Attention Myth Busters!

T

Travelor

New member
I am a novice when it comes to reading the wind and coping with it, but I "think' I am able to read ballistic tables.

The fellow shooters at the line and on the Long Range Shooting Forum keep telling me that the 223 will not hold up to the wind as well as a 308 - they refer to bullet weights and field experience. They say that the 223 is MUCH HARDER to shoot well at 1000 yards due to greater affects caused by the wind on the lighter bullet.

Running the ballistic tables and cross checking velocities with a chronograph, I see that I can get a 223 Rem with a Berger 75 grain VLD to out perform a 308 with a Sierra 155grain MK's as far as wind drift is concerned. Also, I know from personal experience that my wife's 6mmBR with a 107 SMK requires less wind correction than my 308 with a 155 SMK when we shoot side by side in the same match as we compare wind settings and results.

Am I missing something or is this just an old range myth?
 
Ray,

That's because we're smarter, and know when to ignore benchresters! :D

Seriously, one of the issues we're up against is the BCs themselves. My experience says the published values aren't correct, but others disagree. On top of that, the most common model (G1) fails to adequately describe the performance of boattailed hollowpoint projectiles. Not surprising that predicted vs actual results fails at long range.

Solutions:
  • Generate your own ballistic tables. This means measuring muzzle and target velocities, or times of flight.
  • Use a more appropriate ballistic model. G5 or G7 work much better for boattail match bullets, especially if velocity near the target approaches the transsonic range (Mach 0.8 to 1.2). G5 is more appropriate for shorter radius ogive boattailed projectiles (i.e., Sierra 155), while G7 better models the behavior of low drag projectile designs (i.e., VLD bullets, and long ogive projectiles such as .224" 80 grain and 107 grain 6mm Sierras).
  • Accept the difference. Do a better job reading the wind, and outshoot your opponents. In other words, become a true rifleman.
 
mikecr said:
No you've got it. Simple BC
Click to expand...

Simple BC combined with muzzle velocity does determine both wind deflection and total drop. However, there is more to accuracy than that. All bullets have some level of instability even if they are perfectly made. Some computer programs can roughly predict the level of that stability but none can predict the trejectory varitions caused by it to the extent they can predict shot to shot point of impact or even group sizes. This is why short range benchrest shooters (with "short range" sometimes including 1000 yards) don't use the highest BC's or the highest velocities possible. That simply doesn't give the best accuracy unless the wind is so unpredictable that it dominate all other error sources.

Both the 308 and the 223 have a relatively low combination of muzzle velocity and BC (not a simple multiplication) compared to the top cartridges used for 1000 yard shooting but they are fairly competive with each other with proper bullet choice.

While Mythbusters is a fun show sometimes their experiments differ enough from the myths they're trying to bust that their conclusion (in my opinion) are wrong. A good example was how far you have to be underwater to be safe from a rifle bullet fired from above including a .50 BMG. They were definitely not using the .50 BMG ammo which would give the longest underwater range. I also question their conclusions about bullets fired into the air being deadly or not. Certainly dropping bullets from a balloon wasn't a valid experiment.
 
I guess it all depends on how you figure BC. Using Serra method, that has velocity as part of the component. Which would mean that the BC is ever changing with distance as velocity falls off.

Anybody bother to look-up the origin of BC and see the relationship between black powder and to today's use of the term?
 
I'll try again..
Regardless of cal, if you're competing at 1K with lower BC bullets(albeit accurate -up close), you've likely lost to the field before taking a shot.
This is because wind is the dominant factor at distance, and not accuracy. If it were the other way, the 6PPC would rule there as well..
No
Nearly everyone on that line is using heaviest per cal bullets. Some enduring way more recoil than they should to ensure this condition.
You should be grateful for any BC standard, and you should not deny the importance of it.
Especially, if you're one of the 99% shooting heaviest per cal...
 
Travelor

Myself and several others on this board shoot a local match each summer, that is broken into 3 classes. They are 223, Factory 30 cal, and anything,
factory30 meaning 308 & 30/06 in factory action and twist, ANYTHING meaning any gun 300 win mag & lower.

At every match the 223 shooters post higher scores than Factory 30. This has been a regular discussion, as most are loading 80gr Berger's out of 7-8 twist barells,& the 30's are mostly 178 SMK's out of 10 twist tubes.

Course of fire is 600,800,900,&1K, 5 rnds @ each, with no sighters. The score is 1 MOA= 10pts, 2 MOA= 5 pts, not as easy as most think,but the 223 pulls 10-12% higher scores.

I don't know if it help's you out, but it's what I have seen here over the last four years.


Mark
 
Mark,

It'd be interesting to see a break-down of the scores vs. caliber vs. range for that match.

I could easily see a .223 cleaning up at 600. I could even see it at 800. We don't see a lot of .223 in F-Class around here, but I have to wonder if they get far enough ahead and stay there.

I know myself and some others have toyed with the idea of a second gun in .223 rem for closer yard lines (600yds and in) since rule 9.1 (switching rifles) continues to get 'ignored' in F-Class. Figure if they're going to flaunt the rule (at least the Nationals specifically write it in the match bulletin that its is being ignored) might as well play along.

Monte
 
Well the one thing that strikes me as "funny" here is that no one tackled the obvious bullet problem.
You aren't compareing apples to apples. The 75gr in 223 I have no problem with, But the 155gr in 30 IS NOT a 1000 yard bullet! Unless you have a "holy-crap" house load, 168gr isn't a 1000 yard bullet. The 168's go sub-sonic somewhere after 900.

You need to compare the 175-178's to be apples to apples.
 
Darkker said:
Well the one thing that strikes me as "funny" here is that no one tackled the obvious bullet problem.
You aren't compareing apples to apples. The 75gr in 223 I have no problem with, But the 155gr in 30 IS NOT a 1000 yard bullet!
Click to expand...


Excuse me?!?

Pretty sure they work just fine to 1k, and a whole hell of a lot of people use them as such in Palma, TR, and F/TR

Generally speaking, the reason for comparing 75/80gr bullets to the 155s is because a) in some parts of the world (Canada for one), F/TR is limited to 81 grains or less in .224 cal, and 155gr or less in .30 cal, and b) the factory advertised BCs are comparable. The Berger 75 VLD lists at .447, and hte 80gr VLD at .471; by way of comparison, the 155gr BT lists at .453 (very close to the 155gr SMK and Nosler bullets, fwiw) and the 155gr VLD at .472. And the loads are going at comparable velocities (2900-3000+). So tell me again how we're not comparing 'apples to apples'?

YMMV,

Monte
 
Last edited:
Travelor said:
I am a novice when it comes to reading the wind and coping with it, but I "think' I am able to read ballistic tables.

The fellow shooters at the line and on the Long Range Shooting Forum keep telling me that the 223 will not hold up to the wind as well as a 308 - they refer to bullet weights and field experience. They say that the 223 is MUCH HARDER to shoot well at 1000 yards due to greater affects caused by the wind on the lighter bullet....
Click to expand...

Please post a reference to the thread from the LR forum.

In reading some ballistics tables.

.223 at 2900fps w/ 80gr Berger has 8.75moa wind drift @1000yds (10mph 90 degree to line of flight)

.308 at 2900fps w/ 155gr SMK/palma has 9.75 moa drift@1000yds (10mph 90 degree)

.308 at 2500fps w/ 210 berger vld has 7.50moa drift@1000yds (10mph 90 degree)

Kinda depends what you are comparing. Makes sense when you compare heavy for caliber bullets in both chamberings.

Thanks,
AJ
 
Last edited by a moderator:
Same BC, different caliber/weights

-----Just edited the post, with the hope of making it more understandable-----

I have never seen a treatment on wind deflection with transients conditions considered. The approach we all use is considered "static", in which the bullet drifts the whole duration of its retardance time.
No consideration is given that there is always some "slippage" at the very start/stop (transients) due to inertia, and this inertia is directly proportional to weight.
Let's consider this condition; a total reversal of wind conditions at half way down range. A shooter using same BC with light bullets, will read the condition closer to him, compensate for it, and get a wrong shot, because the wind downrage was capable to more than compensate the initial/closer drift, and maybe even make a reversal on total drift. Results: the shooter misread the condition and missed the shot.
In those same conditions, a shooter using same BC, but with heavier bullets, his shot placement was not as bad, because the downrange conditions was not able to outdo the inertial (kinetic) energy created by the first half of the drift, causing the bullet to impact in a more predictable manner, most likely NOT with a total reversal.
Taking the light bullet case/with same BC to its limit, an infinitesimally small/light bullet (zero+ grain but with same BC as a much heavier and practical one), will drift instantaneously to changes in wind, making it close to impossible to correct (dope) in any long range scenario. This case I think shows why heavier bullets are more "wind readable" in practice. All this is happening with the same BC, with the same muzzle velocity, with accordingly same ballistics.
All in all, I am a total believer of heavier is better for longer range. The problem is in having a heavier bullet with the same accuracy. To do same BC and heavier, it calls for a larger caliber, and handling the extra recoil becomes the issue.

Good shooting,

George
 
Last edited by a moderator:
2900-3000+ and you don't call that a hot load in a specific gun, for a 308?!
As I said, average load for each, not holy crap!
If you stay in the average range the 155's will be going sub-sonic before the 1,000yard mark.
I'm not saying it Can't be done. I'm saying the heavier bullets are easier to get it done.

IF, as it has been pointed out since the post, you are comparing apples to apples; you must compare "heavy for caliber" against "heavy for caliber" bullets.
Not heavy versus light.
Next time you go towards the Tri-Cities Monte, you bring your loads, I'll buy lunch, and we'll have a good time throwing lead.
 
Nope. No a hot load at all, and it's one thats been in use for years (probably decades) in Palma/TR. Long (30-34") premium match barrels with tight chambers, short throats and slow twists (1-12, 1-13, etc.) help, but I've also punted 155s out at 2890-2930fps from 26" factory Savage and Remington barrels. My factory 12 F/TR tube did 2960 w/ a Berger 155gr VLD.

Honestly, it really is a 'standard' load. If I'm not mistaken, the U.S. Palma team specs 2950-2975 as the 'target' velocity for team members to load their ammo to. The 155 really sings in that region, and it simplifies the wind calls for the coaches to have everybody shooting nearly the same load. Ask any Palma or TR shooter how fast their 155 loads are going: The slowest I've heard of is the load the Brits used @ the World LR championships this past summer - 2860fps w/ a Berger 155 BT.

Like I said, the standard Palma .308 load is a 155 @ 2900-3000fps, and since the bullets have comparable BCs, the .223 loads get compared against it. I've heard (and sadly, heeded) the same 'wives tales' mentioned by the OP. Generally I've found that by the time the gents on the line make it to High Master w/ a sling, they've tried enough stuff that I tend to take it seriously but usually I follow the 'trust but verify' creed. I certainly wouldn't mind shooting a .223 if it holds up in switchy winds - less recoil almost always allows a shooter to perform better.

There's a Palma/65 match for Prone/F-Class down @ Rattlesnake on February 23rd... 15rds each @ 800/900/1000, plus another 20 @ 1000yds. See ya there.

Who do I ask for again? ;)



Monte
 
Last edited:
Milanuk found it

I knew soon or later someone would find this same posted question by me with replies on the Long Range Target Shooting Forum. I posted here as I believe this Forum is more analytical than the other one when it comes to theory meeting the target.

The posters on LR Shooting Forum were reporting on field observations rather than ballistic tables which is undeniable the best way to analyze as long as everything else is equal, HOWEVER, one wonders if this field observation is based upon similar level shooters or not. My very limited observations are that 223's are shot more by entry level shooters that 308's. Remember I said very limited observations.

My thoughts are that to see if there really is a difference would be to shoot equal qualitiy guns in the two calibers from a bench by the SAME High Master shooter on the same day and see how the scores/groups fall out.

Thanks for the thoughts and insights. Learning every day.

George
 
Travelor said:
I knew soon or later someone would find this same posted question by me with replies on the Long Range Target Shooting Forum. I posted here as I believe this Forum is more analytical than the other one when it comes to theory meeting the target.
Click to expand...
Horsefeathers. Many of the same people there are here as well. That pool of shooters includes retired and practicing engineers, race car mechanics, pilots, and even farmers. All of whom are very much interested in how theory translates to the real world - and often, how well the theory applies. Some of the posters in your LRTS thread are also some of the best in the world in the prone shooting game - lots of experience.

The posters on LR Shooting Forum were reporting on field observations rather than ballistic tables which is undeniable the best way to analyze as long as everything else is equal, HOWEVER, one wonders if this field observation is based upon similar level shooters or not. My very limited observations are that 223's are shot more by entry level shooters that 308's. Remember I said very limited observations.

My thoughts are that to see if there really is a difference would be to shoot equal qualitiy guns in the two calibers from a bench by the SAME High Master shooter on the same day and see how the scores/groups fall out.
Click to expand...

Heretical Statement: Shooting from the bench isn't the only way to test how well a rifle and ammo shoot. Quite a few accomplished long range shooters don't. When you're talking about prone and F-Class shooting, remember this: It's the archer that usually makes the biggest difference, not the arrow. A 1/4 MOA rifle in the hands of a 1.5 MOA holder (RSS = 1.52) simply won't perform as well as a 1 MOA rifle in the hands of a 1 MOA holder (RSS = 1.41 MOA).

There is also an intangible factor that shooting from a bench probably won't give you. I know of at least one HM who gave up shooting .308s and switched to .223s for the long range prone game. Not because of a difference in group size, but because the cumulative effects of less recoil made it easier to shoot the .223 well over several days. (Prone matches usually consist of 60+ shots/day.)

DISCLAIMER: I am an Admin at Long-Range.com, though derive no financial or material benefits from doing so.
 
Darkker....

155 at 2950 is not a holy crap load... It is a standard when shooting Palma, the key is Palma rifles have 30 inch barrels. This is easily achievable with Lapua Brass, Sierra 155 bullets, Federal GM 210 M primers and, a dose of Varget.

Paul
 
Louis Boyd said:
While Mythbusters is a fun show sometimes their experiments differ enough from the myths they're trying to bust that their conclusion (in my opinion) are wrong. A good example was how far you have to be underwater to be safe from a rifle bullet fired from above including a .50 BMG. They were definitely not using the .50 BMG ammo which would give the longest underwater range. I also question their conclusions about bullets fired into the air being deadly or not. Certainly dropping bullets from a balloon wasn't a valid experiment.
Click to expand...

My Son saw this programme the other day and asked me about it and bullets in the water. He had heard me tell stories of what happened to the NVA and Vietcong when they would dive in the canals, trying to escape us overhead shooting at them with M-60's from helo gunships. I see in my minds eye the results often, what goes down must come up. When people are in a panic, they use up O2 much faster. These people were in a panic, the canals were no deeper than 12 ft. not once do I remember any man that jumped into the water surviving, you can't tell from the surface how deep a man is under the surface. Every crew member knew that a man under the water was a dead man. This was shooting one in five, ball, tracer 7.62 NATO ammo. That friends is the real world of bullets in the water, not Hollywood's version.
 
You must log in or register to reply here.
Back
Top