October 5, 2004, 05:39 PM
What cartridge overall length do you use for the .308 Winchester when reloading?
Do you fine tune it in or out or just load and go?
Semi-auto rifles: Should you stick with a standard length?
168 match calls for 2.80.
FMJ/147gr./mil-type seems to be in the 2.75 to 2.777 range.
How about Nosler 125 & 150 Ballistic Tips?
Been loading for a FAL, and using standard/published lengths.
October 5, 2004, 05:57 PM
It's hard to measure COL consistently because most bullets tend to have varying lengths from base to tip because the tips are not all consistent. The tolerances aren't that precise, yet.
My .308 loads with 175 Sierra Match Kings measure around 2.812" +/- .005 COL. But I use a bullet comparator to make sure it's seating consistently in my Redding Competition Die and those measurements come out to a +/- of .001".
October 6, 2004, 12:25 AM
I fine tune for my bolt gun, and use published specs for the bullet in question for my semi-auto.
October 6, 2004, 10:55 AM
I "fine tune", if that's your description of setting an OAL for each rifle. It only requires one "single" effort to figure out the "correct" OAL. For semi-autos, this is actually a quicker process, because the magazine is the limiting factor in the OAL length. I set my semi-auto loads about .007" short of the interior mag dimension, and I'm done.
For bolt guns, I used a Stoney Point OAL gauge--remove the bolt, insert the tool, measure the length from the base of the case to the bullet ogive and record that measurement. From there, I set my bullet seating depth so the seated, assembled bullet is ~.002" short of the recorded measurement, from base to ogive. Whatever the OAL turns out to be is of no consequence; that'll vary according to the consistency of the bullet manufacturer. In that sense, the Stoney Point "OAL gauge" description is a misnomer; it should be "Ogive gauge", but by convention, most understand what it means.
If I wanted to tweak the last accuracy out of that reload recipe, I'd tinker with the seating depth a little more, in .003" increments--my initial load was .002" off the lands and grooves, so I'd back off to .005", .008", .011", and maybe even try some right on the L&Gs at .000" (but it is reputed that the higher resultant pressures are detrimental to the chamber). At least, that's what most folks claim the benchrest shooters do for best accuracy.
168 match calls for 2.80. FMJ/147gr./mil-type seems to be in the 2.75 to 2.777 range.
The discrepancy you're seeing in these published measurements is caused by the different shape of the bullets being compared (since the ogives are at different points on each OEM bullet, the resultant OAL is different); also, the FMJ "slop" of 2.75-2.777" is a direct result of mass production seating and bullet consistency (or the lack of it, actually) from one to the other within the same OEM. That's the reason OAL measurements aren't really significant; as a general rule, that dimension is useful to insure the round is compatible with the rifle, but it doesn't really help define the round. More important to the reloader is the 'length to ogive' measurement.
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