Need Seating Depth Clarification PLEASE

[sigma2chi]

I'm currently loading my .308 with 168gr SMK and Lapua Brass. I've been seating them to a depth of 2.0975" THAT is measured using a Sinclair Bullet Comparator with my Micrometer. From what I understand the Sinclair Comparator measure from the transition of the surface bearing area and the ogive. Coincidentally that is where the Redding dies applies pressure as well.

The problem is that from what I can tell my 168gr SMK's are not very consistent in length from that point to the tip of the bullet. I am trimming each bullet back .003 to clean up the meplat's.

My problem is that even though I am getting very consistent readings of 2.0975 with my Comparator. When I measure from base to meplat without the comparator I am getting some bullets as long as 2.860 which is .050 over my chamber and giving me a slight jam.

Not that I'm scared to jam one a little but I am however concerned at the potential of accuracy loss due to some bullets just touching the lands and some being jammed in .050.

HERE's the kicker, my extensive workup of potential loads gave me this seating depth as the best/most accurate otherwise I would just push it down in there a little further.

So I have a few questions:

1. When measuring my seating depths, should I use the Sinclair Comparator or measure without it from base to meplat and adjust die accordingly to compensate for the SMK lengths thus better controlling my "jam vs. jump" length?

OR

2. If not that should I be measuring each SMK and trim meplats accordingly?

3. If I do that will one tip being "pointyer" that another affect accuracy/trajectory?

 

[brocot]

If I'm understanding you right from the base of the cartridge to the ogive you are getting a consistent 2.0975 measurement. However, the measurment from the base of the cartridge to the tip of the bullet (metplat) varies as much as .050. If that's correct then you don't need to worry about some of them jamming into the lands. The tip of the bullet can't jam into the lands, only the ogive (and the rest of the bearing surface) can. So as long as your measurement from the ogive is consistent you won't have to worry about how inconsistent the length from the ogive to the tip is (as far as jamming goes, accuracy might be another story I really don't know). Hope this makes sense.

 

[Rhyno]

Your probably jamming on the magazine, if your running a R700 short action the internal box magazine will only feed cartridges about 2.82 from cartridge base to tip.

That could cause the bullet to be pushed back if you feed aggressively.

 

[sigma2chi]

If I'm understanding you right from the base of the cartridge to the ogive you are getting a consistent 2.0975 measurement. However, the measurment from the base of the cartridge to the tip of the bullet (metplat) varies as much as .050. If that's correct then you don't need to worry about some of them jamming into the lands. The tip of the bullet can't jam into the lands, only the ogive (and the rest of the bearing surface) can. So as long as your measurement from the ogive is consistent you won't have to worry about how inconsistent the length from the ogive to the tip is (as far as jamming goes, accuracy might be another story I really don't know). Hope this makes sense.

actually that makes perfect sense. I'm embarrassingly not sure why I didn't think of that........... I'm gonna go have another beer.....

 

[brocot]

Haha, no big deal man. We've all done something like that.