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Questions on 300 RUM ladder testing

 
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  #1  
Old 03-11-2013, 12:38 PM
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Join Date: May 2012
Location: Northern Colorado
Posts: 92
Questions on 300 RUM ladder testing

Hey guy's,
Thought I'd quiz and get direction from some of you who are knowledgeable and experienced.
I'm working on my first load development for a 300 RUM. I've only been handloading for about 1 yr. Played around with 7mm-08, now working on my RUM.

Heres where I'm at. I'm shooting 210 gr. Berger, Nosler cases, Retumbo. I do have a Berger manual. After reading the manual, and hearing from numerous people how difficult VLD's can be to get shooting well, I first did a bullet seating depth test per Berger instructions with a starting load of 88 gr Retumbo. With once fired brass shoulders bumped .001, it shot every seating depth better than I had expected at 200 yds., but at .010 off lands did a little bit better. Dont remember off the top of my head, but it was a little under 1" at 200.

Heres where I can use direction. I am planning to shoot a ladder test starting at 88 gr, and working up in .2 gr increments to 92, which is the max in Berger manual.
I only have access to a 200 yard range without driving a long distance, and paying for range time. Last week I took 5 rounds of virgin never fired brass loaded 88 gr to get centered on target for my ladder test. Took 2 rounds to center at 200, and my next 3 printed in at just over 3/4" at 200. The unfired brass has about .012 headspace. This is a good sign to me, I think, though I would not have expected the new brass to shoot that well. Will the 200 yd ladder test described above tend to tell me anything at 200 yds? I've not chrono'd anything yet. I've got one, never used it, and dont know if it would be very accurate. Its a pro chrono. The conditions where I shoot, I dont believe would be very good for chrono'ing. The sun is always down at the target end of the range.
The gun is a custom build on a blueprinted 700 action. 1:10 twist #4 Hart barrel. No break, I take the beating. May add a break later, but I dont know. I dont like them, too loud.

I'm all ears, and open to any direction any of you guy's might have. Being of little experience, I need suggestions. Should I continue with the test, or see what that starting charge does at distance? Should I do more testing differently than I've planned? I fully expected to be battling this load out, but things seem to be going well to this point. Could it be an anomoly, or am I on the right track with a bullet that my gun seems to want to shoot well?

Thanks for any advice you guy's might have.
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  #2  
Old 03-11-2013, 03:51 PM
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Join Date: Dec 2006
Posts: 337
Re: Questions on 300 RUM ladder testing

You probably don't want to hear this, but my ladder groups at 200 yards weren't telling me anything. At 300 yards, they started acting the way I expected (and read)...i.e. the low charge hit low and the higher charges started "walking" up the paper until I hit an accuracy node.

Good luck!
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  #3  
Old 03-11-2013, 05:15 PM
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Join Date: May 2012
Location: Northern Colorado
Posts: 92
Re: Questions on 300 RUM ladder testing

Quote:
Originally Posted by old_heli_logger View Post
You probably don't want to hear this, but my ladder groups at 200 yards weren't telling me anything. At 300 yards, they started acting the way I expected (and read)...i.e. the low charge hit low and the higher charges started "walking" up the paper until I hit an accuracy node.

Good luck!
I appreciate your honesty. I dont really know thats why I ask. I know what I've read here on this site. I know the general consensus is shoot ladders at 300, or more but have seen on here where guy's have done 200 yd tests. Thought maybe there may be a trick to reading the results at 200, and could possibly make it work.
In the end I think I will have to bite the bullet, and travel some place to shoot 300.
I guess if your gonna do it, do it right?
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  #4  
Old 03-12-2013, 08:58 PM
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Join Date: Aug 2006
Location: Missouri
Posts: 143
Re: Questions on 300 RUM ladder testing

If 200 yds is the farthest you have available readily, I think you would be better of working up a load using the OCW test method. You can read all about it here: OCW Overview - Dan Newberry's OCW Load Development System
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  #5  
Old 03-12-2013, 09:16 PM
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Join Date: May 2012
Location: Northern Colorado
Posts: 92
Re: Questions on 300 RUM ladder testing

Quote:
Originally Posted by sharpshooterbr View Post
If 200 yds is the farthest you have available readily, I think you would be better of working up a load using the OCW test method. You can read all about it here: OCW Overview - Dan Newberry's OCW Load Development System
Thanks Sharpshooter, I have looked in to that, and have worked on it a little bit with a 7mm-08. I might just have to use that OCW
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  #6  
Old 03-13-2013, 09:24 AM
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Join Date: Dec 2005
Posts: 2,114
Re: Questions on 300 RUM ladder testing

Folks need to realize that the OCW system is based on one huge myth and one big error.

The huge myth is that when the muzzle's expanded by a pressure wave, accuracy is bad.

But all those 7.62 NATO Garands the USN and USAF used in competition with their lands and grooves worn away 3/4" behind the muzzle with no copper wash from pushing steel cleaning rods down the muzzle after 3000 rounds still shot just as accurate as when new; under 4 inches at 600 yard with good lots of commercial Federal match ammo. And countless match grade bolt guns with a front sight band clamped on their muzzle had smaller bore and groove diameters under that band than behind it; those barrels shot just as accurate with or without that band.

The big error's in that pressure wave's speed and starting point in the barrel.

Depending on whose data one reads, sound travels in stainless steel between 13,000 and 18,000 fps. Mechanical engineers doing vibration analysis typically use about 16,000 fps. But where does that pressure wave start at? And there'll be several breech to muzzle cycles of that pressure wave in the 1.X milliseconds the bullet's in the barrel. If the wave starts anywhere other than the bolt face, there'll be two of them for each shot; one starting forward and another starting backwards. Now there's two shock waves moving back and forth in the barrel. each making several round trips until the bullet exits. It's the same as a rock thrown in the lake; waves go in all directions form its entry point.

And what about the same load shooting the same excellent accuracy level at long range from several different barrel lengths leaving at different velocities? The timing of bullet exit to shock wave position's all over the scale.

To say nothing about the accuracy level of all loads tested will have to be extremely good to discriminate what caused the difference in bullet drop's cause between muzzle velocity and other three or four things that causes vertical shot stringing.

One's better off shooting at least 10 shots with each load then using the one that shot the smallest group.
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  #7  
Old 03-14-2013, 08:29 PM
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Join Date: May 2012
Location: Northern Colorado
Posts: 92
Re: Questions on 300 RUM ladder testing

Quote:
Originally Posted by Bart B View Post
Folks need to realize that the OCW system is based on one huge myth and one big error.

The huge myth is that when the muzzle's expanded by a pressure wave, accuracy is bad.

But all those 7.62 NATO Garands the USN and USAF used in competition with their lands and grooves worn away 3/4" behind the muzzle with no copper wash from pushing steel cleaning rods down the muzzle after 3000 rounds still shot just as accurate as when new; under 4 inches at 600 yard with good lots of commercial Federal match ammo. And countless match grade bolt guns with a front sight band clamped on their muzzle had smaller bore and groove diameters under that band than behind it; those barrels shot just as accurate with or without that band.

The big error's in that pressure wave's speed and starting point in the barrel.

Depending on whose data one reads, sound travels in stainless steel between 13,000 and 18,000 fps. Mechanical engineers doing vibration analysis typically use about 16,000 fps. But where does that pressure wave start at? And there'll be several breech to muzzle cycles of that pressure wave in the 1.X milliseconds the bullet's in the barrel. If the wave starts anywhere other than the bolt face, there'll be two of them for each shot; one starting forward and another starting backwards. Now there's two shock waves moving back and forth in the barrel. each making several round trips until the bullet exits. It's the same as a rock thrown in the lake; waves go in all directions form its entry point.

And what about the same load shooting the same excellent accuracy level at long range from several different barrel lengths leaving at different velocities? The timing of bullet exit to shock wave position's all over the scale.

To say nothing about the accuracy level of all loads tested will have to be extremely good to discriminate what caused the difference in bullet drop's cause between muzzle velocity and other three or four things that causes vertical shot stringing.

One's better off shooting at least 10 shots with each load then using the one that shot the smallest group.
So, if I understand your saying all this overcomplicating of a far simpler process is unnecessary, and counter-productive.
I'm a simple guy, and a simpler way is what I'm looking for. Its possible that I'm reading much to much into all this stuff I read. If its really not that complicated, I'm in.
All the theorizing that ranges from one extreme to the other makes my head spin anyway.
I think I'll just pick a few charges up through the range and see what they do.
I already know my start charge 88 gr Retumbo shot on both occasions, different days shot 1/2 MOA at 200. Theres got to be something on the upper end that shoots as well. In the end, if all else fails I'd give up some velocity for accuracy and go back to 88 gr
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