Firing at an angle, or "canted"

[Pierruiggi]

Some days ago, it occured to me that I don't know how to read my sights when firing at an angle; I don't mean having the pistol canted, but your whole body (or at least the index part of the body), like when firing from the side of a barricade. Please teach me to interpret them!

The red dot simbolizes POI.

[dajarrel]

Although I'm no ballistitian, I beleive that you will find that at short distances, say less than 20 yds, your POI will be approx. where you sight picture shows it to be. However at longer distances (>35-50 yards) I believe you will see the POI on the lower right quadrant of the target you show.

The bullet should rise in the vertical plane, in relation to the pistol and then react to gravity causing it to fall to the right.

I believe this to be correct, but if I'm mistaken, soneone please let me know so Pierruiggi doesn't get any bad info.

FWIW

dj

[Flexmoney]

Shoot some at various distances and find out.

(I know...I'm no help. )

Seriously, the two fators you have to think about are:

- gravity...which pulls straight to the center of the earth

- vertical angle of barrel with relation to sights.

I am pretty sure your hits will show up right like the pumpkin on the post that you have in the left diagram (assuming that is truely where the sights are when the bullet exits the barrel)

[Jake Di Vita]

What happens is this. Since the bore and sights are not on the exact same plane there is a difference to where to bullet will impact at various distances. If your gun is sighted dead on at 20 yards, what happens is the bullet is fired at an upward arc. If you are shooting at a 20 yard target the POI will be exactly where the sights are. If you are shooting at a 30 yard target the POI will be higher than the sights because the bullet is continuing it's upward arc.

Take rifle shooting as an example. If you have the rifle zeroed at 50 yards, it should hold just about the same zero at 200 yards. However if it is zeroed at 50 yards (first time the bullet passes the plane of the sights) but you are shooting at a cant at 200 yards (2nd time the bullet hits the plane of sights) the shot will be off because gravity did not pull the bullet back directly down to cross the same plane.

I hope this actually makes sense because I can't really think of a better way to describe it.

[Turtle]

I think the problem with a canted sight picture is a combination of "point of aim/ point of impact" and "calling the shot". As Jake touched on, where is your round impacting the target at different distances? This will make a big difference if your sight picture is canted. It may be only a matter of shooting high or low A's with a level sight picture but with a canted one, you're talking about shooting low left or high right (with the example you showed above). That's with an optimal sight picture (equal height, equal light) and trigger press. Now think about where your round will hit if you have a less than optimal sight picture/ sight alignment and/or trigger press. TJ told me a long time ago to avoid canting the gun if you could help it and I think that's good advice. Sometimes you can't help it though so just slow down a bit and let the shot go where you want it to. Hope I made some sense...

Regards,

Todd

[Steve Moneypenny]

what you seem asking is "how to read the sights" and what has been answered is the effect on the trajectory of a bullet vs. the sight alighnment .

presuming you do not change your grip the sight should track exactly the same. which in your second picture would be a line at about 2 o'clock

impact at ipsc distance should not be effected though recoil will have a different impulse and for me tendancies to do stupid things like milk the gun worse when at an angle.

if you are under 15 yards it really shouldn't matter. however shooting strong/weak hand for competition. Sage words by todd from todd.... strait guns track better. Fighting with guns other positions have slight advantages.

[Pierruiggi]

Thanks to all of you for your input.

I was recalling and analizing my experiences while shooting like this, and this is the conclusion I reached.

Perhaps people with more knowledge of ballistics (and shooting of course) can either agree or correct me on this.

Forgive me if I use less than accurate terminology.

I'll start with a concept you must probably already know, but I'll include it, just in case.

There is a line that extends from your eye, through the aligned sights and into the target. I'll refer to this as Line of Sight, the spot where this line meets the target is the Point of Aim.

Now, picture a line that extends from the center of the barrel; I'll call this Line of Bore.

Since bullets do not travel in a straight line; in order to hit the intended Point of Aim, the Line of Bore should never be parallel with the Line of Sight. An angle must exist between them. This angle's value is dictated by several factors, such as the projectile's mass, velocity, ballistic coeficcient, distance to target, etc.; and should be between 0 degrees to 45 degrees.

When you regulate your sights to hit lower or higher, you are in reality changing the Line of Bore, not the Line of Sight.

Now, to my "revelation".

If you could fire two LASERs, one following the LoS and another following the LoB, you'd find a vertical difference between the two LASER dots at the target. Unless we are talking about extremely close ranges (exactly wich range depends on how high your sights are installed in relation to the barrel), the upper dot will always be the one corresponding to the LoB.

Let's assume, to give an example, that at 30 yds (27,43 mts) the distance between the dots is 5 inches (12,7 cms).

So, if you cant the gun, although your LoS will be the same, you'd be changing the location where the LoB meets the target. So, as an extreme canting example, suppose you are aiming at a 90 degree angle (GANGSTA STYLE!! ), those 5 inches "between dots" at a vertical plane needed to compensate for a number of vectors of force (such as gravity, bullet drag, etc.) are transferred to a horizontal plane causing the bullet to hit 5 inches to the left or right depending on wich direction you canted your gun to. Furthermore, you'd be no longer compensating for these vectors on the vertical plane I mentioned before, so you'd be hitting low too!

I know no one on their right mind shoots at such an extreme angle, but even though the effects would be less if shooting from, for example, a 30 degree cant, there would be a disparity between the PoA and the PoI. This only gets worse as the distance increments.

This theory seems to be in agreement with my experience.

I would also assume it'd be extremely difficult to know where to aim to get the PoI where needed; not to mention calling shots...

I know around here, benchrest shooters put levels (those things with a bubble suspended in liquid to determine if something is... well, leveled... I don't know the english word) on their rifles to ensure they are shooting with their guns perpendicular to the ground.

All of this insight served me for what...? To listen to Todd Jarret and shoot with my gun straight damn it!!!

[Steve Moneypenny]

ensure they are shooting with their guns perpendicular to the ground.

this is not accurate Perpendicular is not where you want to be, for example you are on a hill side with a steep grade, our rifle is on a "fixed" bipod and is at the same grade as the spot of earth you are on. your bullet has NO clue of this. nor does gravity... your gun must remain LEVEL thats why we have adjustable legs on bipods. This is a really big deal past 300 yards with a sniper rifle. the gun MUST remain strait... i believe it is springfield armory who integrated a bubble level in their scopes.

the pics are a great idea.. but (presuming no wind) and these targets would need to be atleast 50 yards if not more, it would always be strait down (down being the direction at which gravity sucks a "plumb bob" if held up in front of the muzzle)

so, the third pic the target being a clock face. it sould go more towards 6 o'clock i believe.

[Flexmoney]

This theory seems to be in agreement with my experience.

OK...now we are getting somewhere.

Your not hitting where you think you called the shot, right?

My guess is that you didn't call the shot properly.

The difference in your "dots" isn't likely going to be 5 inches at 30y...

I like your diagrams, but I don't think they correspond with reality. Your sight high is likely less than 0.75 above the centerline of the bore. I'm not sure how slow of a bullet you would need to get the trajectory that you've proposed, but I am pretty sure that isn't the trajectory of your actual gun/load.

It sounds like you are looking for a gun explaination...when what is likely happening is a shooter problem.

Supporting this:

All of this insight served me for what...? To listen to Todd Jarret and shoot with my gun straight damn it!!! 

Depending on your temperment, you might need to figure out this trajectory stuff and get some closure on it before you move on. But, in the end, I think you will come to realize that you just weren't seeing the sights when the bullet left the barrel. (Sounds like you were seeing them in some amount of time before the bullet left the barrel.)

[sfinney]

For what its worth, I don't like shooting canted.....but about a year ago, there was a stage I shot that required you to go prone through a low port, and it was a very tight shooting box depth wise, plenty of width - every one was losing time getting down and set up in a normal prone position, I decided to drop straight to my left side and shoot laying on my side, gun canted sideways about 80 degrees, with iron sights....

There were about 6 pieces of steel at about 15 yds..... all of my hits were right on point of aim, center of steel with 180gr 40SW. So I didn't see any real difference at this distance......

Now, for rifle shooting, at 100 yds plus..... I think your diagrams would hold some truth. But for IPSC distances, I think you may be over analyzing it a little

[rwmagnus]

Pierruiggi.... just wanted to say nice post, very thoughful and informative post

[Pierruiggi]

Steve Moneypenny:

You are absolutely right, I didn't thought about your example when I wrote "perpendicular"; "level" should be the word.

Flexmoney:

No, you misunderstood me or I assumed certain things would be taken for granted. My general question when I created the topic was about the changes that happen in gun behaviour (that Steve Moneypenny already covered saying that should be none; if you maintain your grip and index); the bullet trajectory and where it will hit on the target at a medium to long range; if PoI correlates with PoA; and human approach to this factors AKA "what to do".

I am not blaming the gun on this! Absolutely not! It could very well be that I am not calling my shots correctly since this is something I'm still learning to do with consistency. But in order to call my shots, I need to be KNOW that the gun will CERTAINLY hit where the sights are when the bullet leaves the barrel. This is where I have my doubts, my diagrams were an exageration (and the bullet trajectory was made up) to demonstrate my point, I know the difference at, say 15yds, won't be as severe as I portrayed it, but it will be present nonetheless. This would also change with different bullet trajectory, flatter shooting calibers would suffer this problem less than a .45 for example.

For whatever's worth, I'm shooting a .45 so that's the caliber I'm mainly interested in.

sfinney:

Regarding rifle shooters, yes, this does get worse with distance. I'm mainly trying to stablish at wich range this phenomena starts to become a problem at handgun ranges.

About your experience, I remember watching videos of the 1991 nationals, where everybody except Jerry Barnhart (or was it Doug Koenig? I don't remember) and a few other competitors were using iron sights. There was a stage where the shooter had to engage targets from both sides of a barricade (a wall is maybe more appropriate since it was really wide), the whole stage was shot from there, and for some reason I don't remember you had to shoot from a low position, not standing up. One thing caught my attention.

The different positions top level shooters shot from. Some of them tried a very uncomfortable looking crouch with a lean, some with their leg extended, some not. And some others, like Rob Leatham and Jerry Barnhart (or was it Doug Koenig damn it!?) laid on ther sides and shot with their guns semi canted. This, to me, meant world class shooters didn't agree on what was the most efficient shooting position on that particular stage.

rwmagnus:

Thanks.

[Pierruiggi]

I used a ballistic simulating progam to set a more accurate example. The cartridge data is taken from this website.

I linked the pictures because some of them are quite big.

Note: Everything is program generated, i limited myself to input data and take screenshots. I measured the height of sight line myself from the center of the muzzle to the top of the front sight.

Cartridge data

More data

Table from 0 to 23 meters (25.15 yards)

Table from 24 meters (26.24 yards) to 47 meters (51.4 yards)

Table from 47 meters (51.4 yards) to 70 meters (76.55 yards)

Simulated Line of Sight, Line of departure (what I called Line of Bore) and Bullet path

A closer look

So, it appears that in my example, at 30 yards, the "distance between dots" (and where the gun's barrel is truly pointing at) is close to 9 inches instead of the 5 I suggested.

[sfinney]

Looks like your data is for a 230 gr .45? Maybe 9 inches of "drop", regardless of cant, is possible with a .45 at 30 yds...... dunno. I'd question whether you'd have anywhere near that amount of drop in a faster moving .40 or 38 Super.......

Really great tables, and data, though, very thought provoking.

[Pierruiggi]

OH YES!!! I forgot to mention what I was talking about!

I use a .45 with military loads, so it does approximate to that table

And to answer your question with the same ballistic program, the results for a .38 Super cartridge of 130 grains with a BC of 0.155 (taken from Winchester website) and with a muzzle velocity of 1380 fps; the "distance between dots" (I'll keep calling it like this until someone informs me of the proper term) would be 3.75"; indeed a lot less than with the .45 load.

With a .40 caliber 180 grains BC of 0.167 (again from Winchester) with a muzzle velocity of 995 fps; the distance would be 7". Considerable.

These examples are at 30 meters.

[Flexmoney]

Your numbers seem are way off.

Forget ballistics for a second....

You state that you are sighted in a 30y, correct? And that your sight is 0.63 above centerline (as measured by you), correct?

Think about that. Lets use your Line Of Sight as a Zero Line. At the muzzle, you are 0.63 low. The angle of the barrel is such that the bullet is on a rising path. Zeroed at 30y...your bullet is rising 0.63 in 30 yards.

Forgetting gravity, in twice your zero distance...in 60 yards...you would only be 1.26 high. (0.63 x 2 = 1.26)

[Pierruiggi]

No, the bullet rises more than 0.63 inches, and then falls back. Its in the tables from the ballistics program. Look under "height above sightline".

If sighted at 30 meters, using the load in my example, the bullet would reach the top of its arc at 18 meters, being 0.41" over the sightline. So, If I have my gun sighted at 30 meters and shoot a target at 18 meters, I would hit 0.41 inches above my Point of Aim.

And anyways, I'm not talking about bullet path, I'm referring to the "distance between dots" I mentioned in my second post in this topic. While the dots representing where the line of sight meets the target (point of aim) and where the line of bore (or line of departure) would meet the target (if it touches it at all) are in a vertical plane, everything is fine since this compensates for bullet drop; but if you cant the gun they become a part of the horizontal plane too, making the point of impact to move either right or left, depending on which direction you canted the gun; and when you cant the gun, you change the vertical value too so the bullet hits lower.

Perhaps this is more noticeable in iron sighted rifle shooting. Have you seen those old WWII Mauser sights? If you put them at the 1000 meter+ regulation, it is very obvious that a straight line following the bore (like a LASER or a bullet not affected by forces) would pass WAY over the target, that means, the barrel is not pointing DIRECTLY at the target.

An even more extreme example would be grenade launching systems (like the M79 with its "ladder"type sights) or even mortars.

I'm NOT comparing mortars and grenade launchers to competition handguns, I'm just trying to make my point more clear through these examples.

I'm sorry, I can't forget about ballistics since this is ballistics.

And also, I think it'd be impossible to call your shots like this, isn't the two principles of calling the shot to see the where the sights are on the target while the bullet leaves the barrel and to KNOW that the bullet will hit that spot?

Having to compensate for a lateral drift and a vertical drop "on the go" seems like a very bad idea.

The difference between PoA and PoI could be neglectable at certain ranges I assume (since no gun hits EXACTLY PoA, even when fired from a completely static platform), but there is a limit for sure.

No gun canting at ranges over 10 yds for me thanks!

[Mike_Kerr]

" I'm sorry, I can't forget about ballistics since this is ballistics. "

It is also confusing. Such is life.

Regards,

[Dalmas]

I tilt my index, I aim, I fire, I look at the target and say "Gravity Sucks!!" Next time I know where to aim.

Edited November 8, 2004 by Dalmas

[Flexmoney]

Omar,

My mistake. Your numbers aren't off.

[Steve Moneypenny]

this whole 9" and 7" at 30 yards is fubar. you will be down that MAYBE at 100.

If sighted at 30 meters, using the load in my example, the bullet would reach the top of its arc at 18 meters, being 0.41" over the sightline. So, If I have my gun sighted at 30 meters and shoot a target at 18 meters, I would hit 0.41 inches above my Point of Aim.

your going to be within 2" which is probabally beyond the accuracy of the gun you are using.... not to mention the accuracy potential degrding withthe speed you would be shooting an action pistol match.

just think you could have been practicing keeping your gun strait instead of runnnig ballistics programs. ... unless it's out there and with a rifle. i seem to make a handgun hit out to 75 yards very reliably.

you sound like a friend who worries too much about the little things, whle the rest of us are just doing them :-)

[Pierruiggi]

this whole 9" and 7" at 30 yards is fubar. you will be down that MAYBE at 100.

Well Steve, with all due respect, I think you misunderstood what I said. First of all, I never talked about a bullet drop of 9" at 30 yds when the gun is level, but if you cant it 90 degrees (as an example...) you'd be tranferring the angle on the vertical axis used to compensate for bullet drop to the horizontal axis. So essentially it would be like if you shoot your gun sighted at 0 yds (actually is worse than that since now this horizontal angle affects whee the bullet will land laterally).

And I DO practice with my gun, but since I always loved math and physics I find that analizing this kind of phenomena is healthy and entertaining to my mind and soul. I do NOT consider it a waste of time.

I do recognize though that I am a little bit finicky, but I like to know how things work, it helps me to interact with them better.

I also already said that I'll try to avoid shooting canted altogether or at least try it to be at close distances. So I'm not losing any sleep or practice time over this.

I just love the mix between technique, physics, personal experience and will of mind.

[thread hijack]

That's why I love the movie Equilibrium's Gun Kata, a martial art with guns based on mathemathics! Plus it looks cool

Read my sig, its a monologue from the movie by the character who teaches this art describig it and its origins. Also watch the movie!

[/thread hijack]

[Pierruiggi]

I tilt my index, I aim, I fire, I look at the target and say "Gravity Sucks!!"    Next time I know where to aim.

Dalmas, this whole deal got into my mind after shooting a prop in practice, at the moment I did what you said, look where the bullet hit and compensate. But then the itch to know why things happen started. Besides, that is no proper way to call a shot

[Flexmoney]

You should be able to calculate the verticle drop of a gun canted on it's side by putting in a sight height of zero, right?

[Pierruiggi]

Well, by putting the sight height on 0 and zeroing on 0 yds...

That means, making sure the bore line is level, then record at each distance the drop that the bullet suffers.

But even like that it wouldn't show the lateral deviation caused by firing canted. And the bullet drop would also be affected by the cant angle.