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I have just worked a load straight out of the hornady book which is for the 162 grain SST that is meant to have a muzzle velocity of 3000 FPS for my Sauer 7mm Rem Mag. The only difference is that i have pushed the projectile .003 of the lands rather than using SAMMI guides.

The deal is my chrony is measuring it at 2800 FPS.

I have the chrony five meters from the muzzle as per manufactures instructions so i expect a little difference but not 200 FPS"

This has happened often to me with many differing rifels and loads

any idea's?:
 

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their data will have come from their test barrel or equipment. you would have to have the same length of barrel with the same twist and all the same conditions to get what they did. i have also been led to believe that even using the same powder as suggested from the manual can have subtle differences from batch to batch. also, primers can change data along with brand of brass.
i have a low cost chronograph that works decent but i wouldnt bet my life on it. if its happening alot maybe your chrony is defunct.
 
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Here is the thing most of these guns are not guns at all that they used to test. Many are actions with test barrels that have pressure transducers on them. These barrels are almost always cut to SAMMI minimum specs. Your right will not be cut to min specs it will be cut with in a specified ammount of a spec.

The only powder to give equal to higher velocity from the listed specs is VV powder. I had a load for my 223 that was listed in the book as a 3300 fps load and when I chroned it she was cooking right along at 3700 fps with no signs of over pressure. I even went back and pulled 5 bullets and reweighted the powder charge all were within .3 grains of each other at the correct load weight.
 
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