Seating depth variations

[fivehundredlimited]

So I decided to measure my max col using a bullet in a case with very little neck tension and chambering it in my gun and measureing the col. I got 2.264 twice and 2.263 once so I figured 2.264 would be the max(touching the lands) so I wanted to seat the bullets to 2.261 which would be 0.003 off the lands .

The problem I'm running into is that after setting up my RCBS die on my t-mag press, several bullets seated to the correct depth, then one seated to 2.263. Then the next few seat to the proper 2.261 , then I get another seating too long.

So I'm wondering

-is this because of variations in bullet dimensions from bullet to bullet?
-it appears that the seating die pushes on or near the ogive of the bullet, so does that mean that the ogive will still be off the lands and still be safe to shoot without increased pressures? And therefore the increased col is due to the tip of the bullet being longer.

I am loading for a cz 527 varmint 223 using 52gr Speer HPBT.

 

[silverfoxdj]

Just wondering did you sort and trim your cases to a standard length before you setup your dies and tried just a couple.

Sounds like a variation caused by the seating die

 

[fivehundredlimited]

Yep, I am currently just using once fired Winchester cases, I neck sized them then trimmed them all to the same length.

 

[silverfoxdj]

Could the neck tension not be firm enough to cause the bullet to shift

 

[fivehundredlimited]

Could the neck tension not be firm enough to cause the bullet to shift

I did have that problem before, I could push or pull the bullet out by hand, but I readjusted my neck die and I can no longer move the bullets by hand . Is it safe to assume that there is enough neck tension.?

 

[silverfoxdj]

I would think it would be okay if you could not move it by hand ..

You may want to try to just full size a few without neck sizing and see if the problem gets resolved..

 

[spatrick]

Are you measuring your COL from the tip or from the ogive of the bullet? In my oppinion, measuring from the ogive is what you need to achieve consistency.

 

[fivehundredlimited]

Thank-you for your help, I will give some fl sized cases a try tomorrow and see if that works.

 

[fivehundredlimited]

Are you measuring your COL from the tip or from the ogive of the bullet? In my oppinion, measuring from the ogive is what you need to achieve consistency.

I am measuring from the tip....how would I accurately measure to the ogive?

 

[spatrick]

You will need to use a bullet ogive comparator along with you caliper to accurately measure the seating depth.

 

[silverfoxdj]

Thank-you for your help, I will give some fl sized cases a try tomorrow and see if that works.

My pleasure sometimes it's a matter of process of elimination to get back on track good luck

 

[laker415]

You need to measure to the ogive as bullet tips have a lot of variance. Hornady makes an ogive comparator.

 

[spatrick]

I use the Hornady Lock-N-Load comparator.

 

[PitBull1973]

If you are measuring for ogive it should stay that way . As long as you can load it In The mag then oal don't mean nothing stick with ogive. Lots of different tools out there

 

[H4831]

I am measuring from the tip....how would I accurately measure to the ogive?

You seem to be doing your best to create a problem, where none exists.

1) Quit trying to measure OAL. Measured over the point it is a completely useless figure. And what difference does the OAL make anyway? Just as long as it fits in the magazine.

2) Seat the bullets so the bolt will close on them without extra pressure.

3) Load and shoot away.

 

[manitou210]

You will need to use a bullet ogive comparator along with you caliper to accurately measure the seating depth.

XX22 and get yourself a Redding Competition Bullet seater or Forester Micrometer seater
For VLD bullets 5 to 10k in lands anything else Kissing

 

[sharp shooter]

what you're measuring is normal. Like the others said, you need a comparator to measure that accurately.

 

[fivehundredlimited]

Thanks guys, sounds like I should invest in an ogive comparator.

 

[Lead hammer]

Measure 10 of just the bullet base to tip, you will see quite a difference likely.

 

[maynard]

You will need to use a bullet ogive comparator along with you caliper to accurately measure the seating depth.

I agree. Measure 10 bullets with your caliper and see if there is a difference. You will find that you are chasing your tail. Also "trim to length" of your brass has nothing to do with seating depth or OAL length of a loaded round.
You will probably find that .020" off the lands works better than .002". I know guys that jump Berger Bullets .040" to the lands.