Hornady OAL Gauge faulty concept??

[drfroglegs]

So... I'm glad you guys brought this thread back to life. I went to the field last weekend and tried out some of my ubber accurate reloads (or so I thought)...

Turns out it is NOT a good idea to resize your fireformed brass to match the headspace of the hornady modified case. Let me explain... My fireformed 300 win mag brass reads ~2.278" using the E420 bushing and the hornady headspace gauge. The hornady "modified case" I used to calculate my optimum OAL measured 2.2520". I decided to bump the shoulder down to match the 2.2520" of the modified case...

1st shot, case separation (obviously due to excess headspace)... These are about the 3rd time reloading the brass, I usually only neck size too... Needless to say, I'm pulling the other 19 bullets and discarding the cases with the low shoulder. I'll use my other method from now on, utilizing the measurement from the ogive to the shoulder datum instead of modifying MY cases to match the "modified case."

Just a warning to those who might be considering a similar method!!!

[deepforks]

at least hornady is making the cases close. just checked mine with the same equip. and came up with 2.254".

[TheTinMan]

I drew up a picture to make sure I had it squared away myself. The Hornady OAL gauge measures the long dimension from the case head to the ogive (or meplat) of the bullet. (The 2.520" dimension in the drawing is only an example for a .308 Winchester cartridge.) However, the critical dimension for the distance between the bullet's ogive and the lands is from the ogive to the shoulder. The shoulder stops the forward movement of the cartridge in the chamber. Therefore, if your headspace dimension (case head to shoulder) is shorter than the modified case, then your bullet will be closer to the lands than you expect.

My guess is that Hornady deliberately uses the minimum headspace dimension for their modified cases. That way you err on the side of having the bullet's ogive farther away from the lands rather than closer/on the lands.

This effectively makes very little difference in service rifles where chambers typically have a long throat. So long you can't seat a bullet long enough to hit the lands and still have the cartridge fit in your magazine. However, it could make a difference in your bolt action rifle or in a rifle with a "match" type chamber.

Please note that I exaggerated a variance in the headspace dimension since .308 Winchester maximum is 1.634" with a variance down to 1.627" per SAAMI drawing.

[drfroglegs]

@TinMan I think you hit the nail on the head. I believe Hornady intentionally makes the cases have a shorter neck such that your fireformed cases will seat a bullet further from the lands than their modified case (thus ensuring the pressure doesn't increase markedly). Nice drawing btw!

I started an excel spreadsheet so I can quickly input my shoulder length (w/ headspace gauge) and it will back calculate what the OAL should be using the oal gauge. It certainly doesn't matter at 200yrds when hunting, but I've never seen anyone (including myself) complain about added accuracy.

[F. Guffey]

Not a fault with the gage, it is a failure of the reloader, I measure the length of the chamber, I use transfers, standards and a method fro verifying. I move the measurements from the chamber to the seating die with a transfer, I have modified cases, I have the Sinclair/Hornady maximum case length gage. I do not find it necessary, back to drilling the flash hole/primer pocket with all the bullet neck hold possible.

I am not the fan of shoving the bullet up to the lands or minute .001” off the land, again, I am the fan f the running start, I want my bullets to have a jump. All the reloader needs to know is the length of the chamber from the bolt face to the shoulder of the chamber and the length of the case from the head of the case to its shoulder, there is not much to keep up with when using modified cases, subtract the length of the case from the length of the chamber then add the difference to the seater die when seating bullets or add the sum to the gap between the shell holder and bottom of the die.

F. Guffey

[Unclenick]

Have to agree there is some misinterpreting of information going on here that needs clarifying. Mr. Guffey's post makes the point that if you mind your geometric fundamentals, you'll stay out of trouble, but until you have all that clear in your head you can trip yourself up. He also reminds us there is more than one way to skin a cat. That's true of using the commercial gauge tools, too.

Several points to consider. First, if you are using the Hornady gauge and custom case gauge service, the reason they want a fired and un-resized case is because they want the neck loose enough for the bullet to slip in and out of it. They don't want the extra work of having to select and run a mandrel in that expands it. If the case was fired near full pressure in a high power rifle, it will be near the size of the chamber and using it as a gauge will tend to give you the longest COL (or shortest seating depth, whichever way you want to look at it). For that reason, I tend to think this service is mainly a convenience for people who are neck sizing only or who are careful not to bump their shoulders back more than a thousandth or two. Even then, all it does is save them a minor bit of measuring and calculation.

For cases resized more than the above, using that chamber sized case as a gauge can give you long COL (inadequate seating depth). I’ve already described seating to the difference between shoulder and ogive for cases that headspace on their shoulder. There’s a simpler way to skin that cat if you will accept a couple or three thousandths less precision.

As with that difference measurement, it frankly doesn't matter what gauge case you use as long as you know the difference between where it headspaces and where your resized cases headspace. If your cases resize with the headspace 0.005" longer, seating your ogives out 0.005" longer as measured by the bullet comparator (from the base of the head) will give you the same jump to the lands as the gauge case had, and vice versa. This is a couple or three thousandths less precise than the ogive to shoulder datum method owing only to the fact there is often that much variation in the length of cases coming out of a sizing die. But for most reloading it’s a second way to skin the jump control cat and do it well enough. Work as follows:

1. Resize a bunch of cases.
2. Measure the headspace datum distance from the back of the case head of at least fifteen (thirty is better) randomly selected ones.
3. Average the results.
4. Measure the headspace datum distance on your Hornady gauge case.
5. Subtract the Hornady gauge headspace measurement from the average for your resized cases.
6. Add the result to the bullet comparator length measurement you got using the Hornady gauge case.

Pay attention to the number sign doing this. If your cases are resized shorter than the Hornady gauge case, then you will have negative numbers, meaning you must seat that much shorter by the bullet comparator readings.

Note that above I referenced measuring headspace. The .300 Win Mag is designed to headspace on the belt. If you are carefully bumping shoulders back by small enough amounts that you actually headspace on the shoulder, then what goes for other cartridges that headspace on the shoulder will apply to it. But if you set the shoulder back far enough that you are actually headspacing on the belt, then two differences apply. One is that you need to measure headspace to the top end of the belt from the case head to get the comparison to the Hornady gauge case. The other is that once you have set the shoulder back far enough to start headspacing on the belt, setting it back still further won’t change the bullet comparator reading you want to use because it’s no longer affecting how far forward the neck can move in the chamber. The belt is then controlling that.

Just to clarify something mentioned earlier, a VLD's ogive is longer between the bullet tip and the place the ogive meets the throat than a normal bullet's is. It is therefore normal for VLD's to have longer-than-normal COL's when the ogive is the same distance off the lands as a standard spritzer nose it. That said, in many guns the Berger secant ogive VLD's like more jump to the lands than the more common tangent ogive bullets do. See this on seating them.

[hooligan1]

jeezus Unclenick be the president please!!!?? I love you man!!!!

[Unclenick]

Do you think I could run on the reloading platform?

[drfroglegs]

Wow Unclenick, you just learned me about 3 things I did NOT know. Most importantly, I did not know the 300 and 7mm mags headspaced on the belt. Kinda makes me feel stupid :banghead: most if not all the forums I read reference the 308, that's my excuse!

Can you explain a method for determining whether my cartridge headspaces on the shoulder or the belt? More specifically, how could I measured a distance so I can know "if the distance is more than x from the datum to the belt it will headspaces on the neck." thanks a ton, I vote you reloading president!

Sent from my HTC Rezound and tapatalk

[F. Guffey]

Wait a minute, change the subject, back to ‘off the lands’ and keeping up with more than one thought at a time, there is a philosophy (not a discipline) the firing pin drives the case, powder. bullet and primer forward to the shoulder of the chamber, if that is so and the difference in length between the case from the head of the case to its shoulder is shorter than the length of the chamber from the bolt face to the shoulder of the chamber by 5 thousandths and the reloader has used all his case comparators, modified cases and bullets etc. and decided to seat the bullet off the lands 5 thousandths and at the same time the reloader sizes his case shorter than the chamber 5 thousandths, when the trigger is pulled and the firing pin drives the primer, case powder and bullet forward the bullet will be at or into the lands, back to the part where I am the fan of the running start, I want my bullet to have a jump start.

I want to know the length of the chamber from the bolt face to the shoulder, I want to know the length of the chamber from the bolt face to the beginning of the rifling as to the point the bullet hits the rifling, that is two different measurements. A friend built some magnificent rifles, 5 in one set, one of the rifles had a problem. He took the rifle to various people, some with bore scopes etc., he called me and explained the difficult he was having with the rifle, I was not not interested in ‘the long story’, but I listened, he wanted to know '”what it was” they missed, I did not care, I explained to him I did not have any lofty terms that would explain the rifles problem, he then ask me where I would start, as in killing water moccasins there is more than one way, Arkansas style is an accepter methods among coon hunters, when my wife found out about the Arkansas style she ban my son from coon hunting in Arkansas, she change her mind when he agreed. She changed her mind when he said he was bringing his does to her, his logic, if I am not hunting, I do not need the dogs.


I explained to my friend where I would start, he went to the Internet and discovered the stick method, cute, anyhow I had him bring a few fired cases that were not sized. I drilled the flash hole/primer pocket out of his cases, seated a bullet short with lots of bullet hold, removed the bolt then used a cleaning rod to push the bullet out ‘to the lands?’ No, I pushed the bullet out of the case, then I continued pushing the bullet forward until it hit the rifling. I then dug out the longest 7mm bullet I had and started over, I then marked the cleaning rod, from ‘out of the case’ to ‘into the rifling’ with a 170 grain 7mm bullet was two hundred and fifth thousandths, 1/4”, and he ask me what caused that and I said I do not know nor do I care, I ask him for the reamer, broken, pieces? Lost/do not remember. I suggested someone was impressed when he read about Weatherby and the his long throated chambers, then I suggested someone got carried away with the throat reamer.

We went to the range with about every combination of reloads possible, too light, too heavy shot like a shotgun pattern, move the bullet out, move the bullet in, shotgun patterns, made no sense to me and I did not care but there was a very narrow window between to much and not enough that allowed the rifle to shot one hole groups.

F. Guffey

[Unclenick]

As near as I can tell, once you get a really long throat like that, seating to get the best hold on the bullet is more productive than trying to get the ogive some specific distance off the lands. Sounds like that one was extra grief, though.


Defroglegs,

You can smoke the outside of a case and gently push it into your chamber and turn it a little with your finger tip. Then withdraw it to see whether the case shoulder or the front surface of the belt has the soot scraped off. The one that does is what you are headspacing on.

If you want to measure a number, you get to learn another term: head clearance. This is the maximum distance between the breech face and the case head when the the cartridge has gone as far forward in the chamber as the headspace (be it shoulder or belt or rim or case mouth) allows. There are a number of ways to measure it, but I think the simplest is this:

Take one case resized the way you normally do it and trimmed to your normal trim length and prime it.

Next, put on your eye and ear protection and fire the primed case in your rifle. When the primer fires it will back out against the breech face with some force. The equal and opposite force will push the case as far forward as it can go, if the firing pin hasn't got it there already. Unlike when firing a load, the primer gas will just vent out the muzzle and the case will have no significant force driving it back against the breech face, as happens when a normal load is fired. As a result, the primer will not be reseated and should be left proud of the primer pocket by the amount of the head clearance. Extract it gently so as not to disturb anything.

Now measure the length of the case plus the proud primer. Then decap the case and measure the case length alone. The difference is the amount of head clearance you have allowed when you resize cases by your method.

For the belted magnum, you want to repeat the exercise, but with a case that has the shoulder as far back as possible so the belt definitely is the headspace determiner. A new, never fired case should be sized this way and would make a good choice. If the head clearance you get in both instances is the same, you are headspacing on the belt with your resized cases. If it is smaller in the case you sized, then you are head spacing on the shoulder.

Normally, if you set up your sizing die so you don't push the shoulder back more than one or two thousandths, you will be headspacing on the shoulder. The benchresters will tell you a one thousandth bump back of the shoulder usually gives you the best accuracy.

[deepforks]

this thread is starting to confuse me. oal/bullet seating/headspace/coon hunting

so, is there a problem with headspacing a belted case from the shoulder, instead of the belt? i was just watching a sierra/tubbs reloading dvd last night and he did all the headspacing on a 7mm, from the shoulder.

[drfroglegs]

@Deepforks

I'm certainly no expert, just learned the purpose of the belt earlier today! But in laymen terms, if the shoulder is past a certain point it will headspace on the shoulder. If the shoulder is shorter than that same point it will headspace on the belt.

Basically, if you use the Hornady gauge(s) the headspace value you calculate is irreverent unless you have a shoulder that is so long that IT "headspaces" instead of the belt. As long as your shoulder is below that point it doesn't matter what it is because it will headspace on the belt and thus your calculated OAL using the gauge will be the same reguardless of your "shoulder headspace"...

So the answer to my original post question should be "The Hornady modified cases are excellent for belted cartridges as long as you bump back the shoulder such that the belt controls the headspace. If you have a beltless cartridge, however, you should just make your own modified case with a shoulder headspace value that remains constant with the cases you shoot."

Correct me if I'm wrong, but that's how I understood it...

[F. Guffey]

“Basically, if you use the Hornady gauge(s) the headspace value you calculate is irreverent unless you have a shoulder that is so long that IT "headspaces" instead of the belt. As long as your shoulder is below that point it doesn't matter what it is because it will headspace on the belt and thus your calculated OAL using the gauge will be the same reguardless of your "shoulder headspace"... “

Back to the “big inning”, there was the rim, then the bottle neck case, after that came H&H with the belt, the rim and belt had a purpose, hold the case to the rear of the chamber, that was it, what ever happened beyond the belt when the case was fired was insignificant, The case expanded, filled the chamber and then? The case was extracted. Back in the big inning there were no bad habits, think, there was no Internet.

Back to keeping up with two thoughts at the same time. The belt was designed to hold the case to the rear, the case had long tapered sides, the shoulder had a slight tapper, again, the case body’s design was to fill the chamber and seal it. Then came the case with the belt and less body and shoulder taper, and the old timers said “a belt is meant to hold your pants up” meaning the belt was not necessary for holding the case back, it was not as necessary for holding the case to the rear as it was for holding the pants of the non-handy population, for plumbers and the handy I do not have an answer.

I have a leaver policy, once the shoulder is established by one of two methods, forming and or firing, I leaver where I finder, I do not move the shoulder of the case back when sizing, I know, it is printed on the box, it is stamped on the die, it is written in the instructions ‘FULL LENGTH SIZER DIE’. Back to the leaver policy, there is nothing printed in the instructions that demand I full length size, again, I know the length of the chamber, to reinforce my measurement of the chamber I can measure the length of the fired case from the head of the case to the shoulder of the case. For me it is a very simple matter of adjusting my die to size the case by controlling the gap between the top of the of the shell holder and bottom of the die with the ram up, and again, there is a difference between methods of adjustments between a cam over and a non-cam over press. One more time, I have 4 Rock Chucker presses, not one of the four cam over, so adjusting my a Rock Chucker is straight forward.

And let us not leave the bench resters out. Bench resters shoot bench rester rifles, I shoot my rifles, I am the fan of cutting down on case travel, I control case travel by knowing the length of the chamber from the face to the bolt to the shoulder. My wife called the shooting range, she wanted me to call her, Dottie, at the range answered the phone, Dottie ask my wife how could she identify me without using the speakers, my wife answered with “Look someone that looks handy”. Then Dottie said, Oh! him, someone ask me if he was a bench rest shooter etc., etc. and I told them etc., etc..”. Anyhow, Dottie came out and told me my wife instructed her to tell me I should not look so handy.

F. Guffey

[Marco Califo]

Hornady will make your "case". From Hornady website:

"If your caliber is not listed, any of your brass, including all wildcat sizes, can be custom modified at our factory for use with either gauge. Please call a support representative at 800-338-3220 for more information.
Click here for a chart of Lock-N-Load Modified Cases."

The way I read this, there is no reason why they would not make mine from my 223 and 308. I am not calling them today on a Sunday.

[drfroglegs]

@Marco

If you have a drill press I would recommend buying the tap and corresponding bit, you can get the for the price of 1 modified case from Hornady and do as many as you want.

There are some good topics on doing this somewhere on the site.

Sent from my HTC Rezound and tapatalk

[Marco Califo]

I read those threads and someone wrote you need to do this on a lathe or some other equipment. A drill press may not be "square" enough. Besides I do not have a drill press and, just as importantly, a drill press vise/clamp to properly hold the case. I would rather spend the $5-10 to: #1 have an expert do it; #2 have them made from my rifles' fire-formed cases (not Hornasdy's SAAMI spec FL sized stock).

[misterc01]

An important step is to get the difference between the modified case and your fired case. Using example data
1. Measured OAL with OAL gauge, modified case and bullet in your rifle:. 2.194
2. Headspace measurement modified case: 1.1619
3. Difference subtract measurement headspace mod case from Measured OA:.
2.194-1.619=.0575
4. Headspace Measurement of YOUR fire formed case 1.616
5. Add actual fired case headspace to difference step 3: 1.616+.375= 2.191
6. Subtract desired jump (.02): 2.191-.02 = 2.171
7. Final desired OAL: 2.171
I put everything in an Excel spreadsheet, then when I am using different cases/bullets I just plug the data in and get the answer.
Having one of your Once-fired cases modified by Hornady will let you skip the math, except for your desired bullet jump.

[T. O'Heir]

OP is 7 years old.
No such thing as a "Head space Measurement". Cartridges do not have head space.

[Unclenick]

Headspace is in a chamber. Head space is room for a toilet.

[RC20]

Navy Lingo, deck not floor. Yea my dad was a sailor. He was pretty focused on course steering as well.

I had to troll him through a kelp patch before he would admit there was times not to steer 270.

ME:? I just measure the shoulders and for the longest fired case, bump it back .003 and the rest are good. I know, I am a heathen. Works

[F. Guffey]

Headspace is in a chamber. Head space is room for a toilet.

I have one for sale, it seems this ship hit the sand to prevent it from sinking etc. etc. long story, one of the heads from the shop was dropped off here; I had rather had the horns.

F. Guffey

[RC20]

Mr. G, Ships do not

hit the bottom

, the right term is

run aground.

[F. Guffey]

Mr. G, Ships do not
Quote:
hit the bottom

, the right term is
Quote:
run aground.

What happens when the -CENSORED--CENSORED--CENSORED--CENSORED--CENSORED- hits the fan ?

F. Guffey

[RC20]

That depends on if you get holes in your ship, how big they are and how good your damage control is.

Midway 4 Japanese got big holes and went down.

The Washington took on a Japanese group in the Solomon's by itself and did fine.

Titanic got a slash and down she went (bulkhead did not go the main deck (another technical water term) and or the slash cut too many compartments open.

Hurricanes you can wind up way ashore (though hard a ground is accurate)