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Dumb question: Does an AR lower really affect accuracy?

Slateman

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Minuteman
Dec 12, 2013
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Do they really matter? Besides being out of spec, is there any accuracy advantage in building an AR with an expensive lower vs. something milspec and relatively cheap (i.e. Anderson or PSA)?
 
Trigger has more to do with accuracy then the lower. If you need proof though build the most expensive lower you can find into a 17 Remington, bring it up here and let’s have a shootoff. winner gets both rifles.
 
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Lock time on AR are much longer than bolt action so a really good trigger and trigger control is crucial for accuracy but that the only part the lower has to do with it. Spent money on a well built upper and a trigger but the lower receiver itself can be average.
Cheers
 
don’t wait for funds. Just buy what you can afford and start building/shooting. Barrel & trigger are the main things to concentrate on.
 
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In the process of building so interested in this
 
IMO not much. Loose or tight don't seem to matter much besides the fact you like them tight and not rattling around.
But I'm not going to say never either, but to me if the trigger, hammer , spring, and fit of these parts are the same, no.

The barrel & scope/sight is one, so it comes to hammer, trigger and speed of hammer fall and trigger creep, pull etc.
 
As long as the lower is in spec and all the measurements are correct. The main thing a higher quality lower does is reduce play and hopefully make the cycle of operations smoother. Which in turn can lead to more accuracy. Less friction on the system. Probably wont make a whole lot of difference, but it feels smooth.
 
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I think that the Lower fit is largely cosmetic, as long as there's no binding going on. IMHO, the crucial factor in Upper/Lower fit is about slop in the mounting pins. As long as the features that depend on the lower (particularly that pin fit, and a good trigger) work, the accuracy comes out of the Upper, IMHO.

Greg
 
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Until evidence is provided to the contrary, I agree with MSTN. Of course it matters.

On many bolt action rifles, torque values on the action screw have a noticeable affect on accuracy... torque values... in that case, the gun has no slip whatsoever, and even the amount of tension (with zero slop) affects accuracy. Thus, backing the screw all the way out until there is actual movement would affect accuracy even more.

This is exacerbated further by different shooting positions. A loaded bipod on an AR can result in the rear of the upper receiver raising up, while offhand shooting sees the rear of the upper seated against the lower. Vastly different harmonics of the upper upon firing.

NOBODY in their right mind would accept a chassis that allowed their bolt gun to wiggle...

That’s what we ALL do when using standard AR configurations...
 
But is there any reason an injected molded composite lower (think Glock) wouldnt be just as good as a machined aluminum alloy lower??
 
When you are polishing turds, how do you tell which one is the shiniest?
 
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Easy enough to test. Put your wiz- bang high dollar proven upper on a buddy’s POS low budget lower...hopefully with a decent trigger.
 
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But is there any reason an injected molded composite lower (think Glock) wouldnt be just as good as a machined aluminum alloy lower??
Not necessarily but I get your point. However, considering it from an engineering standpoint, material density, mass, natural frequencies and other properties of the materials can affect the outcome. The physical properties may be significantly different between aluminum and composite, depending on the composite used. For instance when comparing aluminum, 7075 billet and forged lowers are the same material but have different natural frequencies and other properties and will produce different results. More importantly it is the mechanical resonance of the "system" that has more affect than a single component, so it must be analyzed more as a system. If I were to replace a forged lower on my rifle with a billet lower, both being good quality material, the differences would only be noticeable in a laboratory type environment, not in a practical sense. With all that said, does it matter in our use? Not really. I think we adapt and adjust accordingly to the firearm we are using at the time. I know my rifles are more accurate then I am capable of achieving so for me I just purchase from quality manufacturers. Of course I am speaking in generalities in this post because there are just too many variables to be definitive.
 
In reading a lot about this it seems like a lot of controversial things can impact accuracy in AR's. Not surprising given all that can impact accuracy in a bolt gun (action screw torque, bedding quality, etc.) Probably partly controversial by the very nature most people can't shoot them as well as bolt action guns due to the mechanics. That said if you read lots on what the guys do that build competition uppers, and the AMU etc. you frequently hear them talk about the same things like bedding the barrel extension, facing the upper receiver, either hand picking upper/lower combos so they are super right, or bedding them, hand fitting gas tube alignment, not pinning gas blocks, using a heavier upper than mil-spec, using a super rigid handguard, ensuring front to back bolt play tighter than spec, etc.

Ask a precision rifle shooter to loosen his trigger guard or trigger screws, or action screws and shoot groups and they'll look at you like you are crazy, to me this isn't that different.

Some might say those things are useless, but at the end of the day I've always been in the camp that if they don't hurt anything, there's no penalty to trying them aside the time it takes, and if they help even a little bit it's worth it. When it comes to precision having things loose is almost always worse than having things tight.
 
What is this, Gas Gun Benchrest Central? You want reliable, dependable operation or something you shoot itty bitty groups under controlled conditions and then wipe it down with a diaper?
 
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From an engineering perspective it "can" which then begs the question of "does it" and that would usually be weapon specific because as many have stated that "accuracy" is a culmination, not a single entity.

People here have already identified the obvious things so I'll offer one that isn't so obvious and I see it in industrial machines.

Metals (like anything else) have properties and various ingredients to bring out certain characteristics. ( different alloying metals, forging over pouring etc.)

So it is possible that you could find a lower that although visually indistinguishable can be of an inferior mix and starts flexing or deforming thus affecting everything else.

That would be hard to isolate but I would be careful of really low price lowers because they had to sacrifice somewhere.
Plastic/composite lowers are/were out there to buy, but not very popular because of durability issues.
But they will hold the things that count on a lower-trigger, hammer/spring, so they might work for people that don't use them much, but you still have the flexing that screws with trigger/hammer movement which might become inconsistent.

And for the bolt action comparisons that were made here , there is no comparison, a bolt gun is a totally different animal.
Held in with screws that apply torque, a striker that's contained in the bolt, the ass end also held on with a screw.
Bedding the action is key so the screws do NOT bend anything when tightened up.
An AR barreled action just sits atop a lower, that's it, no pressure applied either. The upper has way more to do with accuracy than worrying about how the lower fit's, worry instead about the trigger/hammer/pull/creep/repeatability.
 
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I have one of those plumb crazy (polymer) lowers. Someone send me a high dollar lower and I’ll do a side by side comparison.. we could talk about this till the cows come home and not get anywhere because both camps are right, to a extent..
 
What is this, Gas Gun Benchrest Central? You want reliable, dependable operation or something you shoot itty bitty groups under controlled conditions and then wipe it down with a diaper?
Good to see you are still around! That 7wsm is another couple barrels in!!
 
Good to see you are still around! That 7wsm is another couple barrels in!!
E-Man!!
Don’t log on much anymore, not that I have anything to offer, but I’ll pm you with a question about another rifle...