There is a couple types of runout, inherent and mechanical. Both are mostly controlled by the brass itself. If the neck thickness (and the rest of the case body as well) is not uniform and the brass ductility is not uniform, there will be some inherent runout as the neck material will expand and contract non uniformly. Turning necks helps but cannot affect the imbalance in case body thickness. When pulling a ball or pushing a mandrel through the neck area the neck will expand more to one side than the other if the material thickness or ductility is not uniform. The case is most uniform while it is fully in the sizing die, but we cannot expand the neck until we withdraw the case some. At that point the case floats and will follow the ball location axis. Extra mechanical runout will not be induced unless the ball axis exceeds the free float space, so a slightly out of axis pin and ball will have almost no effect in inducing additional mechanical runout. Most shell holders also have some side to side float. Therefore, as long as a mandrel is not off center by more than the available side to side float additional mechanical runout will not be induced by the expansion process. Mandrels have some edge over balls as more of the neck is in contact with the expansion surface while a standard ball is only in point contact and the neck ductility may not be uniform over the entire length of the neck. Note: long and tight freebores can almost eliminate the affects caused by runout and is the reason the most accurate current trend is to long and tight freebores.
This. The crux is that no current sizing die type supports the case body while sizing the neck. Thus no current sizing die can correct for inherent case runout.
@@justice1327 i don't believe it does so. A tapered case body can only be fully supported if it is all the way into the die. To do that, you basically have to slide the case up into the die with the neck sizing bushing lifted out, and then size the neck. Thus you need a seperate press on top of the die.
I was pretty big into this subject a while ago, and my data for run-out corresponds with yours. For how well the groups printed on paper, however, I found that sizing the neck with a mandrel generally gave me more consistency/precision on paper. It wasn't a world of difference, it was just something measurable and repeatable. This was generally true across multiple calibers/platforms. The most noteworthy thing was that I tested multiple resizing dies, and one time, while doing a full powder-charge load development I had a Redding die w/ the carbide button shoot drastically better than the expander mandrel --- we're talking the groups were literally half the size. I was used to seeing approximately a 10% difference in favor of the mandrel, up to that point. I quickly found out what the difference was: the carbide button was resizing the case necks to 0.281, instead of 0.282. So, yeah, just like what you touched on this video - neck tension is a thing to consider, and probably a bigger concern!
Thanks for clearing the air with Data Keith. Something I've wondered is how run out with an expanded ball is affected by cases that are not reamed and turned, and also annealed vs non annealed.
I use a Short Action Custom sizing die. The mandrel is placed in the die and the case is expanded as the case neck is moving out of the bushing. This system has provided cases with little to no run-out, as indicated on a Concentricity tool. I really like their dies.
I believe that initially a person should check run out of press/die/brass combined setup if your shooting for competition and accuracy and check it if something changes. Newer die sets cut on cnc machinery can exhibit a problem if QC isn't there. A press can too but I just don't see either one being predominant these days . Brass seems to be the major factor in most cases. No pun intended. I've got a press from the 70s and set of RCBS dies from late 60s and runout is .00025 or less on .308 NATO brass with out shaving neck thickness, and I'm fairly certain those dies weren't cnc turned to the close tolerance of these days. It comes down to paying attention to set up and knowing how to adjust equipment with out having to buy the best available with hard earned money when not always necessary. Shooting competition needs the best you can afford if you want to keep up with the other competitors but if listen to this man he will teach you that attention to details can save time and money and quite possibly your sanity and you'll find the accuracy your looking for a lot easier than some of the other people.
I got on this bandwagon a long time ago. Here's something I think is worth mentioning. The "get rid of the expander ball" came about for me because standard factory dies squeezed the neck down WAAAAAY too much. Then when you had to drag the brass over the expander it was significantly working the brass and in my experience, caused unacceptable runout. This is with NON bushing dies. A solution was to get the sizing die neck honed/opened to a more acceptable diameter if the company that made it would do so. In my case, Forster accommodated me. I had 1000 pieces of Lapua 6.5-284 Norma all from the same lot, so that die was honed accordingly to size 0.0025 less than a loaded round, necks not turned. Served me very well Then, you can take into account using bushing dies. Well, this really helps out quite a bit and makes ditching the expander ball less of an issue because choosing the best bushing greatly reduces the degree of neck sizing, thus, the expander doesn't work the case mouth as much as the aforementioned non bushing die. But, in my experience, using the ideal bushing has eliminated the need to expand anyway. Yes you can argue that the neck tension should be set by working the ID for consistency but I've done this multiple ways and it gets to where hairs are being split To be clear, I do NOT shoot any competition. I only hunt but shoot a lot. Ultimately, I have found that using a bushing die, followed by a final step with a mandrel has produced excellent results for me so I'll stick with it. I did compare this to a bushing die and expander ball with a small sample of 20 rounds of each type but in 14 different rifles and there was a winner but not buy a substantial margin - using the mandrel for final sizing. To sum it up, if you have standard dies, non - bushing, and your necks get squeezed down to a ridiculous OD, the expander ball is not your friend. If your set up is allowing minimal brass work hardening, take your pick, ball v mandrel
We reloaders often fall into the trap of thinking that something we can measure must be something we need to control. But not everything matters. Runout is basically IRRELEVANT. Yes, I said it. If you have a proper reamer geometry and neck clearance in your chamber, then the bullet cannot help but enter the rifling straight. You can shoot dozens of groups of rounds with 4 or 5 thou runout against dozens of groups of rounds of a single thou or less and you’ll never see the difference on paper. Neck tension, however, does matter a good deal. So focusing on consistent neck tension means consistent neck geometry and neck metallurgy (hardness). This is why annealing and neck turning are so helpful for getting low SDs. Variations in neck thickness and hardness are variations in neck stiffness and yield point, which affects bullet release consistency and SD. If course, if your action has terribly inconsistent ignition and your primer seating is a mess, then there’s no point bothering with neck consistency.
Very good philosphy about processes. I tweek the expander size and different neck bushings sizes depending on brass thickness and malleability. Not all brass rebounds the same. For my semiautomatics i like more neck tension vs my bolts. I too rarely check my runout. Mostly as a check and if I change bullets.
Outstanding insight... as I'm venturing in custom chambers. Would love to hear your expirence on custom made sizing dies matched to the chamber. I see many comments suggesting SAC dies but I don't think folks understand what exactly those dies are sizing brass to.
My shooting requires a couple of thousand rounds for chuck season. They are prolific. I have not been using any expander until this winter because I was using a full-length bushing die to set neck tension. I recently, erroneously, diagnosed donuts in my cases. The error happened because the bullet seating process was smooth to a point that on several cases was a hard push. Turned out being a rough neck rim and carbon. ( got lazy and did not tumble this one box of cases) I installed the expander ball back into the die and bullet seating became nice and smooth. I also have a mandrel die and ran several cases through the mandrel die and found that bullet seating was even better. ES and SD in the cases that I ran the mandrel through was slightly better than those sized with the expander ball. I'm in no hurry so I take the extra step to run the mandrel through the necks on all of my cases now. I have all winter to get ready by mid-April so taking my time to achieve better accuracy later is well worth it. I use a repurposed arrow straightener as a runout gauge and all of my cases are at 0.001. Good video.
One thing to think about is the effect on case length of the use of expander mandrels versus expander balls. I find that after passing a sized case through an expander mandrel die, the overall case length is shortened. This effect is somewhere around .003 inch in .223 brass that I have been processing. On the other hand, brass passed through a die with an expander ball of the same diameter as the mandrel ends up with a longer case length than the brass that is run through the mandrel process. This could be due to the fact that the primary neck expansion force with an expander mandrel occurs as the mandrel is inserted into the sized case, whereas the primary force of the expander ball is applied to the neck as the ball is withdrawn out of the sized case neck.
You can hone the expander ball to your specs. Forster has it as a service. I use a Dillon now to speed up resizing on one station, expanding on the next.
I've done this with Lee dies, of all things. The one-piece expander/decapper rod can be easily honed to whatever size you want, and at about $7 for a 223 rod, why wouldn't you do that? Granted, you can't make it bigger, but at .223" to begin with, not many want to go larger than that anyway. People turn up their noses at Lee, but I've found some of their dies to be excellent. My 223 Pacesetter die set builds some of the straightest ammunition I've ever used. Better than the Forster full length die I have, for example.
@TheTraveler807 , that's what I do. I just buy a spare (if necessary), chuck it into a drill, and hit it with 600 and 1,200 grit sandpaper to under-dize it just a pinch. I learned that about 35 years ago and it works great.
Forster has, the Expander Ball set, HIGH Up, in the Die, so very little chance of,.. Run-out ( 0 to .002 max TIR ! ). They ARE,.. Precision ! Be sure to nylon Bush Carbon in neck first, then lightly Lube the inside of Necks with, a nylon brush, Size, then CLEAN out most of, lube with, a Q-Tip ! Leaving, a Tiny Bit of Carbon and Lube in neck, keeps Bullet from WELDING to Brass, over Time !
Thank you for addressing the question of runout. Now what about overworking the brass? I would think expander mandrels help limit how much we work the brass and therefore provide longer brass life.
i wonder how much of the 'run out due to expander ball' can be attributed to salesmen with new stuff to sell. on another note although most of your reloading advice far exceeds my requirements I still find it useful and informative thank you.
I sincerely appreciate you taking the time to collect and analyze the data. Did you deprime as a separate step before both processes (expander ball vs mandrel)?
No, I decapped only a few 223 cased to facilitate proper measuring for sizing, but all of the rest of the cases were decapped as part of the ride through the sizing die.
I'm stuck debating whether to try neck expanding with a mandrel, in place of the Redding free floating carbide size buttons I currently use. The buttons I've measured are just over a thou under bullet diameter (0.2632 for 0.264 bullet) best I can measure, same as the black nitride 21st Century expander mandrels. I use full length Redding size dies and have the necks honed locally to match whatever brass I'm using so they don't squeeze the necks to much. Just not sure if the extra time and expense will be worthwhile for a strictly recreational shooter
Thank you for this video. I really appreciate your no-nonsense and empirical approach to things. The question that I'm left with, let's say the expander ball leaves you with even 0.002" or 0.003" runout compared to the
That is an excellent question. I can't give a scientifically based answer because any difference there might have been in my testing was completely masked by noise in the system. In other words, I control runout because I hope to reduce a variable NOT because I know it makes a difference. I've won my fair share of F-class hardware with .003-.004 TIR on seated rounds.
That's a good question. I watched an F-Class John video a while ago where he tried shooting rounds that had an absurd amount of runout, compared to the same load with very little runout. As I recall, there wasn't much difference in the results. That may be due to other things, though. I did notice that the target used (Shotmarker) showed higher velocity SD numbers for the not-so-straight ammo. Coincidence?
Yes, but so does the mandrel as it goes in. I've crushed cases with the mandrel, but have never found a case that I changed the angle with the expander ball.
What are the 95% confidence intervals of the means? They're very similar values, and with your sample size, we might expect they aren't significantly different
In my experience, using an expander ball stretches-out and reduces the shoulder bump that I painstakenly measured so carefully in the full-length sizing operation. The mandrel process does not change the headspace measurement for me. Has anyone else experienced this?
I have heard (Not tested myself) that you should get more consistent neck tension and more consistent SD's when using a mandrel. It sounds plausible to me, but would like to know if you have tested this?
Hi Kieth, thanks for sharing your experience. Just wondering if or how or what you lubricate the inside of the neck with prior to expanding? I find that I have to lube with something or it puts a lot of pressure on the brass. I use RCBS lube on a brush but then have to wipe it out. I feel like I’m doing something wrong. Could tumble them again but seems like a lot of tumbling.
I lube cases with Dillon spray lube. There is enough lube inside the neck to allow easy sizing. I only tumble (in corncob media) after sizing and trimming.
I don't like the concept...more work on brass...possible marring of inner neck. Lee collet for me...and ..no lube.. Thanks for presentation...expander balls..not as bad as you might think...possibly... Always well done by you..Keith
