hoogste spoed met minste dryfmiddel?

[bullseye]

Middag manne

Het iemand dalk al kon uitwerk watter kaliber die beste perform met die minste dryfmiddel? Ek het so bietjie op Quickload gespeel en dit wil lyk of die 6mm Dasher een van die bestes is.Ek sien Quickload praat van "ballistic efficiency".Die rede hoekom ek vra is, hoe beter ballistic efficiency is hoe langer behoort loop te hou.Byvoorbeeld 6.5x47 lapua en 260 rem lyk vir my baie beter as 6.5x284.Laasgenoemde lyk vir my baie swaarder op brandstof te wees.
Wat ek eintlik soek is ,die platste trajek dit wil vir my voorkom of spoed meer bepalend as bc is alhoewel bc die 2de belanrikste is, in terme van trajek. Byges? trajek tot op 400m.
Hoop iemand kan beter verduidelik . Daar is seker nie n beste nie, maar daar behoort een baie naby te kan wees.

Groetnis
Ben.

[Francois Marais]

Ben

Baie interresant....sal die post bietjie dophou....

Mooi loop
Francois

[Gerhard]

Ben

Baie interresant....sal die post bietjie dophou....

Mooi loop
Francois

Francois,

Hoe vergelyk die Koevoet ?

[IndianLima]

Ek het op n stadium n 6mm Dasher geskeit in F-Open, sy trajek was maar dieselfde as die 260 rem of soortgelyk. Sy loop het ook maar hier by 3000 skote suid begin gaan...

ek dink min kalibers kom by die loop leeftyd van n .308 Win?

Ivan lamprecht

[Danie Lombard .243]

Ek sou ook reken saam met Indian Lima dat die .308 Win die meneer is waneer dit by loop leeftyd kom. Ek myself het al paar duisend skote deur my .308 en hy in nog baie akkuraat.

[MJK]

Ek is nou terug, gaan gou popcorn haal 

Stem vir die 308Win

[BLOK]

Ek haal die man se vraag aan.

"Wat ek eintlik soek is ,die platste trajek dit wil vir my voorkom of spoed meer bepalend as bc is alhoewel bc die 2de belanrikste is, in terme van trajek"

Hy soek nie n gradeboog geweer nie

Nou het ek hom gesturrr

Sal maar ook die popcorn gou gaan skiet.

[bullseye]

Ek hoor wat jy s? Ivan en Danie, dalk druk ek myself nie reg uit nie.Ek stem saam 308 sal goeie loop leeftyd he.maar 308 het nie n goeie trajek nie, daarmee s? ek glad nie dat 308 nie akkuraat is nie, in iemand se hande wat afstand skat goed kan doen sal 308 uitstekend werk.

Waarna ek soek is die platste trajek met die minste brandstof.Bedoelende ek besef hoe platter die trajek hoe meer ibrandstof is nodig. byvoorbeeld ek vermoed dat dasher meer doeltreffend as 22-250 kan wees,bv 25 koevoet en 25wssm ligter op brandstof is as 257 weatherby.

Ek het die teorie al op internet raak gelees  : n langer dop met n ligte punt beter perform as n lang dop met n swaarder punt, n korter dop met n swaarder punt beter as n kort dop met n ligter punt, dink julle daar steek waarheid in?

GROETNIS
BEN

[MJK]

O - ek het weer verwys op die term "ballistic efficiency"

[300Winmag]

Waarna ek soek is die platste trajek met die minste brandstof.

Ek dink die 260 is beter opsie as die .308 as jy die bg kyk en dit wil doen tot op 400 meter

[Wouter Roets]

Ben

Net vir interessandheid. Ek speel ook baie hiermee rond en my laaste kaliber wat ek aangeskaf het gee met ons poeiers vir my baie naby aan die beste van al die werelde nl die 6.5 Creedmore van Hornady. Hy doen basies wat die 260 Rem doen met minder poeier. Met die 28duim loop konfigurasie slaan hy om alles te kroon presies n node op maksimum druk met 130gr Bergers. Die looplewe na wat ek kon opspoor op die net behoort ook uitstekend te wees.

Groetnis
Wouter

[IndianLima]

Ben,

Daar is n Amerikaanse s? ding wat gaan "the shorter, the fatter, the better!". As ek net my Dasher kon kry dat hy betroubaar uit n magasyn voer was dit beslis die gun vir my!

Ek het maar 33,5gr gegooi om die Berger 108BT hier by 3000fps rond te gooi. Hy het bitter mooi gewerk tot hier op 600m en selfs op 900m as dit lekker windstil was.

[JACQUES BOTHA]

IL
AS DIT SO GEWERK HET OP MENSE WAS EK EN USAIN BOTL VANDAG IN KOMPETISIE....
EK IS STOUT OOR DIE KORT VET DOPPIES EK REKEN MENS KAN N 243 UGLY OOK IN REKEN IN DIE KORT VET DOPPIES?
MAAR SAL NOGAL N 6MM PPC GENIET EN OOK VAN DIE ANDER, SODRA HULLE DOPPIES GEREDELIK BESKIKBAAR IS EN HULLE MOOI GLAD VOER IN N ROER..
EK JEUK AL LANKAL MAAR MAAK GEREELD N DRAAI BY DIE TURKSVY BOS...
MOOILOOP
JACQUES 

[300Winmag]

Net vir interessandheid. Ek speel ook baie hiermee rond en my laaste kaliber wat ek aangeskaf het gee met ons poeiers vir my baie naby aan die beste van al die werelde nl die 6.5 Creedmore van Hornady.
Wouter

Voor ek die Sweed gekoop het het ek die een ernstig oorweeg - Classic Arms sal een vir mens invoer - maar ek was bang ek sukkel
met doppe.

[Wouter Roets]

300

Hy kom standaard in die Ruger Varminter en die doppe kom van Hornady. Ek het 600 bestel so dit behoort my vir so n rukkie te hou!

Groetnis
Wout

[bullseye]

More manne

Jacques en Wouter, ja dit wil lyk asof die dop se vorm of skouers baie met dryfmiddel effektiwietyd (torque soos in enjins) te doen het.Met ander woorde dop met meer effektiewe skouers kan hoer spoed gee met dieselfde lading dryfmiddel en gewig koel

plat trajek en loop leeftyd = spoed+dryfmiddel+bc+dopform.
As ek anders om kan vra ,wat dink julle sal die beste kaliber wees rondom bogenoemde formule? Gegewe die maksimum afstand 400m.
Verstaan ek dit reg: as verskillende kalibers koels skiet teen dieselfde spoed en dieselfde bc vir beide kaliber koels dan sal trajek dieselfde wees?

groetnis
Ben.

[bullseye]

middag manne

hierdie stukkie interresante inligting op net gekry:hat?s Wrong With .30 Caliber? Bryan Litz BSL135@yahoo.com
Introduction
In recent years, long range shooting has evolved in many ways. One of the major trends is towards smaller calibers. Calibers as small as 6mm, and even .224? are commonly being used in 600 and 1000 yard prone and Benchrest competition. In spite of the once common knowledge that ?bigger is better? for long range shooting, the ?benchmark? has shrunk from the big .30 cal magnums to the more moderate 6.5mm. Long range championships are being won with the tiny 6mmBR once thought underpowered for all but short range Benchrest competition. Why is this? Why is the once venerated .30 caliber loosing so much ground to the smaller calibers for long range shooting? Recoil, of course, plays a major role, but that?s not all there is to it. Applications and Assumptions
This analysis will focus on the external ballistic performance of small arms bullets, specifically for long range prone and benchrest target shooting as well as long range hunting and tactical applications1. In these applications, one of the most important measures of ballistic performance is wind drift. Therefore, the relative quality of bullet performance will be judged based on how resistant the round is to wind deflection. In this article, the terms ?scale? and ?scaling? are used to in the context of ?scaling the size?, not ?weighing on a scale?. Bullet Weight and Scaling The May 2007 Issue of Precision Shooting [Ref1] featured part one of a series authored by yours truly that focused on the effects of scaling bullets. The mass, Ballistic Coefficient (BC), stability, velocity, recoil and other effects were described. For this discussion, I would like to focus on bullet mass, and how it?s affected by scaling between calibers.
It?s a generally accepted fact that the heaviest bullet in a given caliber is the best bullet to use for long range target shooting. There are several credible studies on this topic, [Ref2] [Ref3] and it is one of the fundamental truths of long range ballistic performance. Assuming constant form factors (drag profiles) heavy bullets will have higher BC?s than lighter bullets of the same caliber. Heavier bullets will also have lower muzzle velocities than lighter bullets, but when loaded to the same pressure, the higher BC of the heavier bullet is more valuable than the higher muzzle velocity in terms of retained velocity and wind deflection at long range. German Salazar put it aptly: ?Muzzle velocity is a depreciating asset, not unlike a new car, but BC, like diamonds, is forever.? For
1 Not all bullets used in the examples are recommended for hunting, but the trends apply to hunting bullets as well.
this reason, the present discussion focuses on the heaviest bullets available in each caliber.
Figure 1 shows how bullet weight is affected when you scale the well known ?heavyweight? 6.5mm 142 grain Sierra MatchKing bullet up and down in diameter. You can see that a ?heavyweight? .224? bullet is ~89 grains. Makes sense, as 90 grains is the heaviest .224? bullet available. The heavy 6mm bullet is 112 grains. Ok, we know that 115 grains is about the practical upper limit for that caliber, and there are several fine offerings from Berger and DTAC in this weight range. The 142 grain 6.5mm that was chosen as the basis of comparison is in good company. In that weight class, you have the Berger 140VLD, 140BT and 140 Short BT, the Sierra 142 MK, the Hornady 140 Amax, the Lapua 139 Scenar, and the 140 grain JLK. That?s 7 legitimate ?heavyweight? bullets in 6.5mm. Move up to 7mm where the ?heavyweight? is supposed to be 177 grains, and you have the Berger 180 VLD, the Sierra 175 MK, and the JLK 180 VLD.
Now move up to .308 caliber. According to the established trend, a real ?heavyweight? .30 caliber bullet should weigh 229 grains. How many .30 cal bullets are that heavy? You?ve got the Sierra 220 and 240 grain MatchKings. Next heaviest things are
Scaled Weight Compared to Actual Weight
Predicted Weight scaled from 142 gr bullet
89 gr
112 gr
142 gr
177 gr
229 gr
Weight of actual bullets (gr)
90 gr
115 gr
142 gr
175 gr
220 gr
Figure 1. The true ?heavyweights? for various calibers.
the Sierra 210, Berger 210, Hornady 208, etc. So there are only two bullets, the Sierra 220 and 240 grain MatchKings that are even in the neighborhood of what a ?heavyweight? .30 caliber bullet should be. Let?s take a look at the 240 grain MatchKing. This ?mamba-jamba? freight train of a bullet shares the same tangent ogive nose design as all of the .30 caliber MatchKings down to 155 grains. The ogive looks short and blunt on such a long bullet which affects the aerodynamics which will be the topic of the next section. The long bullet has other common problems as well, in particular, the excessive copper fouling caused by the long bearing surface. Prolonged success with the 240 grain MatchKing is intermittent at best, and experiences vary among those who?ve tried them in competition. At 11 grains over the trendline, maybe it?s just a little too long.
The 220 grain MatchKing is only 9 grains below the trendline, which isn?t so bad. As far as legitimate ?heavyweight? .30 caliber bullets, this is probably the best option available, yet it doesn?t seem to be very popular.
I think part of the reason these heavy .30 cal bullets get overlooked is because many shooters think that a 185-190 grain bullet is ?heavy? for .30 caliber. In fact, a 190 grain .30 caliber bullet is somewhat of a ?middleweight?. To put it in technical perspective, a .30 caliber 190 grain bullet is proportional to a 150 grain 7mm bullet, 120 grain 6.5mm bullet, or a 95 grain 6mm bullet. The 155 grain bullet used in Palma competition is very much a ?lightweight? for .30 caliber. 155 grain bullets are used for international Palma competition because the rules specifically require it, not because 155 grains is the best weight for a .30 cal bullet at long range. Recently, some 155 grain bullets made by Berger and Sierra are designed with different, more aerodynamic profiles that help to compensate for being so light. The reduced drag helps them make up some ground compared to their conventional heavier counterparts, and introduces the next section of this article: aerodynamics.
History also plays an important role in the perception of ?proper? bullet weights for .30 caliber. As pointed out by Dr. K. C. Erikson in 1995 [Ref5], and more recently by German Salazar, .30 caliber shooters used ~173 grain bullets as their standard for many decades before long range shooting became popular and the modern push towards really heavy bullets came about.
Aerodynamics
Ballistic Coefficient is comprised of three components: mass, cross sectional area, and drag [Ref1]. Mass was discussed in the previous section. The cross sectional area is related to the caliber of the bullet. The drag of the bullet, measured by the form factor, is a big part of the problem with .30 caliber bullets.
The aerodynamic drag which acts to slow a bullet down is related to how streamlined its profile is. Just like a Corvette has less wind resistance than a VW Bug, so a long sleek VLD with a boat-tail has less aerodynamic drag than a short, fat, flat based bullet. If two bullets have the same mass and diameter (same sectional density), the one with less drag will have the higher BC. The ?drag? part of the BC equation is quantified by the form factor. The form factor simply relates the drag of the bullet to the drag of some standard bullet. For this
discussion, I?ll refer to the G7 standard because it?s more appropriate for long range bullets than the classic G1 standard [Ref4]. A bullet with a G7 form factor of 1.000 has exactly the same drag as the G7 standard projectile. A G7 form factor less than 1.000 means the bullet has less drag than the G7 standard, and a form factor greater than 1.0 means the bullet has more drag than the G7 standard. A bullets BC is simply its sectional density divided by its form factor.
Let?s take a look at some of the ?heavyweight? bullets in various calibers and see what their form factors are. Figure 2 shows the profiles of some popular heavyweights in 6mm, 6.5mm and 7mm along with their G7 form factors, sectional density, and G7 BC. The BC data presented in Figrure 2 was measured using a technique of proven accuracy and repeatability. The details of the BC testing are not important, it?s just important to note that these numbers were all measured in the same way, and were not obtained from the manufacturers [Ref4].
So what do the numbers tell us? Well, the G7 form factors of the 6mm bullets are right around 1.0, which is pretty good. The form factors of the heavy 6.5mm and 7mm bullets are on average less than 0.95 which indicates extremely low drag. The G7 form factors of the more blunt .30 cal heavyweights are ~1.08 average. That?s about 13% higher drag than the 6.5mm and 7mm bullets. 13% more drag is a huge deal. It would mean 13% lower BC if the bullets had the same sectional density, but the heavy .30 caliber bullets have about 9% to 13% higher sectional density than the 7mm and 6.5mm bullets, respectively. The result is that the heavy, blunt .30 cal bullets have a BC that?s only marginally greater than the 6.5mm bullets, and about equal to the heavy 7mm bullets.
One more thing to consider about aerodynamics is the effects of aftermarket bullet modifications, specifically, pointing. Bullet pointing reduces drag more for smaller caliber bullets than for larger caliber bullets. The reason is because nominal meplat diameters are proportionally larger on smaller bullets,
6mm
i7
Sd
(lb/in2)
G7 BC
(lb/in2)
115 VLD
0.987
0.278
0.282
115 DTAC
1.007
0.278
0.276
6.5mm
140 VLD
0.944
0.287
0.304
142 SMK
0.968
0.291
0.301
7mm
180 VLD
0.946
0.319
0.337
175 SMK
0.948
0.310
0.327
.308 Caliber
220 SMK
1.068
0.331
0.310
240 SMK
1.092
0.361
0.332
Figure 2. Notice how blunt the heavy .30 cal bullets are compared to their smaller caliber ?heavyweights?. The relative bluntness of the .30 cal bullets produces more drag, and hurts the BC.
so reducing them helps more. For example; a 0.065? diameter meplat is only 21% of .308 caliber, but it?s 27% of the 6mm caliber. Squeezing the meplat down to 0.040? makes it 13% of .308 caliber and 16% for 6mm caliber. The difference doesn?t seem like much, but there are two things to remember. First of all, the area of the tip is what?s important, and the area scales with the square of the diameter (meaning the smaller caliber has even more of an advantage than indicated by the above numbers). Second of all, the smaller bullets tend to operate at higher average speeds than the larger bullets. The reduction in wave (supersonic shock) drag is more significant for the smaller bullets traveling faster. Effects of bullet pointing are brought up because it?s another variable in favor of smaller calibers. However, the rest of the discussion will go back to considering unmodified bullets.
A Closer Look at Recoil
I?ve mentioned recoil as a negative effect of the larger calibers, but the subject warrants a little more discussion. The following discussion is about recoil in general, and is not specific to the .30 caliber.
There are basically two different ways in which recoil is bad for accuracy and precision. The first is the effect it has on the mental state of the shooter, and their ability to deliver well executed shots. Many shooters develop a ?flinch? from anticipating the heavy recoil. This is a problem that affects shooters to various degrees, depending on mental discipline, physical size, etc. Heavy recoil also has a way of ?loosening up? a position, requiring the shooter to re-adjust periodically thru a string of fire. This seemingly minor inconvenience can prevent a shooter from shooting as fast as they would like. Speed can very often be of the essence, especially in Benchrest shooting where you don?t have to wait for pit service.
The second aspect of heavy recoil is the effect it has on the rifle itself. The high pressure and heavy masses moving around tend to set the rifle in motion early (before the bullet exits the muzzle) more so than a smaller caliber shooting lighter faster bullets. German Salazar describes this as ?barrel movement during barrel time?. It reasons that when shooting such heavy recoiling rifles with slow heavy bullets, that accuracy is much more sensitive to the quality of the shooters hold, trigger squeeze, and most importantly Natural Point of Aim (NPA).
To sum up: heavy recoiling rifles are harder to shoot accurately. Even if a shooter overcomes the mental aspect of heavy recoil, the ?system? is more sensitive to minor imperfections in shot execution. This may be another reason that drives .30 cal shooters down to the ?middleweight? 190 grain class bullets instead of the proportionally heavy 220-240 grain bullets.
Note; the above discussion on recoil is most pertinent to prone target shooting where the rifle has to be supported by the shooter. Benchrest shooters who use heavier rifles, supported by steady rests are not as subject to the ?barrel movement during barrel time? gremlin as prone shooters, and may be why .30 caliber hasn?t fallen out of favor for Benchrest as much as prone shooting in recent years.
Conclusions
The heaviest 7mm and .30 cal bullets have practically the same BC, which means that given equal muzzle velocities, both will be deflected an equal amount in a given crosswind.
However, consider the statement: ?assuming equal muzzle velocities??. Even a moderate 7mm chambering is capable of delivering 2800 to 3000 fps with the heavy 7mm bullets, much faster with magnums. The heaviest .30 cal bullet requires a big magnum just to get to 2800 fps. So the first problem is: you can?t get the heavy .30 cal bullets going as fast as the heavy 7mm bullets! Even if you could get the same muzzle velocities from the heavy .30 cal bullets, it would take much more powder to do it, barrel life would suffer, and you?ve only achieved parity with the 7mm. The various negative effects of the incredible recoil is really just the ?nail in the coffin? for the heavy .30 caliber bullets. If the available heavy .30 caliber bullets had lower drag profiles, they would have higher BC?s, and wouldn?t require equal muzzle velocities. Remember, when loaded to the same pressure, a bullet with a higher BC will have less wind deflection even though it starts at a lower muzzle velocity. But the truth of the currently available heavy .30 caliber bullets is; they don?t have higher BC?s than the heavy bullets in smaller calibers.
To answer the question posed by the title: What?s wrong with .30 caliber? I offer the following explanations:
? Lack of legitimate ?heavyweight? (~230 grain class) .30 caliber bullets.
? The bullets that are in the ?heavyweight? class for .30 caliber have higher drag profiles than the heavy bullets in smaller calibers.
? Most .30 caliber long range shooters use 190 ? 210 grain bullets, thinking that?s ?heavy enough?, when that?s actually a ?middleweight? bullet for .30 caliber. These ?middleweight? bullets, even from .30 cal magnums, will tend to suffer more wind deflection (if only slightly) when compared to the ?heavyweight? 6.5mm and 7mm offerings.
? The energy (powder) required to propel a truly ?heavy? .30 caliber bullet to reasonable speeds produces recoil that?s considered prohibitive for most applications, except maybe unlimited class Benchrest where rifles have no weight restriction.
Many people do very well with .30 caliber rifles at long range. I have to ask: are they doing well because of the caliber, or in spite of it?
Acknowledgment
I would like to thank German Salazar for his contributions to this article. In particular, the resources and advice provided on the historical perspective of .30 caliber match bullet development are critical to the understanding of this caliber today. Furthermore, an explanation of the recoil affects by someone who?s shot a lot of 240 grain .30 cal bullets downrange was a valuable contribution.

groetnis
Ben.

[bullseye]

MORE MANNE

EK SPEEL NOG STEEDS MET QUICKLOAD EN DIE VOLGENDE WAS BAIE INTERESANT VIR MY. ONGEAG DIE LOOPLENGTE WAS DIE SPOED DEURGANS BASIES DIESELFDE VIR BESTE NODE, KLEIN VERSKILLE IN SPOED.AL WAT GEBEUR HET WAS DAT DRUK OPGEGAAN HET IN KORTER LOPE.EERS OP 28.5 DUIM LOOP KON OORGEGAAN WORD OP ANDER NODE VIR HOER SPOED. AS DIT DIE GEVAL IS DAN VAT EK MAAR EERDER N KORTERLOOP VIR MAKLIKER HANTERING EN VERLOOR DAN MAAR N PAAR SKOTE AS GEVOLG VAN HOER DRUK.HELP MY ASSEBLIEF AS EK VERKEERD REDENEER.

GROETNIS
BEN.


LENGTE LOOP SPOED DRUK NODE KRUIT

20 3628 59553 0.853 38.1
21.5 3617 55395 0.918 37.2
22 3621 54510 0.936 37
23 3608 51936 0.981 36.4
24 3602 49881 1.022 35.9
25 3603 48294 1.062 35.5
26 3593 46376 1.106 35
27 3690 44895 1.146 34.6
28 3585 43458 1.187 34.2
28 3923 58608 1.036 37.9


55GR SIERRA 1455 PUNT
SEATING DEATH 4.52MM
CARTRIGE LENGTE 2.541"
WATER KAPASITEIT 45.5
WEIGHTING FAKTOR .4
S355  80FHARENHEIT
BURNING RATE FACTOR .5400