I measured 7. 4 of which measured exactly 3.240". The others were real close to that -/+ a hair. I think you told me before that your bullets were set .1 off the lands and mine are barely jammed so that would make ours chambers pretty similar.
That's about what mine are seated. I don't have any issue with them moving so far. My 243 loads for yoting have about 2/3 that much and I have had no trouble with them moving yet either. I think neck tension is critical when seating the like this. I had to knock some loose the other day. Then first whack of the puller most of the bullets didn't move. Kinda like pulling a nail that's been in for a while. Takes more pressure to "break loose" the nail and then it will come out smoothly. Make sense? This has been my experience with the couple dozen bullets I've pulled over last few years.
The first picture shows a measurement of a 140 VLD seated to the lands and and the amount of bearing surface that would be under tension from the neck. This case was cut to 2.162. Book trim to length is 2.160 with max being 2.170. Total bearing surface inserted in the neck is .154, so say .150 for ease sake.
The second is simply a visual of the bullet in the case seated to the lands. This is the properly trimmed case and annealed by me. This will be this cases 6th reload. The case neck was sized .002.
The measurement of the ogive to the lands is 2.582. COAL is 3.241 on this particular bullet. It easily fits the mag. I didn't measure the mag this morning before heading to work but there is close to .25" clearance. Makes me think the 6.5 SIN will fit my mag just fine. hee hee
So what is important in this scenario?
My understanding is that bullet tensions and seating depth are vital to the rifles overall repeatable performance. Perhaps this is just as important as how much powder is in each case; unsure. The seating depth is more a function of how much tension is created to properly align and keep the bullet aligned. Most books say .001 to .003 is the proper tension. They also seem to agree that a bullet should be seated the equal depth of the bullets diameter. In this case that is .264. .264 - .154 = .110 of the bullets diameter is seated into the case.
Does this amount of bearing surface (.154) create enough tension to keep the bullet aligned? Is case pressure a discussion point?
Also, I cycled the cartridge a couple of times and checked OAL. No change. I used my concentricity guage and aligned the bullet with the center line of the case. I stuck the cartridge in my pocket and will carry it around all day etc. Tonight I will check alignment and see if it changed at all. I will probably accidently drop it a time or two as well.