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280 AI replacement for 270 Win.

 
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  #78  
Old 03-17-2010, 01:06 PM
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Re: 280 AI replacement for 270 Win.

Quote:
Originally Posted by cowboy View Post
I have learned that my chronograph readings are for reference only. When I was shooting at various distances to get data to have a turret built I finally had the light bulb come on. Shot very same loads over 3 different chronographs. Called the manufacturer up of the chrony I use and was told they are accurate to+ or - 3%. On 3000 fps that is a 180fps difference total. I will always use actual shooting data over a chronograph readings any day. If you are not sure of this call the manufaturer of the chronograph you are using and ask them for their accuracy limitations.
See my post under this thread: Es/sd

Jon A has also posted in the past that he regularly gets single digit delta on the difference in velocities from his two Oehler chronographs.

The notion that quality chronographs give readings that vary by 180 fps on a common basis is misleading. If you haven't played with them, you're not is a position to comment on the real-life repeatability of the data they are able to reproduce with high consistency.

If you disregard chronograph data, then how do you determine your muzzle velocity for purposes of inputing MV into a ballistics program? Same question for you that I posed in my post under the above referenced thread. Do you try to determine your MV from measured drops? Now that would be a real stretch of the imagination - something that makes chronographs likened to God's gift to the LRH by comparison.

If you never hunt other than where you develop your drop chart, you'll be OK with drop charts. If you relocate to hunt in the mountains, you'll have to develop a new drop chart under those environmental conditions prior to engaging game at long range, or else miss.

Last edited by phorwath; 03-17-2010 at 06:37 PM.
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  #79  
Old 03-17-2010, 05:19 PM
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Location: Billings, Mt
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Re: 280 AI replacement for 270 Win.

phorwath: I probably didn't explain what I mean be using a chronograph for reference only very well. I have been using a chronograph for 20+ years and now have 2 of them. I use them extensively for a number of reasons including MV and whenever I change to a different lot of powder in the same rifle/load etc. What I did mean was that I do not get hung up on single digit ES or SD. If field testing meets my self imposed criteria for accuracy I do not get hung up on single digit spreads. No one implied that chronographs are always off 180 fps. But I can tell you from years of experience that what I think is 3000 fps on my machine is probably a little different on yours. By the way - I live here in Montana and we hunt/shoot from 3000-9000 ft. on a weekly basis depending on the time of year.
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  #80  
Old 03-17-2010, 06:39 PM
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Re: 280 AI replacement for 270 Win.

cowboy,
Do you use a ballistics program for the varying elevations, environmental conditions, and shooting angles of inclination/declination? Or do you develop field-proofed drop charts and rely on you drop charts only?
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  #81  
Old 03-17-2010, 09:49 PM
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Re: 280 AI replacement for 270 Win.

Quote:
Originally Posted by phorwath View Post
cowboy,
Do you use a ballistics program for the varying elevations, environmental conditions, and shooting angles of inclination/declination? Or do you develop field-proofed drop charts and rely on you drop charts only?
To answer your question - I have used all the above as well as none of the above. I have used a couple of different ballistic programs and have not found a reliable unit for some of the conditions we are in at times. Ex: Our elk camp is at 8500' and a 2 day horse pack trip in. Wall tent has been in same spot for 32 yrs. Have had trips where warm was barely zero and cold was -20. That temp with 3' snow and 10 days and ipods just don't work for me.
I am not a keyboard commando by any means of the sort and don't mean to start any peeing contests. As a matter of fact I do not consider myself a LRH but I do consider myself long range capable. I have set up rifles for various elevations and use confirmed drop charts mostly when weather will not allow an ipod or equivalent. I also feel very comfortable with the range that I have self imposed on myself for those conditions.
I have been shooting long range way before it became the in thing. I've tried the holdover methods, Ballistics reticles, dial up methods and for the last 2 years been testing a couple of turrets. They all have their place and there place in my opinion is based on individual equipment and the capability of the nut behind the bolt.
My comment on don't count on your chronograph being 100% reliable was based on a lot of trigger time compared to the average individual plus the fact that an engineering degree taught me that not everything functions as it was intended 100% of the time. After burning up more barrels than I like to admit chaseing the one hole zero with single digit SD/ES I have developed the opinion that I will use my chronographs constantly but will never overide field testing even if my SD/ES says double digits.
The 280AI that I am using now showed an ES of 40 and a SD of 15 the last time I checked it on the chronograph with 168VLD's. That same load has been a little lower and a little higher at times past. With that said field testing at 6- 8 and 1000 showed vertical spread much less than the chronograph would have led me to believe. Bottom line is I don't feel the chronograph has the final say in what I'm going to shoot. The chronograph is a VERY valuable tool but it doesn't get final say.
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  #82  
Old 03-17-2010, 10:19 PM
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Re: 280 AI replacement for 270 Win.

How does that 168 do on elk?
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  #83  
Old 03-17-2010, 10:50 PM
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Re: 280 AI replacement for 270 Win.

Quote:
Originally Posted by Limbic View Post
How does that 168 do on elk?
Very well to date. 7 one shot kills on elk between my son and I who also shoots a 280AI. Closest for us was probable 50 yds and longest just over 400 yds. No complaints to date. I used the Nosler Partition for many years, switched to BarnesX and then to the TSX when they came out. I will have to say I prefer the Berger 168VLD's to the others but they react completely different upon impact to what I had been accustomed to for many years. I have a small box full of retrieved bullets from previous years and when you go to bone out a animal killed with these Bergers - all I've found is little bitty pieces of fragments. There have been no picture pretty mushroomed bullets as in years past.
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  #84  
Old 03-17-2010, 11:30 PM
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Join Date: Apr 2005
Location: Alaska
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Re: 280 AI replacement for 270 Win.

Quote:
Originally Posted by cowboy View Post
My comment on don't count on your chronograph being 100% reliable was based on a lot of trigger time compared to the average individual plus the fact that an engineering degree taught me that not everything functions as it was intended 100% of the time. After burning up more barrels than I like to admit chaseing the one hole zero with single digit SD/ES I have developed the opinion that I will use my chronographs constantly but will never overide field testing even if my SD/ES says double digits.
The 280AI that I am using now showed an ES of 40 and a SD of 15 the last time I checked it on the chronograph with 168VLD's. That same load has been a little lower and a little higher at times past. With that said field testing at 6- 8 and 1000 showed vertical spread much less than the chronograph would have led me to believe. Bottom line is I don't feel the chronograph has the final say in what I'm going to shoot. The chronograph is a VERY valuable tool but it doesn't get final say.
I don't claim my chronographs read 100% accurate velocity, or operate 100% reliably. I don't claim I can know the recorded velocity is accurate to within +/- 10 fps or even +/- 20 fps. But no one has identified any other affordable technology better able to establish the MV of my loads, or their loads. There is no better tool available. What better option is there?

You stated you owned two chronographs, but not whether you shoot over the two simultaneously in order to establish their reliability and credibility. I own two, and I run them in tandem as described in the ES/SD thread. Es/sd By doing so I do claim to be able to identify any significant hiccups in reported velocity, and to be able to ID accurate ES and SD, because ES & SD are difference-based calculations, and my dual chronograph method establishes the credibility of the relative difference in velocity when the delta of the difference in velocities is low for all shots included in my ES/SD data set and determinations. For that reason I discard a load with unacceptably high ES/SD based entirely on my chronograph data - if the load is intended for long range hunting. Even if it one-holes-em at 100 yds. I know they'll string vertically at long range, because I know the variance in muzzle velocity must be expressed in vertical stringing at extended range. Disregarding the high ES simply means I need to work a bit more until I find a different load with lower ES that also shoots well out of the rifle.

I'd always heard the 280 AI was an easy-to-load for cartridge, and expected to have an easier time getting the ES/SD down to lower numbers than I'm getting. I'm struggling to improve upon ES in the 25-30 range and SD in the 10-13 range. The numbers are tolerable, but not what I'd hoped for. H1000 is the most consistent powder thus far, having tested H1000, Retumbo, and RL17. I'm not finished yet, but closer to the end than the beginning of load development with the 168 VLDs. I may try one box of 180 VLDs and see if there's any significant improvement. My barrel is 9 twist so stabilization with the 180s should be fine.

I don't long range hunt in the severe temperature and snow conditions that you describe, and have experienced. Hunting my style in Alaska under those conditions leads to a wilderness survival experience or worse, rather than an enjoyable hunting experience. No roads, no horses, no cell phone communication, no help. I haven't joined the ranks of hunters carrying Satellite phones up here, in spite of the the obvious health & safety benefits. For the temperature conditions I do hunt in, I pre-print drop charts for three separate elevation/atmospheric pressure conditions including angled/sloped shots of 0, 10, 20, and 30 degrees, as well as a column for a 10 mph cross wind. Those charts are packed along with the pocket PC/ballistic software program. I use these charts for back-up confirmation that the predicted dope from the ballistics software hasn't been botched by bad input/operator error. And for back-up should the pocket PC fail. The dope off the chart is generally very close. If it's more than two clicks off, I'll rerun the PC program again for confirmation prior to prepping for the shot.

I won't go out of my way to compete with you in this thread. That wasn't and isn't my interest. My background is graduate engineer, practicing and professionally registered in the State of Alaska. Been shooting and hunting with rifles for the past 41 years, the last 32 in Alaska. Doesn't mean I'm special, better or worse, or anything of that sort. Simply posted here for purposes of supplying my background & experiences.

Last edited by phorwath; 03-18-2010 at 07:40 PM.
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