Changes in the impact point

Hi all,
How much does the impact point change between different shots, eg. from the should as opposed to shooting on the bipod?
When I was at the range sighting my rifle in I used the wooden block as my rest at the front of the stock and at the butt of the stock I had another block of wood but had my hand between the wood and the stock. I didn't have my hand on the front of the stock at all, I just rested it on the wood. I now realise that this was a mistake and that having it on the wood would change the point of impact from shooting out in the bush. I'm shooting 7mm08. Do I need to worry or would the impact point change be so small that it wouldn't make a difference. I'm not shooting long range, just bush stalking and at the very most shooting at 200m for a clearing or a slip. I don't shoot with a bipod. What do you think?
Cheers

I wouldnt even bother getting hung up about your predicament. Its not going to move 6 feet like i you seem to think it will. The difference will be miniscule.

It won't be a problem Phillip.

Sorry guys but I don’t agree the change in the point of impact is not worth sorting out. Always, always, always sight your rifle in how you will be using it. I like to have absolute confidence when I have to take a 200m shot that my rifle is going to hit where I am aiming – not 4 inches out to the left and high (maybe…). Even at 200m you could be shooting in enough wind that you will want to take it into account so by not having your rifle sighted in you are simply compounding the errors. :(

How much the POI moves really depends on the rifle and how you sighted it in to start with. I have seen rifles that the POI shifted more than an inch at 100 yards from bipod to off the elbows and then again when shooting off the sling. I have a friend that was sighting in his rifle (Tikka T3, 260Rem) using almost the exact same technique as you describe above and he was getting groups 2-3MOA. He talked to me about it and I recommended he hold the fore end with a sandbag under his arm. He was concerned that he wouldn’t be as steady when holding the fore end but would try it as that was how he hunted with the rifle. He rang me back afterwards telling me of his now sub MOA groups…

Having the rifle out by a couple of inches at 100m might not be a problem for the ideal side on shoulder shot but what happens if, for whatever reason, you want to take a head shot? Say finishing a wounded animal that all you can see is the head? :oh noes:

When sighting in one of my rifles I might do accuracy testing off a bench rest but I always sight them in how they are intended to be used out hunting. If I have a bipod then I’ll sight it in off the bipod and then make sure I am still happy with it shooting prone, off my elbows with a sand bag under my arm holding the rifle fore end. If the rifle won’t be used with a bipod then I simply sight it in off my elbows using the sand bag.

How can you be sure its the stock moving shooting on/off it. it could just be the shooter when not having a decent support?

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Originally Posted by Tussock

I had a plastic stocked savage 17HMR as I have said many time, with the worst tupaware stock ever made. The measured difference to POI from going from the bipod to a sandbag was 4" at 100m! I could not hit a rabbit with the thing, then I would go to the range to see what was wrong and shoot real bugholes with it. If I had 4" change with that thing, you can garuntee their are a few tupaware stocked centerfires that are similar.

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Interesting, I swapped mine (22 rather than 17) to a laminate stock cos the flex annoyed me, but I never noticed a significant POI shift just better consistency with the stiffer stock. I guess flexy stock effect differs depending on harmonics etc and whether the flex creates contact with the barrel.

Agreed that its worth checking though, if it makes no difference it just makes you more confident in taking the shot so there is nothing to lose by testing except a bit of ammo.

I get what you mean about that feeling. I hate using other peoples guns and they are off and I know its not me but they give me shit anyway. But I mean getting small groups off a bi-pod and trying to get small groups without a bi-pod isn't really a fair test.

Like the guys said above, it should not be a problem.

Gillie, not sure I agree with you. I suspect you will find that POI changes in different positions is more about the person behind the rifle... Assuming that you are able to get consistent grouping from a particular position, so we can discount bedding and stock issues. You should be able to change from prone to kneeling to offhand for the same distance and windage without having to re-zero or adjust the scope in any way.

It does raise an interesting point about consistent positioning of the rifle and scope in different positions. For me it helps to have a little mental checklist to run thru before each shot:
- check the edges of the scope, some scopes go noticeably brighter the moment you are correctly aligned
- are my hands relaxed ?
- are my shoulders relaxed ?
- is my cheek / ear lobe touching the rifle stock in the normal position ?
- is my body position ok, or am I pushing/pulling the rifle in any way to get it pointed at the target ?

Theoretically, if you have good discipline and can achieve a consistent hold / cheek weld in different positions (bench, prone, offhand), you should not see a major difference. Its easy enough to test. If you are getting noticeable differences, start by double-checking your body positioning...

Haha Tussock, yup minute of deer vs internet sniping :P

Wouldnt bother unless your shooting longrange.. then sight in how u plan to shoot out far... a bypod or rest can lift the poi and also projuce vertical stringing with poor technique.. not by alot.. maybe an inch at 100m..

Also the possibility of poi change from a harmonic difference if ur stock isnt up to play when u use a bypod vs rest!!!

Ebf some guns just won't shoot well from a bipod with a flexi stock it's pretty simple really.
So i"m with gillie on this one bag it up if that's how you hunt:)

Gillie / Tussock there is no way that I wish to debate rifle accuracy with the two of you as I know less than a new born babe about the subject. That said, Phillip will be with me during the roar and there will be little chance of him shooting beyond 100 metres let alone 200 with most of the shooting opportunity likely to be in the <30 to <50 metre range hence my assurance to him that it was not going to be an issue. I have not seen Phillip shoot but let's for the sake of conducting an exercise assume that he is not good and only capable of shooting a 4 inch group at 100 metres and then lets also assume that there will be another 4 inch shift in the point of impact between how he has sighted in his rifle and how it will perform when he is shooting off hand or resting against a tree. Even under these extreme (assumed) circumstances, surely he should be capable of hitting a deer at <50 metres. My council will be for Phillip to be taking shoulder or heart/lung shots anyway as if he gets a stag he will likely want to take the trophy.

Phillip, listen to and learn from the knowledge and wisdom of these far more learned members as I am no expert on the accuracy of rifles. But my comment stands, "It won't be a problem"

I was curious about this same question, so last time at the range I did a wee test. Shooting a 25/06 Rem SPS (new-style synthetic stock, tip-bedded, so not floated at all). One shot each from:

- sitting, braced on knees/sling
- sitting at bench, holding rifle up, elbows on bench
- prone/bipod spikes in the dirt
- bench/bipod, spikes on wood

The group size for the four shots was around an inch at 100y, which suggests basically no POI shift at all. Your mileage may vary of course, but I'm now pretty happy shifting shooting setup and still trusting my zero.

Happy hunting whatever you take. Walking out of the thred now.

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Originally Posted by ebf

Gillie, not sure I agree with you. I suspect you will find that POI changes in different positions is more about the person behind the rifle... Assuming that you are able to get consistent grouping from a particular position, so we can discount bedding and stock issues. You should be able to change from prone to kneeling to offhand for the same distance and windage without having to re-zero or adjust the scope in any way.

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ebf, i agree with you it is always about the shooter. Particularly how they hold the rifle and as a result how it recoils while the projectile is still travelling down the barrel. I agree you should be able to change from prone, sitting (excluding the cradle), kneeling and standing wihtout changing the scope. That said most hunters hold their fore end basically the same way in these positions. But when we are talking about a "free recoiling", no resistance foreend compared to loading it up the crap off a bipod i suspect with a lot of cheaper stocks there will definately be a POI variation.

Gillie, you got any plans for a Welly or Wairarapa long ranger. Be good to meet you and get some of the Welly crowd to throw lead at longer distances ;)

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Originally Posted by Rushy

Gillie / Tussock there is no way that I wish to debate rifle accuracy with the two of you as I know less than a new born babe about the subject. That said, Phillip will be with me during the roar and there will be little chance of him shooting beyond 100 metres let alone 200 with most of the shooting opportunity likely to be in the <30 to <50 metre range hence my assurance to him that it was not going to be an issue. I have not seen Phillip shoot but let's for the sake of conducting an exercise assume that he is not good and only capable of shooting a 4 inch group at 100 metres and then lets also assume that there will be another 4 inch shift in the point of impact between how he has sighted in his rifle and how it will perform when he is shooting off hand or resting against a tree. Even under these extreme (assumed) circumstances, surely he should be capable of hitting a deer at <50 metres. My council will be for Phillip to be taking shoulder or heart/lung shots anyway as if he gets a stag he will likely want to take the trophy.

Phillip, listen to and learn from the knowledge and wisdom of these far more learned members as I am no expert on the accuracy of rifles. But my comment stands, "It won't be a problem"

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Awesome Rushy, at those sort of distances you are right, it won't make enough of a difference. Bush hunting roaring stags is easily some of my most exciting memories. Phillip, you are going to have some fun - and as you are thinking about POI change you might as well go and check it at the range to save you thinking about it again! :thumbsup:

Rushy, I am afraid this topic is a pet peev with me - i like to advocate people shoot more and have rifle sighted in exactly where they expect. I like to have absolute confidence in my rifle. The downside to this is that it is always my fault!!

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Originally Posted by Tussock

Why? Hope I didnt offend. Was not my intention.

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No absolutely no offense taken just had nothing more to contribute to the conversation and not one to be an antagonist. All good.

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Originally Posted by Gillie

Rushy, I am afraid this topic is a pet peev with me - i like to advocate people shoot more and have rifle sighted in exactly where they expect.

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People like me must frustrate you then Gillie. I take a rifle out of the safe and expect it to hit where I aim and perform just like it did the last time I held it. I load, ready and fire and expect to see an animal on the ground (which is by and large always the result although some may bolt the gap for thirty metres or so) and then away the rifle goes after being cleaned, ready for the next time - same deal. Still that could all change if and when I get the rifle I am endeavouring to have imported.

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Originally Posted by Rushy

People like me must frustrate you then Gillie. I take a rifle out of the safe and expect it to hit where I aim and perform just like it did the last time I held it.

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Nope with that attitude it not the people "like you" that frustrate me and i expect exactly the same out of my own rifles. :thumbsup:

The people that frustrate me say things like:
"But my mate said he sighted it in"
"Nah, as soon as i could hit the paper that was good enough"
"The shop sighted it in with their in store laser"
"Nah, i just use the cheap ammo to sight in with, not the hunting stuff"
"its just come back from the gunsmith, it'll be fine"
"Torque? WTF? Nah mate, did mine up with a screw driver, didn't need to talk to it"
Wheres it sighted in? - response "about 100 yards i'll just aim a bit high for that 300m goat"
Wheres it shooting? - response "last time i checked it, it was about 2 inches hight and 3 to the left" - At what distance? - response "I think it was about 100 yards"
"what do you mean, i sighted in on 9 power. It'll be bang on on 3 power as well"
"bit funny wounding that one, thought it was sighted in"
Done anything to your rifle since then? - response "Nah, i mean i took a tumble with it last trip but that won't do anything"
"nah never shot anything past 100m except that goat at... must have been 400 yards. Got it too, never found it but it was definately hit"

Can't think of anymore i have heard. Pretty sad i have heard all of these, several of them more than once... :pissed off:

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Originally Posted by Gillie

Nope with that attitude it not the people "like you" that frustrate me and i expect exactly the same out of my own rifles. :thumbsup:

The people that frustrate me say things like:
"But my mate said he sighted it in"
"Nah, as soon as i could hit the paper that was good enough"
"The shop sighted it in with their in store laser"
"Nah, i just use the cheap ammo to sight in with, not the hunting stuff"
"its just come back from the gunsmith, it'll be fine"
"Torque? WTF? Nah mate, did mine up with a screw driver, didn't need to talk to it"
Wheres it sighted in? - response "about 100 yards i'll just aim a bit high for that 300m goat"
Wheres it shooting? - response "last time i checked it, it was about 2 inches hight and 3 to the left" - At what distance? - response "I think it was about 100 yards"
"what do you mean, i sighted in on 9 power. It'll be bang on on 3 power as well"
"bit funny wounding that one, thought it was sighted in"
Done anything to your rifle since then? - response "Nah, i mean i took a tumble with it last trip but that won't do anything"
"nah never shot anything past 100m except that goat at... must have been 400 yards. Got it too, never found it but it was definately hit"

Can't think of anymore i have heard. Pretty sad i have heard all of these, several of them more than once... :pissed off:

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I totally understand.

I've said most of whats listed

There will be an impact shift generally high or low when going from a bipod then with out. How much, depends on the marriage between barrel and stock and more importantly the strength of both.
Also, the surface you are shooting off of ie grass, sand to something harder will play a major role due to, jump. Train so you shall fight, zero so you shall shoot. Simple.
If you do not notice a change in mpi when changing thru prone, kneeling, sitting and standing unsupported you need to be in the olympics. Because the nature of the positions themselves require special technique and training in order to maintain a constant mpi thru positions and ranges. Maybe not so much within 100yrds on animals. The rifle is constant within reason, the operator is not.

Cheers for all the input guys. Its good to hear varying opinions (though it can make forming your own a little harder). I'm pretty confident that at the distances Rushy and I will be shooting, it won't be an issue. Nevertheless, its worth me taking a trip to the range at some point to sharpen my shooting and get to know my gun better.

Gillie, or anyone, can you explain the relationship between POI and varying the power on the scope? I'm afraid that one on the list would come out of my mouth if prompted at the moment haha

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Originally Posted by Tussock

There should not really be one, apart from parralex error. If you keep your cheek welded to the same spot on the stock you have done all you need to. Not something you need to fret about for normal hunting.

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Cheers for the clarification, I didn't think the cross hair should move at all with changing the power. Will make sure to centre the crosshairs and not be looking through the scope on an angle (just like using iron sights)

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Originally Posted by R93

Train so you shall fight, zero so you shall shoot.

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What does this mean pls ?

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Originally Posted by R93

If you do not notice a change in mpi when changing thru prone, kneeling, sitting and standing unsupported you need to be in the olympics. Because the nature of the positions themselves require special technique and training in order to maintain a constant mpi thru positions and ranges. Maybe not so much within 100yrds on animals. The rifle is constant within reason, the operator is not.

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Anything specific other than natural point of aim ?

R93, did you guys ever come across completely natural shots in the army ?

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Originally Posted by Tussock

Completely natural shots are very common. They are known as "women".

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:D yup - my wife ... night shoots where it is all instinctive - she is deadly !

Probably because women LISTEN when they are taught something!
I have a qualification as a fly fishing instructor and used to teach quite a lot back in the UK. Women nearly always picked up casting quicker than men because they listened carefully and didn't have the macho attitude that most men have with some sports.

ebf, I was more or less confirming or agreeing with Gillie. Train so you shall fight is an expression that justifies training, like you intend to operate.

Yes there were plenty of so called natural shots in the Army. Some of the best ones knew fuck all about ballistics and principles as well, funny enough.
Natural point of aim is imo, is most important, but finding it in its true form in other positions is subtle and takes a lot of practice.

I have tested the differing impact versus holding method many times over the years. The worst performers are always the softer synthetic stocked rifles. I have experienced an eight inch of impact point change at 100 yards with the worst one (AR15) when rested on a hard surface. Many other bolt guns with plastic stocks will also throw the shots all over the place particularly when shot off hard surfaces using the non tilting type Bipods. It is very easy to twist load these. Although poor fore end support (read block of wood here) will mostly result in shots going high, this is not guaranteed. Even bedded wooden stocked (including laminated) and fiberglass stocked rifles will throw shots off centre when fired in that manner, generally not as far off though.
If you want to sight in for <100 yard shots in the roar with any rifle, just do it as you intend to shoot it in the bush, with the same ammo you are going to hunt with.

For the record I use a Caldwell cradle for all load development, as this takes as much of "me" out of the process as possible. I'm only looking for tight groups here and not so fussed on point of impact. All subsequent sighting in is done in the actual shooting position I'll use when I shoot for keeps. I will often shoot a hunting rifle off my pack (as fore end support), then bipod, then sling prone, sling sitting, sling standing, and free hand standing to check differing zero points. All will usually result in slightly differing zeros. With a good hold technique the effect can me minimized. I find big, heavy, free floated, fiberglass stocked rifles usually have the least variation. They are also the least likely to be dragged through the scrub after animals.

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Originally Posted by R93

Natural point of aim is imo, is most important, but finding it in its true form in other positions is subtle and takes a lot of practice.

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Very true :thumbsup: I'm a bit of a stuck record on natural point of aim. IMO its the holy grail of shooting well...

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Originally Posted by Tussock

There should not really be one, apart from parralex error.

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Agree, there shouldn't be one... but in many cheap scopes there is. It is one of the very first things i have checked when mounting a new scope. With the bore sighter still there leave the rifle in the vice and watch through the scope for cross hair movement as the power is adjusted. In cheap scopes it can easily be 3-4 MOA...

When i have brought a scope with this problem i have sent it back to the supplier and gotten them to replace it.

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Originally Posted by ebf

Very true :thumbsup: I'm a bit of a stuck record on natural point of aim. IMO its the holy grail of shooting well...

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Yep, absolutely agree. Teaching it in prone is not too hard. Most people i have seen don't think they need to worry about it when shooting off a bipod... and then they wonder why the rifle bounces sideways. Learning natural point of aim in the sitting kneeling and standing positions can be difficult, adjusting your natural POA while in position can be even more difficult to learn

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Originally Posted by Gillie

Yep, absolutely agree. Teaching it in prone is not too hard. Most people i have seen don't think they need to worry about it when shooting off a bipod... and then they wonder why the rifle bounces sideways. Learning natural point of aim in the sitting kneeling and standing positions can be difficult, adjusting your natural POA while in position can be even more difficult to learn

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yup, fun watching people have a light-bulb moment when training for IPSC. tell them to close their eyes before drawing, and then see where the pistol ends up pointing. when you add movement or forced positions it gets pretty interesting... one of the training clinics I attended we did a lot of fire at targets with both front and rear sights obscured by patches... pure body position and muscle memory.

I find when using a bipod that if I place a folded up towell, ie something soft under the bipod I don't get the POI shift compared to with the bipod on the bench or concrete.
Was always taught never to rest the rifle on anything hard, even in the field place your hand under it or your hat if you need to when resting on a branch or fencepost etc.

I've recently just brought a bipod, unfortunately yet to use/sight in with or even used one on the rifle before but this is how it'll work for me:

I'll sight the rifle in with the bipod and will probably do another shot or two over my daybag for interest sake but if I don't i wont be bothered as my theory will be that i got the bipod for the stability in the longer shots - 3 - 500yds so it makes sense the rifle will be sighted in for with it and at those ranges i'll have plenty of time to piss around taking it out of my pack and putting it on. Now on shots less than 300 I probably wont even bother with the bipod and I wouldn't imagine my POI without the bipod is going to make bugger all difference under 300yds that it's going to make me miss a shoulder shot.

Up to the individual to have confidence in his rifle and himself to know where it's shooting.

I only carry a bipod if there is a fair chance i will be shooting 4hundred plus.
Other wise its off day pack or sitting shooting of knees or in bush the nearest tree/branch standing

Sent from my GT-S5360T using Tapatalk 2

i sight in on a bipod - anything shot at range is with the pod, sub that is off hand and the distance isnt big enough to worry about poi changes