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DaveT

A basic lesson re-learned!

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Could kick myself sometimes!

 

Recently had to do a very quick zero and get drop tables for my AR prior to my first CSR comp.

 

Went to a local farm and used a table to get enough elevation to clear obstacles to target backdrop.

 

Lesson #1.....plan ahead and allow time!

 

To get an accurate zero I used a front rest and settled the handguard on it.

 

Got a great / accurate zero and then 200 yard & 300 yard drops using same setup.

 

Shot the CSR match and noted that most rounds were going low by a good 1 or 2 MOA when prone....put this down to my nerves etc first time out.

 

Tried the AR again today Mag-rested as per the CSR match prone stages ....guess what ......it shoots much lower than when rested via the handguard.....Doooh!

 

Lesson #2 (re-learned beginners stuff....no excuses!) .....always zero with the same setup you intend to shoot with!

 

The added​ 'wrinkle' here is that when NOT mag-resting the rifle in prone (IE sitting , kneeling shots etc) it shoots to the same zero as when I rested it on the handguard.....so I will need to revisit my drops to note what I get regarding differences between prone (mag rested) and positional shooting.

 

All my previous target shooting has been prone with bipod (IE always a consistent setup) ......its too easy to forget changes induced by positional shooting.

 

We live and (hopefully) continue to learn!...That's what makes it interesting.

 

 

 

 

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I've made similar mistakes. One thing I note from zeroing in stalking locations is that on undulating terrain, longer range zeroes are of dubious value as it's very hard to assess if there is any vertical wind component or not. I will check a 100 yd zero in a number of locations, but if I'm shooting further out, all I can really expect to get is a group, nothing more.

 

Regards

 

JCS

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Could kick myself sometimes!

 

Recently had to do a very quick zero and get drop tables for my AR prior to my first CSR comp.

 

Went to a local farm and used a table to get enough elevation to clear obstacles to target backdrop.

 

Lesson #1.....plan ahead and allow time!

 

To get an accurate zero I used a front rest and settled the handguard on it.

 

Got a great / accurate zero and then 200 yard & 300 yard drops using same setup.

 

Shot the CSR match and noted that most rounds were going low by a good 1 or 2 MOA when prone....put this down to my nerves etc first time out.

 

Tried the AR again today Mag-rested as per the CSR match prone stages ....guess what ......it shoots much lower than when rested via the handguard.....Doooh!

 

Lesson #2 (re-learned beginners stuff....no excuses!) .....always zero with the same setup you intend to shoot with!

 

The added​ 'wrinkle' here is that when NOT mag-resting the rifle in prone (IE sitting , kneeling shots etc) it shoots to the same zero as when I rested it on the handguard.....so I will need to revisit my drops to note what I get regarding differences between prone (mag rested) and positional shooting.

 

All my previous target shooting has been prone with bipod (IE always a consistent setup) ......its too easy to forget changes induced by positional shooting.

 

 

 

 

 

 

I rest my case

Always zero from the positions you will shoot in and at the distances you will shoot in those positions from

 

It's always about confidence, Example 400yds sitting

A smart man will take his sighters sitting, no matter how wobbly he may feel.

 

A Ladyboy® will take them prone with a bipod, because he doesn't have the confidence to shoot through the wobble.

 

Same with 100 standing and kneeling

It's standing and kneeling, not shooting of a bipod

 

PS, don't see your Nov entry yet....and we already have 75!!!

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Is this more to do with the structural integrity of the AR platform rather than confirmed zero's? What moves/flexes to induce a moa move between mag rested and bipod?

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Is this more to do with the structural integrity of the AR platform rather than confirmed zero's? What moves/flexes to induce a moa move between mag rested and bipod?

Recoil induced departure angle

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Mark

 

I am in Spain for the Nov match but WILL be there for Dec....when is the first entry date for Dec?

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Recoil induced departure angle

How so?

 

The rounds when mag rested were 1 to 2 moa low, wouldn't recoil tend to produce a higher poi?

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Not sure about the physics but the reality is there.

 

Guess the fore-end rest produces more leverage in recoil so prints higher?

 

All I need to know is that I have two POIs resulting.

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My match gun is perfectly zeroed at 100 yards. Its spot on when shot in any position at that range, but lean against a post or barricade when shooting CQB and it will shoot 2" high. Never got to the bottom of it, but its without doubt, how I hold it in that position.

 

My little CQB gun does exactly the same.

 

They are all female......

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I and another member on here are experts at zeroing in the dark and last minute load development.

 

Pleased it's not just me.

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That was my mistake in not zeroing properly ...I won't repeat it.

 

The gun shoots 'cock-on' when I do things right.

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didn't someone say these guns were ok for foxing? 2moa shift on live quarry.... how can that be acceptable?

 

nice toys though, still lusting after one for some reason! :wub:

Says Gary who's never done anything than shoot prone off a rest....

There's loads of space on 7th Nov, and most of it's prone

 

Perhaps you could pop along and show us all how it's done :lol:

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didn't someone say these guns were ok for foxing? 2moa shift on live quarry.... how can that be acceptable?

 

nice toys though, still lusting after one for some reason! :wub:

I think the principle applies to all rifles. Not just the AR.

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How so?

 

The rounds when mag rested were 1 to 2 moa low, wouldn't recoil tend to produce a higher poi?

 

depends where the barrel is on its harmonic cycle and when the bullet leaves the muzzle compared to the position the recoil leaves it in

same reason a heavier slower bullet shot from a rifle can impact higher at a 100m zero

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depends where the barrel is on its harmonic cycle and when the bullet leaves the muzzle compared to the position the recoil leaves it in

same reason a heavier slower bullet shot from a rifle can impact higher at a 100m zero

 

We are talking same load, same bullet. If that's leaving the barrel at different times due to a change in position and causing a 2 moa move in poi then something is wrong.

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MJR makes a good point.

Barrelvibrations may be somewhat like a tuning fork,and barrel tuners-especially developed on 22rf,which has some dispersal by 100 yards-minimise this-there is much less work with cfs-though Browning's pioneering system had some promise,this has not been followed up...

 

But we can hardly be talking about 2 moa dispersion from this cause-and furthermore,most rifles somehow don't show such effect,or at least such a large effect (it would rather make a sub 1/2 moa group exceptional,no?)

 

Warped stock/bad bedding get a bit nearer,maybe add in flexing bipod under variable loading',and maybe shooting posion pressures could be responsible.....

Effects won't tend to show/ be noticed unless fairly good accuracy/precision is required....better eg than government work....or civilian facsimilies thereof.....fig 11s at 300y eg...

 

gbal

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I think that we are not comparing apples v apples in the above posts commentary.

 

Most positional variants with a std Bolt gun will see the point of rest somewhere near to where a bipod is typically fitted and we all take care not to rest on the barrel or hard surface ....so we expect similar poi's.

 

Sitting an AR on its mag or way down the fore-end seems to me to be very likely to alter the recoil effects and resultant poi........would probably have similar effect on a std bolt but it's unlikely that you would rest same on the mag........for an AR it's done to get elevation to align the eye with the scope as much as for stability.

 

Analysis not much use....the effect s there and I will compensate.

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I found that shooting prone, sitting and standing zero shifts between every position. When I was doing lots of shooting in the past. (SLR those were the days)

Zero prone and I found shots would go low right sitting and Hi left when standing.

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Dave,I accept that barrel harmonics may not be the cause of your POI shift-I was just reinforcing MJRs post-as I understood it-that such vibrations might not be enough anyhow for a 2 moa shift....though I also note in the " different varieties of apples' category perhaps,your correct observation of avoiding bare barrel on support,really seems to be an interference with normal harmonics point...though it also might displace the barrel a tad before the shot is fired.Both probably!

I seem to recall in the early days of 'that dismal rifle' (which a lot of us nonetheless quite fancy!) that resting the GI magazines on the ground was 'discouraged' in military training,on grounds of causing malfunctions,then reversed on the more supported (pun intended) finding that this monopod improved accuracy(and didn't malfunction with decent magazines). Don't understand the 'recoil' suggestions,though.

Could it be that what is happening prone is that the ideal/comfortable eye to sight line-up is compromised a bit-the magazine forces the shooter to be a bit higher than otherwise? That might lead to POI- changes (even parallax?).

As you say,if it's consistent/reliable -even if negative- you can allow for it,so there is a pragmatic fix,and we ae not in ultimate precision land,nor need to be. And,as Cooper snidily observes,a large capacity magazine may well be a reassurance to those who expect to miss with the first shot. Ouch! :-)

 

gbal

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If you don't have an AR you can all pontificate as much as you like, there is nothing fundamentally wrong with the AR15 system, what you all seem to be missing out on is the fact that you need to learn to shoot whatever rifle you have, they are all different. Stalking and Hunting is not the same as competition shooting so don't try to draw direct comparisons.

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John,no question that training is beneficial.It's possible to give someone's view without accepting it as Pontif Gospel,and comment accordingly-( "many of us would like one' seems braodly supportive of eg UK CSR,and refering to Cooper's magazine comment as 'snide' hardly suggests agreement-it's just a bit subtler than 'pray and spray',but very much a discuss.

 

Lt Col Cooper did offer extensive training in what he considered appropriate small arms at his Arizona Gunsite facilities. His dismissive opinion on the late 60s M16 and its cartridge continue to inspire improvements ,even after 50 years of military R&D have gone a long way to improve the black rifle.

It is true he did not think the then military training was effective,nor the M16 a system that offered what he desired-effective accurate military small arms fire at distance,by well trained marksmen. It becomes opinion to what extent his strategic aims were sound,and his sceptcism well founded,as the world changed.

He did seem to be rather pontifical politically-and even an ass,though very much more an Rep elephant ,than a Demo donkey !)

He is worth reading still on small arms,if not uncritically in both positive and negative senses.

 

Agreed too-different shooting disciplines are just that-variably different-horses for courses- as the generalisation has it and let's have a few Abrams to be well tanked up.Not much wrong with the concept of a good first round hit though,even if more are needed.

As a current guru (Bryan Litz) argues,more improvement comes from understanding the causes of misses,and reducing them. POI changes would be one cause.

 

g

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If you don't have an AR you can all pontificate as much as you like, there is nothing fundamentally wrong with the AR15 system, what you all seem to be missing out on is the fact that you need to learn to shoot whatever rifle you have, they are all different. Stalking and Hunting is not the same as competition shooting so don't try to draw direct comparisons.

 

Can't say I agree with your point of view here John. The OP posted an observation regarding his moving poi between mag resting and bipod resting his AR. Individuals ownership or not of an AR is irrelevant.

 

Fundamentally there is something wrong. Both the OP and Baldie have observed moving poi with their AR's dependant upon postion - fact, not pontification.

 

I stalk, I hunt and I also shoot competion occasionally with a bolt gun. I do not observe any signficant poi shift when shooting positional with the rifle rested on bipod or forend - on several occasions on its side(i never mag rest it)that is attributable to the gun. I do observe a poorer accuracy when shooting positional but that is down to my lack of stability/marksmanship, not the rifle itself.

 

So why the poi shift with an AR? I don't know. But it must be a pita to have to account for it when transitioning from one position to another......

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Its not a problem at all. I don't even think about it. If one does enough actual shooting, rather than discussing, one finds it becomes second nature.

 

Rifle familiarity is the key here. All AR,s behave differently, just like all bolt guns do.

 

To say a bolt action does,t have different points of aim, dependant on the position just shows one thing up....the shooter does,t know the weapon inside out. Every one of my rifles shoots differently dependant on its position. My 338 does not like being shot off a bench at all, but the Tubb does, and the impact point differs slightly.

 

Take a rem off its bipod and shoot it off its mag and see what happens. Same goes for any mag fed gun. It will behave differently, I guarantee it. It may not be the gun however, but the shooter.

 

I shot a cqb match this morning. I know the gun shoots high off the post so allowed for it. Result, a 8-2 which is a good score.

 

Last detail this morning, was 100 yards, standing/kneeling.

 

Slung up and in a wind I shot a perfect 10 wash without any adjustment or aim off.

 

I say again....its Rifle familiarity , not a fault.

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Yes Dave but when you say your bolt guns differ you are introducing another variable - a bench and a post.

 

So I say again. The original op was observing a difference between mag and bipod resting, no other variables.

 

I too know my guns shoot differently from a bench. They also shoot differently if I place a rubber mat under the bipod feet on the bench.

 

Maybe I know my rifles a little better than you give credit?

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OK, let one of you guys try this out and report back then.

 

Take a bolt gun out and shoot a group off a bipod. Then shoot a group off the magazine. If thats not possible, rest the gun on something hard where the magazine/floorplate would be.

 

I know what the result will be already.

 

An AR is no different.

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