Questioning My Hornady OAL Gauge

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Blantz23

New member
Loading for a Remington 788, 22-250. Previously had always measure OAL with a home made contraption that I thought actually worked well. Recently though I have purchased a Stoney Point (Hornady) OAL gauge. I am getting huge discrepancies from measurements taken from my previous method. Here's my quandary... According to the Sinclair some of my cartridges will actually be touching the lands and be less than the SAAMI 2.350 as specified in the loading manuals. Has anyone ran into this scenario? I hate to think that I am doing anything wrong as the gauge is very simple to operate. Also, I am using the Hornady bullet comparator.
Example:
Previously OAL on lands for one pet round 2.403"
With Hornady OAL gauge 2.349"
This means I would have been jamming the bullet .054" into the lands. BUT I have absolutely no resistance with the bolt.
It all just seems a little strange and looking for a logical conclusion.
Thanks.
 
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Best way to find the lands is take a sized case, cut a slit down the one side of the neck with a dremel tool. Start the bullet in the neck by hand, then chamber the round. Extract the round ( be extra careful doing this with a 788 ), measure your OAL. Now you'll have your measurement to the lands with that bullet.
I've never used the hornady gadget, but know some folks that switched to that technique after using one for some time.
 
Slickerthansnot: Exactly.. That was always my problem before was that I had to go a little further from the lands than what I wanted just to get them to fit into the magazine which is 2.400".

One difference that I can think of is that my old way I was using a fired case and with the Hornady tool I am using the "modified" case that you have to buy. Will be comparing the two later today.
 
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the 788 in 22-250 comes from the factory with the best o.a.l. gauge you can get. use the magazine. use those fancy gauges for other rifles where they might be helpful.
 
The Hornady OAL gauge doesn't work unless you correct your measured OAL taken with the Hornady modified case against a once fired and NOT RESIZED piece of brass.

I recently measured my wife's 223rem once-fired's against my Hornady modified case. There was over 10thou difference in headspace. So if I seated those bullets to the same depth, I would have had an extra 10thou jump over what I was targeting!!!

There's a few ways to skin this particular cat. Either you correct your Hornady OAL gauge measurement to reflect that seating depth in your once fired cases, OR you can use a bullet comparator and a headspace comparator to ensure that your Hornady OAL gauge measurement from bullet ogive to shoulder is the same as that on your sized brass and seated bullets.

But yeah, out of the box, the hornady OAL gauge and modified cases give you absolutely useless readings.
 
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Or you could make your own Hornady case gage with a drill and tap using your own fired cases. About $15.00 to get set up. I did that and finally ended up going to the Sinclair. Much faster and repeatable IMHO.

Greg

 
Varminterror,

Correct me if I'm wrong.

If your modified cases have the same specs as your personal brass...AND you're using a comparator, all you're doing is measuring from the case head (or outside of the rim, should I say) to where the ogive kisses the lands. Therefore, your measurement stays constant as long as the bullets are constant.

Seems logical...
 
Dooger,
Your response seems logical to me as well. In my mind, it shouldn't matter what length the case is, whether it's the Hornady or once-fired that you tap yourself.

Varminterror, could you elaborate, please? I have questioned my Hornady gauge because to get the recommended depth for Barnes TSX 70gr bullets I have an OAL of 2.19" to get .07" off the lands. What you're saying intrigues me, but doesn't click in my mind!

Edited after some research: Now I get that it can make a difference since the case is resting on the shoulder. I checked the distance on my .223 cases from case head to shoulder with a .30" comparator and found that my Hornady case was within .001" of one of my resized cases. I understand that this isn't the right tool to properly measure that distance, but I feel its close enough that I shouldn't have to account for the difference when determining COAL. Thoughts?
 
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Originally Posted By: SlickerThanSnotthe 788 in 22-250 comes from the factory with the best o.a.l. gauge you can get. use the magazine. use those fancy gauges for other rifles where they might be helpful.

If all I care about is 1MOA+- out of my 788 in .22-250, you're
right. But if I want the ol' gal to do her best, that OAL
gauge just plain sucks. She will do 1/2" groups with 50gr SBK's
that will not fit the magazine, and has to be used as single
shot. Remington would have done much better with 1/8" longer
magazine.
 
I understand what verminterror is saying, I put my Hornady factory modified case in my Savage 112 (223),after closing the bolt I could hear the case sliding when I moved the rifle forward and back. Never tried that before,a resized case made less (shorter)sliding sound. Tried the TC dimension(223) no case movement with modified,fired or resized cases. So if I want a bolt face to lands measurement the hornady tool will work better in the TC then the Savage, and when I use my Sinclair comparator there will be an oal change since I measuring from case base(bolt face).
 
As your 788's get long in the tooth, the 55g Sierra semi point will restore accuracy because they have more bearing surface.

Also, the 63g Sierra semi point will shoot very well in barrels with high milage and work well in a 14 twist(imr 4350, win primer).
 
Just looked at the Sinclair gauge. They want you to measure the distance from back of a seated bullet to the back of a fired case and then subtract the length of the bullet. Isn't that why we use comparators? A bullets base to tip measurement can vary .010 to .020 easy.
 
You add the lenght of the bullet to the measurments. You then can seat THAT bullet to the lenght to set your dies up. I measure the cartridge base to ogive so I can deal with the bullet tip variations. I set that bullet back so I have it for reference in throat erosion.

Greg
 
Originally Posted By: DoogerVarminterror,

Correct me if I'm wrong.

If your modified cases have the same specs as your personal brass...AND you're using a comparator, all you're doing is measuring from the case head (or outside of the rim, should I say) to where the ogive kisses the lands. Therefore, your measurement stays constant as long as the bullets are constant.

The answer is "Maybe" - you said "same specs as "personal brass," but didn't mention what state your brass are in? Once fired, resized, factory new? If your Hornady modified cases (or home-made modified cases) have the same headspace as your once-fired brass, neglecting any spring back, then you are the lucky one that they actually will work for without any extra calculation. If your Modified cases do not match your ONCE FIRED brass, then you're measurements are purely irrelevant.

Originally Posted By: simojoIt shouldn't matter what length the case is, whether it's the Hornady or once-fired that you tap yourself.

It ABSOLUTELY does matter how long the case is, or rather the headspace length of the case. The Modified cases go in as far as they can, then headspace on the shoulder. They WILL give you the proper length between ogive and shoulder, but if the headspace isn't the same as your ONCE FIRED brass, then it's 100% irrelevant.

Originally Posted By: simojoVarminterror, could you elaborate, please? I have questioned my Hornady gauge because to get the recommended depth for Barnes TSX 70gr bullets I have an OAL of 2.19" to get .07" off the lands. What you're saying intrigues me, but doesn't click in my mind!

Edited after some research: Now I get that it can make a difference since the case is resting on the shoulder. I checked the distance on my .223 cases from case head to shoulder with a .30" comparator and found that my Hornady case was within .001" of one of my resized cases.

Your resized cases don't matter at all. You should be using ONCE FIRED brass as your reference. When you resized your brass, if you bumped the shoulder at all, you changed the headspace.

A 223rem should use a 0.330" headspace comparator, not a .300".

What you are really doing with the Hornady OAL Gauge - you're pressing a case into the chamber, and headspacing it against the datum line of the shoulder, then pressing the bullet into the chamber against the datum line of the rifling/ogive. However, the rifle cartridge's headspace is measured from the bolt face/base of the case to the datum line of the shoulder - since the bolt isn't involved, the base of the case is just floating in air, and completely irrelevant for your chamber.

Unless the Modified Case has EXACTLY the same headspace length as your once-fired brass, you're really not seating to anything relevant at all.
 
The actual OAL can appear to be different, depending on the bullet type in the same caliber...If you are using a factory round for an initial measurement, then you need to use the same bullet with your comparator and your reloaded round...

I recently found out that there is a substantial difference between the Hornady V-Max 120gr and the Sierra 123gr BTHP that places the Sierra much farther out of the case than the Hornady, but still achieves the same OAL with respect to the distance from the lands when measured to the ogive...
 
I took the time to measure one of my 223rem's before I left for the airport.

Hornady Modified Case Headspace = 1.455"

COAL with 50grn V-max = 2.2140"

Once fired brass Headspace = 1.458"

So, if I seated the bullet in the Hornady Modified case to 2.2140" with a headspace of 1.455", then from my datum line on the shoulder to the tip of my bullet is 0.759". So if the case is held all the way forward to headspace on the shoulder, it would be "kissing" the lands at that length.

Now, if I take that 2.2140" COAL to my once-fired brass with 1.458" headspace, I'll actually end up seating the bullet 0.003" deeper into the case, so when the case headspaces on the shoulder, I'll only have 0.756" from the datum line to the tip - meaning I'll have 3thousandths jump, but I'll THINK that I am kissing the lands.

Alternatively, look at what might happen the other way around if my Hornady Modified Case headspace was longer than my once-fired brass (i.e. a bit longer than my chamber).

If my Hornady modified case was 1.458", with a 2.2140" COAL, then I'd be kissing the lands with 0.756" from the shoulder datum line to the tip.

But then when I load a once fired brass that's 1.455" headspace to a 2.2140" COAL, I end up with 0.759" from the headspace to the tip, so I'll actually be jamming the rifling by 3thousandths - never knowing it, but praying I don't end up with an over-pressure condition!!

The only measurement that you can take to the bank with the Hornady OAL Gauge is the distance from the headspace datum line on the shoulder to the ogive of the bullet. THAT is the fixed dimension in the chamber that the gauge is really useful for measuring. You HAVE to correct for the headspace on your Modified case vs. your once-fired brass, otherwise you're just taking shots in the dark.
 
Originally Posted By: LeadbellyBest way to find the lands is take a sized case, cut a slit down the one side of the neck with a dremel tool. Start the bullet in the neck by hand, then chamber the round. Extract the round ( be extra careful doing this with a 788 ), measure your OAL. Now you'll have your measurement to the lands with that bullet.
I've never used the hornady gadget, but know some folks that switched to that technique after using one for some time.

This. ^^^^^
 
Varminterror: Thank you for the detailed explanations and measurements thus far, it's very enlightening!!

Now can you explain the reasoning for the once fired case vs a resized case? My assumption (I know..) is that a fired case represents the length from bolt face to datum line and accurately represents the "correct, appropriate, or repeatable" case length after powder detonation but before the bullet starts any movement. Whereas the resized case would be shorter and not representative of the bolt face to datum point length.

If this (or some version of this) is correct, wouldn't the method described by Leadbelly need to use a once-fired case as well? If by "sized" they mean neck sized on an already fired case, then it shouldn't matter, but if they are full length resizing it would.

Does any of this change if its in an AR vs a bolt gun? As stated above, it seems to be more of a full length resizing vs neck sizing issue.

I'm not trying to pick apart anyone's methods, just trying to understand the reasoning behind it! Thanks again.
 
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