God video, tak for linket [
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Jeg svinger imellem at have venstre hånd på sandsækken (pølsen) under bagskæftet og solidt fat i forskæftet. Prøvede idag at skyde over sandsække for og bag med en 30.06’er, og der er måske en tendens til at gruppen åbner sig en smule op ved ”loose hold”. Jeg tager altid et par tøraftræk imellem skuddene, så piben får lidt køletid, og ved loose hold så ses der mere bevægelse under tør-aftræk pga det manglende hold i forskæftet (med mig som skytte). Så om det er finger bevægelse ved aftræk eller ”barrel movement during barrel time” kombineret med ændret rekyloptag, der åbner gruppen ved ”loose hold” kan jeg ikke afgøre.
3 skud i center af target med hold i forskæftet
![[Image: njJiaql.jpg]](http://thumb.ibb.co/ejWwzn/njJiaql.jpg)
3 skud mere med frit forskæfte
![[Image: 5masE6K.jpg]](http://thumb.ibb.co/eTCmzn/5masE6K.jpg)
Når man laver samme test med samme riffel og ammunition skudt fra bænk med fast ”bagkappe” er variationen loose vs hard hold 2-3 cm. Så skydebænken er ikke altid Guds gave til hjemmeladeren der tester ladninger[:I]
”Froggy” her siger at loose hold/free recoil ikke virker for ham med hans 308win, men han konstaterer at det virker for andre med 6mm kalibre http://www.6mmbr.com/TacticalFroggyA1.html. Og free recoil virker jo fint med fx min STR med 22LR, så måske går der en form for grænse mellem 6mm- og .30 kalibrene og behovet for hard hold for os almindelige dødelige ?
Her mr. Salazar’s spekulationer om rekyloptag, ”barrel movement during barrel time” og kaliberstørrelse
"An analysis of many years of plot sheets from 600 to 1000 yard matches shows that I, like many shooters, tend to lose points to shots “in the corners” at 2:00 or 10:00. These shots are not simply the innocent byproduct of a poorly timed pulse beat and an unseen gust of wind; they are most frequently the result of the muzzle moving in that direction just as the shot breaks – even if that movement is within the X ring. These plot sheets also show that these corner shots happen far less frequently with cartridges such as the 6BR and 6XC than with the .308 and .30-06. Do we move less when shooting small calibers? No, of course not. The real culprit is the amount of muzzle movement after the shot breaks but before the bullet clears the muzzle. This is barrel movement during barrel time (BMBT). BMBT tends to carry the muzzle in the direction in which it was moving when the shot broke. How far it carries the muzzle is the salient point of this discussion.
Let’s assume for the moment that we have three cartridges with a muzzle velocity of 2800 fps. A 6BR with a 105 grain 6mm bullet, next a 6.5-08 with a 142 grain 6mm bullet and a .30-06 with a 190 grain bullet. All three will have roughly the same barrel time, but we can agree that the recoil will be markedly different. In fact, we quickly realize that unless the shot breaks with a perfectly still muzzle, the additional BMBT of the heavier 30 caliber bullet will result in the muzzle pointing further away from the center of the target at the moment the bullet exits. Thus, whereas the 6mm that breaks in the X ring moving towards two o’clock will still give you an X at two o’clock, the 6.5mm will often give you a 10 at two o’clock and the .30-06 will give you a nice fat 9 at two o’clock. Increasing the bullet weight will make this worse, not better. In order to eliminate the effect of BMBT, we would have to scale the rifle and shooter as well as the bullet. Since that might be a tad impractical, a higher BC bullet in 30 caliber will have to rely on low drag design, not increased mass if it is to have any chance at success; but even then, a similar design in a smaller caliber would be a better choice."
Kilde:
http://riflemansjournal.blogspot.dk/2009...lemen.html
Testet:
Tikka Varmint 3006, 2-7x33 Leup VXR
165grs SST, 51grs RP15, S&B hylstre
Mvh Pete
]Jeg svinger imellem at have venstre hånd på sandsækken (pølsen) under bagskæftet og solidt fat i forskæftet. Prøvede idag at skyde over sandsække for og bag med en 30.06’er, og der er måske en tendens til at gruppen åbner sig en smule op ved ”loose hold”. Jeg tager altid et par tøraftræk imellem skuddene, så piben får lidt køletid, og ved loose hold så ses der mere bevægelse under tør-aftræk pga det manglende hold i forskæftet (med mig som skytte). Så om det er finger bevægelse ved aftræk eller ”barrel movement during barrel time” kombineret med ændret rekyloptag, der åbner gruppen ved ”loose hold” kan jeg ikke afgøre.
3 skud i center af target med hold i forskæftet
3 skud mere med frit forskæfte
Når man laver samme test med samme riffel og ammunition skudt fra bænk med fast ”bagkappe” er variationen loose vs hard hold 2-3 cm. Så skydebænken er ikke altid Guds gave til hjemmeladeren der tester ladninger[:I]
”Froggy” her siger at loose hold/free recoil ikke virker for ham med hans 308win, men han konstaterer at det virker for andre med 6mm kalibre http://www.6mmbr.com/TacticalFroggyA1.html. Og free recoil virker jo fint med fx min STR med 22LR, så måske går der en form for grænse mellem 6mm- og .30 kalibrene og behovet for hard hold for os almindelige dødelige ?
Her mr. Salazar’s spekulationer om rekyloptag, ”barrel movement during barrel time” og kaliberstørrelse
"An analysis of many years of plot sheets from 600 to 1000 yard matches shows that I, like many shooters, tend to lose points to shots “in the corners” at 2:00 or 10:00. These shots are not simply the innocent byproduct of a poorly timed pulse beat and an unseen gust of wind; they are most frequently the result of the muzzle moving in that direction just as the shot breaks – even if that movement is within the X ring. These plot sheets also show that these corner shots happen far less frequently with cartridges such as the 6BR and 6XC than with the .308 and .30-06. Do we move less when shooting small calibers? No, of course not. The real culprit is the amount of muzzle movement after the shot breaks but before the bullet clears the muzzle. This is barrel movement during barrel time (BMBT). BMBT tends to carry the muzzle in the direction in which it was moving when the shot broke. How far it carries the muzzle is the salient point of this discussion.
Let’s assume for the moment that we have three cartridges with a muzzle velocity of 2800 fps. A 6BR with a 105 grain 6mm bullet, next a 6.5-08 with a 142 grain 6mm bullet and a .30-06 with a 190 grain bullet. All three will have roughly the same barrel time, but we can agree that the recoil will be markedly different. In fact, we quickly realize that unless the shot breaks with a perfectly still muzzle, the additional BMBT of the heavier 30 caliber bullet will result in the muzzle pointing further away from the center of the target at the moment the bullet exits. Thus, whereas the 6mm that breaks in the X ring moving towards two o’clock will still give you an X at two o’clock, the 6.5mm will often give you a 10 at two o’clock and the .30-06 will give you a nice fat 9 at two o’clock. Increasing the bullet weight will make this worse, not better. In order to eliminate the effect of BMBT, we would have to scale the rifle and shooter as well as the bullet. Since that might be a tad impractical, a higher BC bullet in 30 caliber will have to rely on low drag design, not increased mass if it is to have any chance at success; but even then, a similar design in a smaller caliber would be a better choice."
Kilde:
http://riflemansjournal.blogspot.dk/2009...lemen.html
Testet:
Tikka Varmint 3006, 2-7x33 Leup VXR
165grs SST, 51grs RP15, S&B hylstre
Mvh Pete