concensus on ar donts

[Bezoar]

ive been seeing every where online lists of things not to do with an ar, particularly if it has a NON FREE FLOAT tube.

1. do not hold it in anyway by the barrel assembly - youll bend it
2. do not lay the fore arm down on a rest/sandbag/etc or youll bend the barrel assembly and lose accuracy
3. do not put ANY attachment on the bayonet mount like a bipod.

issues with this common knowledge

1. thats how every manual i see says you hold it. its how i saw it shot by everyone else in the army.

2. every article i see in a gun rag always has this rule be violated when the article writing person tests for accuracy

3. its where i see alot of bipods being used. especially in competition circles on the net. if the professional shooter has no issue with a bayonet lug mounted bipod, why is it faux paus for ME?

come on, Kel Tec made the Su 16 with a bipod that clamps to the barrel. that hasnt hurt accuracy.

 

[Jackal]

POI shifts are caused by putting differing pressure on the barrel. Those poi changes are usually what affect the accuracy. If you shoot the weapon in exactly the same manner everytime, its fine. If not, then your poi will shift around causing groups to open up. Free float tubes are very over touted for improving accuracy, usually only netting a meager half moa increase in accuracy, using match ammo in my experiences. They are more for attachment points/long sight radius (with a 15" tube).

 

[taliv]

1. do not hold it in anyway by the barrel assembly - youll bend it
2. do not lay the fore arm down on a rest/sandbag/etc or youll bend the barrel assembly and lose accuracy
3. do not put ANY attachment on the bayonet mount like a bipod.

i don't know where you got that, but it seems likely taken out of context.

I would say, DO NOT hold the AR by the barrel assembly because you will burn yourself. It gets really hot.

You won't 'bend' the forearm by laying it on something. It's a forearm. it was designed to be held! However, touching the barrel with something will change it's harmonics a bit and will have a small affect on the POI, so if you are shooting 3gun or on a battlefield, don't worry about it. If you are shooting benchrest, then yeah, don't let anything touch the barrel.

The bayo lug isn't a great place to run a bipod. GENERALLY speaking, if you are using a bipod, it is because you need very fine accuracy, and as the bayo lug is attached to the barrel, touching it changes the harmonics of the barrel resulting in an unpredictable POI.
If you need a reasonable amount of accuracy, like hitting a 8" plate at 300-400 yards, the preferred method is to use the 30 rnd magazine as a monopod and leave the bipod at home.

 

[Robert]

especially in competition circles on the net. if the professional shooter has no issue with a bayonet lug mounted bipod, why is it faux paus for ME?

I have never seen a professional competitive shooter do this. Heck I have never seen a shooter at the local match do this. Using a bipod puts you in Open Class and most people do not want to shoot against purpose built race guns.

 

[LocoGringo]

It's not that the barrel will get "bent" so much as inconsistent pressure put on the barrel will change the point of impact and open up any group you may have. I wish I had the link, but there is a video on YouTube where a guy shows the differences in POI doing exactly what you are talking about and the changes are dramatic...like several inches of variation, shooting at 100 yards from resting the rifle on the handguard (even a handguard attached to the barrel rather than a free-floating) versus resting the rifle on the barrel using sandbags. The upward pressure of resting the rifle on the barrel during shooting raised the group several inches, if I remember correctly.

A free-float handguard helps in this regard quite a bit. It allows the barrel to do its thing unhindered and consistently every time, no matter where the rifle is rested or held.

The general rule is that you don't let the barrel touch anything while you are shooting, whatever the model rifle you are shooting. If a bipod is mounted on a bayonet lug, technically, the bipod is putting upward pressure on the barrel because the lug is part of the barrel and the weight of the rifle is resting on the bipod. Unless you've zeroed the rifle that way, your distant shots will be off. If you've zeroed the rifle that way, your shots will be off if you shoot any other way than resting on the bipod. It's a bad idea.

 

[redneck2]

Go to Varmint Al's website and look at the section an barrel harmonics

 

[primalmu]

Free float tubes are very over touted for improving accuracy, usually only netting a meager half moa increase in accuracy, using match ammo in my experiences.

Wait a second... 1/2 MOA increase in accuracy is MEAGER? My Rock River Arms with a non-FF tube shoot under 1 MOA (with cheap Fiocchi VMax ammo) if I do my part. If I can expect a 1/2 MOA improvement by switching to a FF tube, I would hardly call that meager! Now, if you're shooting 2-3 MOA groups, I see your point. But if your rifle is shooting 2-3 MOA groups with match ammo... well, something is wrong, and it ain't the non-FF handguard!

 

[Jackal]

Wait a second... 1/2 MOA increase in accuracy is MEAGER? My Rock River Arms with a non-FF tube shoot under 1 MOA (with cheap Fiocchi VMax ammo) if I do my part. If I can expect a 1/2 MOA improvement by switching to a FF tube, I would hardly call that meager! Now, if you're shooting 2-3 MOA groups, I see your point. But if your rifle is shooting 2-3 MOA groups with match ammo... well, something is wrong, and it ain't the non-FF handguard!

2" groups with a Colt 6720. With the free float, accuracy increased to about 1.5"-1.7", not really worth measuring or the cost for accuracy alone. Not when a simple heavier barrel swap costs about the same as a decent ff tube and could yield sub moa results (which would obviously defeat the purpose of a lightweight rifle in the first place).

 

[12Bravo20]

2. do not lay the fore arm down on a rest/sandbag/etc or youll bend the barrel assembly and lose accuracy

If that's the case then there should be all kinds of bent barrels in military arms rooms. I know I got out in 96 but I don't see the military changing how you shoot during sight in and qualifications. In the Army that is 20 rounds from supported position (sand bags)

Yes different shooting positions/rests can effect POI.

 

[splattergun]

delete

 

[Welding Rod]

Free floated is more about preventing change in POI than improving accuracy. Significant difference.

 

[LocoGringo]

^^^
Wish there was a "like" button. This is the answer stated very simply.

 

[Welding Rod]

I tried shooting two High power matches slung up and using the mag as a monopod and the results were dismal. Way higher scores when getting the mag off the ground.

 

[4thPointOfContact]

Wait a second... 1/2 MOA increase in accuracy is MEAGER? My Rock River Arms with a non-FF tube shoot under 1 MOA (with cheap Fiocchi VMax ammo) if I do my part. If I can expect a 1/2 MOA improvement by switching to a FF tube, I would hardly call that meager!"

It depends on context, if you're sport shooting paper bullseyes on a square range at long distance then .5 MOA can be significant.
If you're shooting a rifle designed for combat, in combat, at combat ranges, against enemy combatants then .5 MOA doesn't mean diddly.
The human torso is roughly 18" wide. Worst case acceptance for an AR to meet military standards is 4MOA with most in the 1.5-2.0 range (last time I heard). At 300 yards that means the worst mil-std M16-series rifle should have a 12-inch group and more likely 6-inches. Tightening that by another .5 MOA wouldn't achieve anything.
2.0 MOA is plenty to put the opposing team hors de combat.

 

[MistWolf]

A free float tube can help with combat accuracy as well. One guy related, while using a VFG on a non free float handguard, he was able to shift POI 4 inches at 50 yards when the adrenalin kicked in during a firefight.

The free float tube also keeps the POI from shifting when resting the rifle on a barricade or other makeshift rest.

I wouldn't want a bipod mounted to a bayonet lug. That will create enough leverage to cause a significant shift in POI. No brainer on that one.

None of this means you have to have a free float tube to make hits with your rifle. Just means that if your resting the forearm on something and your groups become inconsistent, you know what to check first.

The big reliability "DON'TS"

DON'T run cracked, worn or damaged magazines
DON'T use an extractor or extractor springs that are worn or damaged
DON'T shoot junk ammo
DON'T forget the lube

 

[Bezoar]

even if you just look for good varmint accuracy, ive perused to many forums and its the most common thing to see is "this is the sandbag i use as a rest on my back deck railing"
or just skip the sandbag.

better yet just the "dont hold it by the barrel/fore stock if it is a NON FREE FLOAT TUBE" means, "do not hold the ar-15 the way the original us amry/usmc/usaf cartoon manual showed you how" as that is going to create so much pressure on the barrel, that youll pattern like buckshot out of a rifled barrel.

 

[rcmodel]

Any pressure on the barrel from a sling or bi-Pod will change the zero.

It was a proven fact during the Vietnam war that the 'clothespin' bipods that clamped to the barrel under the front sight / gas block caused the barrel to spring enough (Not bend permanently, just flex) to cause major POI changes. (Usually Up & right.)

A tight shooting sling attached to the front swivel does the same. (Usually low & left)


Clothes pin Bi-Pod & case:


Clothes pin bi-pod attached.


They were only useful for keeping your rifle up out of the mud and ready in a foxhole.
But you best take it off if you wanted to hit anything at longer range.

Bottom line is, anything that touches the barrel will adversely affect accuracy.
On any rifle, not just an AR-15.

rc

 

[Bezoar]

then if anything on the barrel will affect accuracy, why does keltec make there semi auto rifle, with a built in bi pod, that pins directly to the barrel? that hasnt seemed to hurt accuracy for anyone..

 

[rcmodel]

Yes, it actually has.

If you go to THEKTOG.ORG and do the reading.

I haven't seen too many claims for Sub-MOA accuracy for the Kel-Tec SU-16 in the first place.
And it gets worse with the barrel mounted bi-pod deployed.

rc

 

[Welding Rod]

then if anything on the barrel will affect accuracy, why does keltec make there semi auto rifle, with a built in bi pod, that pins directly to the barrel? that hasnt seemed to hurt accuracy for anyone..

Any rifle will change POI if you rest the barrel on something. Never do this with ANY gun unless conditions allow for a decided change in POI. I shot a Remington 700 220 Swift with a long floated heavy barrel. I shot it several times with the barrel on a bag rather than on the for end. The POI shifted almost 6 INCHES at 100 yards!!!

By the way I did this because my friend kept shooting all over the place and couldn't figure out why. I noticed he was resting the barrel on a bag. So I tried it with the barrel and then the forend on the bag several times each and show him the result. That severe POI shift even shocked me.

 

[50 Shooter]

On AR's they try to mount bipods on the gas block/front sight post to keep minimal things touching the barrel. That way barrel harmonics are disrupted as little as possible, even the hand guards attach at the same place in the front.

Look at bolt action rifles, good ones have nothing touching the barrel, stock is kept close but there's always a gap and the sling and bipod are attached to the underside of the stock.

 

[Davek1977]

What Kel-tec does, and what produces the best accuracy, are hardly one and the same. How many people are shooting precision matches with kel-tecs? They aren't known as the most accurate of firearms, so emulating them, and hoping for excellent accuracy, seems to be a strange course of action for someone to ponder taking.

 

[Tirod]

Military spec accuracy from a new weapon accepted from shipment from the manufacturer is 2MOA, which is a 10" group at 500m. From there, a used service rifle is considered good enough up to 6MOA before replacement of the barrel. That is a 30" group.

How bad is that? Horrible in competition. In combat, the reality is that soldiers rarely take aimed shots past 125m because the target is doing everything it can to use cover and concealment. Opposing forces do not slowly walk around upright and stand waiting for you to take a shot. 6MOA at 125m is just over a 6.25" group on a 18" center of mass target. Still plenty good enough.

Therefore the design intent was not to worry about square range accuracy for paper punching, and a shift in the point of aim isn't a problem. It's EFFECTIVE accuracy for military combat purposes.

A soldier cannot shoot, move, and communicate slung up Olympic style in combat traversing rough terrain or in a foxhole. And gravity resting on a sandbag alone doesn't affect the natural dispersion of a 2MOA gun enough to make a difference.

If someone has noted a 4" shift in the point of aim, fine, that is 4" over for a small group on a 18" COM target, and a hit outside of that is still a hit that can reduce the combat effectiveness of that soldier.

There's no problem - shooter skill under stress is much more an issue, and again, lets not forget the target is doing anything and everything they can - including shooting back. Which means we've completely ignored the issue of having to duck for cover and only getting a few seconds to return fire.

Try this some time - set up in the prone with a paint ball gun and try to hit someone at 25 yards shooting back at you.

Discussing target range issues for a combat rifle is using the wrong frame of reference and where a lot of mistakes in understanding occur. Target range performance is like autocross or drag racing, you against the clock in an abstract contest of measurement. Combat is a demolition derby. Completely different rules.

 

[Sam1911]

Bezoar, you seem to be missing a sense of scale in your thinking about this.

Yes, putting any pressure on a barrel will change the way if vibrates, which will change the point of impact and group size (both). Each rifle is different and how much the effect matters to the shooter will depend on the situation.

If you're a benchrest groups shooter, or a varmint shooter, or a long-range precision shooter it matters a WHOLE LOT. Use free-floated barrels, don't ever clamp anything to the barrel, and don't rest the barrel on anything. That's what the fore-stock of the rifle is for.

If you're using a military M-16/M-4, or a civilian copy of one, the rifle's handguards and sling swivel are hung on the barrel itself and pressure against the barrel is expected. That's how it is designed and the overall accuracy of the weapon is expected to exhibit the variations caused by using it that way.

If you're an Army or Marine infantryman the difference isn't significant for the conditions you're shooting under and the size of targets you're shooting at.

If you're a CMP/HiPower shooter, you practice doing everything EXACTLY the same way from shot to shot, so the pressure the sling is putting on the barrel is EXACTLY the same each time and your sights are adjusted to compensate.

I don't know why you keep bringing up KelTec, exactly, but a KelTec is just a utility rifle like a basic M-4 carbine or a Mini-14 and isn't ever expected to produce amazing accuracy. Decent accuracy, sure, but no one buys a KelTec and then complains that they couldn't hit a groundhog at 400 yds. with it off the bipod. Or that they didn't clean the 1,000 yd. match rifle course with it.

You don't buy a Ford Focus and then complain that you just can't break 12 sec. on the quarter mile. It isn't built for that.

Use your match grade free-floated rifle and rest the barrel on something or clamp a bipod on it and you might as well be trying to run your Mustang down the drag strip with a stack of cement in the back seat, or pulling your bass boat. You're hurting what it is capable of doing.

 

[Bezoar]

maybe i should avoid the bushmaster website, to many "no no" going on in their photos and videos.

everything points to the ar family as being decent shooters, but is that only if i spend 1200 on one?