hornady concentricity tool

ired case diameters are smaller than chamber diameters
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but they are concentric , yes ? no bent necks ?


consensus has it that Lapua brass has a springback of .0005"-.001 after sizing or expanding. With tens of thousands of psi inside that case for a few milliseconds that case will conform exactly to the chamber. That case is going into the sizing die concentric it's when the neck is being pulled or pushed while the shoulder is not supported that pulls it off axis. Only reason I can see is the expander button. I tossed all of mine and the concentricity problems went bye bye. I use the bushing style dies so I can play with neck tension and neck turning, otherwise any decent die from Lee on up will work
 
Well then... I must be doing something wrong here. Tweeked the rounds with the new tool. Got them down to 1-1.5ish runout acording to the dial. Left the worst 10 alone as a controal. Marked the brass with their reading. These were 4-5.5 ish (thousandths) runout. Went and shot today (FINALLY), the two 10 shot groups top right and left were the "fixed" rounds, center is the last 10 out of whack rounds. Must say I am verry disipointed. Groups actally opened up after tweaking them. Center group is normal for me at 100y, top left and right I could see randomizeing as I shot. If I had stoped at 3 or 5 shots it would have looked like crap. Same point of aim for all groups, think i was shooting 150s last time I shot with this scope so zero was different (these were 168 HPBT over IMR4064 CCIBR2- my go to in .308). I made no scope adjustments through the 30 rounds fired.

Side note: bottom left is 20 round 223/556 with 75gr HPBT over blc2 shot conceteveally in one string. all shots taken at 100y @ 79F Wind: SSW at 4 mph, Wind Gusts: 8 mph Humidity: 53%
 

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So now begins the neck turning? Or do I just have a $120 paper weight. Or, do I just accept the groups I have been getting and assume it is me or the rifle? I am shooting off bench with bipod and rear bag (sand filled shot bag) Savage model 10-T-SR with break, otherwise stock. Sweet shooting rifle, dont like the plastic stock but it seems to work.
 
Our own rifle aiming and shooting techniques effect shot group sizes. Firearms shoot smaller groups in free recoil or from accuracy cradles.

20-shot groups are much more indicative of ammo performance
 
Just my opinion but if you went from cloverleafs to 1 inch plus groups you got problems concentricity and neck turning never caused and won't solve.
 
Refer to post 16. "When I say clover leafs at 100, I mean bullet holes are touching at the end of a 5 shot string off bench with bipod and rear bag. Not nessarally in a perfect patteren." just a dude with stuff. But can I do better?
 
I’m just a dude with stuff as well . I recently decided to stop trying to buy better groups like golfers think a $2k set of clubs is going to knock 10 strokes of there game . I played with a used $150 set of clubs for years then bought a nice set of clubs , I literally shoot the exact same score as I did before .

I’ve bought a lot of “stuff” in the last 10 years to be able to load very consistent rounds . After buying the Redding competition seater die and concentricity gauge last year and nothing getting better . I’m done spending money on groups . Hell if you ask me I shot smaller groups $500+ ago then I do now .

I’ve decided to recommit to working on load development and shooting then I do on case prep . YMMV
 
what Metal God said

work on load development and range practice if you want smaller groups. .308's are probably second only to the .223 for easy load development becasue both cartridges have been loaded in every way possible over the years
 
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