OAL

M

Micro man

New member
Been working on some reloading stuff since my wife has confined me to the house. I purchased a Hornady OAL gauge with the modified case to check the jump in my Howa 1500 6.5 Swede.
I used a 6.5 140 grain HPBT bullet to determine distance to the rifling but am having problems. When I push the bullet to the rifling with the OAL gauge and check it only about 3/16” of the bullet is in the neck of the cartridge, not enough by far to hold it in place.
I have tried this with my 6.5 Creedmoor with appropriate case and seems to work fine, any idea what I am doing wrong?
 
Unfortunately, you have a long throated rifle. In such a case, it is recommended to seat the bullet to a depth in which you have 1 full bullet diameter (.264") in the case. Hope that helps.

Don
 
If you seat the bullet .076" further into the case you would have .264" of bullet bearing surface in the case neck. Also worth noting is that the Hornady modified case is likely minimum spec. That will throw off your measurement a little.

What I like to do is to size, trim, debur and chamfer a case as you would with your normal brass
Then I use a dremel cutting tool to split the case neck only to where it transitions into the shoulder. I start a bullet with my fingers and carefully close the bolt on it. It helps if you can get the case rim under the extractor before closing the bolt.

Extract the case and measure bullet base to ogive. I use that measurement.
 
I too like seating one bullet dia down. But I also try it seating the bullet to the base of the neck. One of the two works well for me!
 
I've no idea where or when this "one caliber deep" bullet seating standard originated. Nor seen in print the logic and reasoning for it. What's the ballistic advantage?

It's been ignored for decades in service, hunting and match grade ammo without any detrimental effects.
 
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I've no idea where or when this "one caliber deep" bullet seating standard originated. Nor seen in print the logic and reasoning for it.
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Can't say where it originated, but its been around for generations, possibly as long as bullets seated inside the case. It was one of the basic "best practice" things I learned when I started handloading over a half century ago.

It's been ignored for decades in service, hunting and match grade ammo without any detrimental effects.
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Disagree. I'd say its been followed.

Where I think we are having a disconnect is some of our keyboard commandos incorrectly re-stating the principle, and then deciding it's a rule/law/ standard that must be adhered to or the sky will fall and you'll be eaten by dragons, etc.

What I learned, all those years ago, and what is not being said today is the words "at least". Bullets should be seated AT LEAST one full caliber deep, to provide proper neck tension and for the round to have the strength needed for field use. AT LEAST one caliber, and more hurts nothing.

What I'm getting from context is that "at least" is being dropped or ignored and that somehow people think that bullets should be seated to one caliber depth and no more...(which is ridiculous) Seems to go hand in hand with people thinking that the listed max COAL of a round is a length that must be achieved. Also seems to go along with people thinking that if you go outside SAAMI specs even by a cat's whisker you are in mortal peril.

The AT LEAST one caliber "rule" isn't a law, its just a good practice for general ammunition.

Seating one caliber deep AND seating 0.xx" off the lands is not always possible with every bullet design. (not possible at all with any bullet in a revolver :rolleyes:)

I think you'll find that most sporting ammo and military ammo has bullets seated more than just "one caliber" deep in the case neck.
 
That is one of the many reasons that I reload ammo. I have a few rifles that have never had any factory ammo thru them.

I do not adhere to "at least" and never have. That is freedom of choice. Mine of course. YMMV
 
Even the venerable 173-grain BT FMJ M1 Type match has a bearing surface that is less than one caliber long (about 0.27, IIRC; I should go measure one, but I am having my evening beer at the moment). The idea behind the one caliber seating depth is to produce a minimum bullet pull. It has no bearing on military ammo where the bullets are glued in by the pitch sealant. It has some validity with friction fit cases, but I believe it is based on an assumption the average interference fit between the neck and bullet is about 0.0015" (in other words, around 0.001" to 0.002"), and would not necessarily be a good average if the interference were greater or if your case neck wall is thicker than average.

Micro man,

One thing to keep in mind is that a bullet touching the lands produces about 20% higher peak pressure than a bullet that is about 0.030" off the lands. That more than compensates for the loss of bullet pull in determining the start pressure of the cartridge, so I would say you are good to go with that short seating depth. Just be sure your load is 10% below the normal starting load, as a 10% lower charge is about right to reduce pressure by that extra 20% with most rifle powders.
 
I have to agree with Bart B.

The real test is whether seating the bullet out further than having 'one bullet diameter in the neck' reduces accuracy.

I have several rifles that shoot best with 1/2 that amount of bullet in the neck.

Remember, many, if not most, of the bullets we shoot are not flat based so the bullet body is shorter by the boat tail and that reduces the amount of bullet body touching the neck even more.
Since not all boat tails are the same depth, good luck figuring out what the appropriate OAL might have to be to allow 1 bullet diameter of bullet body to be touching the neck.

I always thought those 'general rules' are generally worthless without corresponding data to prove they are valid. I have never seen any data that indicates that anyone ever tested that particular rule.
 
Unclenick said:
Even the venerable 173-grain BT FMJ M1 Type match has a bearing surface that is less than one caliber long (about 0.27, IIRC; I should go measure one, but I am having my evening beer at the moment). The idea behind the one caliber seating depth is to produce a minimum bullet pull. It has no bearing on military ammo where the bullets are glued in by the pitch sealant. It has some validity with friction fit cases, but I believe it is based on an assumption the average interference fit between the neck and bullet is about 0.0015" (in other words, around 0.001" to 0.002"), and would not necessarily be a good average if the interference were greater or if your case neck wall is thicker than average.
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That's right. Note the match bullet's pull force specs were about one third that of service specs. 20 pounds minimum for M72 and M118, 60 pound minimum for most regular service ammo. Service ammo has to survive all sorts of abuse going from ammo plant to the rifle chamber in a combat environment when it has to function most reliably.

When M118 and M72 ammo was rebulleted with smaller diameter commercial match bullets, pull forces were in the 5 to 10 pound range and accuracy test groups were one third to one fourth the size of those produced with the original match rounds
 
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Good point.

I remember Mid Tompkins, whom you would know better than I, describing his method of loading by "soft seating". The bullets are seated loosely enough to be moved in the case neck by hand but seated way out to have excess throat contact so the throat becomes the final seating die when the round is chambered. Obviously, it didn't hurt his accuracy, nor the rest of his family's.
 
The last couple of years when I was shooting 1,000 yard F Class, I was soft seating the bullets on chambering as well. However, I had my custom built rifle made with a short throat and there was still plenty of bullet in the case neck. Back to the OP's situation, he is going to have to forget about seating out to the throat and find an OAL that leaves enough of the bullet in the case neck so as to promote proper alignment.

Don
 
Thanks for all the useful information. I had not heard about seating at least 1 caliber before.
I think I will play it safe and stay within reloading manual OAL to start and then experiment a little and see how it works out.

Thanks again I learned a lot from members comments.
 
What about all those rifle bullets whose crimping cannelure is less than one caliber forward of its heel?
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Is there a question in there ?

How about the crimped case helps hold the bullet or wait how about that sealant on the insides of the neck gluing the bullet to the neck . We just supposed to ignore those things ?

Instead of asking open ended questions with no direction . Maybe explain how there are exceptions to the good practice of seating to at least the depth of your bullets diameter . Especially for less advanced reloaders .

Don't those Palma shooters load one at a time , softly and slowly into a bolt action rifle so they don't upset that very light bullet hold ?

I say what about asking questions you already know the answers to ? Is it if you never answer the question or explain your opinion you're less likely ever to be questioned ?
 
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Can't say where it originated, but its been around for generations, possibly as long as bullets seated inside the case. It was one of the basic "best practice" things I learned when I started handloading over a half century ago.
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I don't have a dog in the discussion, but there is a difference between stuff handed down and a statement like "best practices"

Like the 8 glasses of water a day, someone pulled it out of their hat in an article they finally traced it back to.

Sometimes like a tourniquet, oooops, no you don't want to do that if at all possible.

Me? If I had a long throat aspect I would play with it to see where the best accuracy was. Its not like the bullet is going to tip over and go down the barrel backwards.
 
Regarding bullets whose crimping cannelure is less than one caliber forward of its heel....

Metal god asks is there a question in there.

Yes, sentence ends with a question mark. 'Twas done to inspire thought, answers are optional.

How about the crimped case helps hold the bullet or wait how about that sealant on the insides of the neck gluing the bullet to the neck . We just supposed to ignore those things ?
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that sealant's primary goal is water proofing the case just like the sealant around the primer. Crimped case mouth prevents bullets accidentally being pushed in too far to function.

Instead of asking open ended questions with no direction . Maybe explain how there are exceptions to the good practice of seating to at least the depth of your bullets diameter . Especially for less advanced reloaders .
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I'm not convinced caliber depth seating is a good practice. What percentage of reloading data specifications state caliber depth seating?

Don't those Palma shooters load one at a time , softly and slowly into a bolt action rifle so they don't upset that very light bullet hold ?
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No. Some have to shoot unaltered military ball ammo. Or single shot shoot bolt guns fast before the wind changes. Between light and medium bullet pull, just a few pounds, is normal.

I say what about asking questions you already know the answers to ?
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Makes people think then respond if desired.

Is it if you never answer the question or explain your opinion you're less likely ever to be questioned ?
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No.
 
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Nevermind , Sorry I was clearly feeling a little sassy on my last post . Didn't really mean to come off that way . After reading it again , it reads as if I had a rather large chip on my shoulder .

Sorry about that Bart , :o
 
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