Neck run out
- Thread starter tomL
- Start date
- Location
- Western Manitoba
John Barsness (American writer) was trying to do similar - he believed that pulling OUT the expander ball increased run-out, so he removed his expander ball and shaft completely - resized the brass in his FL sizing die with NO expander, then ran the expander into the case after sizing - he wrote that resulted in less measured run-out, for him.
You might want to measure your runout after re-sizing without that expander ball in the die - see if that makes a difference for you.
You might want to measure your runout after re-sizing without that expander ball in the die - see if that makes a difference for you.
It does make a difference.
I resized 2 (different brand) cases through the way you suggested and my neck run out is 2 to 3 thou.
Now my question is, why such a difference. You are basically just splitting the process in 2 steps?
Tom
Now I got it.
When you do it in 1 step, you are pulling the expander ball from inside out to open the neck diameter. Whereas if you do it in 2 steps you are pushing the expander ball into the case. Makes a difference.
Thanks.
Tom
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Now try it with the expander ball up further in the die (high enough that decapping pin is not protruding) and don’t tighten the lock nut on the shaft allowing it to wiggle a little bit. Works in similar fashion but only on dies with a threaded decapping rod. Inside neck lube also helps.
Break it down. Measure the run-out on the fired cases, then on the sized ones, then on the completed round. Figure out where the run out is introduced to the system and go from there. Some chambers are crooked. Some dies can’t size a straight case, some brass will never come out straight and some seating dies will make crooked ammo on a straight case. Measuring run out on a sized case is a bit of what ifs too. Are you measuring how crooked it is or are you getting the variations in neck wall thickness? What if horror upon horror the case is actually straight but you’re measuring how much the neck is off center? How about my competition seaters that will often make a straighter loaded round than the case was in the first place? That one made my head hurt, but probably more about measuring out of roundness of the sized neck or the bullet pushing the insides of bushing sized necks to the outside or maybe its just evil spirits. Those things are pests; should be a bounty on them.
Want to try something fun while still being humbling? Sort out all your ammo into batches based on run out then go to 600,800 or a thousand or whatever distance you’re hoping to make a difference at and shoot the worst against the best with large enough numbers of shots in the group to kinda sorta prove something and see if you gained anything. Sad to say but I did that a few times, sometimes because I’d loaded more ammo than I could fly with and figured I might as well take the straightest ones. Made the mistake of shooting the bent up banana welfare junk against the good stuff at 650 yards on my little home range and the junk was just as good at head shooting IPSC targets as the good stuff. I didn’t know whether to be happy or sad to be honest, but couldn’t shake the feeling that I’d spent a lot of time alternating between chasing my tail and barking up the wrong tree. My dogs think its endlessly entertaining to do both but I’m not that convinced.
Another is my 338 Edge built by Shawn Carlock of Defensive Edge on a BAT action
and enough other stuff to weigh 16
pounds. Sizeing up tje 300 RUM cases to 338 with a tapered expander ball gave run outs up around 13 thou on loaded ammo but they came out if the gun straight after they eere fired. That banana stuff probably got straightened out some just by chambering it. Tried expanding mandrels and it wasn’t any better. A friend called me to tell me about the goof he made late at night when he literally forgot to neck up the 300 RUM cases and ended up setting 300 grain 338 SMKs on a 308 neck and ramming them home. Not being the sort to let a buddy laugh alone I did some too. Those ones roll tested at 2s and 3s. WTF? How is that even possible? When I shot those at 1/2 mile I couldn’t tell the difference between them and the straight fire formed stuff. 1/2 MOA at 1/2 mile. Maybe I should find a new tree to bark up
Want to try something fun while still being humbling? Sort out all your ammo into batches based on run out then go to 600,800 or a thousand or whatever distance you’re hoping to make a difference at and shoot the worst against the best with large enough numbers of shots in the group to kinda sorta prove something and see if you gained anything. Sad to say but I did that a few times, sometimes because I’d loaded more ammo than I could fly with and figured I might as well take the straightest ones. Made the mistake of shooting the bent up banana welfare junk against the good stuff at 650 yards on my little home range and the junk was just as good at head shooting IPSC targets as the good stuff. I didn’t know whether to be happy or sad to be honest, but couldn’t shake the feeling that I’d spent a lot of time alternating between chasing my tail and barking up the wrong tree. My dogs think its endlessly entertaining to do both but I’m not that convinced.
Another is my 338 Edge built by Shawn Carlock of Defensive Edge on a BAT action
and enough other stuff to weigh 16
pounds. Sizeing up tje 300 RUM cases to 338 with a tapered expander ball gave run outs up around 13 thou on loaded ammo but they came out if the gun straight after they eere fired. That banana stuff probably got straightened out some just by chambering it. Tried expanding mandrels and it wasn’t any better. A friend called me to tell me about the goof he made late at night when he literally forgot to neck up the 300 RUM cases and ended up setting 300 grain 338 SMKs on a 308 neck and ramming them home. Not being the sort to let a buddy laugh alone I did some too. Those ones roll tested at 2s and 3s. WTF? How is that even possible? When I shot those at 1/2 mile I couldn’t tell the difference between them and the straight fire formed stuff. 1/2 MOA at 1/2 mile. Maybe I should find a new tree to bark up
- Location
- Western Manitoba
I was in the "same boat" about 15 or 20 years ago - I was convinced that "runout" was going to solve my groupings - I ended up to buy the "full meal deal" of stuff (at the time) and read a lot of "how to to do it" - I fussed with hundreds of cases in 338 Win Mag and 7x57 and various loads. I ended up to shoot five shot groups of .005" measured runout or less versus .006" runout or more - at 100 yard target with my factory, stock Winchester Model 70 in 338 Win Mag - R-P (Remington) new brass, Fed 215 primers, probably RL 19 powder - Runout numbers did not make a difference for me - I could not show on 100 yard 5 shot groups that "runout" made a difference in group size, for me, with that rifle. I "wrote it off" as "not significant" for a factory, massed produced chamber and barrel, and felt the whole effort was "busy work" for my rifles that I tried it in (all factory stuff - bought in store or from CGN). I now believe that bullet brand, "jump" to rifling, muzzle velocity, powder brand has a LOT more affect on group size, than does "runout" - but it was a good "phase" to go through ...Break it down. Measure the run-out on the fired cases, then on the sized ones, then on the completed round. Figure out where the run out is introduced to the system and go from there. Some chambers are crooked. Some dies can’t size a straight case, some brass will never come out straight and some seating dies will make crooked ammo on a straight case. Measuring run out on a sized case is a bit of what ifs too. Are you measuring how crooked it is or are you getting the variations in neck wall thickness? What if horror upon horror the case is actually straight but you’re measuring how much the neck is off center? How about my competition seaters that will often make a straighter loaded round than the case was in the first place? That one made my head hurt, but probably more about measuring out of roundness of the sized neck or the bullet pushing the insides of bushing sized necks to the outside or maybe its just evil spirits. Those things are pests; should be a bounty on them.
Want to try something fun while still being humbling? Sort out all your ammo into batches based on run out then go to 600,800 or a thousand or whatever distance you’re hoping to make a difference at and shoot the worst against the best with large enough numbers of shots in the group to kinda sorta prove something and see if you gained anything. Sad to say but I did that a few times, sometimes because I’d loaded more ammo than I could fly with and figured I might as well take the straightest ones. Made the mistake of shooting the bent up banana welfare junk against the good stuff at 650 yards on my little home range and the junk was just as good at head shooting IPSC targets as the good stuff. I didn’t know whether to be happy or sad to be honest, but couldn’t shake the feeling that I’d spent a lot of time alternating between chasing my tail and barking up the wrong tree. My dogs think its endlessly entertaining to do both but I’m not that convinced.
Another is my 338 Edge built by Shawn Carlock of Defensive Edge on a BAT action
and enough other stuff to weigh 16
pounds. Sizeing up tje 300 RUM cases to 338 with a tapered expander ball gave run outs up around 13 thou on loaded ammo but they came out if the gun straight after they eere fired. That banana stuff probably got straightened out some just by chambering it. Tried expanding mandrels and it wasn’t any better. A friend called me to tell me about the goof he made late at night when he literally forgot to neck up the 300 RUM cases and ended up setting 300 grain 338 SMKs on a 308 neck and ramming them home. Not being the sort to let a buddy laugh alone I did some too. Those ones roll tested at 2s and 3s. WTF? How is that even possible? When I shot those at 1/2 mile I couldn’t tell the difference between them and the straight fire formed stuff. 1/2 MOA at 1/2 mile. Maybe I should find a new tree to bark up
For example - seating bullets - I never owned a target or micrometer seater - just what came with the full length sizer - was a thing I discovered or read and confirmed with my own reloading - seat a bullet part way - then pull out and rotate that case about 180 degrees and finish seating the bullet - that most definitely resulted in less measured run-out - it became a habit - I still seat a bullet that way, even though I no longer measure runout when I reload.
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I do find reasonable amount of bullet run out does not affect accuracy. But in pursuant to perfection I still like to achieve minimal neck and bullet run out.
Tom
I do
All of them under 2 thou.
I did when I was in my collet die stage. They load straight ammo. Proving by shooting results that there were improvements that I could detect was more elusive but that is hardly limited to the collet dies. I moved on, looking for the next magic missing factor.
Agree .... I've found that it's a list of several small improvements as well. There is no one single silver bullet.I did when I was in my collet die stage. They load straight ammo. Proving by shooting results that there were improvements that I could detect was more elusive but that is hardly limited to the collet dies. I moved on, looking for the next magic missing factor.
I've been using them for years but never did buy a gauge to measure the improvement I used to try to only buy chamberings that Lee had collet dies for. I don't shoot a lot of different rifles so this isn't that hard now. The only one I don't have a collet for now is a 358Winchester and I'm sure it will shoot well enough when I get it going.
There is an article on accurate shooter on how to setup a regular die to make the least amount of runout possible.
https://bulletin.accurateshooter.co...-reducing-run-out-with-standard-seating-dies/
It’s for seating dies but maybe try and apply the same principles. Put pressure on the die with the ram and case then tighten down your locking nut.
https://bulletin.accurateshooter.co...-reducing-run-out-with-standard-seating-dies/
It’s for seating dies but maybe try and apply the same principles. Put pressure on the die with the ram and case then tighten down your locking nut.
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Just started using my standard rcbs die that way.
Decaping pin out just far enough to pop out the primers but not let the die size the brass.
Remove the decap rod and size the brass.
Reinsert the decap rod and size the neck.
If seam like extra steps, but since doing this I haven't had to do the extra steps of trimming any brass.
Carbide neck sizer is on the shopping list.
Decaping pin out just far enough to pop out the primers but not let the die size the brass.
Remove the decap rod and size the brass.
Reinsert the decap rod and size the neck.
If seam like extra steps, but since doing this I haven't had to do the extra steps of trimming any brass.
Carbide neck sizer is on the shopping list.
Is the run out in your expander or the die body?
Is the jam nut holding the expander (recapping rod) off centre in your die?
Are you turning your necks to uniform them?
Is the runout at the case mouth or in the middle of the neck?
Also, sorry to ask so many questions, but when you measure are you using a dial indicator or handheld calipers?
I started using the method Potashminer recommends and the run-out is less than .002" now.
