How Does One Get Consistent Readings with the Hornady OAL Gauge

[cw308]

The problem with using the Hornady length kit is if your finding you ogive measurement and your case headspace is not known when you seat your bullet to the Hornady measurement and your case sized case has wiggle room , how accurate is your CBTO measurement. It will not be consistent. Finding your case headspace first , this measurement will not change but your ogive will from use. Benchrest shooters will check every 500 rounds or different lot # even with the same bullet. Can't go wrong with the closed bolt method , you can check it out on line. I found it very accurate for both datum and ogive measurements
PS: The problem with soft seating you bullet to find the lands is when the bullet comes in contact with the lands , the bullet will stick and pull slightly out of the case neck . I found seating with normal neck tension bullet seated long and testing in chamber , lowering the bullet in the press until you find your touch , from there you can set jump or jam . This is done with a sized , no primer or powder in the sized case and used as your dummy round for touch measurement.

 

[AckleymanII]

If you use a fire formed case from that chamber, things get easy, real quick. You have to invest in a drill and tap, and I have them if you need them.

 

[Laurie]

I found seating with normal neck tension bullet seated long and testing in chamber , lowering the bullet in the press until you find your touch , from there you can set jump or jam . This is done with a sized , no primer or powder in the sized case and used as your dummy round for touch measurement.

My usual method too these days for match chambers. A really good quality magnifying glass is a boon too to see hair-thickness rifling marks on a clean bullet at the point where 'feel' suggests there is no resistance to bolt closure.

 

[dellet]

I would say that if you are getting results that are not repeatable, then either you have a very heavy hand, or the neck tension on your modified case is too tight. It's likely that it is harder to move the bullet in the case neck, than it is to stick it in the lands.

If you take an empty case with a bullet loaded long so that you know it will jam, then set your rifle muzzle up on the bench.

Bolt out and insert the round into the chamber with finger pressure, if it does not drop out under it's own weight, you used too much pressure. it's surprising how little it takes to jam the bullet enough to hold.

When you get a feel for that pressure, that's a bit more than you should feel using the Hornady tool.

 

[Old Tanker]

Instead of seating the case then pushing the bullet in, try the opposite. Place the bullet long in the case, tighten the thumb screw then push the bullet and case in until it stops. Then, loosen the thumb screw and seat the case the res of the way. Tighten the thumb screw and remove the assembly from the chamber.

 

[power55316]

Best way is to not use one do the bolt drop

 

[South Pender]

Many thanks to you all for your suggestions. I think that the error I was making was in trying to find the minimal (lightest) touch point. I was obviously misreading the feel of the rod. Once I switched to finding a definite impact point, measurements became much more consistent. I'm guessing that, with the latter approach, I am probably finding a point .01" or so into the lands because when tapping the unit out with a wooden dowel, there is definitely slight resistance at first.. So subtracting something like this amount from my measurements will probably give me what I'm after.

I found the technique used by ronemus gave me the most consistent measurements.

 

[Chasin Beaver]

I've found this approach to give very consistent results:

Push the wire that pushes on the base of the bullet out far enough so the bullet will hit the lands
Gently put your finger on the end of the wire
Push the tool with the bullet into the chamber, allowing the bullet to push the wire back out [so, your finger has to be quite gentle on the end of the wire]
When the tool is all the way in the chamber, tighten the lock screw and measure.
=> Consistently get 1-2/1000's variation in measurements.

I used to seat the bullet so it would not engage the lands; push the tool all the way into the chamber, then push the wire so the bullet just touched the lands. Easy to get over 10/1000 difference in measurements.

Exactly how i do it, and how I used to do it.

 

[chkunz]

I am late to the party but I will add that measurements are more consistent on a new barrel than a well worn barrel. Anyway, the Hornady OAL gage is not a precision instrument but you can do better than 0.040 variation but do not expect too much from this tool.

 

[D-4297]

Being a retired toolmaker , with sensitive touch , the very first thing I did with the Hornady tool was take a X-acto knife and drag all the parts to remove the burrs on the shaft . then polish the shaft with some fine grade lapping compound . Eliminates a lot of "Variation" issues . My method to using the tool is to take ten measurements . Throw out the Long and short ones , and avg. the balance left . Ironically ; the remaining numbers are usually within a plus or minus of one or two thousandths . Just takes a little patience , and not getting in a hurry .

 

[msilbernagel]

On Greg’s advise I went with the Sinclair and it works great for me

Reading this thread made me curious, as I'd not yet tried the Sinclair (on the shelf). I found it quite difficult to get consistent readings; only doing so by using the lightest touch so as not to force the bullet in farther (ELD-X 178 30cal). Even then I wonder if I could keep measurements consistent to 0.010". Both the case and the bullet did this. The extremes were as much as 0.04"-ish.

I then tried the stripped bolt method, took a fired case, and worked it with the FL die until it closed without resistance. It was like night and day better and I think the consistency will be far better. The movement between no-go and go was about 0.2" at the edge of the RCBS (std) die lock ring. It was very obvious when I found it's happy place.

I've not measured it with a comparator yet, that's next.

Got to learn how to strip a CF bolt of a M70. That was interesting.

 

[drano38]

I use a small dowel rod down the bore, and push the bullet on and off the lands a few times to get the feel.
Then I take several readings, and average them as mentioned above.
Of course, its a baseline to then move from to try various in and out of lands loads. So if I'm off by a few thou, I don't worry because I'll find an accurate bullet length with load testing.

 

[INTJ]

I've been experimenting with the Hornady OAL gauge and am finding poor consistency in the results. Of course, the measurement you get depends on how hard you jam the bullet into the rifling with the tool. Nonetheless, when operating the gauge with what seems like consistent pressure on the rod, I'm still getting differences in COAL running .040" from one measurement to the next. I"ve watched the Hornady video on using the tool and am following their suggestions.

Have some of you guys used this tool to determine the OAL that has the bullet just touching the rifling? If so, have you developed a technique that yields consistent measurements?

There is a big difference between getting .002 to .005" errors and .040"+ errors. The small errors are mitigated by practice and developing a consistent approach. Precision measuring is an art.

However, the .040 and greater errors are often caused by a cased not being pushed fully against the shoulder. This can be due to an oversize COAL case, a tight chamber, the hole in the COAL case not being straight, by misalignment when putting the case in the chamber, and by not holding the case against the chamber when tightening the thumbscrew. I have some all of these and I am sure there are more.

So the first step is to make sure the COAL case is pushed fully against the chamber. Make sure the case isn't overly tight in the chamber and it freely goes in and stops.

Next is to make sure you are pushing on both the case and the bullet rod while tightening the thumb screw.

The next step is to pay attention to how it feels when you use light pressure, medium
pressure, and heavy pressure.

Finally, practice a bunch.

 

[Aeon]

Best way I have found is to leave the gauge on the bench and use the wheeler method.

For the AR I use it and a cleaning rod. Average 5 and go from there

 

[coldboreshot]

Practice and more practice. I abandoned the Hornady and went to the Sinclair. Much quicker and more repeatable IMHO.

Greg

^^^^^^^^^ +1. I primarily use the Sinclair device. A little more time consuming but better accuracy. I think if the seating rod in the Hornady was a slicker harder material other than plastic, It might stand a chance. I had issues with dragging of the plastic rod. The cutout in the Hornady tool for a caliper is too delicate. I have had one snap off at the head.

 

[D-4297]

^^^^^^^^^ +1. I primarily use the Sinclair device. A little more time consuming but better accuracy. I think if the seating rod in the Hornady was a slicker harder material other than plastic, It might stand a chance. I had issues with dragging of the plastic rod. The cutout in the Hornady tool for a caliper is too delicate. I have had one snap off at the head.

Agree on wishing the shaft were made from a different material , say brass , or aluminum , but that's why I scraped and polished it . My usual "run" will generally be within .001 , but heavy-handed gorillas need not apply . I've done due diligence on this with a chamber mold , to confirm chamber dimensions , checked on a comparator . As @INTJ said , it takes practice to get it right . And no matter what method used , you will get variations . There's always more than one way to skin a cat .

 

[GLShooter]

Agree on wishing the shaft were made from a different material , say brass , or aluminum , but that's why I scraped and polished it . My usual "run" will generally be within .001 , but heavy-handed gorillas need not apply . I've done due diligence on this with a chamber mold , to confirm chamber dimensions , checked on a comparator . As @INTJ said , it takes practice to get it right . And no matter what method used , you will get variations . There's always more than one way to skin a cat .

My "HORNADY" tool is a Stoney Point, the original. and it's push rod is aluminum.

Greg

 

[Old Navy]

Nothing wrong with the Hornady. Just takes practice and a light consistent touch.

 

[INTJ]

My "HORNADY" tool is a Stoney Point, the original. and it's push rod is aluminum.

Greg

I have a steel shaft in mine, but I use a plastic one at work and I think the plastic might be better. You can't force things as much.

 

[lotech]

Some seem to have an aversion to anything simple today or maybe spend too much time on YouTube, but I've used the Sinclair nut for more than thirty years. It works well and measurements are repeatable. It takes but a little practice to become familiar with its use.