Just got my Forster dies in and I have noticed that 140gr ELD-M range from .762-.758 from bullet base to ogive. So, as I am seating the bullets, I measure the CBTO and have to adjust the micro head then seat it deeper as needed. Is this normal? What do other people do, just set the micrometer and go for it?

Cartridge overall length is important for function. For accuracy, ogive length is more important.

Don't keep adjusting your die. Just set it at a length that can function in your firearm and stay there.

My goal with adjusting the die was to get a consistent CBTO (cartridge base to ogive)

.004 variance ain't horrible from my experience with the same die. Probably 80-85% of mine measure with .002, but I do always seem to get a few "fliers" up in the range you're seeing. If you're seeing that kind of variance in a small sample, there may be something amiss. I'd suggest making sure the seating stem is clean and also that it's playing well with that ELD bullet.

You can sort into groups and load/fire them in like strings or leave it, that isn't too bad.
Depending on where your comparitor measures and where the seating stem pushes and where the length difference is(is the ogive different or the bearing length or BT length?) you could end up with the same BTO measurement without adjusting the die. This may mean that more bullet ends up in the case from one round to another, a small amount probably will have no effect on pressure.

Inconsistent brass(neck wall thickness variation, work hardness variations) will cause seating depth inconsistency too so you won't know which is the cause, bullets or brass unless you sort the bullets.

Just checked 50 or so of my 147eldm from two different boxes same Lot#, and had a .003" spread. BTW I try to use the comparitor insert that falls closer to where my seating stem touches so for 6.5 with my 6.5 Forster die I use the 2-22 insert.

I suppose I will have to shoot a few of each to see what the results are. I loaded some that I adjusted the seating depth to get the CBTO (I think that is the same as BTO?) consistent, and I also loaded up some that I just loaded them and called it good.

I am not 100% sure I understand what it is you were saying, but I read it as if the seating stem engages the ogive at a different spot due to variances in the bearing surface/ogive length then it might push the round more or less? I might need to brush up on my bullet nomenclature

There were some that I could tell right off the bat were a neck tension issue because I could just feel less resistance.

I don't have my data in front of me but +/- 0.0015" seems like a lot of variation for Sierra bullets.  0.003" dispersion is what I see in the Hornady bullets as lot-to-lot variations but even there, I do not see that much variation within a lot.

It seems to me, the benefit of these gages is to measure/control the distance from the ogive to where it engages the lands.  That would require the use of the proper insert for the caliber.  If you do this, it would not surprise me if the variation was reduced.

In my case, even the 0.003" dispersion would not be problematic, as I always leave 0.010" or 0.020" jump.  A few thou more or less has never shown to be a problem with the Sierras I've tested.  VLD's?  Maybe.  Non-VLD Sierras?  Not a problem.

If you have several inserts, you could use them all and get (diameter, length) data.  This might show if the dispersion is due to variations ion the tip angle, the tip diameter, deformation from inserting the plastic tips or bending of the long, skinny ogive.

I want to be measuring and sorting bullet base to ogive at the same point as the seater stem rests in case the the ogives are slightly different along their length.

If I measure the bullet base to ogive near the bearing surface and find them all the same but my seater stem rests near the point, I may find BTO oal vary and wonder why, maybe neck tension, maybe ogives are different along their length. It really isn't important just something I do to eliminate possibilities if I have a seating variance issue.
I am measuring at the same point the seater stem pushes so even if the bullets are different lengths I should still get consistent cartridge base to ogive length, if not, it is a brass problem(possibly a compressed charge difference).

And as I said if the bullets are different lengths but end up all the same OAL well then some have more bullet in the case than others, this will change the pressure a little bit. In Quickload with my Grendel load I happen to have up .004" difference changes the velocity 1fps.

The 147eldm is Hornady, to be fair out of the bunch of 50 or so, they were all +/-.001 but one made the spread .003" total.

You are correct about the inserts but I too am off the lands enough to where a little difference won't be an issue, I do it to for the reason I explained above.  I am using the tool to measure seating depth consistency only. If I were loading to the lands I would want to measure at that point.

Did some measurements here with some 230otms Bergers. I measured them all withe the .220 insert and separated them into three groups of lengths .022, .0225 and .023. Then colored the tips for their groups. I attached the .300 insert and remeasured and grouped them into .096, .0965, .097, .098. You can see there is a difference, long ones at the bearing surface were not necessarily long measured nearer the point.

I'm interested, so I'll have to measure a few.  It's been a while since I've done this.  I can't remember offhand what the dispersion was.

Lots of good info here.

It leaves me with a question, though.

Would it be worth while to get a custom seating stem and comparator to touch the spot where the bullet will engage the lands since that is the part we are trying to control?

I'd say no, it's not.  A few mils is not important unless you are jammed into the lands.  Even then, maybe not.

Load.  Shoot.  Be happy.  Don't obsess over a few mils.


Are you jamming into the lands?

it's hard to tell how far off the lands I am because the freebore is tight on this barrel, but I am touching right where the tension is. I loaded a couple .002 longer and noticed some cratering and a pierced primer so I imagine those were jammed.

I have yet to measure the all over the groups, but just from eyeballing, the rounds that I adjusted the CBTO for shot better the rounds I just seated and called good... well, good as in smaller group at 100



Freebore is tight, which is bad... but this thing still shoots, even with a loose scope base, which I noticed after shooting last night.  

I agree, a couple thou won't make much difference.

I'll do some more testing between the two methods in the coming week... but adjusting the seating depth to a consistent CBTO did well at 599yd.  I called a slight buck on one of the shots, assuming it's the low one.

Compared some loads. One set I backed the micrometer off .005, sat the bullet, measured, sat the bullet the remainder of the way to the desired CBTO. Other set I set the micrometer and sat the bullet, called it good.

They both shot well at both 100 and 550, but the set with that was not remeasured had a couple pierced primers. I haven't calibrated my quickload to this powder and case yet, but the difference should not be that bad, maybe my tight freebore, and being right on it is probably the cause of the pierced primers.

Just calibrated my quickload.
Adjusted my Grains H2O to 52.16 (my average of 5)
Adjusted my burn rate factor to 0.5283 to match my average velocity of 2,792fps and my max pressure is now 59556psi. this might not be a safe load.... will look for a node below this.... one day

This is how I load my precision loads.

It goes really quick and ensures consistent ogive to base loads.

From your video it seems like I am doing basically the same thing... only on  a single stage and without the instant indicator.

How do you like the T7? I have had that and a coax in my shopping cart for a little while debating between the two. It look like the t7 with indicator really saves time.

Absolutely love it. Note that is not my video, that's where I learned about the setup and bought the stuff to replicate it. I take no credit for the video or the idea at all.

I will have it setup to load 308, 6.5 Grendel and 6.5 creedmoor soon all on the same turret. Get it set once, never ever move a die, pump out precision loads really quickly. I've only loaded 308 so far and it worked really well.

I would say 95% of the rounds I have loaded have runout less than 0.004" with redding competition dies. Love the setup.