Runout Is Dead / Long Live Runout
- Thread starter CarlGeorge
- Start date
Measure the neck to body runout of your fired cases.
Then measure the neck to body runout again after your sizing process.
If the runout changed, you caused it.
Now perform root cause analysis...
Think 5 whys
and 4 Ms... Man, Method, Machine, Materials.
On my tight neck chambers I get almost imperceptible runout every single time. Practically nothing... Always.
On factory chambers I get runout every time.
Why? Neck clearances.
It is not your dies. It is how much sizing you are doing that causes runout.
Then measure the neck to body runout again after your sizing process.
If the runout changed, you caused it.
Now perform root cause analysis...
Think 5 whys
and 4 Ms... Man, Method, Machine, Materials.
On my tight neck chambers I get almost imperceptible runout every single time. Practically nothing... Always.
On factory chambers I get runout every time.
Why? Neck clearances.
It is not your dies. It is how much sizing you are doing that causes runout.
I did this and found that using a mandrel to expand the neck to accept the bullet helps to reduce the induced runout that is caused by pulling an expander ball back up out of the neck. It is an extra step but I just load for factory bolt guns, with a single stage press, in small quantities, so I have the time. I'm not sure how much it helps on paper, but it sure makes me feel better knowing what is happening, err, or should I say, not happening???!
Ned Ludd
Silver $$ Contributor
I recently purchased a pet Chimp to load ammunition for me. His name is Cocopuff, and we are now BFFs. Cocopuff mastered brass prep, priming cases, and charge dispensing quite easily. However, as you can see from the attached image, I do occasionally need to use my concentricity gauge, simply to ensure the runout of his loaded rounds is acceptable. Otherwise, this tool would collect dust on the shelf.
Attachments
BoydAllen
Gold $$ Contributor
So, before you use the mandrel, after the cases are sized, what does their runout look like?
I have a Sinclair tool and it seems to be less than .002 consistently. Sometimes nill. I use a L.E.Wilson neck reamer on my 1x fired brass and I think that helps take out "high spots" off the inside of the necks, which contributes to more uniform neck tension.
Every time I read posts on subjects like this I feel stupid. The opinions do nothing but confuse me. Granted I have never shot at more than 300 yards and mostly shoot at 100 yards due to not having a range near me for longer shooting.
Most of my rifles want to be seated close to the lands. When the bullet leaves the case even if it is not tightly seated in the lands, it travels under great pressure through 20 to 28 inches of barrel. It seems to me that a really good barrel and chamber will take care of most everything else. If you are shooting five shot groups and they are between .200 and .250 how much better can the average Joe shoot? I am no stranger to 5 shot one hole groups in the ones either.
My priorities are placed on the quality of the chamber, concentricity of the brass and of course the entire barrel. While I have checked some loaded rounds for runout, I have never done so extensively.
While I don't shoot competitively, it seems I am king of the hill with the five guys I shoot with every week. My targets are always praised by them. I think we sometimes we over complicate things.
I am sure that most of you will read this post and cringe. Do not fear telling me I am all wrong. At 85 years old, I am too ignorant to be insulted.
Most of my rifles want to be seated close to the lands. When the bullet leaves the case even if it is not tightly seated in the lands, it travels under great pressure through 20 to 28 inches of barrel. It seems to me that a really good barrel and chamber will take care of most everything else. If you are shooting five shot groups and they are between .200 and .250 how much better can the average Joe shoot? I am no stranger to 5 shot one hole groups in the ones either.
My priorities are placed on the quality of the chamber, concentricity of the brass and of course the entire barrel. While I have checked some loaded rounds for runout, I have never done so extensively.
While I don't shoot competitively, it seems I am king of the hill with the five guys I shoot with every week. My targets are always praised by them. I think we sometimes we over complicate things.
I am sure that most of you will read this post and cringe. Do not fear telling me I am all wrong. At 85 years old, I am too ignorant to be insulted.
hoz53
Gold $$ Contributor
I feel Im a fortunate guy now and if Im still shooting at 85, I will feel really fortunate. More power to you Nick.
Nick is correct, a really good chamber is the key.
Guys that don't have a really good chamber cannot get away with latitude afforded to those that do.
I have 2 barrels for my 223 for example... Both have a free bore of 0.190", long for a 223.
One barrel has a freebore diameter of 0.2259", the other 0.2246"
The 0.2246" freebore diameter barrel could not shoot a bad group if I put the bullets in backwards
The 0.2259" freebore diameter barrel has me chasing ghosts constantly. Once in a while it prints a 0.375" group and I think there's hope for it. 5 minutes later it's 0.600". Some guys would be happy with that, but I'm not one of those guys. The 0.2246" freebore diameter barrel shoots 0.375" on a bad group.
I'm left to wonder how many of you guys have actually measured your actual throat diameter, not off the reamer... actually took a chamber cast and measured it.
How does a guy obtain a barrel with a bonafide 0.2246" diameter freebore? That's the real problem. Reamer guys cant comit to the tolerance, and the pipe fitter probably has more slop in his spindle than it takes to repeat that. Personally, I have special tricks.
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PT
Can you tell me if free bore has any effect on powder residue on the cartridge neck. I recently had a 6BR built by Keith Weil AKA Cigarcop. After shooting it, there is absolutely no powder residue on the neck. I wiped them down and could find no evidence of powder on the cloth. I have fired a total of 66 rounds through it so far. The neck is turned to .271 and I use a Redding bushing die with .268 bushing and Lapua brass as it comes out of the box.
Nick
That's an interesting question Nick.
I once borrowed 6PPC that blacked the brass, but I never investigated why.
On my 223, I wish I had some fired cases I could photograph, but they are all re-loaded. Never really noticed a difference. My neck clearances are really tight so that's probably why I never noticed a difference, but I will try and pay attention next time.
I once borrowed 6PPC that blacked the brass, but I never investigated why.
On my 223, I wish I had some fired cases I could photograph, but they are all re-loaded. Never really noticed a difference. My neck clearances are really tight so that's probably why I never noticed a difference, but I will try and pay attention next time.
AckleymanII
Gold $$ Contributor
Boyd's statement: "If dies neck IDs are less undersized, that will help".
This Helps tremendously! Forster will modify one of their new dies for you for a $12 fee. Others will use a Bushing die, then straighten with a mandrel.
If a person is paying attention to bullet run out, then they are paying attention to other important details like uniform neck tension on the bullet, among other things.
This Helps tremendously! Forster will modify one of their new dies for you for a $12 fee. Others will use a Bushing die, then straighten with a mandrel.
If a person is paying attention to bullet run out, then they are paying attention to other important details like uniform neck tension on the bullet, among other things.
A couple decades ago I obsessed about runout. Then my loading technique improved and I haven't even thought about runout in loaded rounds for a very long time.
About the only time I pay attention to runout is when necking up 7mm cases to 30 cal prior to neck tuning on my HG LR BR guns. If there is runout prior to turning the neck turning doesn't go so well.
I think a big part of solving loaded round runout is to make sure you have minimal case neck wall thickness variation.
About the only time I pay attention to runout is when necking up 7mm cases to 30 cal prior to neck tuning on my HG LR BR guns. If there is runout prior to turning the neck turning doesn't go so well.
I think a big part of solving loaded round runout is to make sure you have minimal case neck wall thickness variation.
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