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Chronograph Results

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Unread 01-05-2004, 10:43 AM
Bronze Member
Join Date: Jan 2004
Location: Roaring River, NC
Posts: 46
Chronograph Results

Ok folks, being new to this game I was wondering what type of variations in speed are normal etc. Im playing with this used .300 WinMag Sendaro using several bullets from 168gr to 210gr. Powders have been Reloader 22 and 25 so far. I have used the chrono, but im workin in the dark here. I have no data to benchmark my results against. Could you guys chime in and give me some examples of your standard deviations and extreme spreads etc? So I can see how my stuff is stacking up.
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Unread 01-05-2004, 11:02 AM
Silver Member
Join Date: Mar 2002
Location: Prince George British Columbia
Posts: 128
Re: Chronograph Results

Depends what your planning to do with the rifle. For 1000yd BR. you better have ES under 20fps. With my 300 win mag. I like bullets 190gr. and up. They are more forgiving on load variations. Whats your plans.
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Unread 01-05-2004, 05:34 PM
Bronze Member
Join Date: Jan 2004
Location: Roaring River, NC
Posts: 46
Re: Chronograph Results

Im interested in long range hunting, however I may try my hand at a 1000yd match since we have a 1000yd range about 20 minutes away from where I live. I think it would be a good place to do some learning.

I havent done much chrono work yet, just a few 5 or 10 round groups with different bullets and powders. My ES has been higher than I wanted to see it. However, in some cases I cant for the life of me figure out why it is so high. For a 5 round group I have had some 29s etc. Sometimes I get a lower one. Then, once in a while I get a 90fps spread on some ammo that I know was loaded very carefully. Primers? Bad lot of powder? I have weighed the bullets and brass into uniform groups. Neck and length turned the cases. I throw my charges with a RCBS electronic scale and dispencer then I do the final .1 grain or so by hand on a beam scale. I have been VERY careful with the powder measurements to make them as uniform as I can. I wish I had two chronographs to set up to compare measurements. The chrono im using is a Pact Championship Timer/Chrono.

Any suggestions?
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Unread 01-05-2004, 06:08 PM
Platinum Member
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: Chronograph Results

Sometimes just ain't so easy, other times ES is just so low you wonder how it happened when everything has been so close to the same with other components etc. Really, the bitch about it is, there is numerous combinations with a cartridge and when one component is changed it can change the dynamic (it must) enough that the numbers get large.

Before I screw with checking ES, my barrel is good and fouled in with the load with 5-10 shots after cleaned so it's stable, trip down the bore each shot meets the same friction etc.

Change only one thing at a time and test a large sample.

Primer seat uniformed, right?
Primer seated consistant
Flashhole deburred

Neck tension

Often getting them below 20 fps ES takes some serious persuit, sometimes though 10-15 just falls in your lap though.

I'm not familiar with the Pact chrono. I know one guy who had one who posted on AR that he went to an Oehler, but his was quite old and still wasn't sure Pact wouldn't fix it, he never did go to them and just went and bought the Oehler 35P. Really, I think he just wasn't too sure of the readings it was giving him, for some reason or another, not that it wasn't working, he just wasn't sure about it anymore was the way I understood him.
If you ever doubt your chrono, go to the range, ambush someone that has another good chrono [img]images/icons/grin.gif[/img] with them and ask to set yours up with theirs and shoot a string or two to check it out. This will at least tell you something usefull, one way or the other. ES over the two should be nearly identical if they both are functioning correctly.
Brent Moffitt
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Unread 01-05-2004, 07:58 PM
Bronze Member
Join Date: Jan 2004
Location: Roaring River, NC
Posts: 46
Re: Chronograph Results

Thanks for the feedback. I have turned the necks etc, so I hope the neck tension should be the same. As far as the primer deburring I havent done that. I have cleaned the primer pockets. Primers are seated the same.. did it by hand. And the powder is measured as uniformly as I am capable of doing with the equipment I have.

I havent ever done any rifle shooting at a public range. Perhaps I should pack up one day and make a trip [img]images/icons/smile.gif[/img]
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