The odds of 308win accuracy increasing with a change to a magnum primer are low,occurring most commonly with ball powders.In most cases,the best accuracy is achieved with a primer that is just hot enough to provide consistent ignition of the powder.
Generally I try not to buy into everything I read, but Per the article you referenced:
As a rule of thumb, standard-force primers have been recommended for all rifle situations except those employing ball-type powders and those using more than fifty grains of slow-rate extruded powder such as IMR-4350, H-4831, and IMR-7828.
Max charges in the 308 would exceed 50 grains of imr4350 with 150 grain bullets even when limited SAMMI OAL. My nosler manual lists 52 grains of imr4831 with 150/155 grain bullets and 50 grains of imr4350 with the 180s.That would seem to indicate that magnum primers are actually what the author is recommending for this situation in the article.
quote:
The magnum primers will decrease the effective burn time and increase velocity.
To begin, the main difference between a standard-force and a magnum-force primer is in the length of its burning time. A magnum-force primer burns longer than a standard force and therefore tends to increase chamber heat variously depending upon the primer's own power, the powder involved, and cartridge case size plus bullet weight.
Stubble I thinkyou misunderstood my post based on the quote you pasted above. I was not referring to the primer burn time, I was referring to the cartridge burntime or powder burn rate.
We can go round and round forever regarding accuracy the bottom line is summed up bestin the article you referenced.
Changing to a magnum-force primer, on the other hand, might run up quick, stiff chamber pressures which bring the individual barrel closer to its best vibration pattern for uniformity. Or, in some instances, the quicker jolt of chamber pressure from a magnum primer could have the reverse effect and inject greater irregularities in vibrations than the standard ones. You simply never know how they'll all work unless you try them, because each rifle is a physical law unto itself; for the molecular structure in each barrel can be different from that of any other barrel, even if the bore and cambering are identically cut.
The quote above from the article youreferencedseems to indicate that primer selection is a flip a coin affair for the most part between magnum and standard primers. Getting back to my original post I recommended the magnum primers to increase velocity in the 308 with 4350 notto increaseaccuracy in the 308. Only his rifle will determine which is actually more accurate but an increase in velocity is almost certain in my experience.