Theory of the Rifle

The Rifle: Winchester Model 70, a real one, of walnut in .270, with B.O.S.S.

This comes up due to our discussion of the mini-14. You see the fine weapon above has a medium 'sporter' barrel and is subject to barrel 'whip' as is the mini-14. The major differences between the two are the diameter of the barrel, the quality of the barrel and action (I know smartass - one's a semi and the other bolt), and attention in design to the requirements of precision shooting.

Now, none of the above requires explanation except the part about attention in design to the requirements of precision shooting.

'Whatever do you mean by that JACIII?', you ask.

Pay attention, Grasshopper:

Whenever a cartridge is discharged in a chamber and a bullet is propelled down the tube a wave is propagated along the length of the barrel. When you read Gregg refer to 'tuning' a gun, whether he knows it or not, he was referring to the process through trial and error of finding a combination of powder charge (acceleration) and bullet weight (mass) that relate to the wave propagated by same charge and bullet consistently at bullet exit. This is no small task and requires much knowledge, skill (both at the shooting bench and the reloading bench), patience, and attention to detail.

While most rifles are 'tunable' with good results, some are not. I consider 'good results' one minute of angle or a roughly one inch group at 100 yds.

Now, that's not really good enough. When you read Nate, Welldigger, or
myself post about a shot group we are referring to the absolute diameter of the
group of holes, center to center, in a target. This is not the common
standard reference which is more like a standard deviation measurement.
Good enough is under one half inch at 100 yds and 'one 0.270
inch hole' is what we are after.

Comparing the two guns mentioned above we see Gregg 'tuned' his mini-14 to two inches through meticulous trial and error and experimentation (A gun magazine would have within one inch of the center of a shot group; that's 2 inches in my book) whereas the Model 70 can be 'tuned' to 0.350 inches (that's 0.1750 inches in a gun magazine) by the simple artifice of turning a weighted suppressor with a micrometer thread, barrel, lock, and index marks to the listed value in the owners manual for the desired bullet weight. Granted the manual's value was the starting point, but it wasn't far off my final setting.

These two guns are in the same expense class (below $750).

Do you now see, Grasshopper, why the Mini-14 is a piece of shit?

note: Data for above Model 70 was with refired cases, H4831SC powder, and a 130gr Sierra HPBT running at 3600+fps in a molycoated barrel with no signs of overpressure. DO NOT TRY THIS YOURSELF. DEATH OR INJURY MAY RESULT.