Full Length or Neck Only; What's Best Resizing for Accuracy?

[keithcandler]

The chamber has to be in perfect alignment with the bore dia or you are screwed from the get go.

throat dia has .0005 over bullet dia as a general rule on a custom chamber, that is .00025 per side. Get it?

If the bore has a sweep in it where the bullet engages the lands, you are in a mess when it comes to alignment. If the bullet starts straight into the lands chamber/bore, lots of this discussion is a moot point because you are shooting way less than .250, then consider the wind conditions.

A chamber that is .006 out of alignment with the bore, what difference is all of this nonsense that is being talked about? Chas'en your tail like a neurotic dog!

 

[Mram10us]

The chamber has to be in perfect alignment with the bore dia or you are screwed from the get go.

throat dia has .0005 over bullet dia as a general rule on a custom chamber, that is .00025 per side. Get it?

If the bore has a sweep in it where the bullet engages the lands, you are in a mess when it comes to alignment. If the bullet starts straight into the lands chamber/bore, lots of this discussion is a moot point because you are shooting way less than .250, then consider the wind conditions.

A chamber that is .006 out of alignment with the bore, what difference is all of this nonsense that is being talked about? Chas'en your tail like a neurotic dog!

Where are you getting the .006" from?

 

[Bart B]

This shouldn't have any part of a productive discussion. We only learn and get better if we debate differing views.

I left that forum because too many ignorant people refused education. Typical ignoratiolinguist behavior on their part.

 

[Bart B]

throat dia has .0005 over bullet dia as a general rule on a custom chamber, that is .00025 per side.....

The throat is the tapered rifling from the front of the freebore (or chamber mouth if no freebore) to bore diameter. I think you're referring to the freebore diameter between throat (leade?) and chamber mouth.

 

[bigedp51]

I left that forum because too many ignorant people refused education. Typical ignoratiolinguist behavior on their part.

I prefer that the people at accurateshooter.com know bovine scat when they read it and told you to take a hike.

Look at what you did here, you started a thread just to flatter your own ego. And you think you are the only person in the world who can educate the reloading masses. So where is your webpage or books on reloading if your such an expert?

The unsized case neck in a bushing die below centers the bullet more than the shoulder does. And again rimmed and belted cases with shoulder bump have a case shoulder that never even contacts the shoulder of the chamber.

 

[bigedp51]

The throat is the tapered rifling from the front of the freebore (or chamber mouth if no freebore) to bore diameter. I think you're referring to the freebore diameter between throat (leade?) and chamber mouth.

The SAAMI drawings are guidelines, look at line "G" freebore diameter below for a .224 diameter bullet. And ask yourself what centers the bullet, the most you have is .0015 on each side of the bullet.

I wonder if the case shoulder will center this bullet?

Where is the rub mark on the case shoulder showing it is centering the bullet below, this bullet has excessive runout and is rubbing one side of the throat. (but no marks on the case shoulder)

"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."

The Rifleman's Journal
Germán A. Salazar

 

[keithcandler]

Where are you getting the .006" from?

From some used custom barrels I bought. I cut the threads off and re chambered. They were either take offs sold by a gunsmith(they would not shoot well) or an extra barrel that was chambered for an action, no longer in use.

Many guys are having their reamers ground with the freebore dia cut at .0003 over bullet dia, this is a new trend you don't hear much about. Typical custom reamers have .0005 over bullet dia., freebore dia.

Current thinking now is that full length sizing is the most accurate, and most, if not all, of the top shooters are doing some sort of full length sizing.

Mating dies and chambers is a can of worms. Factory chambers and a lot of custom chambers have MUCH more than .001 diametrical clearance in the web. This extra clearance helps eliminate the click at the top of the bolt lift. Also, in hunting rifles, .003 clearance on a loaded round and web dimension is not unusual at all to help in extraction. For example, 20 years ago, I had my 7 STW reamer ground .002 over brass dimension, this ended up being tight, too tight for regular full length sizers to work. So I had to order a small base sizer to get my brass back down to where it had good clearance due to spring back. 20 years later, advise is to order the reamer with a minimum of .003 clearance on new brass, and .004 would not be out of line, hunting rifles. Best to buy your full length sizer ahead of time and get some measurements so you do not get stuck with an expensive bill in having a custom full length sizer made.

Biged, a chamber that is not in alignment with the bore will cause the condition you see on that scraped bullet, also. The chamber would also have to be pretty sloppy. We assume that the chambers are in alignment with the bore, and only in the best of custom barrels we see machined by world class gunsmiths is this true. In sloppy chambers, the ejector can push a case off and give indications like biged has shown. In these sloppy chambers, a neck sized case or a shoulder bumped case may give better accuracy, but it is trial and error. As biged has shown, turned necks help in alignment. When neck sizing, I have found that if your bolt closes easy on one case then a tad harder on another case, you are going to get flyers, this is where shoulder bumping improved group sizes in factory hunting rifles. Shoulder bumping is not were near the level of alignment that is described by biged in his post above.

Getting a bullet started in the throat perfectly straight is our goal, and there is a lot of rabbits to chase getting to this point.

Dealing with factory rifle chamber dimensions can be a much different approach than dealing with custom bench rest and long range custom rifles. Learn the basics on alignment, and apply those basic principals to your situation, best you can. You will learn from the compromises you are often forced to make.

 

[Orange Dust]

The SAAMI drawings are guidelines, look at line "G" freebore diameter below for a .224 diameter bullet. And ask yourself what centers the bullet, the most you have is .0015 on each side of the bullet.

I wonder if the case shoulder will center this bullet?

Where is the rub mark on the case shoulder showing it is centering the bullet below, this bullet has excessive runout and is rubbing one side of the throat. (but no marks on the case shoulder)

"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."

The Rifleman's Journal
Germán A. Salazar

I am not an engineer and dont even play one on tv but i must agree with this because this has produced the most consistantly accurate ammo for me. There may be a better way but ive tried my share, but am always open to new things.

 

[keithcandler]

Hopefully, we never quit learning and trying different things. Being open to learn from others is a good start.

 

[Bart B]

The SAAMI drawings are guidelines,

That's not a SAAMI drawing. Use one for the .223 Remington and you'll learn there's no freebore anywhere.

I wonder if the case shoulder will center this bullet?

depends on how far the chamber is off center to the bore to compensate for using non uniform case neck walls.

"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat.

He Is ignoring the case shoulder centered in the chamber shoulder.

 

[Tree Farmer]

I've been trying to understand everyone's recommendations and apply them to my situation (factory barrel/chamber). I full length resize and normal case prep but I don't neck turn. In a factory rifle/chamber, will some degree of neck turning make any difference for bullet alignment? My bullet runout is normally <.002 without neck turning.

 

[Edd]

That's not a SAAMI drawing. Use one for the .223 Remington and you'll learn there's no freebore anywhere.

There is on my SAAMI drawing and it is the same as what is shown on that posted chart. It isn't very long but it is the tightest part of the chamber.

 

[Bart B]

I've been trying to understand everyone's recommendations and apply them to my situation (factory barrel/chamber). I full length resize and normal case prep but I don't neck turn. In a factory rifle/chamber, will some degree of neck turning make any difference for bullet alignment? My bullet runout is normally <.002 without neck turning.

Maybe, maybe not. If the neck wall varies less than .002" thick, I doubt there would be any significant difference in a factory barrel. Try it then test to verify.

 

[Orange Dust]

I've been trying to understand everyone's recommendations and apply them to my situation (factory barrel/chamber). I full length resize and normal case prep but I don't neck turn. In a factory rifle/chamber, will some degree of neck turning make any difference for bullet alignment? My bullet runout is normally <.002 without neck turning.

It has for me, but only if you don't overdo it. Just clean up about 50%-60% of the neck, knocking off the high side, and taper, size, and expand the necks with a mandrel die and use a benchrest seater. I'm not going to say your groups will tighten much. BUT they will be more repeatable and consistent from day to day. At least for me they have been.
I NEED TO ADD: I have had better luck with Forster and Redding dies when using a press. I have also had better luck using a fl die and an expanding mandrel die than using a neck die with a bushing from the same sources. I also adjust the FL die so the bolt will just close with very minimal resistance, (just enough that you can tell there is something in there) so you could say it is "partially" resized. I also feel it would be an advantage to have dies made up from fired cases, but have not tried it in a hunting rifle. Mine shoot pretty well. I do know you can load very straight ammo that fits the chamber pretty well this way. I also seat bullets a way an old benchrest shooter taught me years ago with RCBS dies. I start the bullet, back off a little and turn the case 1/3 turn, come down a little more, and repeat until the bullet is fully seated. Don't know if it matters with benchrest dies with the floating inserts, but it is a 50 year old habit.