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Neck sizing vs full length

So, what I'm taking away from this thread is:
It isn't just FL sizing. It's full length sizing with custom dies to a minimum of brass movement to MATCH THE CHAMBER.

Concentricity/alignment/runout etc. are ALL very important. But they are achieved with the kind of dies and processes described above. Without variation. We know the brass is going to be a close fit still but loose enough to be easily chambered and ~usually~ easily extracted. Depending upon load.

Each load with the right process in reloading with the right dies will produce CLOSELY repeatable results. Anytime there is a component failure, i.e. brass, barrel, there is an as closely approximated replacement as can be obtained. Do you go back and make a new set of barrels if the reamer you used before is different? Or, just find a way to regrind the reamer to an exacting set of specs based on what the barrels you still have are?

I understand brass is the flexible part of the equation, but where is the datum point at which the brass chambers the exact same every time? Is it held the same in the rear of the chamber and the expansion during ignition pushes it into the shoulder where it centers? Or, is it tight headspace on part of the shoulder that hasn't been bumped back? While the part of the shoulder that has been bumped gives the flexibility?

It's that last little question about neck sizing that holds the brass 100% in the chamber vs. custom dies that hold the brass 99% and rely on expansion to fill the chamber and hold the brass during ignition.
 
sandwarrior said:
So, what I'm taking away from this thread is:
It isn't just FL sizing. It's full length sizing with custom dies to a minimum of brass movement to MATCH THE CHAMBER.
Click to expand...
Not necessarily. For example, I shot a 200-15x at 1000 this past weekend. My die was not a custom. I bumped the shoulders 0.0035” on this load. Bullets were not jammed...0.033” off light touch in fact. Powder charge and seating depth...repeat...powder charge and seating depth. :)
And...I couldn’t tell you about the concentricity of my loaded rounds...didn’t check. I use my gage to make sure my dummy round is straight so checking CBTO with a stripped bolt is true. I am a bad, bad boy for breaking all the rules. o_O
 
Last edited:
rardoin said:
Not necessarily. For example, I shot a 200-15x at 1000 this past weekend. My die was not a custom. I bumped the shoulders 0.0035” on this load. Bullets were not jammed...0.033” off light touch in fact. Powder charge and seating depth...repeat...powder charge and seating depth. :)
And...I couldn’t tell you about the concentricity of my loaded rounds...didn’t check. I use my gage to make sure my dummy round is straight so checking CBTO with a stripped bolt is true. I am a bad, bad boy for breaking all the rules. o_O
Click to expand...

That reminds me, I took a pic of that for you. I think you kept shooting cleans so I didn't take anymore pictures of those targets.


Imagine how good you'd of shot if you'd been neck sizing; probably shot a new national record. The jimmies that would be rustled....it would be epic.

"New national record with A-Tips and neck sized brass." That's an AS thread I want to see.

20201010_084443.jpg
 
rardoin said:
Not necessarily. For example, I shot a 200-15x at 1000 this past weekend. My die was not a custom. I bumped the shoulders 0.0035” on this load. Bullets were not jammed...0.033” off light touch in fact. Powder charge and seating depth...repeat...powder charge and seating depth. :)
And...I couldn’t tell you about the concentricity of my loaded rounds...didn’t check. I use my gage to make sure my dummy round is straight so checking CBTO with a stripped bolt is true. I am a bad, bad boy for breaking all the rules. o_O
Click to expand...
What cartridge? What type target?
 
Let's start another controversial thread - barrel cleaning. :) Just kidding.

I don't know if it's still available, but the article entitled "Basics: Headspace, Setting Proper Headspace on Resized Cases" published in The Rifleman's Journal by German A. Salazar is a well written and well supported article regarding this subject.

Also, the article written by Todd Spotti entitled Dealing with Head Space posted on the Redding Reloading web site is informative. I don't know either gentlemen but I've been told that they know what their talking about, i.e. they are "experts" which I am not except when it comes to groundhog behavior. :rolleyes:

Even though I've been reloading for almost 50 year now and have made just about every mistake possible I'm always open to learning more to improve both my shooting and reloading; something that has value which I learned a long time ago in competitive sports and bulls eye pistol competition.

You younger guys are so lucking to have these resources available to avoid the mistakes I made. When I started reloading there was no social media or computers. Most people who reload are reasonably intelligent and do a fair job of evaluating articles / advice as to whether it's logical and makes sense. The more experience you gain will aid in this evaluation process.

Granted, target shooting requires a lot more precision that hunting ground hogs and predators and I wasn't any less successful neck sizing case which I did for years but the improved and consistent functionality of full sizing with a shoulder bump is worth the effort for me. Also, I have some expensive rifles with custom barrels so reducing wear on the lugs appeals to me thus full sizing is right for me.

But let your own experience and judgement guide you - usually you'll come to the approach that is best suited for you.

PS: Neck sizing dies make great paper weights.:)
 
I check cartridge concentricity on brass necks when using new sizing dies for the first time to ensure the die is making my brass nice and straight. Then I check concentricity on bullet bearing surface with any new seating die or if I start using a new bullet. Lastly I will check concentricity on a handful of fired brass necks after being fired in a new barrel to verify the chamber is cut nice and straight as well. If everything is good initially, there is no reason for me to ever check it again.

I know a handful of top level 1K BR shooters that have told me their concentricity gauges have been sitting in the corner collecting dust for years. These guys are shooting 5 shot groups in the 2”-3” range at 1K without ever check concentricity on rounds so you can take that bit of info however you choose
 
sandwarrior said:
So, what I'm taking away from this thread is:
It isn't just FL sizing. It's full length sizing with custom dies to a minimum of brass movement to MATCH THE CHAMBER.

Concentricity/alignment/runout etc. are ALL very important. But they are achieved with the kind of dies and processes described above. Without variation. We know the brass is going to be a close fit still but loose enough to be easily chambered and ~usually~ easily extracted. Depending upon load.

Each load with the right process in reloading with the right dies will produce CLOSELY repeatable results. Anytime there is a component failure, i.e. brass, barrel, there is an as closely approximated replacement as can be obtained. Do you go back and make a new set of barrels if the reamer you used before is different? Or, just find a way to regrind the reamer to an exacting set of specs based on what the barrels you still have are?

I understand brass is the flexible part of the equation, but where is the datum point at which the brass chambers the exact same every time? Is it held the same in the rear of the chamber and the expansion during ignition pushes it into the shoulder where it centers? Or, is it tight headspace on part of the shoulder that hasn't been bumped back? While the part of the shoulder that has been bumped gives the flexibility?

It's that last little question about neck sizing that holds the brass 100% in the chamber vs. custom dies that hold the brass 99% and rely on expansion to fill the chamber and hold the brass during ignition.
Click to expand...

We don't need custom FL dies to shoot well at long range. As I posted earlier, I and others have found that there is no accuracy difference between brass sized in a custom FL die and brass that is sized in a small base die, and the small base die reduces the diameter even further than a custom die. In fact, the best shooting barrel I have is one where I made a rookie mistake on the chamber and wound up getting the chamber base .002" oversize. I did not get special dies for that chamber. Even in that huge chamber with a sloppy fit, I managed a six target LG agg of 5.376" at 1000 yds, good for third place over the two day match. On the tuning day before the match, that barrel shot three consecutive sub 2" 3-shot groups at 1000 yds.

The critical part of the chamber is the throat area. What is behind the throat isn't as important as we used to think. Thus a snug fitting case in the chamber, like we get with neck-only sizing, isn't any advantage. It however can be a huge disadvantage if the bolt is not smooth to open.
 
INTJ said:
We don't need custom FL dies to shoot well at long range. As I posted earlier, I and others have found that there is no accuracy difference between brass sized in a custom FL die and brass that is sized in a small base die, and the small base die reduces the diameter even further than a custom die. In fact, the best shooting barrel I have is one where I made a rookie mistake on the chamber and wound up getting the chamber base .002" oversize. I did not get special dies for that chamber. Even in that huge chamber with a sloppy fit, I managed a six target LG agg of 5.376" at 1000 yds, good for third place over the two day match. On the tuning day before the match, that barrel shot three consecutive sub 2" 3-shot groups at 1000 yds.

The critical part of the chamber is the throat area. What is behind the throat isn't as important as we used to think. Thus a snug fitting case in the chamber, like we get with neck-only sizing, isn't any advantage. It however can be a huge disadvantage if the bolt is not smooth to open.
Click to expand...

I have never noticed any accuracy change between brass being loose or tight in the rear. However, if you are too loose in the rear and your sizing die is working that area above the case head really hard, you will mostly likely have case bodies start cracking from the work hardening.
Happened to me last year with Peterson brass that was a good ways out of spec on my 300 NMI. After 3 firings on the brass, I noticed all my case bodies were cracking anywhere from about .300” to just under half way up the case. Measured the brass and found that the brass bases were grossly undersized. Switched over to Lapua brass that was built to proper spec and have had no issues since
 
Ledd Slinger said:
I have never noticed any accuracy change between brass being loose or tight in the rear. However, if you are too loose in the rear and your sizing die is working that area above the case head really hard, you will mostly likely have case bodies start cracking from the work hardening.
Happened to me last year with Peterson brass that was a good ways out of spec on my 300 NMI. After 3 firings on the brass, I noticed all my case bodies were cracking anywhere from about .300” to just under half way up the case. Measured the brass and found that the brass bases were grossly undersized. Switched over to Lapua brass that was built to proper spec and have had no issues since
Click to expand...

That is why I stopped shooting that barrel. It ruins brass. Once a case expands in the head a certain amount, it's very hard to put it back. I will rechamber that barrel though.

Regardless, the important point is brass that fits the chamber tightly is not the accuracy enhancement we all used to think it was.
 
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