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Old February 15, 2022, 05:46 PM   #20
Join Date: March 4, 2005
Location: Ohio
Posts: 19,897
Bart B.,

If you read the old Precision Shooting article Secrets of the Houston Warehouse, they found (IIRC) 21.75" to be a sort of magic number.

Originally Posted by Bart B.
Here's the probable source of Old Roper's claims › 2018/01PDF
American National Standard Voluntary Industry Performance Standards for Pressure and Velocity of Centerfire Rifle Ammunition for the Use of Commercial Manufacturers -

Averages, the Inclusion Limits are determined as follows: VELOCITY: MEAN = Same as Corrected Average. HIGH = MEAN + 50 fps. LOW = MEAN – 50 fps.
Ahh! You may be right!

@Old Roper,

If that is the set of numbers you were referring to, I can understand the confusion. If you look them up again, you will see they are in the section describing reference loads and do not apply to production ammunition sold off the shelf. For production ammunition, they say:

Originally Posted by SAAMI Centerfire Rifle Standard
Ammunition tested subsequent to manufacture using equipment and procedures conforming to these guidelines can be expected to produce velocities within a tolerance of ±90 fps of the tabulated values.
Note the second word in that sentence is "tested". This means fired in a SAAMI standard pressure and velocity barrel at some other place and time, and do not refer to firing them in someone's production gun. SAAMI has no control over anybody's production gun, so they can't make any kind of claim about velocity in such guns, especially not with manufacturers producing so many non-SAAMI chambers for special purposes, or else making the throats extra long, as Remington garnered a reputation for doing.
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