Spin Drift at 1500 yards

[sinister]

Re: Spin Drift at 1500 yards

A suppressor, muzzle brake, bore evacuator, etc. doesn't affect drift caused by rifling spin. The bullet is going to drift slightly into the direction it's spinning.

At 2200 Meters (7,260 feet) the bullets will indeed "Beat up" a zone. The bullets will have drifted to the right of true line-of-sight aiming. The television and thermal sights of an AC-130 will have to compensate for drift since they're launching 7.62 rounds from their miniguns at 12,000 feet above ground level from a moving platform (i.e., add in lag and lead compensations).

 

[Lowlight]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TJ.</div><div class="ubbcode-body">Nice 300-yrd group but the thread is about SD at 1500.

If you are shooting at 1500 yrd, are confident you have nailed the fundamentals of trigger, cant etc and are confident in your wind calc...would you or should you adjust for SD ?</div></div>

Sorry I don't have images of shooting at 1500m and beyond, though I do shoot that.

Do I dial SD at those distances well I already answered that in this thread.

The answer yes, last time out shooting it, to include out to 2000m I used .2 mils, the computers request about double, I tend to use 1/2 of what the computers tell me.

I do not use it inside 1250m at all. And would only consider it there on bullets not going supersonic. And then the predictability is going to be so low anyway, so, it's a wash. Lastly where I shoot and I mean everywhere there is wind, usually more than 3MPH so it is well past a wash.

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Sinister,

Your perspective is greatly appreciated... by me.

I have often thought that the bravado, masquerading as "experience", which is often displayed in threads like this is only slightly less magical than a jihadi spraying the air with bullets in hopes that Allah will do the heavy lifting.

As the demands placed upon long range small arms increase, so will the tools, and methods come to mirror what has been standard practice among artillerymen for more than a century now.

 

[Lowlight]

Re: Spin Drift at 1500 yards

Bravado masking as experience, gee Noel that sort of diminishes all the hard work that went into the process for years.

It dismisses the hours on the line, the calibration put into the system used to predict the shot, the dry practice, the days in the classroom. All that leads up to the experience, to include exposing yourself to technique and products over the years. Forget the hundreds of students I have seen try this stuff and fail because their shooting doesn't give the science a chance, no I think experience counts for something.

One would think you plugged a few numbers into a computer and came out with a winning bullet right out of the gate. Why didn't the math provide you with the right answer the first time? Why do the ELR bullet makers constantly change the bullet when the flight science has already been determined? Heck with all the information and computing power available today why hasn't every bullet maker updated their bullets in a drastic way?

I may talk like I point the barrel and pull the trigger, but the reality of the situation would surprise a few of you.

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Frank,

I would not even contemplate denigrating hard work on the range. It is not only what we learn, but what we learn to question, that has seeded genuine progress.

Your point about bullet development is a case in point. I could have released a decent projectile years ago... but I knew I could do better; I did not know enough, and I *knew* it.

 

[sinister]

Re: Spin Drift at 1500 yards

Frank, I think he's agreeing with you.

ELR with a rifle is in its infancy in the United States -- there are very few who are speaking from first-person experience who can teach new shooters. Even many ardent Palma and F-class shooters haven't fired <span style="font-style: italic">past</span> 1,000 yards.

Unlike standard military equipment there are a lot of variables. Where we have 1-10 through 1-12 barrels and folks shooting 175-grain .308 Match Kings to 1,000, US ELR is in the Wild West of experimentation and wildcatting based on both good and bad experience and trial and error.

Factory 338s range from AI, Sako, Remington, Barrett, DTA, and Savage. Bullets range from 250s through 300s. We have all kinds of flavors of 338 Lapua and others.

It's a very exciting area and one still surrounded by good information and bullshit. Kinda like sniping less than 20 years ago when the Leupold and Super Sniper were the few affordable and available options with mil-dots, Plaster's <span style="font-weight: bold">Ultimate Sniper</span> was one of the few single go-to mass media books, and the 700P and V were the few off-the-shelf big-box store options for 600-yards and in.

 

[Lowlight]

Re: Spin Drift at 1500 yards

I'll take it as that...

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Frank,

You would be correct in taking it that way.

I intended no offense to you personally.

 

[goober]

Re: Spin Drift at 1500 yards



Frameable

<span style="color: #990000">I have often thought that the bravado, masquerading as "experience", which is often displayed in threads like this is only slightly less magical than a jihadi spraying the air with bullets in hopes that Allah will do the heavy lifting.</span>

I havent shot ELR or past 1 kilometer as yet but even upto 1k I always use SD because my ballistic caculator allows it in the equation .What I do know though is even if it didnt I imagine my results would probably be much the same because as Frank is getting at the "wash" of wind effects and shooter induce error would negate the perfect math -never the less it is always allowed for on in my calcs[color:#CC0000][/color]

 

[Lowlight]

Re: Spin Drift at 1500 yards

Just because a ballistic calculator is calculating it, doesn't necessarily mean it is doing anything more than giving you a flat rate, most of which was based on the 308 going 2550fps with I believe a 1-12 barrel. So my question has always been, if it's telling me to use 1 MOA <span style="font-style: italic">(which most do at 1000 yards)</span> and then they give you some percentage of 1 MOA inside that distance and out, <span style="font-style: italic">(which is why people have begun to dial it at 600 yards or so)</span>, aren't you still adding error in if your bullet is actually flying better, like with a 300WM which shows the SD to be half of the 308 number.

My point, if they say a 300WM is 5" @ 1000 and the 308 is 10" @ 1000, based off the older information as most use, what if your actual SD is 7" @ 1000 ? Do we say, well the .25 here or there is okay, which is essentially what i am saying. The USMC taught that it was really only a factor at the point in which the bullet slowed down and begun to transition from supersonic, so that is why you find them not referencing it for the most part. In retained supersonic flight with better barrels and bullets, the number I have seen puts it closer to .3 MOA to .6 MOA @ 1000 which is why they and I mostly ignore it.

My biggest bother in all this is guys have walked in the door of the classroom who dial this stuff at 400 yards and say it makes a difference, or say, how they had trouble hitting something until they started dialing it and found out they are in fact using 2 MOA at 1000 yards. <span style="font-style: italic">(we heard this a lot) </span> It has become the worse game of telephone out there, guys see their trigger errors show up downrange dial left and call it SD then claim they are seeing the difference. With my shooting I never "saw it" until well beyond 1000 yards.

ExBal the original ballistic program had the shooter actually "shoot" the target and measure it... because he knew.

If we were smart, and I think we are, especially going back to the 60s and 70s, you would ask yourself, why didn't we <span style="font-style: italic">(being a country in the Northern Hemisphere)</span> simply move to exclusively use Left Twist Barrels, to negate a large portion of the effects, by having SD and CE cancel each other ? Instead of constantly having this "essential" adjustment hanging over every shooter's head, just remove it as much as mechanically possible from the system ? Maybe they felt it wasn't worth the effort ? Opened ended I know but still begs discussion on from those who are more inside than I.

If I was building a cutting edge dedicated ELR rifles, it would in fact have a Left hand twist... maybe a gain twist, but definitely turning to the left.

Everyone likes to quote Hatcher, McCoy, etc... Pesja has less than 1 page for both CE and SD in Modern Practical Ballistics, and goes on to summarize both by saying,
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The effect of gyroscopic drift is difficult to analyze precisely because of many variables are involved. Drift tables, which have been determined mainly from well controlled army and navy tests, indicate that gyroscopic drift is roughly double the effect of Coriolis drift, and thus is also negligible for most purposes. It is interesting to note that with counterclockwise or left-twist barrel rifling, gyroscopic drift is to the left in the northern hemisphere and more than cancels the effects of Coriolis Drift. </div></div>

He says calculating both, that CE is about 1" @ 700 yards and if SD is double that, say 2" @ 700, how it goes to 10+" from 2" ? I suspect it is the transonic nature of the bullets originally tested, but then again it might just be my thinking on 1 man's opinion based on his figures provided, but I also look at the time he spends on it to come to those conclusions as well my own experience.

No I agree it is there, but my question is from where it has gone, from .6 to 2 MOA, and he further states because it is an extremely small effect, and is constant and repeatable, it is negligible for most purposes. Here he is not talking ELR, but he is definitely talking 1000 yards and in... hence my conclusions and resistance to the necessity.

 

[Bigwheels]

Re: Spin Drift at 1500 yards

Wow. Thanks LL. This is the 1st time I have ever heard of SD being attached to a bullet's going trans sonic. I'm definitely no ballistic engineer, but your description seems to make sense, & after a little thought is probably why I have not needed it since my rebuild.(better brl, better fitting stock, better bedding, etc.) The 300Wm with 225's @ 2860 doesn't start going trans sonic 'till about 1600-1700yd. Now I wonder if the Shooter for Android actually does a calculation, or an estimate based off the original military testing. It does have a place for both twist, & bullet length.
Just checked it's SD output for my last shots @ 1250, & with no wind it calls for .7L, so It can't be correct. I was hitting center with 1-2 moa in a 1-3 mph wind from 8:00. Adding .7 for SD would have brought my impacts left off the target. I could buy 1/2 of that tho. I know I can't hold 1 click @ over 1000 yd in any wind.

 

[sinister]

Re: Spin Drift at 1500 yards

Here's a link to an old Navy text that teaches gunnery ballistics. A lot of fascinating and interesting trivia relating to stuff shot out of a gun and flying through the air:

http://hnsa.org/doc/firecontrol/partc.htm

 

[Lowlight]

Re: Spin Drift at 1500 yards

I think Naval gunnery range and projective speed is a factor as well as the angle of fire, which is why they drift more. They are talking 15,000+ yards to 50,000 yards and it clearly says:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The amount which a projectile will drift at a given range has been determined experimentally,</div></div>

The question I would have, what is the range to speed ratio, from my research at the muzzle these shells are going less than 3,000 fps and have a range well beyond 20,000 yards, so they are moving very slow which would tell me, MORE DRIFT. Speed them up I bet they drift less until they cross that threshold again. Their ELR Sabot Shell is only going 3,600fps for a 1,100lbs shell going 70,000 yards, its not like that distance is being shot under supersonic conditions.

Which is why artillery and naval gun guys account for it more, they are lobbing heavy shell very slowly so they are less stable and drifting more, speed them up I bet the drift drops quite a bit.

 

[Bigwheels]

Re: Spin Drift at 1500 yards

Is there any way to actually calculate SD other than trying to find a spot where you can fire @ 1500yd with no wind? (I'm pretty sure there is no such place.) Any math wiz's out there care to tackle that one?

 

[Lowlight]

Re: Spin Drift at 1500 yards

Yes, there is a math for it, but I also believe you need a special computer for the complete answer, and you have to know the exact variables down to a measured twist rate, bullet measurements, etc. Like all the texts say, it is very difficult in practical terms and this is why most people "model" it on a computer, but the modeling does not take the "shooter" into account which in my opinion sways where the bullet actually leaves the barrel, which can change the downrange results, maybe not the amount of drift, but where the bullet ends up based on the shooter.

So like in your case, the modeling may say, .7L of drift, but how you actually release the shot makes it .3L instead, someone else it might be .7L for drift but they need 1L because of where they release the shot. How the body manages the recoil and the shot will determine where the barrel is pointed so you have to calculate the drift from there, and not from a modeled shot in a vacuum, or from a fixture.

 

[Bigwheels]

Re: Spin Drift at 1500 yards

Ok. Well I guess that the next time I get to shoot to 1500+ I'll give a 1/2 value to the solution & see what happens. Thanks. I love this site.

 

[fastnf]

Re: Spin Drift at 1500 yards

I'm jumping in as a newb. But in case you have not tried it....

Lapua's free desktop software does have SD and the pro version will do Cor Drift, but I also wonder if it is as much as they say. You can also download the Lapua drag tables for most of their bullets.

If you change the rate of twist, the calc changes the amount.

 

[Bigwheels]

Re: Spin Drift at 1500 yards

After more thought, I'm reconsidering my earlier decision. The last time I shot @ 1950yd I spent about 20 min watching the wind before the shot, & were I able to get a more accurate distance... I fired a cold bore shot that hit dead center, but 1 moa low. I came up 1 moa, I hit 3 of the next 5 before the wind changed. & After using Google Earth to double check the range, my GPS range was 10 yd short. Adding that 10 yd to the solution was 1 moa. I would have had a center mass hit @ 1950 yd. So I'm not changing anything. That was some of the best shooting I have ever done in my life, & I did it without correcting for SD. If it's not broke, don't fix it.

 

[Alpine 338]

Re: Spin Drift at 1500 yards

Today I was shooting a Rem 5R / 308 /24" barrel using FGMM 175-gr, started at 200-yards on steel, and moved out in distance at 100-yard increments. Absolutely no wind at my position (covered deck), US flag was perfectly still, and the impeller on the Kestrel was also perfectly still. Around 800-yards and beyond both my spotter and I observed mirage moving left to right, est. less then 5-MPH because my wind hold at 1000 was 0.5 mil, 1.0 mil or less at 1200, and my FDAC indicated twice that value for a 5-mph wind. Anyhow, it was a fairly constant wind at distance.
As I was trying to hit a 10" plate hanging in the air at a 1000, both my spotter and I were having a difficult time telling if my missed were short or long, but they were all consistant POI (hits in the dirt) aligned verticaly with the target
...except once where my POI was exactly where my POA was, as soon as that occurred, I noticed that the mirage was perfectly vertical., and my spotter also verified/reported the same. So, was there any measurable SD?

Just an observation, and proving to myself, that SD is such a small factor that I have no reason or need to correct for it, at least out to 1200-yards.

Good discussion here guys.

 

[Arbiter]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Alpine 338</div><div class="ubbcode-body">Today I was shooting a Rem 5R / 308 /24" barrel using FGMM 175-gr, started at 200-yards on steel, and moved out in distance at 100-yard increments. Absolutely no wind at my position (covered deck), US flag was perfectly still, and the impeller on the Kestrel was also perfectly still. Around 800-yards and beyond both my spotter and I observed mirage moving left to right, est. less then 5-MPH because my wind hold at 1000 was 0.5 mil, 1.0 mil or less at 1200, and my FDAC indicated twice that value for a 5-mph wind. Anyhow, it was a fairly constant wind at distance.
As I was trying to hit a 10" plate hanging in the air at a 1000, both my spotter and I were having a difficult time telling if my missed were short or long, but they were all consistant POI (hits in the dirt) aligned verticaly with the target
...except once where my POI was exactly where my POA was, as soon as that occurred, I noticed that the mirage was perfectly vertical., and my spotter also verified/reported the same. So, was there any measurable SD?

Just an observation, and proving to myself, that SD is such a small factor that I have no reason or need to correct for it, at least out to 1200-yards.

Good discussion here guys.
</div></div>

Are you left handed?

 

[Arbiter]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">I think Naval gunnery range and projective speed is a factor as well as the angle of fire, which is why they drift more. They are talking 15,000+ yards to 50,000 yards and it clearly says:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The amount which a projectile will drift at a given range has been determined experimentally,</div></div>

The question I would have, what is the range to speed ratio, from my research at the muzzle these shells are going less than 3,000 fps and have a range well beyond 20,000 yards, so they are moving very slow which would tell me, MORE DRIFT. Speed them up I bet they drift less until they cross that threshold again. Their ELR Sabot Shell is only going 3,600fps for a 1,100lbs shell going 70,000 yards, its not like that distance is being shot under supersonic conditions.

Which is why artillery and naval gun guys account for it more, they are lobbing heavy shell very slowly so they are less stable and drifting more, speed them up I bet the drift drops quite a bit. </div></div>

I'd never heard about the LRBA naval loads. 47 miles from a battleship would've been one hell of a thing to see...

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">4) In the spring or summer of 1967 when USS New Jersey (BB-62) was being activated for Vietnam, Indian Head Naval Ordnance Station proposed taking 23,000 non-nuclear 280 mm (11") shells left over from the Army's "atomic cannon" program and converting them via a sabot and obturator to be used in 16" (40.6 cm) guns. This was apparently a part of or in conjunction with the "Gunfighter" program for developing Long Range Bombardment Ammunition (LRBA) projectiles. Test shots were fired in 1968 and 1969 at Yuma and at Barbados, with the latter location using two 16"/45 (40.6) cm guns welded end-to-end and achieving ranges out to 83,850 yards (76,670 m) with a 745 lbs. (338 kg) shell fired at a muzzle velocity of 4,550 fps (1,387 mps). The program was apparently halted when New Jersey was decommissioned in 1969. An image of the disassembled saboted round is on the additional pictures page.</div></div>

http://www.navweaps.com/Weapons/WNUS_16-50_mk7.htm

 

[Alpine 338]

Re: Spin Drift at 1500 yards

No, right handed, I was shooting off a bench, on a bag rest, and rear bag supported.

 

[Lowlight]

Re: Spin Drift at 1500 yards

Another thing to note with Naval guns, reading those pages, it appears they figured the round was spinning only about 4,000rpm at the muzzle, which is slow compared to the spin of a rifle bullet. (100,000+rpm)
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The AP Mark 8 has a radius of ogive of 144 inches (366 cm) or 9crh and leaves the barrel rotating at about 4,000 RPM. </div></div>

I would suspect artillery and mortars are also spinning slow which lends credit the idea that bullets drift more as they slows down, and not nearly as much at full on speeds. When you combine the data from naval guns / artillery / mortars such as speed and rotation along with the distances and trajectories, the thought that like a top spinning at max speed will stay in roughly one place, it then begins to drift as it slows down. I understand some say the nose angle doesn't act the same, but when you compare everything it does put the pieces together. That is why with modern barrels, bullets and powders, which have increased the speeds of the bullets can mean much less drift.

We are getting velocities today out of 18.5" barrels they only saw with 26" bbls. So seeing how that has changed dramatically over the years, I would say the data needs to be updated a bit. I still understand people like Bryan shooting this down, but the reality on the ground seems to support it more than the reverse that the drift is as great as it is. Just goes to show how hard this is, and the fact it is not working out the same for everyone again supports my <span style="font-weight: bold">"Human Factor" </span>, it should be universal where everyone sees it exactly the same, but we all know this is not true.

 

[sinister]

Re: Spin Drift at 1500 yards

I agree, Frank.

Just within the last ten years (using the .338 Lapua Magnum Sako TRG-41/42 as a yardstick) twist rates and bullet weights have increased (from an original 1-12 twist and a 250 Sierra Match King at 2950 fps to today's longer and heavier 300-grain Scenar and Berger Gen II Hybird at 2850 needing a 9.2 to 1-10 twist) the projo is spinning slightly faster but it's also flying slower.

Even slower from a shorter barrel.

Different rounds from the same mortar required different drift correction, with more drift as velocity decays at the extreme ranges.

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Frank,

Rather than thinking in terms of absolute rpm, when using the phrase "slow", look at circumferential rotation velocity in comparing caliber sizes.

The 16" naval shell, at 4,000 rpm, has a radial surface velocity of 150,000 inches/minute. A 338LM fired from a 1: 9.2" twist at 2,850 fps has a radial surface velocity of 223,043 inches/minute... only a 36% difference. This not really much when you factor in a near absence of engraving deformation on the 16" shell, and testing on small caliber banded solids tends to support the effect that engraving has in increasing drift.

The longest hit recorded by a .45-90 Sharps rifle, on a human target is 1,538 yards by Billy Dixon in 1874. He used a tang vernier high elevation rear sight... much as artillery is used. When we use modern rifles in a similar way, you will see SD acquire the same importance.

 

[Lowlight]

Re: Spin Drift at 1500 yards

Noel isn't the MV of a sharps less the 1500fps? Gives new meaning to lobbing.

So how do you compare a modern bullet going 2x faster, my 338 with a 250gr Scenar is going about 3100fps, so if the computer is saying .5 to .7 and my used is .2 to .3 that 1/3rd makes a heck of a difference.

It still lends to the speed factor, if you look at past 300wm numbers and the velocity used and figure a modern 308 is at least 200fps faster than the numbers used, it brings the round closer to the previous 300wm recorded SD which I believe is 5". drop the 12" down by 1/3 because of experimental error and then increase the velocity, you see things begin to trend lower not higher.

Bullet engraving noted, I have yet to see engraving depth measured and used in the calculation, so the engraving debate is null, their is no data I have seen other than to say deeper = more drift, but I ask,

How deep does my barrel engrave the bullet to calculate MY drift?

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Frank,

The 6+ caliber bullets that I have been playing with will not trace the high trajectory that the .45 slug can. The PDT core version will, and it will do it in a smaller caliber at modern muzzle velocities, and a high BC.

For moving targets the flatter trajectory, 6+ caliber, stuff is still the projectile of choice. It is likely that these will largely negate an SD correction even at their effective range limit. This is an experimental determination, not a calculated one. There is an individual on this board that probably could do a CFD analysis on your 338 for SD, but it would still need field verification notwithstanding.

 

[wadcutter]

Re: Spin Drift at 1500 yards

Isn't spin drift influenced by time of flight?

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Yes, it is. SD is also amplified by launch angle, which is why the vernier sights of the 1800's had a cant built into them to adjust for it. The P-08 artillery Luger incorporated the same capability into it's rear tangent sight.

 

[Muskett]

Re: Spin Drift at 1500 yards

And natives put their sights at max elevation because then their guns were more powerful.

If you look at arrow flight they curl and archers compensate for it. Crossbow bolds do it too.

I think what this thread shows is that with modern rifles there is an effect but out to 1000m not enough to get excited about. Beyond that then if your ballistic calculator has the function it is probably over compensating so halve it. Even then there are so many other variables that need addressing that SD is washed out in the big picture. If you want give it a bit but don't overdo it. When you miss SD is not an excuse!

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

"When you miss SD is not an excuse."..
... It is certainly a smaller part of the excuse, proportionally, when factors like unconscious rifle cant are not fully appreciated.

 

[Lowlight]

Re: Spin Drift at 1500 yards

What happens with TOF is, the ballistic calculators that don't have the option to "zero the drift" will always give you the same answer. Even changing the zero range, if it says to use 1 MOA for 1000 yards, and you change the zero range to 600 yards, you still get 1 MOA for SD from the ballistic calculator. Now if you have the ability to zero the drift it will change it.

Simply checking the box to use SD is not always helpful, only a couple of ballistic calculators try to use it instead of just putting a flat rate number from the start and leave it there no matter what. Change your zero range to see if gives you a different answer, because if you "zeroed" your rifle at a distance other than 100 yards, the drift has been reset to zero. I know Ballistics has this as well as some others, so you can see it goes from .98 MOA to .91MOA if you say it is zeroed, then if you change the range to 600 yards it will go to .52MOA. Other software will stay at .98.

One note to something I said earlier, and this goes to the 36%, now Bryan can correct me if I am wrong, but I believe he said his new 175gr bullet used in his Tactical Ammunition is a 7% change from the Sierra Match King. That 7% results in a .3 Mil gain in both elevation and windage at 1000 yards. When I received a few boxes of it, I tested it out of my known rifle alongside M118LR to 1000 yards. The MV was roughly the same, it's within about 15-20fps of anything else I shoot, in fact out of my 20" AX it goes 2645fps. Well before leaving Texas I shot it under sea level conditions and it was flatter by .3 mils and had much better wind drift by about .3 also. This was shot and not calculated. Fast forward to CO and I used it to shoot the LRRC at CRC which is a 550 yard Prairie dog competition and it gave me a second place showing tying and besting many of the 6mm / 6.5mm bullets on the line.

If a 7% improvement can accomplish this, and I firm believer in his ammo, I use quite a few Berger loads for both my 308 and 260, then imagine a 36% change over time modernizer everything from barrel to powder, to bullet.

The software is great, it has opened a lot of eyes but I still find it gives people a built in excuse sometimes, as well short cuts their practice, while keeping expectations high. Back in the day people understood the idea of practice, today they figure the computer will solve the problem.

 

[Muskett]

Re: Spin Drift at 1500 yards

Thank you Lowlight, I'm finding your posts very informative being a bit of the old school shooter myself and trying to catch up with new developments.

Had an interesting day the other month when a friend of mine and a colleague of his with some new ballistic software were trying to persuade me that my range marks on my scope turrets were wrong as they didn't correlate to their calculations.
Anyway I hit the 6 in gong at 400m in a howling gale first shot and they with their rifles had to walk them in.

There is a place for ballistic calculations but its the practical that counts. Ballistic calculators are only as good as the information you give them and much of that needs to come from real field results. Nothing actually beats getting out there and actually doing it. Ballistic calculators will get you near and give you something to work from but they are no substitute to good marksmanship.

The challenge remains: to get that first shot strike from a cold position over terrain you have never shot over before. Threads like this can but add to ones confidence.

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Frank,

I really have trouble understanding why a software writer would include a SD function at all unless inputs for a specific barrel/bullet combination were part of the set-up... even then, the programming would be empirically based (like PRODAS).

That is alot to ask.

I am not following your 36% comment.

 

[Lowlight]

Re: Spin Drift at 1500 yards

welcome to my point Noel,

Some just have an "on or off" switch to "consider it" - i.e.: Bulletflight

Most are adding in the stability factor now, but previously it was pretty rare to find anything more than an on or off dialog. A few were not even putting in a barrel twist. For CE they ask for azimuth and such but I doubt anyone is breaking out a compass for the data, they just turn it on with the preset 45 degrees and go.

The thinking is, for a 308 1 MOA gets the job done, and is enough to let people "notice" it, but as for actually figuring it out. Not so much. They are using an acceptable, rounded, average.

 

[goober]

Re: Spin Drift at 1500 yards

Even after inputting all that I still have to adjust for the failings of my chronograph but real time POI -all part of the "WASH"

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

Frank,

So you are not playing down the utility of minor targeting corrections, you are simply critical of current software that pretends to predict them.

... That is reasonable.

My point is that these error budget items are, and will increasingly become, important as the tools that are used in ELR advance in capability.

There was a time when all that was needed to work on the family car was a Crescent wrench, and a hammer. I think that the state of small arms development is not far from that.

 

[Lowlight]

Re: Spin Drift at 1500 yards

Noel,

if you look at the images I posted, or any images of me on the line you will see a Trimble Nomad and my Databook. I also will spend a full day at the range calibrating my system (Scope, Rifle, Ammo, Shooter) and then return to confirm the data I have collected and calibrated.

I use good LRFs, Kestrel, good software and a GPS enabled PDAs, along with written data to estimate my initial shot. Especially in an ELR context, that coupled with some extra time setting up my position, fine tuning my NPA, and even pulling off a few dry fires before going live, because I know all the best data in the world will not help a poorly executed shot. ELR should, should, give me time and opportunity a target at close range does not. So care is to be taken in the execution.

Now, when all tools for ELR start to creep inside 800, 600, 400 and people begin to discuss "seeing" things people see beyond 1250m at shorter ranges, well then you'll get an argument from me. Because even in the context of ELR, very few at putting the time in to understand the execution of the shot is more important than anything else, because poor fundamental coupled with 6DOF computations are not gonna get you a hit, no matter what the computer says.

 

[Noel Carlson]

Re: Spin Drift at 1500 yards

"(When) people begin... seeing things people see beyond 1250m at shorter ranges, well then you'll get an argument from me."...

The thread title implies agreement with you. I know that you buy good tools, but you must admit... the stuff that you already know about, and cannot buy, is pretty impressive.

 

[Muskett]

Re: Spin Drift at 1500 yards

In times of people expecting instant gratification and the solution is all too often to just throw enough money at it, then its nice to see someone put the work load and application in. Then kind of them to share their results and thoughts. So thank you for that Lowlight.

Lowlight you are lucky though to be able to get out there and do it as for all too many there just isn't the time nor chance. Work load, family commitments and no 1500m range on their doorstep gets in the way somewhat.

However, having said that there really isn't any excuse for anyone not to get their marksmanship sorted, rifle, scope and ammunition set up just right. Even at shorter ranges there is a lot that can be done, and a lot of that away from the bench. I find too many shooters once they leave the firing point or bench go to pot. As you said all the calculations in the world aren't going to help solve a poor shot. At ELR then without making good the shots any hit is but luck. For too many shooters their first encounter of open country, live fire zone, are when they are hunting. Not the place to sort ones sh*t out. Fundamentals go out the window.

Its practice and building confidence which a lot can be achieved through familiarization of ones equipment and finding a shooting routine that one can stick too. A list of checks. Its the difference between letting go a good shot and just winging one off. Range shouldn't be an issue as you should be doing exactly the same be it 200m, 500m, or 1200m. What I find too often is that shooters don't set themselves up properly before going into taking the shot. Second or third shot they discover their error but thats a bit late. Setting the rifle down with some thought and then getting behind it properly, nestling down, is time well spent.

Just realized I'm typing for my own benefit, going through my own routine. Sorry for the indulgence, its wet, snowy and cold here, and reading the SD thread just make me want to get out there and try some stuff. Roll on some good weather. (Shooting in bad weather is good too).

 

[kraigWY]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">What I find too often is that shooters don't set themselves up properly before going into taking the shot. Second or third shot they discover their error but thats a bit late. Setting the rifle down with some thought and then getting behind it properly, nestling down, is time well spent.</div></div>

I think Muslett hit the nail on the head with this one.

Honestly looking back, I've done that myself, more then once.

We lay out in our back yard range shooting little targets yet muff a shot at an antilope at 400 yards because we ignor fundamentals because those suckers are so big we don't need fundamentals.

 

[Topstrap]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">

We lay out in our back yard range shooting little targets yet muff a shot at an antilope at 400 yards because we ignor fundamentals because those suckers are so big we don't need fundamentals.

</div></div>

Lots of us have run into the same thing over the years, smack that wee lil target way out there then miss a big one that might even be closer. I learned long ago to look at the very center of a target no matter how big it is and that is where we want to hit it. It's easy to think there is no way to miss that big target and get careless, strive for center hits no matter the size or distance and you'll get way more hits.

Topstrap

 

[Muskett]

Re: Spin Drift at 1500 yards

Imagine there is a tiny zit, tick or fly on the target. Concentrate on hitting the zit by placing the cross point of the cross-hair on it. Carry on concentrate on that until the rifle goes off. And keep doing it even after recoil. It takes time to decide and find your zit and some adjustment to get the cross point to settle on it. Thats your calm settling in moment to sort out your breathing and last blink. Only carry on when you are really relaxed, and had that last breath. Then go for max concentration and calmness.

You don't shoot at the target you shoot at a minute dot on it.
You don't use the reticule just the pin point.
You don't want to know when the gun goes off as you should be so much in the zone of keeping that pin on the dot that nothing else matters.
You don't need oxygen at that moment.
Keep on doing it after the event.
A zillion years later you can wake up from the zone and wonder what happened.. time to work the action and get back to reality.

Lastly, you can only hold the zone for about three seconds, and if you haven't let the shot go by then then you may as well breath, have some oxygen, and start all over again. You can't out wit your natural wobble so calm down and keep it to the minimum. Never deliberately pull a trigger just squeeze until it goes off.

Anyway thats how I do it, or something like it.

 

[wadcutter]

Re: Spin Drift at 1500 yards

Been out shooting a couple of times this week. Started off with 2345, 2334 and 2272 yards testing B.C. numbers on Berger 300 grain pills in dead calm conditions. Next day was back to 610, 543 and 385 yards busting clays for fun in a gusty wind.
Used S.D. and C.E. on the first day to the tune of 1.25 to 1.5 MOA left value and it seem to work out quite well.
No difference to the level of fun I had. Had a ball both days. Just love to get out there and send some lead!

 

[Lowlight]

Re: Spin Drift at 1500 yards

1.25 to 1.5 MOA @ 2k+ seems very reasonable... but being you are upside down, doesn't CE cancel a right hand twist barrel SD there ?

If CE cancels out a majority of the SD in a left hand twist here, (roughly) I would think the opposite is true for you ?

No matter, I would suspect that is closer to right than wrong, and if it worked then it was... At least you weren't using 1.5 MOA at 600 like a lot do here.

 

[wadcutter]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">1.25 to 1.5 MOA @ 2k+ seems very reasonable... but being you are upside down, doesn't CE cancel a right hand twist barrel SD there ?

If CE cancels out a majority of the SD in a left hand twist here, (roughly) I would think the opposite is true for you ?

No matter, I would suspect that is closer to right than wrong, and if it worked then it was... At least you weren't using 1.5 MOA at 600 like a lot do here.

</div></div>
Frank,
"Shooter" gives me 2.0 MOA left for SD and 0.7 MOA right for CE here at -38 deg in the South for my longest shot. So CE only cancels out about 1/3 of the SD for me.

 

[fuzzyjoe]

Re: Spin Drift at 1500 yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">Wow....

Shit like this is why we need more trigger time and less keyboard time folks.

If what you are doing works, then work it. If it doesn't then change it. Don't let math and theory get in the way of putting lead on target. </div></div>


How true!! practice... practice.. practice... till you get it right, and keep the data book up to speed and when you finally get it use the data book.