OAL

[Micro man]

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?

[USSR]

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

[kilotanker22]

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.

[Don Fischer]

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!

[Bart B.]

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.

[44 AMP]

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.

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.

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 )

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.

[Dufus]

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

[Bart B.]

This drawing ...

https://www.google.com/search?q=draw...LaS_SEeDJXuwM:

... shows the 7.62 NATO M80 bullet that has about one half caliber seating depth approximately .153" deep in the case neck.

155 grain Palma bullets in 308 Win cases have similar seating depths.

What about all those rifle bullets whose crimping cannelure is less than one caliber forward of its heel?

[SHR970]

Disagree. I'd say its been followed.

Except in cartridges like the 300WM (SAAMI neck is .266"). This supposed rule has been broken for a very long time.

[Unclenick]

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.

[Rimfire5]

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.

[hooligan1]

Micro Man, try book lengths , and afjust a tad from there....

[Bart B.]

Originally Posted by Unclenick

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.

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

[Unclenick]

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.

[USSR]

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

[Micro man]

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.

[Metal god]

What about all those rifle bullets whose crimping cannelure is less than one caliber forward of its heel?

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 ?

[RC20]

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.

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.

[Bart B.]

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 ?

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 .

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 ?

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 ?

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 ?

No.

[Metal god]

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 ,

[Bart B.]

Just remembered that arsenal made 30-06 match ammo originally had both asphalt sealant in case necks and case mouths crimped into cannelured bullets. When production resumed after WWII in the early 1950's, tests proved accuracy was better when bullets were not cannelured nor crimped in place. The cured sealant had enough grip on the 173 grain bullets to require at least 20 pounds of force to pull bullets from the cases.

The last stage of case forming was to expand the case mouth to a thousandth or more than bullet diameter. But leaving a small "donut" at the case shoulder. The warm sealant was smeared around inside of the case neck then a bullet was seated. Bullets often rested crooked as the sealant cooled and dried.

This is the main reason bullet runout in arsenal match ammo is up to several thousandths. I've seen up to .007" on both 30-06 and 7.62 match ammo.

[Unclenick]

That matches what was in A. A. Abbatiello's old study of runout effect on accuracy, but I have to say I've achieved 0.008" runout myself by seating 168-grain SMK's with a Redding standard seating die into resized LC 30-06 cases. It was back in the '80s that I first got a runout gauge and became aware of it. At the time, I was unaware of the use of the Lyman M-die to enable bullets to start into the case mouth straight. I tried the trick of rotating the case as the bullet was seated in steps, but it didn't help much. In '89, when Redding came out with their Competition Seater Die I got one and it reduced my worst-case runout to 0.002", the same as the offset in the worst-case neck wall thickness runout.

I think the one-caliber seating depth is one with which many guns seemed to work well enough in terms of accuracy, and I expect it made a lot of gun writers comfortable that they were securing the bullet well enough for self-loading. It is also in the ballpark that enables a lot of assembled loads to fit into magazines easily. Overall, those add up to making it a reasonable broad ballpark recommendation. I found that much seating depth to be a good accuracy seating depth with many bullets in my old '96 Mauser in 6.5×55, for which I wanted to fit the rounds in the magazine. I've also found that bullets that have a good accuracy node seating depth near the lands will often have a second one deeper that can correspond to close to a caliber of seating depth (did in the Mauser), but not always. "Not always" is the problem. There are so many exceptions out there that I've stopped considering that I will find an optimum seating depth without experimentation.

[Bart B.]

Too bad commercial runout gauges don't use the same front reference like the rimless bottleneck cartridges use when fired. Commercial gauges use a point on the case body next to the shoulder. That point is clear of the chamber wall when fired. The back of the case at its pressure ring may be off center a thousandth or so against the chamber wall.

Such cases have their shoulder hard pressed into the chamber shoulder where they center perfectly. Runout gauge's front reference should be a round hole whose diameter is about midpoint on the case shoulder.

The further the dial indicator is from the front reference, the greater runout will be seen on the dial. Some standard dimension should be established for each cartridge so comparison between reloaders results would be meaningful.

[Unclenick]

My first cartridge concentricity gauge was the Bonanza unit that became Forster's later. It supports the head and the bullet tip. This was the style Abbatiello used for his 1960s study of 47 lots of NM ammunition, and it will measure how far off the overall cartridge axis a bullet tip is tilted if you add in a little calculating. At the time, I wanted an apples-to-apples with Abbatiello's method, so it was fine for that. It will not give you a bullet centering number at the case mouth, though, which your gauge concept would add into the mix, if I understand it correctly.

[Bart B.]

Then there's the situation where a crooked case neck perfectly aligns it and the bullet on the chamber and bore center when its pressure ring is off center at the back of the chamber to do that.

A perfectly straight cartridge with its back end a thousandth off center in the chamber will have its bullet tip off center in the throat one to two thirds that much in the opposite direction as it pivots about its shoulder against the chamber shoulder.