Neck pain

C

cdoc42

New member
In a lifetime, you can never experience everything. As time goes on, even things you knew but forgot about, return to remind you.

For my .270 I compared full-length resizing, moving the shoulder back 0.002" to just neck-sizing, using a specific die, and I found I squeezed out tighter groups by neck sizing.

So I loaded up 50 rounds of 140gr Hornady SSTs and went off to chronograph them. After 5 rounds, I found one that would not chamber, but neither could I remove it without using a wooden block and hammer to knock the bolt open.
As I continued, I found more and more of the same but I had learned not to try to fully engage the bolt.

I came home and measured the necks. The Lyman manual shows the neck should be 0.310 inches. Those that chambered were that, or slightly below. Those that would not chamber were above 0.310 inches.

I pulled the bullet, poured the charge into a full-length sized and primed case, removed the depriming pin from the die and full-length resized the case. The length was fine, so I returned the powder charge and seated the bullet. It easily chambered.

In 1976 I read "The Complete Book of Practical Reloading" by John Wooters, so I rechecked what he said about neck sizing. Sure enough. When you neck size, expect to full-length resize after about 3 or so rounds. He didn't find much advantage to it, so it was his policy to always full-length resize.

So now I have a pain in MY neck, faced with pulling about 30 rounds and going through the process described above. I think I'll retire the neck-sizing die.
 
Interesting observation and experience. Thanks for sharing it.

I'll admit I've done both over the years. I now have gone to full length resizing without the stem and mandrel expanding with all my rifle cartridges. I've seen better performance on paper in all circumstances so far.
 
you did not say what neck sizer you were using but if it was a Lee Collet, it needs to be adjusted

what I found interesting was that you aid some would chamber and some not. That would be caused by spring back which would indicate that the brass was not annealed or at least not annealed enough

how to adjust the Lee Collet

https://www.youtube.com/watch?v=4PWdVNg4O98
 
I would think the op would have noticed that the bullets had hardly any neck tension.
I have been doing the Lee collet neck sizer die adjustment that I found on this website, it works very well using the RCBS Rockchucker, and consistent, BUT, I feel I am wearing out my Rockchucker press by camming over so much, I noticed this months later after using this method, and now my bullet seating seems to not be as accurate and consistent as it used to, due to excessive play in the press.

https://forum.accurateshooter.com/threads/tip-for-those-using-lee-collet-dies.3753910/
 
I'm not exactly sure how to measure those two, to compare the press play and shell holder play. All I know, is I can change the seating depth of a precision bullet like Berger from .0005 to almost .0025 just by how much I press on the handle. Also with the handle down, I can wiggle all the pins and joints quite a bit.
So is it written anywhere how much play is to be expected in RCBS shellholders?, that's the only kind I use.
 
While it is true neck-sized cases will gradually tighten a little with each shot, how often you have to do a full-length resize on them depends entirely on how hot your load is. The Lee Loaders are neck-size-only tools but come with powder scoops that generally throw moderate loads and some folks will get 20 reloadings with some of them. Having to resize once every five times is a common number you hear, though. Every three times suggests a fairly warm load to me, though your choice of brass will affect it, too.

Neck-sizing-only started to fall out of favor when bump sizing started to become popular in the '90s. Both have fallen out of favor currently, and full-length resizing just enough to move the shoulder back a thousandth or two has come into vogue. Nonetheless, as with all things handload-related, there are going to be some guns that like neck sizing best anyway. You just have to try it to see, and see if you can find a good load that lets you go a little longer between FL resizings.
 
Hounddawg said: (1) "you did not say what neck sizer you were using but if it was a Lee Collet, it needs to be adjusted"

(2) "what I found interesting was that you aid some would chamber and some not. That would be caused by spring back which would indicate that the brass was not annealed or at least not annealed enough"

(1) I used a RCBS .270 neck sizing die

(2) I think those that chambered had not been reloaded as often as those that did not.
( never got into annealing my brass)
 
lugerstew said: "I would think the op would have noticed that the bullets had hardly any neck tension."

Actually, I think it was just the opposite. I used a Hornady bullet puller die and collet and I had to use some serious force to remove the bullets.

I may be wrong, but I wondered if the necks had gotten thicker and reduced the internal dimension and when I seated the bullet, the outside diameter was greater than 0.310 and prevented chambering. Of interest is when I pulled the bullet and dumped the powder, the empty (primed) case did chamber, but with the bullet seated, it did not.
 
I've always found that I get better groups with neck sized only rounds but they don't always feed well. Long ago I was told that if you are shooting them in the same rifle and they feed ok, there's no practical reason to full length size. Your mileage may very...

I have 2 sets of .270 dies, both RCBS. One set is full length and the other is neck size only. There's only one .270 in our family and the plan is to eventually only neck size rounds for it...

Tony
 
Cdoc42: When I neck size only, I ALWAYS check the headspacing with either the hornady comparator or a dial indicator mounted to a vertical rod with a machined base. If the the necksized brass is +.001 bigger or less than my rifle, I finish loading them, if the brass headspacing measures more than +.001 than my rifle, then I FL resize those to -.002 headspace. I don't have a way to anneal my brass, but I know I should, another toy to buy.
 
cdoc42 said:
I may be wrong, but I wondered if the necks had gotten thicker and reduced the internal dimension and when I seated the bullet, the outside diameter was greater than 0.310 and prevented chambering.
Click to expand...

That's actually the key point, and my previous post wasn't any help with it. If you look at the SAAMI drawing, the 270's neck is slightly tapered. It is 0.310 maximum at the widest point, next to the shoulder, but is only 0.308 at the case mouth. A minimum chamber is made with 0.0008" minimum clearance at both places, so a minimum chamber would be 0.3108" next to the shoulder and 0.3088" next to the mouth of the neck. Chamber diameters at those two locations have a +0.002" tolerance, so yours might be as wide as 0.3128" at the shoulder and 0.3108" at the mouth if it is a maximum chamber, and 0.3118" and 0.3098", respectively, would be average. Assuming your chamber is average, that would explain the >0.310" necks starting into the neck at the wider shoulder/neck junction and then wedging tightly into the chamber neck as it narrows toward the mouth. It is likely a very good thing you couldn't chamber and fire them, as the pressures might have got disastrously high.

So, why are your necks that thick? The periodic FL resizing needed to recover the neck-sized cases will form an internal donut at the neck/shoulder junction, the same as any other bottleneck round can do, but neck thickening forward of that point, except for cases formed from a larger caliber piece of brass is not something you usually hear of.

I realized after my last post that because the 270 is rated for 65,000 psi by SAAMI, which is as high as any magnum or other cartridge they list, it may be normal for it to require those more frequent one-every-three-firings FL resizing than would, say, a 30-06. However, the neck thickening is not a normal complaint.

One thought is that if your brass was formed to match the SAAMI drawing with its neck is thicker near the shoulder, the thick part would gradually move forward at each FL resizing, and every time you trimmed, you would find the brass a little thicker at the mouth as a result of that. Alternately, if you weren't trimming, the case would gradually start bumping the end of the neck portion of the chamber on closing the bolt on the neck-sized cases, and that could cause the mouth to thicken in the same way an RCBS X-die does, and then on the next FL sizing without trimming, that thick portion would move forward.

Personally, I would section one of the thick-necked cases to see if I could spot the thickening favoring one area to better diagnose the problem, but there are a couple of other ways to check. One is to see if the thickness over the seated bullet bearing surface is even, or has the same taper angle as intended, but is just wider near the mouth. Another is to resize with the expander removed and run a neck turning mandrel down into it to have a uniform diameter on the inside of it, then measure all down the neck length, looking for that. You could also just take tubing micrometer measurements from the neck to the shoulder of a normally resized case to get a map of the thickness down its length.

In the end, though, the cure is going to be the same. Inside neck reaming if you want to clear the excess thickness and any donut, but maintain the taper of wall thickness in the neck, or outside neck turning if you are satisfied to make the neck a uniform thickness and lose the taper. That would tend to make the brass a little less resistant to bending upon rapid feed from a magazine, but shouldn't hurt when single-loading.
 
good point about the doughnuts Uncle Nick , I had not considered that.

On the linkage play. If the case is inserted in the die far enough to be sized it is what is known in manufacturing and machining terms, a press fit in that die At that point any linkage play is irrelevant. I suppose it is possible that the case head could be bent off perpendicular but that seems unlikely considering the thickness of the brass in the web area. During seating no one has ever been able to explain why a bullet would would bend the neck instead of the bullet following the internal walls of the neck. That would require a considerable amount of lateral force.

People, water, electricity and even bullets will always follow the path of least resistance.
 
Thanks, Unclenick, that's helpful to better understand the situation. 2 questions with regard to this:

"One thought is that if your brass was formed to match the SAAMI drawing with its neck is thicker near the shoulder, the thick part would gradually move forward at each FL resizing, and every time you trimmed, you would find the brass a little thicker at the mouth as a result of that. Alternately, if you weren't trimming, the case would gradually start bumping the end of the neck portion of the chamber on closing the bolt on the neck-sized cases, and that could cause the mouth to thicken in the same way an RCBS X-die does, and then on the next FL sizing without trimming, that thick portion would move forward."

1) The max case length in a .270 is 2.540" and trim to is 2.530." Is it possible that what you describe can happen even if the OAL of the case is not yet 2.540"?

2) The only cases I have ever had trouble with during trimming is my AR in .223. They simply will not easily pull off the pilot and they appear to be thicker at the mouth once trimmed, to explain it. Does what you describe play a role?
 
hounddawg said:
During seating no one has ever been able to explain why a bullet would bend the neck instead of the bullet following the internal walls of the neck. That would require a considerable amount of lateral force.
Click to expand...

If the bullet is not starting straight down into the center of the case neck, it could be wedged slightly off in the seating die ram or the ram and shell holder could be out of alignment, having failed to self-center. In either case, a cocked bullet pressed down by the seater acts as a one-sided wedge driven into the neck, forcing the case mouth to the side. Another way to look at it is the tilted bullet causes the downward force to be applied off-center. This causes there to be more force on the side of the neck in the direction of the tilt than on the other side, so the neck bends as it self-centers the case mouth with the bullet.


cdoc2,

1) Yes. If the thick part of the neck is moved forward by enough sizing and trimming cyles, it could.

2) A dull cutter will both cut and tool the brass. Tooling, in this context, is working the brass to lay sharp edges over by friction. You may be seeing some of that effect.
 
sorry Nick, I can't buy into that neck bending theory. The bullet will follow the path of least resistance and the least resistance amount of resistance would be for the bullet to slide in parallel to the neck walls. To bend the neck walls would you would have add in force to bend the neck on top of the force need to stretch the brass. It is just common sense
 
Ah, so it isn't that there is no explanation, but rather just that you don't accept it. That's different. I think the problem is exactly what you said, which is that you don't see where the perpendicular force bending the neck could come from. I do, so what is common sense to me is the opposite of what it seems to you.

The classic example of this problem presented to physics students is to explain the block and ramp using force vectors. You can set a block at the bottom of a ramp and then apply a purely horizontal force to it in the direction of the high end of the ramp, and the block goes up the ramp. So the question posed to the student is where does the vertical force that raises the block against the pull of gravity come from in that scenario?

Similarly, you can have something keep the block from moving horizontally while you push the low end of the ramp straight forward and under it horizontally along the ground like driving a wedge under the block. Again, the block rises and the question is, where is the vertical force pushing it upward against gravity coming from if your push is just horizontal? Even more important to note is that if the system is frictionless or at least slippery, the force pushing horizontally on either the block in the first scenario or on the ramp in the second scenario is less than the force needed to raise the block. In other words, that vertical force is greater than the horizontally applied force. And as the angle of the ramp gets shallower, the horizontal force needed to achieve the vertical force that raises the block against gravity gets smaller and smaller!

The case neck is like the block and the bullet is the ramp or wedge. So the perpendicular force bending the neck can be much greater than the force applied down on the bullet. What is exchanged for it being a greater force is it can only apply over a shorter distance of travel. Since work is force times distance, the work bending the neck does not exceed the work pushing the bullet in, and thus there is no violation of the laws of thermodynamics.

Your task, should you choose to accept it, is to find the origin of that block-raising or neck bending force by analyzing the force vectors.

As to following the path of least resistance, it is a propensity and not a constraint. If it were a constraint, bullets would not be able to tumble in the air or in a target medium because straight-in point-first is the angle of attack that offers the least resistance to its travel. But in reality, other forces will have their influence, too. We've all seen tumbling happen.
 
I'll take a stab at this. You neck sized and the shoulder kept moving forward just a bit. That is why after several rounds you need to FL size again, back the neck off. When you neck size use the FL die and couple rounds and the case's won't chamber anymore. At that point, using the same case over, adjust the FL die down a bit and then re-size again. If you feel any rub at all it's the shoulder and needs set back a bit more. Move the FL dies down a bit again and re-size the same case again. Keep doing that until you can close the bolt easily. You are in fact FL sizing the round each time you do it but moving the neck just a bit each time until the case properly fit's the chamber of that rifle. That case may and may not chamber in another chamber for that cartridge. You have partial sized it and now it fits that chamber. I have two 243's and both are set this way. Both rifles have their own set of dies. Rounds from one set will fit both chambers and rounds from the other will fit only the chamber they were set for. You" see this also referred to a shoulder bumping. Not possible to move the shoulder at all without sizing the whole case to some degree! You will, by partical sizing size the case to perfectly fit an individual chamber. If you choose to do the bump thing, lot of those guys size just enough to get the case chambered but they can still feel the shoulder rub in the chamber. That is what you felt and had to beat your action open for. Size till the rubbing goes completely away. With my 243's I got to that point and the dies are locked in right there and kept in box's marked for the rifle they are for.
 
Don, do I understand your theory correctly? You said, "You neck sized and the shoulder kept moving forward just a bit. That is why after several rounds you need to FL size again, back the neck off."

Is "backing the neck off" the same as setting the shoulder back?

Would I obviate the problem if I ignore the die instructions setup and turn the neck-sizing die down further?
 
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