Advice needed - COAL Question

[Lee T.]

Using the Sierra manual I loaded about 20 rounds of .30-06 with 46.0 g Varget and the 165 g HPBT Sierra bullets (#2140). Using Varget this isn't a 'right out of the book' load but is very close to the book load with 4064.
The guide has OAL at 3.185 which is shorter than other similar loads I 've done at 3.225 and 3.285 with same powder and 168 g HPBT SMK.

The bullet is seated pretty deep, I got to wondering why so short and if it would create higher than average chamber or port pressure, and might not be a good load for the Garand even though it's a medium load otherwise.

Advice / comments? thanks, lee

[Parashooter]

The Sierra 165 (#2140) is essentially their 168 (#2200) with a shorter jacket and consequently more open point. Since the critical length is not "overall" but rather to the location where the ogive contacts the lands, it's logical that the shorter 165 will give a shorter OAL even if the distance from ogive to lands and also the amount of case volume occupied by the portion seated below the neck were the same. That much said, the pictures above, from Sierra's website, indicate that the 165 has a slightly different ogive than the 168, so there's even more reason to forget about overall length and establish seating based either on optimal magazine length or on land-ogive contact - whichever is less. Since your 46-grain charge is below Hodgdon's listed starting load, 47 grains, with the 168 MK (or 165 SPBT #2145), concern about overpressure is probably misplaced.

[Lee T.]

Wow those excellent graphics, thanks Parashooter.
No, not agonizing, just making sure. That's what this forum is good at, right?
The OAL is all I have to go by, and until I gain experience I find it prudent to check with those who knowwhen something dowsn't feel right.
"Measure twice, cut once"

[Parashooter]

The OAL is all I have to go by . . .

If you have the rifle for which you're loading, you have the only tool necessary to determine both ogive-land dimension and optimum length for magazine feeding.