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243IMP and 107mks simple question

 
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  #1  
Old 02-02-2005, 10:14 AM
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243IMP and 107mks simple question

about to start working up a load for my rifle,a havent shot the 107s before and had been told that I should shoot at 200yds for load testing because it takes that far to stabilize,I really dont see how that could be possible but thats why i am here asking someone that really knows.I have access to 300yrds but I can shoot 100 in my back yrd so I would much rather shoot at 100 but if I will get a better idea of what they are doing at 200 then thats fine.please inform me!!

Jared
gun is question is a 243IMp 8 twist sendero taper 28inch 700aciton built by Hollands.
thanks
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  #2  
Old 02-02-2005, 10:48 AM
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Re: 243IMP and 107mks simple question

Jared,

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.

Good Shooting!!

Kirby Allen (50)
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  #3  
Old 02-02-2005, 12:33 PM
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Re: 243IMP and 107mks simple question

I would shoot at 100 yds to develop a load then tweak at the longer range. Anything under 3/4" is good to go to further testing 1/2" is even better. The VLD's are difficult to tune and I have some factory rifles that will shoot conventional bullets better at close ranges however stretch that distance out to 400yds or 600yds and hands doen the VLDs group tighter. Call it going to sleep or just the fact that they buck the wind better at longer distances. Another thing don't try to make a jam bullet length shoot. I spend about 1/2 of my barrel's life and have come to the conclusion that it shoots best around .015" off the lands for whatever reason.

Lance Wolken
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  #4  
Old 02-02-2005, 12:47 PM
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Location: DFW Texas
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Re: 243IMP and 107mks simple question

We see this same thing happening when shooting a bow and arrow. You can actually get smaller groups at longer distances than you do further away. Simply put, it take time and distance to stabilize and arrow and bullet.

This does not lend itself to convetional thinking so, many people need to see it to believe it. But it happens. In archery, some tuning here or there can lessen the effect.

Kyle
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  #5  
Old 02-02-2005, 12:54 PM
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Posts: 62
Re: 243IMP and 107mks simple question

I do all my load testing at 200. When I first started reloading I tested at 100. Took those same good loads from 100 and shot them at 200. Most shot like crap. I started all over and the loads I scraped from 100 were the ones a tweaked and kept. Here in NC I hunt over a lot of fields and power lines and I don't need a load to perform at 100, I need 200 and more.
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  #6  
Old 02-02-2005, 01:13 PM
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Re: 243IMP and 107mks simple question

makes sense,well now i will get to working up a load,anyone happen to shoot a 243imp? I was going to try H4350 and H4831sc and maybe some N160,any thoughts?
and thanks to all the answered


Jared
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  #7  
Old 02-02-2005, 09:07 PM
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Location: utah
Posts: 302
Re: 243IMP and 107mks simple question

I have shot many 107gr mks out of my 6-284 and they shoot a bit faster than you could get out of a 243Imp. and I would never shoot one at a big game animal,I killed a rock Chuck this summer with one at 1515yds and if it was 15 feet farther it might not have even drawn blood. go bigger bore and heavier bullet's
B
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