Problems with runout or concentricity
- Thread starter igor
- Start date
I have fought runout like everyone. I finally have it down to less than a thou pretty consistently measured on the bullet ogive.
Whether it makes that much diif or not is debatable unless you are a master at reading wind. However my philosophy is to make my rounds as uniform as possible no matter what. OCD is guess!
I only think about controlling runout after the first fireforming of cases matched to my rifle. I never use an expander ball. I triple seat my bullets. And I never neck turn to try to control runout - that dosent work because the case and neck are out of alignment to start with. I only neck turn to shave high spots if they are over min avg thickness by more than .001. If a neck has a thin spot i save it for annealing setup or plinking. But most variances tend to be on the outside - too thick in spots.
I use bushing dies with a co-ax. For some reason ( spring back?) neither a bushing or conventional f/l die seems to sufficiently align the case neck to case body on new brass that has excessive neck runout. Only fireforming will for me at least.
Whether it makes that much diif or not is debatable unless you are a master at reading wind. However my philosophy is to make my rounds as uniform as possible no matter what. OCD is guess!
I only think about controlling runout after the first fireforming of cases matched to my rifle. I never use an expander ball. I triple seat my bullets. And I never neck turn to try to control runout - that dosent work because the case and neck are out of alignment to start with. I only neck turn to shave high spots if they are over min avg thickness by more than .001. If a neck has a thin spot i save it for annealing setup or plinking. But most variances tend to be on the outside - too thick in spots.
I use bushing dies with a co-ax. For some reason ( spring back?) neither a bushing or conventional f/l die seems to sufficiently align the case neck to case body on new brass that has excessive neck runout. Only fireforming will for me at least.
RAT807
New member
You can also remove the decapping rod/neck expander button and roll it on your concentricity gauge. I have found a few that were not straight. I've used a Hornady Concentricity gauge to straighten these rods which decreased runout.
My personal goal is runout below .002 and most of my loads meet and or exceed this. But, I have some brass that was purchased in bags, that was no where near straight. Cramming the press over would not fix it. It had to be fire formed. Inconsistent case wall thickness can also cause problems and produce banana shaped brass on firing. I have 100 pieces of brass, most never loaded, that I have given up on because of multiple issues, case wall thickness being the main one. But my Norma brass is mostly .0015 or less so I know it's not my die or process.
My personal goal is runout below .002 and most of my loads meet and or exceed this. But, I have some brass that was purchased in bags, that was no where near straight. Cramming the press over would not fix it. It had to be fire formed. Inconsistent case wall thickness can also cause problems and produce banana shaped brass on firing. I have 100 pieces of brass, most never loaded, that I have given up on because of multiple issues, case wall thickness being the main one. But my Norma brass is mostly .0015 or less so I know it's not my die or process.
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Originally Posted By: hm1996I don't think reasonable runout makes enough difference to matter until you get to or past 300 yards, but that's just me.
I tend to think of it more in terms of how much under 1/2 MOA than in terms of how far past 300. If you're in 1/4 MOA territory, it matters, even at 100 yards. If your over 1/2 MOA, it ain't gonna matter at any distance.
- DAA
I tend to think of it more in terms of how much under 1/2 MOA than in terms of how far past 300. If you're in 1/4 MOA territory, it matters, even at 100 yards. If your over 1/2 MOA, it ain't gonna matter at any distance.
- DAA
Originally Posted By: DAAOriginally Posted By: hm1996I don't think reasonable runout makes enough difference to matter until you get to or past 300 yards, but that's just me.
I tend to think of it more in terms of how much under 1/2 MOA than in terms of how far past 300. If you're in 1/4 MOA territory, it matters, even at 100 yards. If your over 1/2 MOA, it ain't gonna matter at any distance.
- DAA
Splains it then. If I'm under 1/2 moa, I'm ecstatic w/80 yr old eyes.
Regards,
hm
I tend to think of it more in terms of how much under 1/2 MOA than in terms of how far past 300. If you're in 1/4 MOA territory, it matters, even at 100 yards. If your over 1/2 MOA, it ain't gonna matter at any distance.
- DAA
Splains it then. If I'm under 1/2 moa, I'm ecstatic w/80 yr old eyes.
Regards,
hm
Pleased to report my Hornady dies arrived and my 6.8 spc runout issue is much improved. I really like the features designed into the series 3 2 die set. Runout with the cheap rcbs dies averaged .004 with a few at .007. Average with the Hornady is about .001 after loading 30 rounds! Had 1 that was .0055 and I checked the brass on the runout gauge and it was .0075 out. That brings up another question. Most people say outside neck turning would not improve accuracy on my factory chambered barrels. But it is hard for me to believe that some neck turning would not help fractionally. I wont keep a rifle if it does not consistently fire cold barrel 3 shot groups moa. Most of mine will do .5-.7 groups off a good bench. I cant afford another rifle for awhile but I think the next one is going to be a custom chamber and some bushing dies to go with it.
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