammo
if the barrel is free floated
the trigger
the quality of the barrel
the quality of the sighting system (assuming you can see the target with all of them)
The conditions are a factor as well, but their importance will vary with how much they vary.
Usually, but it’s still part of the ‘what could go wrong?’ equation either way. That part of the build may be out of the end assembler’s direct control, but it is still going to be a factor. Company X may have tighter and more consistent tolerances than Company Y, and that may well show in in price and/or reputation.
Headspace isn’t necessarily set at the factory, as it’s based off of the chamber and bolt face, so someone could stick in a used bolt and wind up with excessive headspace.
And yes, the barrel extension is set at the factory, but if it’s dicked up, or if the user dicks with it, it will degrade the performance of a barrel even if it’s a really good barrel. Not something that is common, just trying to be inclusive in the list of things that aren’t as “plug and play” as some think.
Also, the barrel extension mating with the upper receiver plays a part. A loose fit or a sloped or damaged thread face can degrade precision.
thats another thing i was getting at. is it all plug and play? if both A and B manufacturers do things rights with quality parts then both uppers should be about equal and both good enough to be ran hard so to say? i dont quite know how to word it without saying manufacturer names so that it does sway someones opinion.
Chamber concentricity.
Chamber dimensions especially in the neck diameter and throat/leade length.
Barrel condition.
(Inner)Surface roughness.
Amount of copper fouling and carbon burnishing.
Profile and type of rifling affects how much bullet jacket is deformed
Bore Diameter variances down the length of the barrel, especially at the muzzle. The outer profile and stress relive heat treatments affect the spring back after the rifling button is pulled.
Condition and type of crown affects the release of the bullet.
Individual manufacturer is pretty much the only way to be able to predict performance, or at least that they are doing what they are supposed to be doing.
Right, and I understand wanting to be inclusive for your list, but where I was coming from was that if you’re buying quality components to begin with, as you should anyway, then it really is just plug and play. IMO, at that point, it’s more in the “nuances” and proper procedure for installing a barrel if you’re expecting to be able to assemble and obtain precision.
For example, if I go buy a Noveske 16" SS Recon barrel and “plug” it into a Vltor MUR upper receiver, then it should be reasonable to assume that all parts are within spec and tolerances aren’t being flirted with.
The AR is inherently a very accurate rifle. The two items that have the most affect the mechanical accuracy of the AR are the ammo and the barrel.
Free floating the handguards removes variables that can cause shifts in the POI. Standard handguards can push the barrel in one direction or another and also interfere with the natural harmonics of the barrel. Shifts in POI are not good Changing the harmonics of the barrel could be good or bad.
A mediocre barrel with good ammo is better than a good barrel with mediocre ammo. A good barrel with good ammo is best.
A free float handguard is always good for AR accuracy
Trigger has no affect on mechanical accuracy. The trigger can either help or hinder the shooter in making a precise shot. The same is true with sights
In practicality, yes, you are right.
Some folks do some stuff to gain more consistency, and some places do stuff that hurts consistency, either through ignorance or cost cutting. I’m not saying that you are wrong, just pointing out stuff with the compnonents that can degrade or enhance precision other than the barrel itself.
Understood. I think we’re both on the same page. My main point really is just to buy quality regardless of who is putting it together, and chances are you’ll come out with the results that you’re after.