Seating into the lands and how much to back off powder charge

[Alan Griffith]

I currently load my Rem 700, 30-06 with 57.6 gr H4350, WLR primers, Win cases and 180 Nos BT seated to 3.395" (approx .308" seated into neck). I've determined my dead set OAL with the ogive up against the lands is 3.556". 57.6 grains, though book max is not max in this rifle with bullets seated out to the before mentioned 3.395". I'm wondering if, any amount at all, you would back off the powder charge I mentioned and work back up again. I realize their are two opposing factors at play. The increasing OAL increases case capacity and should reduce pressure and velocity. The bullet, not given the running start into the lands, could cause an increase in pressure. It will probably be wise for me to back a bit, but how much? I don't wish to have to put too many bullets down range to determine my max pressure.

Big Al

 

[wapiti13]

Every barrel is different. Nosler recommends staying .010 off the lands. Some bullets shoot better just touching the lands, but just off is usually safer. It is not recommended to hard seat into the lands. Back off 5-10% and make sure the pressure doesn't spike, then you can start back up a grain at a time. Check your groups since they may get better or worse as you move in towards the lands. Be sure to use the ogive to check OAL, since the bullet nose length will vary and you're going to be near the lands.

 

[Richard338]

In my 260Rem, I either go 44 grains H4350, 15 thou off the lands.
Or I use 43 grains, seated 10 thou into the lands. I get the same velocity, and better accuracy seating into the lands (139 Lapua bullet with moly).
You are moving in from much further back, so I would back off maybe 3 full grains and then work up.

 

[wapiti13]

If you are "hunting" with this round, I would advise developing your load either just touching or slightly off the lands. Pressures can vary when going "into" the lands. This is a bench rest technique and not usually used in a hunting rifle where you might not fire off the round every time, but extract the unfired round. Just a thought.