I've seen several threads on this including one I started myself asking about this.  I figured I'd start clean here.



Task:  
Determine a cartridge length, without measuring from the tip, for 77 SMK that fits in a mag and use that setting from batch to batch.

Even match bullets have varying base to tip lengths due to the way the tip finishes off.  But the rest of the bullet (base to ogive/shoulder) is incredibly consistent from bullet to bullet


Disclaimer:
From my reading these tools and these methods are actually for setting bullet seating depth so that it contacts the barrel rifling at a set distance for each round loaded, specifically for bullets that seat to longer than mag length.


This is meant to show a method with related tools.  There are of course varying combinations of tools to accomplish this.


Tools used:

Lee Bullet seating die from the Pacesetter/RGB set
http://www.midwayusa.com/viewproduct/?productnumber=434975
http://www.midwayusa.com/viewproduct/?productnumber=554943


Sinclair Comparator/Bump Gage Body
http://www.sinclairintl.com/.aspx/sid=66325/pid=34014/sku/Sinclair_Comparator_Bump_Gage_Body

Because I already had it.  The Hornady insert below fits fine.


Hornady Lock-N-Load Bullet Comparator Insert 204 Diameter
http://www.midwayusa.com/viewProduct/?productnumber=126080

Yep, you read that right ................ 204 diameter


Hornady Lock-N-Load Bullet Comparator Anvil Base Kit
http://www.midwayusa.com/viewProduct/?productnumber=584824


Frankford Arsenal 6in digital calipers
http://www.midwayusa.com/viewproduct/?productnumber=604242





Results:














Here is the .224 insert (from Sinclair).  They're are as advertised, bullet comparators, not suited for this method here (though when I ordered I thought it might be) hence the reason I ordered the 204 insert

Does any of that .007 difference show up on target ?

Edit to comment: that last pic looks like the cases are Oversized maybe, very sharp shoulders, via the ring ?

no ............. as long as they're seated to the same depth, which the method shows they are

If you tried to seat every bullet to the same COAL they would vary in depth within the case .................... by .007 across the five rounds in this case


shoulder are fine, optical illusion

Yeah, you finally got it nailed down as to how it all works(with an AR seated to mag length), it basically just shows you that your bullets are seated consistent regardless what the COAL is and if you single load long match rounds you can use the OAL tool & modified case along with the bullet comparator to see where the bullet touches the lands and can adjust from there.

You don't need to use the .204 Hornady insert(the .223 one works right) but the .204 Sinclair insert will probably work perfect, I use the 6.5mm Sinclair insert with my 6.8 bullets to get the correct reading from the ogive like the Hornady insert does and your .204 Sinclair insert will/should work the same also.

Now start measuring concentricity with a Sinclair run-out gauge and see how much work your brass needs

You can throw in neck thickness for proper bullet tension and release if you want, I prefer the K&M turning tool as it does an amazing job in a short amount of time, I was just going to do 50 of my 6.8 Hornady cases for fun and see how much run-out improved and ended up turning them all it went so fast and easy.

Now I need a case neck annealer$450, Giraud trimmer$400, & Sinclair power unit$400, so it might take me a little while but my new Shilen Ratchet rifling barrel seemed to like the neck turned brass this weekend as fliers where none existent except for the 2 I pulled off myself and called.

Actually I had it figured out from the beginning, just needed the right parts to make it happen

Excellent demonstration OP (danpass)...

danpass,  can you break it down barny style for me and explain why the .204 insert was used instead of the .223 insert?  and why the .223 insert looks like it doesnt work right and sinks down to the case?

Do the seating dies listed register on the ogive?  I have a set of Lee dies that use thier "dead-length" bullet seater and I always end up with differing distance to ogives because of bullet tip differences (lengths) that allow the bullet to be seated more or less farther out..?

Sir, I don't intend to critique your post, you have obviously spent a lot of time in it's preparation.

However one point I would like to make is the relative importance of case neck tension on the bullet to the consistancy of the finished ammo.  In my humble opinion die selection and case neck measurement to ensure that one achieves the desired finished dimensions will go a long way to make neck tension consistant.

Most resizing dies I have used resize the case neck too small, that is to say that the inside diameter of the neck is less than it needs to be.  In my experience with loading 77gr Sierra MK bullets with an outside diameter of .224" the finished dimension of the resized case neck should be .222" or slightly less, ie:  .2215".  Most resizing dies use a decapping rod with some type of expander ball to enlarge the resized case neck to the desired dimension.  Since the resizing die has already resized the case neck more than is necessary the friction produced as the expander ball is withdrawn from the case interior will often result is some distortion of the case neck and shoulder which introduces some inconsistancy in each case as it is resized.

There are a number of ways to address this problem, one is to apply some type of lubricant to the case neck interior.  Some will advocate modification of the expander ball to polish it which is also intended to reduce the friction.  One die maker that I know offers an optional carbide expander ball.  While all these methods work to some degree the best solution that I have found is to not resize the case neck to small in the first place which reduces the amount of work hardening of the case neck during the resizing process.  Redding type "S" resizing dies offer the reloader the choice of various size neck bushings which allow the reloader to select exactly how much he wants to resize the case neck.

In the narrative you have posted I noticed a step where you suggested the reloader apply some lubricant to the case neck interior just before resizing.  While I don't disagree with the reloader applying lube to the case neck interior, I never saw where you mention that the lube should be removed before the bullet is seated.  I highly recommend using Imperial Sizing wax which is now sold by Redding.  IMHO it's the best product for the purpose and will last a very long time.  I do however recommend removing any case lube from the inside of the case neck before the bullet is seated.

My last suggestion is that one investigate using the carbide expander ball offered by Redding as well as the case neck expander mandrels sold by Sinclair Int.  Since we're actually addressing the inside diameter of the case neck it seems more prudent to size the inside of the case neck rather than the outside diameter of the case neck because brass case neck wall thickness does vary.  It has also been my experience that if the reloader resizes the cases to a finished neck inside diameter of .2215" there is no need to crimp the bullet.  In fact I do not recomment crimping a bullet that does not have the requisite groove.  Since most brass has a variable case neck wall thickness and many reloaders do not have a consistant case length crimping bullets into cases with variable neck wall thickness and case length introduces an inconsistancy to the finished product that opposes the goal of most reloaders to produce consistant reloaded ammo.  HTH, 7zero1.

Something that I do is I measure the driving band or bearing surface length. I use two .222 comparators, one for the bottom of the bullet and one for the top. You would be surprized how much of a difference there is between them in the same box and even more between boxes. I sort them by bearing surface length in .002 increments and generally have at least 5 different boxes. This is with a very popular bullet brand.

I never did this until I read somewhere the reasoning and it has helped my SD. The explanation I was given was that a longer bearing surface creates more resistance and with that more velocity. The opposite holds true for a shorter surface. And if you have bullets with a long surface and a short surface in the same groups you are going to get a flyer. My SD, since I started doing this, has been 6 fps. This is on a 223 firing 69 grain SMK's at a average velocity of 2954 FPS.

I also seat according to the ogive. I made a seater for my die that has an opening for the bullet that is .221". This keeps me from adjusting the dies all the cime to compensate for difference ogive lengths. Before I would seat with the factory die setup and would get extreme differences when I measured ogive to case bottom.

I uniformed my primer pockets and my flash holes but that is it other than trimming to length. I do not' shoot competition so I don't turn my case necks. Since started doing this my Savage has averaged shot groups  <.4" 100 yards groups. This is well over 200 rounds so far and all groups have been at least this small using my handloads. My groups are all at least 5 shots.

Here is a few psots regarding this and a few other sthings to do from a competitve shooter. His threads are "Handloading for long range" by TresMon.

Dolomite

How much of a jump do these rounds have in your chamber?  Do you do any meplat uniforming or do you shoot them "as is"?

Don't know, I'm loading mag length.

This is just to have the same ogive length rounds from batch reload to batch reload



eta: clarified

The thing I'm wondering about, using the ogive as your reference point works great when adjusting to get a consistent jump to the lands.  But w/o meplat uniforming, and recognizing that there will be OAL variations due to non-uniformed tips, you still aren't getting a consistent OAL which would be necessary if you are targeting your rounds for 2.260 OAL.

If you are jumping many tens of thousandths or a couple of tenths to the lands, using this tool is a waste of time IMHO.  It really comes into play when you're trying to find the OAL sweetspot for 80 VLD-type bullets, and these you are going to single load much longer than 2.260".  And even if you experience a couple of thousandths variation in OAL due to the way the tips are formed, I doubt you're going to see much accuracy impact on the target.

I'd just adjust my seater to something like 2.255" and assume this will cover you in case you get a bullet that loads a bit long.  Or I'd uniform my meplats to get consistent OALs.  JMHO.

+1.  These were my exact thoughts when the OP first brought this up.

Outstanding representation of what I had been suspecting.  

I was going mad that my COALs would vary that much, but suspected that, due to what appeared to be slight irregularities of the tips, that the seating depths relative to ogive were more consistent than COAL measurements were implying.

Thanks for sharing the results!