Update 28 Oct in this post with a bonus question on how to get the best measurements using the tool.

Update 1 Nov in this post with a follow up question about seating the boat tail in the neck to get closer to the lands.

Original post starts here...
So I get the Hornday OAL Gauge to measure bullet seating depth for long loading 80 grain Sierra Match Kings in .223.  

I decide to get the curved model since Glen Zediker recommended it in his book because (he says) it's less prone to push the indicator rod in or out a bit as you tighten the thumb screw.  Website says either will work.

From Hornady's website...
Since I'm not using the .22 Hornet their site says needs the "D" adapter I'm good to go, right?  Nope.

The offset caliper mounting body does not have enough offset to compensate for the indicator rod that passes through the enlarged flash hole of the modified case so the case sits cockeyed in the calipers.

Yeah this is conducive to getting a good reading!
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The not helpful guy at Hornady says it's really made for lever action cartridges like .30-30 (I'm not getting how that will fix the off center problem but whatever and seemed to think taking measurements off of a cockeyed piece is good enough.

Anyone have any input before I use a chop saw on this POS and mail it to Hornady?

Did you try moving the device on the calibers. Maybe farther towards the tips so that you are measuring with the narrower part.

It's hard to see from just one photo.

Oh. And turn around 180' so the beveled part of the tip is facing away from the casing.

Motor

You are holding it crooked. That isn't Hornady's fault.

Seriously, you need to align it perfectly "by eye" and work from that point forward. I don't use it that way anyhow. I take one (1) bullet and seat it until it touches the rifling using Hornady's bent gage or straight gage, it doesn't matter.

I then use that exact same bullet and case measured from base to the tip using calipers. From that point forward I set up my seating die (using that exact same bullet) and set it to seat that bullet .020" deeper than just touching. I work in closer to the rifling or further away until I find my load.

All measurements are recorded for future reference. These measurements are in a constant state of flux. New bullets may or may not be identical to the lot I'm working with. There is some variation within each box of bullets even from the same lot number. My chamber will always grow in length as I shoot more rounds through it. I have to make adjustments, and experiment as I work through this process.

You can not expect these measurements to be perfect, even the Hornady Modified Case will have a different headspace measurement than you're actual rifle, possibly differing by .005" or more. What these measurements do is give you a working window for starting and stopping your seating depth experiments. It will also gice you a number to work with once you find an OAL" that works great for you.

You're doing something wrong but I cannot tell exactly what from the photo.  Work it out, dude!  

Install the gage and centered/lined up with the hole over the closed jaw of the caliper.  You may need to flip/spin/change to get it centered.  Only after centering can you use it.

<Trollslayer runs off to see how his is installed>




Honestly, the curved gage is less useful than the straight gage, which is ideal for an AR action.  The curved gage works on levers and the M1 Garand.  

Use the straight gage whenever possible.  If you were to exchange it for a straight gage,...

Tried every orientation of the calipers, base and case and the photo is the straightest it can be.  Every other option angles the case further off the caliper vertical line.

What do you mean by turning around 180'?

Here are a couple photos showing the offset of the gauge and how much the case is still offset further so that the case mouth does not center up on the gauge.

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I'd be less miffed but the Hornady dude's answer was "yeah just measure it while the case is angled and the bullet is being cocked in the neck.  It'll be close enough."

GUess I'm sending this one back to Brownell's and getting the straight one.

Looks like the comparator body might need to flip 180 on the caliper...if I'm seeing it right.

That's the problem.  It's already flipped so that the bullet hole is offset but it's not enough.  If I flip it back the bullet hole will be centered on the caliper blade causing an even more angled cartridge.

He means, in the photo, you have the pointy end of the jaws facing away from you. Turn them so they point AT you, it'll bring the jaw closer to the centerline.

Also, as stated, they are for getting you close to a starting point, adjust as needed for accuracy.

OTOH, I'd like to see the look on the Hornady tech's face when he opens your envelope with that thing hacked up inside.

Try putting the brass screw on the other side

The other side perfectly centers the bullet hole up on the caliper jaw centerline which would create an even more angled case.

What I mean is unscrew the brass screw and screw it back in on the opposite side of the body. That should push it over just a bit.

I recently got the straight version...it has the same issue with a forced offset of the calipers.  

However, I've found that with a little finesse I can get within about 0.001" from what it should measure.

Do what I did and calibrate the offset.  

Using Hornady's headspace bushings, take a headspace measurement of the modified case (not installed on tool).  Next do the same measurement with the modified case installed on the tool.  Take the difference and apply this offset to your comparator dimensions.  Should get you close.

What irritated me about this tool is...

1.  The description says it will work with any action with straight access to the chamber.  This tool was too short to work in my Mega Maten receiver (I've used a creative work-around for now, and will be machining a longer collar for the end of the tool with the set screw soon).

2.  I called Hornady expecting RCBS or Dillon level customer service and discovered I was on my own.  Zero help.

Thanks that makes sense.  Pretty frustrating when all they need to do is make a body just for the bullet comparator inserts instead of using the same one their headspace comparator uses to save a few bucks.

If the stupid body just had the slot machined further off center to compensate for the sliding rod pushing the case further off center this thing would be golden.

As long as the measuring device has a push rod that travels through the center of the housing, your caliper jaws cannot help but be off center. That's why both the straight and the curved yield pretty much the same results for you.

The best you can do is to measure with narrowest part of the calipers, and be prepared to make the adjustment below:

1) Use an empty case, optionally with the bullet comparator's base installed (rather than against the bare caliper blade)

2) Measure and note the case length with the blade of your caliper directly over the center.

3) Measure and note the case length with the blade of your caliper as off-center as it would be when using the Hornady tool.

4) The difference between the two measurements, if any, is your adjustment factor.

I guess we could file the notch deeper, but then we'd have to worry about the thin aluminum tube breaking.

Yep.  To work it would need to be a larger diameter circle (the body) or the interior hole would need to be drilled off center.  It's not rocket surgery and would be super easy for the manufacturer to do but would require them to give enough of a shit to try.  

It could be made even better if they built enough of a shelf so the side of the caliper blade is not resting against the sliding rod and instead against a machined flat surface.

Did you try putting the thumb screw into the otherside of the body?


It goes in on the thin side btw...if I recall. Have to check when I get home.

Yes I tried both sides and every orientation.  The closest it comes is about 1/8" off center.

Just to be clear, you took out the thumb screw put it the opposite hole then put it on the caliper with the thumb screw facing the dial side.

Ill measure mine when I get home to be sure. You cannot use it like that no matter what Hornady says.

Are you saying that the straight version has the same problem of not properly centering up on the bullet hole in the comparator?  Does anyone else have one of the straight ones and can verify that?

On Hornady's website the straight version uses a solid push rod that has a machined flat spot to allow the side  of the caliper jaw to hit the centerline of the case which should (should) give the case centerline the correct amount of offset for the offset body of the bullet hole to be properly lined up.

The curved one uses a spring "rod" that pushes the case body off center further away from the caliper jaw because it is not machined flat.

I have the straight one, if you put the oal gage on the wrong side it will be crooked. You said you tried every variation.

Cannot really see it that well in my video but I point that out

Yes we are in agreement.

The curved one creates additional offset because of the push rod being round and pushing the gauge further away from the side of the caliper jaw.

The straight version has a flat machined into the push rod so the side of the caliper jaw is the cenerline of the cartridge and the offset body perfectly accommodates that.

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I've put the thumb screw in both sides of the comparator base so that it either centers the hole on the caliper jaws or holds the hole off center to the same side as the case is offset.

The problem is the offset of the base is insufficient for the additional offset caused by the round push rod.

I must use mine wrong, I don't recognize anything you are doing.

My bases are the same as yours(i have 5 of them), 5/16 there where you're scale is shown.

My flat that goes against the caliper is .165".
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If that is the way they all are I would return that and get a straight one, is there some special setup you have to require the curved one?

I'm going to call Brownells and send this one back and get the straight one instead.

I opted for the bent one because Glen Zediker pimped it as the better option in his reloading book.  His stated reason was the curved one was less likely to have the push rod "walk" as you tightened the locking screw.

After careful review no one I found had anything negative to say about it and Hornady's website made it sound like it would work on any gun. I guess not...

Mine measures .168 just under the case and .174 at the bottom of the flat.   The deformation from the bend a bit lowerprobably has something to do with that.

The bigger problem is the push "rod" sticks out further to .221 total width as you can see below.

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Ah, I see now. Can't really put a flat on that stuff.

I guess it wouldn't effect the measurement toooo much but it would annoy me. I want a good positive, repeatable, square feel when measuring.

Exactly!  Yes it's probably within a few thou but the whole idea that we're talking about a process that's trying to hold stuff to the thou is now going to introduce a variable just because is insane!  

Gahhhhhhhh! (Or at least drive me insane)

Sounds like they need to provide a soft copper wire smaller than the offset hole? Anything to hold the bullet in place but small enough to allow a flat surface to ride the calipers against.

I have the straight one and have had no issues with it. My pushrod flat appera even with the red body cut out and everything is centerd. The brass thumbscrew is on the far back end of the silver bushing, which is also on the backend of the red tube. The brass setscrew is on the same side as the cutout.

I have found it best to take the average of 10 different bullet readings and figure your seating depth based on the ogive, not the bullet OAL.
I number the bullets and use them for averaging other measurements like OAL, Shank length, boat tail length etc. You could then load those numbered bullets for range testing to complete your data analysis.

I'm kind of surprised they would sell something that doesn't work but it's simply a matter of a flat on the rod is it possible to create that flat yourself?

Paint it up with a Sharpi and use a dremmel or flat disc die grinder and put a flat on it. De-burr if needed and go.

Who knows maybe when you take the rod out you'll find that it was put in wrong and has the flat on the back side.

Motor

Pull out that flex cable and see if both ends are the same.  You might have be using the wrong end.  

I haven't seen or used the bent version in so long, I don't recall the details.  I do recall it worked just fine.  Then again, they were made by Stoney Point last time I played with one of the curved units.

I reiterate - buy a straight one.

Update!

Returned the curved model (thank you Brownells!) and got the straight version.

As expected the straight model's flat plastic push rod allows the caliper jaw to lay flat against the aluminum body of the OAL gauge and lets everything line up perfectly.  I realize the angle wouldn't have made more than a few thou difference.  It's just a piss poor excuse for a measuring tool when modifying the existing design slightly would allow it to work perfectly.

Here's the new straight body OAL gauge with perfectly straight case and bullet hole lined up.
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Interesting note on the barrel.  

I had a gunsmith borescope the barrel after getting the barrel completely de-coppered and he showed me a few bad spots in the bore he said would benefit from the Tubbs Final Finish abrasive bullets.  He also commented that the throat was long enough that he doubted I could reach the lands with the 80gr SMK's I'm long loading.

The throat was kind of rough and there was a bad rough spot on the muzzle side of the gas port that looked like a burr had broken free and been dragged out of the barrel.    He  suggested the Final Finish bullets before I could ask.  Said 5 of each grit would do a lot of good in reducing the roughness so that's what I did per Tubbs' instructions (two 3+ hour days at the range to fire a total of 25 rounds!) .

It was after doing the Final Finish treatment that I wanted to check distance to lands to see just how far out it was.  That brings me to the next part.

Getting a good measurement to the lands was harder than I expected it to be.  At first I just seated the bullet deep into the case then used the push rod to push the bullet forward into the lands.  That was an inconsistent nightmare so next I held the upper muzzle down and dropped the bullet into the chamber from just over the barrel extension then gently inserted Hornady's modified case into the chamber and slid the push rod in until it made contact with the base of the bullet.  That was much more consistent.

Here are the dimensions of the two different methods of measuring.

Bullet pushed forward out of case..................Bullet dropped into chamber
..................1.924........................................................2.080
..................1.933........................................................2.080
..................1.896........................................................2.081
..................1.983........................................................2.080
..................1.937........................................................2.080

Every "how to" video I saw just showed people using the first method of deep seating the bullet in the modified case then pushing the bullet forward to the lands with the push rod.  I wonder if the ridiculously long throat of the Daniel Defense 5.56 chamber or a very gradual leade from throat erosion and the Final Finish treatment has something to do with the more consistent and longer dimension of the drop method.  
Anyone have any experience with this kind of situation?


The gunsmith was right, by the way, about not being able to touch the lands with Sierra 80's.  The boat tail is halfway up the neck when the bullet is in contact with the lands.

Not possible.  The "rod" on the curved model is actually a very tightly wound small diameter spring with each end soldered (to prevent it "fraying") that has enough flex to easily navigate the curve but still be rigid enough to function as a push rod.  It works very well to do that but if you tried to grind it flat or crush it flat it would be either broken in half or ruined.



The end that pushes the bullet has a little more solder on it to stiffen it up for the last 1/4" but they are otherwise identical.  It's a neat design that could have worked much better if they'd have tweaked it slightly to accommodate the greater offset required by the spring push rod.

Actually, 0.010-0.020" off the lands and having the bottom of the shank above the neck/shoulder junction is ideal.

What is the approx. COAL with an 80gr SMK?

The dimensions in my update post are base to ogive.

COAL for my current 80 grain load is 2.530 which puts the bottom of the shank just about at the neck/shoulder junction.  If I'm remembering from my measurements of loaded 80's before I headed home from my shop tonight that measures about 2.040" base to ogive or about .040" away from the lands using my bullet drop lands dimension.

That .040" jump was shooting 5 round groups of about 1.3 MOA at 200 yards (the max distance of my windless, narrow, tree sheltered range).

24.3 grains of Reloder-15 gave me 2573fps with a 10 round SD of 10.6 out of a Daniel Defense 16" midlength gas system.

Lead angle is probably different, but I was curious how it compared to these.

http://www.radomski.us/njhp/cart_tech.htm

Round count?


Fwiw, most ARs I've checked with a 77gr SMK show approx. 1.90-1.92" BTO.

Interesting.  I have a couple 500 count boxes of 77's I'll be loading to mag length once I get through the annual Snipergeddon match the 80's are for.  Hope to hit up a few Hi Power matches next year.

This barrel has about 3K rounds through it.  Mostly 55gr M193 clones like Wolf Gold or my handloads for Appleseeds and such with maybe 150 80gr SMK's shot through it so far.

It's just a Daniel Defense light weight hammer forged chrome plated barrel I'm trying to get the most out of as I learn how to shoot better.  

I promised my 16 year old son we'd build him an AR once he scored Rifleman at Appleseed and he just did that last weekend so that's first on the build schedule.  Maybe next spring I'll be able to get a "real" precision rifle built for me.

I'm glad you said it

I was thinking the same thing

I don't think I've ever used the comparator during that part of the operation to be honest

Am I understanding that correctly that you're saying the 80's will maybe shoot better if I go ahead and extend the boat tail into the neck meaning less neck touching the bullet?  Run out is not a concern if I do that?

.010" off is what I had read would be a good starting point but with the throat I have .020" would already be really pushing it.  That'll have the front of the boat tail near mid point of the neck!

Isn't measuring depth to lands the only thing the bullet comparator is good for?

If you're loading to magazine length the bullet should be miles away from the lands unless you have the world's shortest throat.

It's rarely a problem with .223, but there could be a bit of a donut, usually after several firings and sizings. 10 to 20 thou is a general sweet spot I've heard from many great shooters. I'd keep the shank between the junction and mid-point.

Or try jumping more than 40 thou. Some have had luck with 80 to 100 or so. Though 1.3 MOA with a chrome-lined DD barrel that's been fire lapped may be it's limit.

Ohhh. I remember that endeavor. You were the goober with a hasty sling, right?

My 90smk AR load at 2.580" puts the BT sbout .050" into the neck(.146" shank depth)

My 230gr .308 load at 3.247" puts the BT .165" into the neck (.130" shank depth)

The shallow seating along with .0015" neck tension actually makes runout less in my experience. ....unless you drop the round on a hard surface.

Not saying it will be better, but there is no reason to make an effort to keep the BT out of the neck..... or even follow that one caliber of bearing surface in the neck rule of thumb unless you are abusive to your ammo.


With less neck holding the bullet, it would make sense that the neck will have less of an influence on the bullet. So perhaps a less inconsistent release due to case variation.

I wondered that too.  I’ll try some different depths and see if I can get a little hotter load (safely).  If I can miracle myself an extra hundred fps that wouldn’t be a bad thing.

I’m using an H3 buffer and Tubbs flat wire recoil spring (changed from a carbine spring and H buffer when I developed the load) so have wondered if I can push the envelope a little on speed now between the heavier buffer assembly, fire lapping and potentially longer COAL.

Guilty!   Although it was my version of a Ching/Vickers “tactical” loop sling rather than a hasty.  

I’m doing it one more time the same way this year to see if I can make 1000. Maybe by next year I’ll be able to build a better rig.

Thanks!  I’ll be necking these with a mandrel for .002 tension.

Just don't sacrifice SD for MV unless they're funky when transonic.

Absolutely!  Heading out to a buddy’s windy property today to test my current load out to 900.  We’ll see how it does!

So it didn’t go too badly!

We couldn’t see the 900 yard plate because he hadn’t had a chance to mow around it but we did get most of the way.

This plate was at 680 yards (lased).  The wind was 10-12 mph but almost exactly a head wind (maybe 12:30).  We were shooting almost straight south.

StrelokPro said I needed 20 MOA to hit it so I dialed 6 MOA and used the bottom BDC dot in the Burris MTAC 1-4x reticle.

After two rounds my spotter wasn’t sure I was hitting (he thought high since he couldn’t see any dirt) so had me aim at low on the plate for round 3.  He still wasn’t sure after that.  Apparently .223 hits are a PITA to see that far out.

I decided to dial all 20 MOA and use a center hold and fired three more.

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What you see is 2 rounds pretty well centered with a third round lower and a little left then another 3 round group right on the right edge at about 2 o’clock.

StrelokPro was saying to aim on the left edge but I just held center for both groups.  I wonder if dialing more vs hold would affect the lateral location of the group or was I just a little more on the trigger with my second three rounds???
On second thought I was using the bottom BDC dot for the first three and it did make it hard to center the target in the dot.  I could have been aiming left of center with that then able to very easily hold center with the center aiming dot with my second (right edge) group.

I didn’t have a tape measure but maybe 5” for those second 3 prone and slung up at 680 yards with a 4x isn’t too bad!

We stopped after those two 3 round attempts to inspect the target because my buddy thought I hit it but wasn’t sure.