Very true. The bullet acts as an expander, which it was not designed to do, and simply expands the neck and you end up with bad run-out or a damaged bullet.
Neck tension
- Thread starter BrentM
- Start date
Help Support Long Range Hunting Forum
So if I understand you correctly, the friction or interference fit of the bullet when seating has no direct relationship (if any) to neck tension, which is related to springback.
The bullet does not move until after it is released by cartridge ignition and the walls of the neck expand outward to the chamber wall. How quickly the neck releases the bullet is related to springback (ie tension), which determines the timing of this release. So whether I have 4psi or 40psi on my hydro press really is of little consequence in this process.
Maybe if there were some "hoop strain gauge" that could actually measure neck tension or springback I could get a better understanding of what my brass is doing, but I don't think there is one commercially available.
OK, just trying to get to the bottom line of what you are saying. I understand what you are saying about the difference between hardness/interference/tension.
People can tend to use the wrong words for the same issue.
Questions for clarification
1) Are you saying that using different size bushings have no affect on bullet impact. If it does affect impact, why so. And given that you have to have a neck bushing, what is the proper size?
2) It's generally accepted that repeated firing/sizing causes brass to harden over time which is a bad thing for consistency/accuracy. If the purpose of annealing is to return the brass to the original metal state/hardness, why is annealing every time a dumb thing.
3) I get that if you have a custom chamber with tight neck clearance (not SAAMI) the brass neck is being worked less and hardens at a slower pace. A) how do you know when it's time to anneal (20 rounds firing, 30, 40, 80?) B) Annealing also affects the shoulder area for headspace sizing. That sizing is only .002 or less. Are you saying that it's not necessary to anneal bc the shoulder movement is so small?
4) tight neck chambers are not a reality for 99.99% of the people reloading. Even competition shooters avoid tight necks because of potential bad issues with tight necks. So if you don't have a tight neck chamber, and annealing does actually return the brass to it's original state of hardness, why would you not anneal every time?
This discussion would obviously be better off over several rounds of beer.
BrentM
Well-Known Member
It's an interesting discussion. I have some test brass I want to play with and see if there is run out or not with increased tension, all else being the same. I also want to use my neck turning mandrel to expand some different tensions and see if the spring back is literally of no consequence. I am definitely happy to mess with this process as I have never really fully understand the dynamics of it. I just have known that results show up on the chrono that are really hard to dispute or reason. Most of us seem to find a lane that gives us excellent results and stick with it because it works, even if we don't fully understand it. I am fine with that, I don't build scope, I don't make powder and bullets, I use what someone else created and stick to it.
BrentM
Well-Known Member
Probably would have helped if Mike mentioned custom chamber specs vs SAAMI and what the target is for clearance and what role that plays. For example, my saami chamber shows to be .299 and loaded ammo is .294. So .005 clearance. I would assume a 296-297 chamber would be the target. Maybe go .295 and turn all the brass to get .002-.003? Now we are working the brass .003 max vs .007-008.
Most likely not.....the number on the seating force gauge can be easily manipulated with the type of lube, amount of lube or lack of, and the speed in which the bullet is seated all with the same sized neck. IMO
Last edited:
Carey Farmer
Well-Known Member
Exactly. Neck tension is a function of how much cold-working you do after annealing.
Brass is pretty ductile, so it takes quite a bit - something like 30% - of deformation to develop full hardness. But brass also work-hardens remarkably well. Fully annealed cartridge brass has yield strength of about 20 ksi. Fully hardened (cold-worked) cartridge brass has a yield strength of about 60ksi.
Typical deformation involved with fired case sizing is down 0.010" then up 0.003" which is about 5% deformation total. Assuming you anneal before sizing, then if you size down .012" then up 0.005", that is 6% deformation total. So you will develop a little more yield strength (and therefore more neck tension) if you size down more.
But neck tension won't change if after sizing down, you size up with a mandrel only .0005" below bullet diameter vs. sizing up with a mandrel .002" below bullet diameter, and then using the bullet to size up the rest of the way up. The only thing that impacts neck tension is the total percent deformation after annealing.
Last edited:
Too much theory in each and every neck tension Thread over the years on this Forum for me. I gave up trying to understand the what, where, how, and why. I conclude neck tension affects MV, ES/SD, and precision.
My contribution to this Thread...,
I've found pin gauges make excellent neck expanding mandrels at a much reduced cost compared to neck expanding mandrels "marketed" as neck expanding mandrels. They can be purchased off FleaBay or Amazon.
I grind a slight taper on one end of the pin gauge, and mount the blunt end into an appropriately sized RCBS bullet pulling collet. Then expand the case necks over the pin gauge, like with any other neck expanding mandrel.
Pin gauges are manufactured of hardened steel, and readily available down to 0.0005" incremental diameters. Even less than 0.0005" incremental diameters, if you feel the need.
Carry on!
My contribution to this Thread...,
I've found pin gauges make excellent neck expanding mandrels at a much reduced cost compared to neck expanding mandrels "marketed" as neck expanding mandrels. They can be purchased off FleaBay or Amazon.
I grind a slight taper on one end of the pin gauge, and mount the blunt end into an appropriately sized RCBS bullet pulling collet. Then expand the case necks over the pin gauge, like with any other neck expanding mandrel.
Pin gauges are manufactured of hardened steel, and readily available down to 0.0005" incremental diameters. Even less than 0.0005" incremental diameters, if you feel the need.
Carry on!
I got 300 firings each on 30 pieces of Lapua Palma bass formed to 6 XC, annealing every 5th firing. Of the 30 pieces, 12 are still going strong. The rest I ruined shooting R#17 with 108g bergers at 3250 fps. grouping amazing with the RAS Tuner/Brake. The case necks are turned with .003 clearance.
On the other hand, I just retired a factory Rem 25/06 where I shot the barrel out with 100 pieces of Winchester blue bag brass shooting 87s at 3500-3600 fps with R#19. I got 12 firings on the brass without annealing, and some necks were starting to split. I never full length sized the brass the entire 1200 rounds, just bumped the shoulder back with a Forster standard neck sizer.
There is an amazing difference in various makes of brass, and often different lot # of brass, such as the older Winchester brass over time.
The hardest brass I have seen is Hertenberger 308 Match brass, and various calibers of brass from RWS.
Back in the Mid 80s, we shot out 6 PPC benchrest barrels with 50 pieces of Sako 220 Russain brass. Nobody ever annealed, and neck clearance was usually .002,.001, and many of us ran .0002 no clearance necks for a while where brass spring back held the bullets in place(this did not prove to be the most accurate as you can imagine, but it was the RAGE for a while).
Alloy content of the brass, and neck clearance are critical issues. The more you work the brass, the more you need to anneal. Lately, the talk hear a lot of is the preaching of Bullet Release Issues where you need .004+ clearance on the neck, resulting in uniform bullet release. I cannot argue with this theory, but annealing will be a must. Brass spring back is always evident, the more the neck expands and gets sized back, the more spring back will be an issue where annealing will be critical for uniform bullet grip
On the other hand, I just retired a factory Rem 25/06 where I shot the barrel out with 100 pieces of Winchester blue bag brass shooting 87s at 3500-3600 fps with R#19. I got 12 firings on the brass without annealing, and some necks were starting to split. I never full length sized the brass the entire 1200 rounds, just bumped the shoulder back with a Forster standard neck sizer.
There is an amazing difference in various makes of brass, and often different lot # of brass, such as the older Winchester brass over time.
The hardest brass I have seen is Hertenberger 308 Match brass, and various calibers of brass from RWS.
Back in the Mid 80s, we shot out 6 PPC benchrest barrels with 50 pieces of Sako 220 Russain brass. Nobody ever annealed, and neck clearance was usually .002,.001, and many of us ran .0002 no clearance necks for a while where brass spring back held the bullets in place(this did not prove to be the most accurate as you can imagine, but it was the RAGE for a while).
Alloy content of the brass, and neck clearance are critical issues. The more you work the brass, the more you need to anneal. Lately, the talk hear a lot of is the preaching of Bullet Release Issues where you need .004+ clearance on the neck, resulting in uniform bullet release. I cannot argue with this theory, but annealing will be a must. Brass spring back is always evident, the more the neck expands and gets sized back, the more spring back will be an issue where annealing will be critical for uniform bullet grip
Last edited:
Neck clearance is whole other rabbit hole. There are many opinions and rationalization on this subjuect. This is just my observation.
Again, 99.99% of shooters should never ever consider a tight neck chamber. Too many bad things can happen.
Easy to ruin brass neck turning.
Dirt, water getting into chamber causing over pressure or not being able to chamber a round.
Etc.
Cost. A tight neck chamber requires buying a barrel blank, having it custom chambered and muzzle threaded. Total cost $800 -$1,000.
Purpose for doing it. If you have a hunting rifle and shooting out to 500 yards, are you really going to spend all the time and money to neck turn to extend brass life particularly when any accuracy gains are marginal at best.
Accuracy - lets look at what the pros say. Bench rest guys neck turn. They belive it helps. When .001 in group size difference wins National championships, you would probably let me kick you in the balls if you thought it would improve your group size.
F Open - arguably some of the best shooters in the world. There has actually been a recent trend away from tight necks/neck sizing in the belief that it just does not produce enough accuracy gain to offset the time and cost. Many of those that still do tight necks and neck turn, still neck turn to produce a .005 clearance. They are also fanatics about consistency and since they burn through several barrels a year, they use the same reamer to produce the same neck, and neck turn all brass to the same thickness so that one barrel to the next and each brass lot they use always has the same neck chamber size, brass neck thickness, so therefore they always have the same neck clearance.
PRS - the best run and gun shooters. Most don't neck turn. Not enough accuracy, not worth time and effort and cost. Can lead to potential problems chambering rounds.
This thread has strayed alot from the original OP's question. Still alot of good information and ideas.
I just wish those that jump in and rant and imply people are stupid, would at least respond to questions. Bushings obviously have an impact on something. Annealing has it's place. It does no good to argue how often to anneal when your gun is a tight neck chamber so therefore you don't have to anneal. Good for you.
It's nice to hear the difference between hardness, interference and tension being used correctly.
But again, neck bushing do have an affect and that needs to be explained some how.
I just wish those that jump in and rant and imply people are stupid, would at least respond to questions. Bushings obviously have an impact on something. Annealing has it's place. It does no good to argue how often to anneal when your gun is a tight neck chamber so therefore you don't have to anneal. Good for you.
It's nice to hear the difference between hardness, interference and tension being used correctly.
But again, neck bushing do have an affect and that needs to be explained some how.
are you saying each piece of brass was fired 300 times?
BrentM
Well-Known Member
Everything has a tradeoff. The main reason for bringing up the subject was to discuss how much sizing is needed. IE in my case if I undersize the brass .006 and use a mandrel that is .004 under bullet size vs .003 and .002, what is the net affect on SD/ES and accuracy? I was concerned about brass life at the time of asking the question if people actually test this or just go with .002 and send it. I think a few actually have messed with it and the rest just use what everyone says to use, rule of thumb .002 under OD. I am fairly convinced at this point more undersizing etc is not netting any sort of gain and in the end just a fluke that the numbers may have panned out. I need to finish dialing in this rifle now that the brass if fire formed to the AW2 chamber vs saami. I think the process I have set up for will yield decent results but so far those have been small samples so the plan is to run as much as reasonable over the garmin to collect the data. If in the end I remain in the single digit sd and accuracy is where it needs to be, I am done. I will rethink my annealing and sizing process and use my new K&M mandrels to get concentric necks with consistent seating of the bullets. All of this just to ensure I kill wolves......... it's not a rabbit hole, its a wolf hole.
