What's Wrong with Neck Sizing?

[Pepe-lepew]

Interesting, that is exactly what Redding said too. I wrote them. Anyway, I am jut going to FL size and forget neck sizing for the rest of my reloading life.

Eric Cortina would think you made a wise decision.

If you don't know who he is, look him up on YouTube. He has several videos about neck sizing and how much it improves accuracy and reliability.

 

[Spitpatch]

And if you look into the technique he advocates, you will discover (as I did) that he's not really "Full Length Sizing" at all. (As is commonly referred to, where the shellholder makes firm cam-over impact to the base of the die, resulting in an overall return to factory brass dimensions.)

He's actually "Partially Sizing": the case goes into the die only enough for a minor shoulder bump. Yes, some resizing of the lower half of the case may occur, but it certainly isn't "Full Length Sizing" as it is commonly and historically known.

 

[thorborg]

Starting with the Lee hand loader and a home made mallet, and moving on to a press thirty years later but still neck sizing when I could, I have necked sized several thousand rounds of mainly .270, but also many .243, .257 Roberts, 6.5 X 55, without ever experiencing your problem. Or any problem. I did have a jap conversion to 257 that gave me a little grief from time to time I never figured out, but it was a work in progress and amusement waned so sold it.
Although I have no insight to help you, I wanted others not to be disparaged from the practice of neck sizing as I truly believe from decades of parallel experience, I received 60 to 70% more reloads than I would have from the same brass if FL sized. My only exception would be semiauto machines would generally prefer FL size leaving neck only sizing for bolt guns.

 

[Pepe-lepew]

And if you look into the technique he advocates, you will discover (as I did) that he's not really "Full Length Sizing" at all. (As is commonly referred to, where the shellholder makes firm cam-over impact to the base of the die, resulting in an overall return to factory brass dimensions.)

He's actually "Partially Sizing": the case goes into the die only enough for a minor shoulder bump. Yes, some resizing of the lower half of the case may occur, but it certainly isn't "Full Length Sizing" as it is commonly and historically known.

It is full length sizing. Changing how far the shoulder set back is by less than 0.010" still full length resizes the body. He is controlling the shoulder set back to be near 1/4 or 1/3 back from max SAAMI specification. Essentially precisely fitting the brass to a chamber verses having an allowable range. His final resized shell dimensions are within SAAMI specifications.

Die manufactures error to over pushing the shoulder back to near or below minimum shoulder length. That is why you see many people often having case head speration issues. They assume die manufactures are perfect and ignore their chamber dimensions leading to excessive case body stretch.

Now this will blow some people's mind. New manufacture ammo specifications allow the cartridge shoulder to be sometimes up to 0.003" larger than the chamber. That does not delineate between semi autos and bolt guns. So a cartridge has to be compressed 0.003" to get the bolt closed. On the flip side, the shoulder of the cartridges can be up to 0.010" shorter than the chamber. That much clearance can lead to case head seperations if reloaded more than twice in a thin case like .223. I have found Hornady dies will over push the shoulder back to minimum on some cartridges. Not a place to be if you want your brass to last very long.

 

[po18guy]

The brass might not be concentric. Might need neck turning. I neck size nearly everything and have had problems with my Savage 10fp after several loads. Crap happens. Too many things can cause crap to troubleshoot here.

As well, for precision shooting, Sinclair and other make gauges to check loaded round concentricity.

 

[Spitpatch]

It is full length sizing. Changing how far the shoulder set back is by less than 0.010" still full length resizes the body. He is controlling the shoulder set back to be near 1/4 or 1/3 back from max SAAMI specification. Essentially precisely fitting the brass to a chamber verses having an allowable range. His final resized shell dimensions are within SAAMI specifications.

If this technique co-opts the term "Full Length Resizing" (from what has been regularly understood for decades as cam-over shell holder contact), then the onus remains (perhaps on those that co-opted it) to produce a new term.

Since his technique is NOT resizing the entire case to the degree that cam-over shell holder contact would produce (rather, "fitting the brass to a chamber"), what shall we now call what we've all come to know to this point as Full Length Resizing?

His campaign shook a lot of people up (and perhaps that was part of his intention). I got over my surprise at his perhaps purposeful choice of terms when I discovered his technique (precisely as you described). Fitting fired brass as closely as possible to the chamber and avoiding any unnecessary working of the brass is something we can all agree on.

It doesn't happen when the brass is pushed FULLY for its entire LENGTH into the die. (Note my choice of terms.)

 

[DizzyJ]

Maybe I'm wrong here but I've always considered full length resizing to mean you shove the case far enough up into the die to bump the shoulder the necessary amount.

Cam over can and will vary based on the shell holder and die.

Neck sizing only is exactly that. Sizing only the neck and not touching the body of the case.

To those terms I have both neck sized only and I've also full length sized.

Redding makes a set of competition shell holders that vary in thickness so you can still "kiss" the shell holder but only bump the shoulder as much or as little as you need.

The problem I have with neck sizing only is that if the case mouth has any runout (varying thickness around the mouth), you're just shoving that variance to the inside where the bullet makes contact, and making the outside round.

This is why I run a mandrel down through the case mouth to keep the neck tension consistent since I don't neck turn my brass. (Yet).

I have seen improved accuracy with neck sizing only, but I have also experienced failure to feed. With full length resizing I have been able to get satisfactory accuracy and 100% reliability.

My opinion may change in the future, but as of now, this is what my experience has led my process to be.

 

[Koda]

Im still fairly new to reloading and my experience in no way will compare to those here so Im going to go out on a limb here but anyone please correct me if Im wrong.... But when I started I jumped right in on the idea of full length shoulder bumping. I did a ton of web reading on the idea of this and it made sense, for me, compared to neck sizing or cam over full length sizing... the three each have their merits but are totally different methods.
Someone correct me if Im wrong, but for any case thats tapered if you dont fully cam over I dont see how the sizing die will form or contact the full length of the case at all. Shoulder bumping only sizes the neck and bumps the shoulder back.

what shall we now call what we've all come to know to this point as Full Length Resizing?

I call it just simply "shoulder bumping".

 

[Pepe-lepew]

If this technique co-opts the term "Full Length Resizing" (from what has been regularly understood for decades as cam-over shell holder contact), then the onus remains (perhaps on those that co-opted it) to produce a new term.

Since his technique is NOT resizing the entire case to the degree that cam-over shell holder contact would produce (rather, "fitting the brass to a chamber"), what shall we now call what we've all come to know to this point as Full Length Resizing?

His campaign shook a lot of people up (and perhaps that was part of his intention). I got over my surprise at his perhaps purposeful choice of terms when I discovered his technique (precisely as you described). Fitting fired brass as closely as possible to the chamber and avoiding any unnecessary working of the brass is something we can all agree on.

It doesn't happen when the brass is pushed FULLY for its entire LENGTH into the die. (Note my choice of terms.)

If this technique co-opts the term "Full Length Resizing" (from what has been regularly understood for decades as cam-over shell holder contact), then the onus remains (perhaps on those that co-opted it) to produce a new term.

Since his technique is NOT resizing the entire case to the degree that cam-over shell holder contact would produce (rather, "fitting the brass to a chamber"), what shall we now call what we've all come to know to this point as Full Length Resizing?

His campaign shook a lot of people up (and perhaps that was part of his intention). I got over my surprise at his perhaps purposeful choice of terms when I discovered his technique (precisely as you described). Fitting fired brass as closely as possible to the chamber and avoiding any unnecessary working of the brass is something we can all agree on.

It doesn't happen when the brass is pushed FULLY for its entire LENGTH into the die. (Note my choice of terms.)

Full length sizing means you size the body of the case vs neck sizing where you only size the neck. Both methods can bump the shoulder a certain amount or not depending on how you adjust the die, the type of die, the type of shell holder or a combination of them. So the term full length sizing is independent of where you bump the shoulder.

"Bumping the shoulder x.xxx inches" means you are precisely setting the shoulder distance to give that head clearance. Camming the press means you are bumping the shoulder to the distance the die manufacture has manufactured the die and shell holder to. That distance can vary wildly between manufactures and between dies and shell holders made by the same manufacture. Hopefully tolerances don't stack and cause excessive head clearance.

So what is Eric doing? He is full length sizing and bumping the shoulder to 0.001 to 0.002" head clearance. That is common terminology. Tomorrow, if I told everyone on the firing line that, all but the less experienced shooters/reloaders would know exactly what I was doing.

As far as sizing to within 0.010" of the shell holder being full length sizing the case or not, the taper on most cases is so small, the difference in case body diameter between the methods is not measurable (0.010"*tan(1 degree)=0.0002"). Dies do not extend to the base of the case because the case head and thick web near the head essentially does not expand. If you size a case with camming over and do it again with 0.010" clearance between the die and shell holder, there will be no measure-able difference in the resized case dimensions.

 

[ddjchemist]

I guess neck sizing is still a very controversial topic in the reloading community judging from the number of replies. Thank you all. I learned some interesting things.

 

[Spitpatch]

Full length sizing means you size the body of the case vs neck sizing where you only size the neck. Both methods can bump the shoulder a certain amount or not depending on how you adjust the die, the type of die, the type of shell holder or a combination of them. So the term full length sizing is independent of where you bump the shoulder.

"Bumping the shoulder x.xxx inches" means you are precisely setting the shoulder distance to give that head clearance. Camming the press means you are bumping the shoulder to the distance the die manufacture has manufactured the die and shell holder to. That distance can vary wildly between manufactures and between dies and shell holders made by the same manufacture. Hopefully tolerances don't stack and cause excessive head clearance.

So what is Eric doing? He is full length sizing and bumping the shoulder to 0.001 to 0.002" head clearance. That is common terminology. Tomorrow, if I told everyone on the firing line that, all but the less experienced shooters/reloaders would know exactly what I was doing.

As far as sizing to within 0.010" of the shell holder being full length sizing the case or not, the taper on most cases is so small, the difference in case body diameter between the methods is not measurable (0.010"*tan(1 degree)=0.0002"). Dies do not extend to the base of the case because the case head and thick web near the head essentially does not expand. If you size a case with camming over and do it again with 0.010" clearance between the die and shell holder, there will be no measure-able difference in the resized case dimensions.

From the RCBS pamphlet included in every die set for decades: (this one from a .308 Winchester set,dated 1991)

"FULL LENGTH OR NECK SIZING

Screw the Full Length or Neck Sizing die into the press until the die touches the shell holder when the shell holder is brought up to the top of the press stroke. Be sure all play is removed from the press leverage system."

And from Hornady Handbook of Cartridge Reloading (also dated 1991):

"Full length sizing is simple. Simply raise the ram, with the appropriate shell holder, to its highest point and screw the full length resizing die into the top of the reloading press frame until it just touches the shell head holder; lower the ram, insert a lubricated case in to the shell holder, raise the ram to its fullest; lower the ram to extract the fully resized case."

Mr. Cortina is free to call his technique anything he wants. But his technique is not Full Length Resizing as such was understood (or "common terminology") for decades and as recently as 1991.

 

[DizzyJ]

Resizing/Depriming - Sierra Bullets

www.sierrabullets.com

 

[DizzyJ]

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[po18guy]

It "might" be the chamber. Only a cast will tell.

 

[orygun]

When I started loading bottleneck cartridges I full length resized them. Then after I started to gain a little confidence I started doing the "neck sizing with full length die" trick. I'd run the die down until I still had a small band of unsized neck at the shoulder/neck junction. This worked well enough. Some cases would be a little tight to chamber after a while and either would get the "full length" treatment, or simply discarded.
When I changed one rifle to an Ackley Improved, I bought a Redding neck size die and used it for all of the cases for a couple of years (small amount of cases). I then bought a Redding Full length sizer. The full length sizer is more of a pain in the butt to use than a neck only. It needs more lube, is more likely to stick a case and takes more effort. However, I found a very accurate load after I started full length resizing and will need to try it with a neck sizing only to see if there's a difference in accuracy.
FYI, all cases were previously fired in the rifle they were being reloaded for.

 

[ddjchemist]

I finished my reloading with usual FL resizing and it worked great. I just wanted to try neck sizing just for sake of curiosity. I am done with neck sizing for good. Here are results from FL resizing at 200 yards.

 

[Pepe-lepew]

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That is an excellent article on the subject of adjusting your FL die for setting head clearance. Even if you have multiple rifles you are loading for, adjusting to set the shoulder to the shortest chamber will improve accuracy and maximize brass life.

 

[bpyycpyy]

Here's what a top shooter and record holder (Eric Cortina) says about it:

 

[Spitpatch]

Here's what a top shooter and record holder (Eric Cortina) says about it:

Well! Finally! an answer to my simple question: "What shall we call Full Length Sizing since the term (as has been used for decades) has now been co-opted to mean something else?"

Hornady calls Mr. Cortina's technique: "Partial Sizing", and I think that is far more accurate toward what he is doing than the "shock value" he purposefully employed by calling it "Full Length Resizing". But, still, (with thanks to him) we need a new term for the operation where the shell holder contacts the die.

And in this video, Mr. Cortina (toward the end, you have to listen for it) supplies us with our new term!

"Oversizing" your brass. Very descriptive and accurate, as it works the brass (usually) more than necessary. But it is still a useful technique regularly employed by experienced reloaders especially when the batch of ammo has to work in more than one gun. (I do it for my .30-30's.)

I can't wait for my next purchase of dies, where, due to Mr. Cortina's obvious influence, they will no longer be labeled "Full Length Die Set", but "Oversize Die Set", followed most assuredly by a re-writing of all loading manuals.

 

[Mikej]

Resizing/Depriming - Sierra Bullets

www.sierrabullets.com

This is how I do my brass for bolt gun.

Here's what a top shooter and record holder (Eric Cortina) says about it:

Does this guy REALLY need to tell people that they are doing it WRONG if the bolt is hard to close on a live round? A can't say about accuracy. I will/would neck size only to SAVE THE BRASS from being worked more than it needs to be. Why on earth would a person bump a shoulder back every time if it didn't need to be? I only have on example t go from, and that's a Swede Mauser. I could bump the shoulder back .003"-.004" to match the factory ammo. But why should I if the the un-bumped shoulder allows the bolt to close with a very slight resistance just before the bolt hits its final resting spot?

I am still sizing the case, not the shoulder, some because a fired, unsized round, needs sizing in this particular gun.