Welcome onboard Hornady railways. Next stop "End of Tether".

[Pond, James Pond]

Actually this is no rant about Hornady per se, but a rant about not being able to find information on what seems to be one of the more popular bullet brands.

For some reason I was sure the OAL for my Hornady .308s was 70.37mm, then I was sure it was 70.10mm but can't find where I got that info. So now I am lost and no closer to find even a remotely functional load for my rifle.

So I type this post on my knees, begging someone to give me a straight forward answer:
Can anyone provide me with the millimeter OAL for a .308 cal cartridge using a 155gr Hornady A-Max?

[FlyFish]

The second poster in this thread at Sniper Central says the Hornady manual lists an OAL of 2.800" (71.12 mm) for that bullet in .308, but why not simply tailor the OAL to your particular rifle?

[Rimfire5]

James,

I find that Hornady match .308s like to be seated a bit deeper in my rifle (0.51 mm deeper to be exact) than the Hornady manual's suggested 2.800 inches - 71.12 mm.

Your rifle's preferences will depend upon the particular chamber depth.
My chamber is pretty deep so deeper seating is not a surprise.
A friend's .308 has a chamber that is much shorter and he actually shoots best under the recommended seating depth.

The most accurate seating depth for any particular bullet type depends more on your rifle than the loading manual recommendations. The recommendation is a good starting point, but your rifle will tell you what works best.

[Brian Pfleuger]

Load it to fit and function in your gun and then change it if you don't like the results. The OAL listings in manuals (and everywhere else) are intended to make sure they always work in every gun, every where. They are completely and utterly irrelevant.

[Pond, James Pond]

My problem in all of this is that there seems to be an infinite number of combinations.
-Find a max load for a bullet, and seat it a smidge deeper, and suddenly you're over pressure.
-Find a load with decent velocity, but then seat the bullet out more, to be closer the the lands and your pressure drops....

The parameters of powder choice, powder charge, OAL and crimp all have substantial amounts of adjustment, each affecting that sweet spot in the pressure curve. I just don't know where to start and it feels like I'm going around in circles.

but why not simply tailor the OAL to your particular rifle?

"Simply"!! You said "simply"!! Good one!


Truth is I have no specialist tools to measure where my lands begin in the chamber, in relation to the cartridge.

The only way I came up with was to fit a bullet into a loose case (pre-resize, for example), way over OAL, then chamber that round, letting the lands push the bullet in.
I just don't want the bullet to get jammed in the chamber through a tight neck, but the neck must be tight enough to keep true to the chamber's depth...

A workable plan?
And if I know my chamber's actual depth, how can I use the information effectively?

[Brian Pfleuger]

My problem in all of this is that there seems to be an infinite number of combinations.
-Find a max load for a bullet, and seat it a smidge deeper, and suddenly you're over pressure.
-Find a load with decent velocity, but then seat the bullet out more, to be closer the the lands and your pressure drops....

The parameters of powder choice, powder charge, OAL and crimp all have substantial amounts of adjustment, each affecting that sweet spot in the pressure curve. I just don't know where to start and it feels like I'm going around in circles.

For rifle cartridges, you've got that backwards.

The pressure doesn't increase with shorter rounds unless and until you begin to SERIOUSLY intrude on the powders burn space. Changes within normal rational limits will not do that in most any bottleneck cartridges. Making the round LONGER puts the bullet closer to the rifling and INCREASES pressure because the bullet gets less of a "running start" before contacting the rifling. The change is also close to being exponential, meaning there is very little change until the bullet start to get VERY close to the rifling, at which point it increases sharply.

Anyway, you can determine the length that will contact your rifling via several methods.

One of which is to size a case and then use a hacksaw (or similar) to slit the neck lengthwise so that a bullet will be held in place but can be fairly readily moved by hand. Seat that bullet extra long and chamber it, extract it slowly and measure the length. Do it repeatedly to check results.

Second, you can tape a bullet to the end of a piece of wooden dowel, push it into the chamber until the bullet contacts the rifling and slide another dowel down the barrel until it touches the bullet. Mark the dowel at the muzzle. Remove the bullet from the chamber, reinsert and close the bolt, slide the dowel in the barrel until it contacts the breach-face and mark it again. The distance between the marks in the length that will touch the rifling.

Third, much easier, if available to you, is the Hornady OAL gage. Which we can explain how to use if you get one.

[Pond, James Pond]

Thanks Brian,

So I guess I can keep working on a powder charge for now and then worry about seating depth a little later.

I think the easiest for me would be the split case neck technique.

What you've told me does give me a bit of a lift.
It was starting to feel like a vicious circle!!

[Brian Pfleuger]

You're welcome.

And to address the rest of your conundrum, you might consider using Dan Newberry's OCW load development.

[FlyFish]

"Simply"!! You said "simply"!! Good one!

Sorry, perhaps not the best choice of words on my part. But like a lot of things, it really is pretty simple once you know how to do it. I've been using the second method that Brian described (except I use a cleaning rod down the barrel) with good results for the last 40 years or so.

[Pond, James Pond]

After clicking on embedded link after embedded link I came across this.

Doesn't help with my choice of OAL, but gives me load data, I had not found up until now! Min to Max N135 loads for the 155gr Amax!!

BTW, on the Dan Newberry OCW instruction page, can someone confirm steps 4 and 5?! They've lost me.
Are these cumulative percentages, or the same percentage of the starting charge?
Is below correct?

Step 4
Taking a theoretically max load of 40grs, I take 7-10% off.
Lets say 10%,
start load of 36gr, load one.
Add 2% giving 36.72gr load another.
Add a further 2%/0.72gr and load another: 37.44gr.

Step 5
Add another 0.72gr: 38.16. Load three.
Add 1% of that: 38.16 + .38 = 38.54gr. Load three.
Continue adding .38gr until over the max: 38.92gr, 39.3gr, 39.68gr, 40.06, and stop at 40.44: load three of each.

[Brian Pfleuger]

It's the same charge.

If you expect a 40gr grain max and reduce it 10%, you're at 36.0gr.

The first three steps are in 2% increments because the assumption is that you don't want to use that low of a charge and you're just proving it safe.

The rest are in increments of 0.7-1.0%, which for 40gr would be 0.28 (rounded to 0.3) or 0.40gr.

All percentages are based on the max charge.

[Sure Shot Mc Gee]

Like Trim Length -Minimum / Max.-- O.A.L also has- Minimum /Max tolerances to be followed as well.

For a 308 Win regardless of bullet profile.

Minimum O.A.L. is:--> 2.530-is-64.26 mm.
Maximum O.A.L. is:--> 2.800-is-71.12 mm.

Just my opinion on your quest in regards to do things right and by the book if you choose too.

If needing to convert US to Metric measurements. Enclosed is a (User Friendly) Web link I prefer to use.
sciencemadesimple.net/length.php

S/S

.

[Pond, James Pond]

All percentages are based on the max charge.

That makes life easier!


I'll use that link max load as a guide, but will probably settle for 42gr or a little under.

For a 308 Win regardless of bullet profile.

Minimum O.A.L. is:--> 2.530-is-64.26 mm.
Maximum O.A.L. is:--> 2.800-is-71.12 mm.

Good to know. Thanks for that.

[Sure Shot Mc Gee]

Your welcome.

[RC20]

Load it to fit and function in your gun and then change it if you don't like the results. The OAL listings in manuals (and everywhere else) are intended to make sure they always work in every gun, every where. They are completely and utterly irrelevant.

I disagree seriously on that.

Its a good starting place, its a good reality check and if you have multiple rifles in the same caliber its is a good place to keep them for safety.

While I do test and check gun specific COAL and fine tune it, that is good data to have and I am surprised Brian would dismiss it like that (he does put it well why its there and its purpose)

Some may never want to change it, some may eventually. Some may not be so good as to see the difference and its always in the book to see not lost in your data sheets.

[Brian Pfleuger]

There's nothing special about listed OAL as a "starting place". It's a "fine" starting place but it's not an important one nor is there any reason to believe it's the "best" one.

It's not a safety issue either,. You wouldn't use a max load from one gun in another without doing a load work-up, so the OAL will be tested in both guns. If you do the testing, OAL is irrelevant.

Some may never want to change it but that doesn't mean that it serves any real purpose either. They could have picked whatever length they wanted out of a hat and it would be no different than what's listed in the book.

Some manuals, Nosler's I believe is one but I could be wrong, don't even list OAL with their data.

[Jerry45]

RC, while a listed OAL may seem like a good starting point and may serve a novas re-loader just fine until he/she learns how to play the game, the truth be told, the best starting point is to measure one's chamber and work up a load from there. I start .002 off the lands. Custom 308 likes .002 of the lands. One .223 likes .030 OTL the other likes .040 OTL. The 30-06 has such a long throat I can't load anywhere near the lands so I just played with OAL until I found a sweet spot. I can't tell you what the books say OAL is for any of them. You're mileage may vary.

[HiBC]

With handgun ammo,a change in seating depth can be significant regarding pressure.
It is different with rifle loads.

With the .308,generally,the 2.800 max overall is a magazine length issue.

A factor I look at is how the cylindrical part of the bullet is held by the case neck.With a 155 gr boat tail,you will not have enough full dia bearing surface to utilize the full length of the neck.No big deal.Say I was loading 168 gr bullets,I'd look at putting the full dia base of the bullet at the base of the neck.Its not an absolute,its a consideration.

Then there is jump to the rifling.Getting that just right seems to be one of the holy grails for the bench rest crowd..to the thousandth.So,its an accuracy tuning tool.

Remember,in some rifles,like a single shot or a bolt sporting rifle,the mag box may accept ammo longer than 2.800.

The same bullets get used in a .300 Savage and a 30-06.They have very different neck lengths.Balance this with other factors,but generally,take advantage of the neck tension/support/alignment to the degree possible.


It will vary,rifle to rifle,but with your bullet/rifle,there is a spot,it may be contacting rifling,it may be .003 off the lands,it may be .030 or .150 off the lands...the endless search.

If I recall correctly,Berger bullets discusses this topic on the web page.

Keep it fun.

[Pond, James Pond]

I did the "rod to the bolt-face, then rod to the chambered bullet tip" test and got a Max OAL of 2.880", or 73.30mm.

That is 2.2mm/.08" more than the listed max .308 OAL quoted by Sure Shot McGee below.

Could I have made a mistake in my measurements or is this quite normal on a rifle?
(CZ550 Varmint .308)

[PawPaw]

Originally Posted by Peetza

Some manuals, Nosler's I believe is one but I could be wrong, don't even list OAL with their data.

I just happen to have a Nosler manual near my desk. Yeah, they list a maximum SAAMI cartridge length on the main page for each cartridge, but don't list a COAL for every bullet.

[HiBC]

Mr Pond,If I understand ,it means when you load that bullet to a 2.800 coal you will have an .08 jump to the rifling,about 2 mm, with that bullet.

Is that good/bad? Depends on how it shoots.If your mag only accepts 2.800 ammo,you can't go longer.Probably no reason to go shorter.Shoot them.

If they will not shoot,try another bullet.Different bullets have different ogives.If you go with a long,skinny VLD type bullet,it will have to be loaded longer to get close to the rifling.

Maybe a non-Amax Hornady 155 match will load a little closer to the rifling.
Or,maybe a 155 Matchking.If you are not shooting at long ranges,maybe a flat base vs a boat tail will help in the lighter bullets.
The gentleman who grinds the chamber reamer has no idea what bullet you will prefer.If the chamber throat was ideal for your 155 A-Max,you may not be able to seat a 168 gr Matchking to 2.800.

If it was easy,you would be done already...then you would need a new project.

[Sure Shot Mc Gee]

When seating a bullet for OAL. I always split the difference between Max and Minimum OAL tolerances. Seems to always work for me not having to force a cartridge that last little bit into it's chamber in order to close and lock the bolt. I like a smooth action. Not one I have to physically force it to lock up.

S/S

[Brian Pfleuger]

0.080 over SAAMI max doesn't sound outrageous.

Check it a few times and see if you get consistent numbers. If you do, it is what it is.

I personally start at 0.020 off the rifling but that number is no more significant than what's in the manual.

Typically, closer is better than farther, as a generality.

[Pond, James Pond]

I double checked with the bullet-in-the-split-necked-case method. I repeated it 4 times. With some small variations, I got a chamber length of 73.23mm, so 0.07mm off my initial "rod-down-the-barrel" method.

That settles whether or not my CZ could really have a chamber of 73mm!!