Re: 243IMP and 107mks simple question
When your working with a fast twist barrel and VLD or ULD bullets, they behave dramatically different then conventional weight bullets in conventional twit barrels.
The conventional weight bullets really do not have enough inertia to really resist the rotational effects of the rifling when they exit the muzzle.
Imagine a 300 lb body builder(the rifling) throwing around a 150 lb IRS worker(bullet, tax time!!!)
The Body Builder has total control of the little government worker and makes him do what ever he wants.
This is true with conventional bullets as well. They just do not put up much of a resistance to the forces exerted on them by the rifling so they settle down or "go to sleep" if you will very quickly after leaving the muzzle.
With a fast twist barrel and a VLD bullet, it is a different story. Now instead of a 150 lb weakling, we are dealing with a 6'6" 275 lb linebacker against out 300 lb body builder.
While the body builder still wins the fight, the much longer, heavier opponant puts up a hell of a resistance when it leaves the muzzle.
What is happening is that the rotaional forces and velocities are to high at the muzzle and the bullet is so long and skinny, that the bullet will acutally wobble as it exits the muzzle.
Thsi wobbling will occur until the bullet, in flight stabilizes around its ballistic and gravitaional center of balance. At which time the bullet actually stabilizes and flies true after shedding off the severe effects of the fast twist rifling.
This "going to sleep" situation happens to every bullet that exits a rifle muzzle. With conventional bullets it happens in the 45 to 70 yard range so 100 yard targets gie a decent idea of a loads consistancy.
The VLD bullets will generally go to sleep in the 150 to 200 yard range. This is why I tell my customers that if they are going to test at 100 yards. Any load tht groups 3/4" or better will generally look very nice at longer ranges. Unfortunately, most wanting extreme accuracy at long range will pass on these loads that print in the 3/4" range at 100 yards figuring they will not perform at extreme range. THis is simply not the case.
I have seen to many VLD loads that print 3/4" groups at 100 yards and then 1.5" groups at 500 yards to not believe this to be 100% true.
Shooting the 50 BMG rifles, this really becomes appearent. When your throwing a 2 oz bullet it takes a long time to stabilize. Generally around 250 yards in fact with the VLD 50 cal bullets.
Any load will gie you a better idea of its consistancy at longer ranges. This is just good practice as it makes it easier to tell a good load from a great load. At 100 yards they will look identical. At 300 yards and out you will be able to more easily tell which is the better combonation.
If you shoot at 100 yards with this bullet, just do not give up on groups that print at or under 3/4" until you can test them at 300 yards or more. They will suprise you, they behave totally opposite of a conventional bullet in grouping patterns.
Do your velocity testing an some accuracy testing at 100 yards. When you find a group of loads that look promising, head out to 300 and try them out.
Kirby Allen (50)
Allen Precision Shooting
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