How To Use the Hornady OAL Gauge To Load More Consistent Ammo

Veteran Brownells Gun Tech Steve Ostrem explains a critical but often overlooked aspect of accurizing handloaded ammo: bullet seating depth. Hornady's Overall Length Gauge - aka "OAL Gauge" - enables you to precisely set seating depth so a chambered round's bullet just touches the rifling, with no freebore gap to cause it to enter the bore cockeyed. The OAL Gauge uses a specially modified case for the cartridge your rifle shoots. Attach it to the gauge, then inert a bullet into the case neck and insert the whole shebang into the chamber. Push on the back of the gauge until you feel the bullet juuuussst engage the rifling. Next, use the Hornady Bullet Comparator in your calipers to get an exact seating depth measurement. This is the CORRECT seating depth for most consistent performance from your ammo. Start loading ammo on your press, checking each loaded round with the Hornady Comparator to work out the precise position of the seating die to achieve that ideal seating depth. A micrometer seating die helps, but it's not absolutely necessary.
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[@tuberaider]

I always enjoy Steve Ostrem's instructional videos. Experience shines through.

[@CalebSavant]

That it does!

[@srt94]

Your comparator appears to be attached to the calliper jaw 180 degrees the wrong way. The slot in the red part of the comparator is machined with offset to ensure that the cut-out in the sliding gauge tube is aligned and square to the axis of measurement. Your OAL measurement was slightly oblique.

[@Karl7219]

Good spot. It’s funny how many “how to” videos on the Hornady O.A.L gauge show people taking their “precise” measurement with the modified case not held square in the caliper jaws...

[@nickpope7624]

I came here to say this. Thank you

[@MarkLeo-h5k]

Zoe Hill

[@chardon59803]

Good Lord, I understood what he did and just increased my knowledge, well, a whole bunch. Clear and clean instructions, wonderful.

[@roykiefer7713]

I wonder what the manufacturing tolerance generally would be for the projectiles?

[@williamfisher2906]

Throw away the " modified " case and make your own from a twice fired brass. Make sure your brass will chamber. Not tightly but evenly. If your modified case just happens to be too short for your chamber, all your measurement will be short accordingly. I even bought a 270 modified case and it wouldn't chamber. It was too long for my rifle' s chamber. The drill bit and tap are available to make your own from your own brass.

[@terrygardner2426]

There is a wealth of knowledge in most if not all of Brownells videos. They are my go to for information whether it be handloading, cleaning, sighting in etc.

[@DLN-ix6vf]

TIP: for the Hornady bullet comparator; I just measured 3 different 223 bullets of different weights and manufacturers and found a total of CBTO variance of some .030. All bullets must have identical O'Gives. Then I removed the plastic plunger and filed down the rounded end into a more pointed end and remeasured a 3 bullets again @ 8 each and found the new total variance of the same bullets to be .010. In two of the bullets the CBTO variance was less than 5%. Very accurate now. My conclusion is the bullet bases are not 100% perpendicular to the concentricity of the bullet and the plastic plunger end is too large to get an accurate reading on a small point from the base of the bullets. This was all done in a brand-new JC Custom barrel just purchased and not installed. I wish Hornady would install a smaller metal pointed end on their plunger for a little extra money.

[@troy9477]

Great series. Seeing something in use is always better than reading directions, even with good photos. U still need to read, understand and follow the directions of course, but seeing it action puts it all together

[@peteshour768]

Thank you for the simple explanation.

[@satched]

Awesome video. The exact info I was looking for. Cheers

[@carsniper]

3.130 is wrong. I know that’s what it says but that that is not the true BTO measurement. You forgot to zero out the 1.0030 inches of the comparator. A 308 is not 3.130 BTO, a 338 Lapua from a SAAMI chamber has less BTO - something like 2.976-2.985. Your 308’s true BTO measurement was something like 2.12-2.13. The OAL of a 308 doesn’t even touch 3.13, it’s 2.810 max. If that 308 is 3.13 OAL I might believe it if that gun is long throated but you measured BTO not OAL. A long throated 338 Lapua is around 3.145 BTO.

[@railx2005]

Lmao. You dont have to zero this. If you are using the same measurement process, it literally doesnt matter

[@carsniper]

It is when your video is telling people BTO is longer than possible with a 308. Sure, if you don’t zero it and just looking for the same measurement every time and don’t care to know the actual BTO then it doesn’t matter. If you actually read my comment you would note that I said 3.130 is not the actual BTO since the caliper was not set to zero off the comparator. I think it does matter if you’re a business and you’re telling people your 308 measurement is longer than it ever could be.

[@RaymondTusk74]

@@carsniperIt doesn’t matter. Chill the f out

[@romainorville]

What happened to taring the calipers or remove 1” from the reading??

[@yojimbo05]

The best instruction video by far thank you so much.

[@KimberlyLopez-d5e]

Gerlach Fall

[@DonaldHall-f6l]

Ritchie Lakes

[@HectorKelley-b4l]

Braun Shoal

[@LeacockFrances-s6u]

Blick Trace

[@EvelinaSebastiane-r1o]

Brown Street

[@williamhall2386]

Should the modified case be fire formed or new brass?

[@herrprepper2070]

William Hall - I had the same question a few years back and discussed it with “Hornady Loader” (RIP). His recommended technique was to use a fire formed case, or to do some calculations involving the measured headspace of the modified case, a fire formed case and even the headspace of new brass you are loading. Frankly, I found that simply using the modified case as demonstrated in the above video provides excellent results without a mind-bending series of measurements and calculations. In my situation, I found only a 2-thousandth difference between the Hornady modified case and my fire formed cases. I just don’t need to hit a fly-speck at 1,000 yards. A fox at 200 yards, or an antifa booger-eater at 500 yards is plenty good for this old Wyoming guy.

[@SkinnySkinch]

@@herrprepper2070 HAHAHAHAHAHA or an "antifa booger eater at 500" hahahaha thanks for the laugh I needed that today

[@rustynut1967]

@@herrprepper2070 Yes. He is leaving out an important step here. Measuring the length of the case to the neck.

[@troy9477]

@@herrprepper2070 I would say abt 800 yds for Antifa. Want to keep them as far away as possible

[@jjgriffin3275]

FYI - the curved version does NOT work on a Henry 45-70, it wont fit in.

[@daviddahms1696]

excellent! Thank you. It had been since 2017 that I reloaded, so I needed a refresher on getting correct OAL and measuring it after seating. Thank you.

[@MrMetalhead0124]

Does Hornady make a modified 22-250 case for the comparator, and does this devise work on the 22-250?

[@tomgiorgini9154]

very clear info thank you

[@jho107]

Very various calibers

[@HamiltonJared]

74705 Madelyn Stravenue

[@michaelw.urbansr.8617]

How about determining the caliber of a rifle? I have a VZ24, built in 1926,the 1st year they were produced in numbers for the Czech Army as well as export. My Grandfather took it off a German solder ,during WWII and its not stamped with a caliber marking. So how can someone figure out what its caliber is,without pouring molten metal down into a plugged chamber? Thanks

[@madbluntz42069]

Could be 8mm mauser, but they did use 7.92×57mm Mauser in early rifles , 7×57mm Mauser, 7.65×53mm ArgentineAction

[@michaelw.urbansr.8617]

@@madbluntz42069 Yea that is true since the 1st year or two were for the other Communist countries as well as their own Czech army. But what if its not? LOL i have an 8mm round although its not 8mm Mauser and it seems as its a bit too big? Is a Russian round i believe? Id have ot go into the safe and dig threw to find it? lol But I have always thought the bullet deforms and stretch's as it travels down the barrel. But im no expert so? hehe

[@davidfee4825]

I have an old set and I need to know which one was for 6.5 . I think it was the number 5 . They range from #2 to #8 . Anyone know ?

[@robertbrandywine]

I have: #2-22, #3-24, #6-27, #7-28, #8-30.

[@MorseOtto]

893 Swaniawski Trace

[@roykiefer7713]

. . . Yes, and his quite, entirely professional and absolutely expert demeanor. It’s difficult to equal and impossible to improve upon.

[@chriskelley2084]

WARNING: Great video, but you took the micrometer measurement wrong (at the 1:50 - 2:20 minute mark). You needed to flip the OAL the other way around. The way you had it, the cartridge was cocked off to one side (which you can see in the video). This gives you a longer measurement than the actual distance to the lands. If you then seat your bullet to those specs, you would hit the lands when you chambered a round. If you then fired that round, it would create a spike in pressure, which can be dangerous.

[@lovethemetals5164]

On all my guns every time i use this they measure out Way over max length . What the hell is going on

[@nathanjames7030]

subtract the length of the comparator.

[@JerrBearTactical]

👍

[@yootoob6003]

Tegridy Farms...

[@dr.haroldweinstein5157]

I miss Potterfield from midway ☹️

[@rustynut1967]

This was a poor example for measuring seating depth. You would need to measure the case length to the shoulder and compare and adjust that length to your resized brass. You are actually wanting to measure the distance between the shoulder and the lands/ogive.

[@WheelerSamantha]

9741 Velva Circle

[@KerryRandolph]

672 Gisselle Turnpike

[@ronniewallace4185]

8949 Dewayne Landing