Concentricity gauges, let's hear it if bench loaders and accuracy guys....

[fotheringill]

On the KM with the wheel. Without the wheel, thumbs work just fine when you roll the case with them. If you are going to purchase the tool, you might want to try it without the wheel first.

 

[WVRJ]

I have found that in a couple of my most accurate rifles,the effort to gauge and correct runout can make a difference.But,it does seem that runout is more of an issue in larger,longer bullets.It makes little or no difference in my 223 bolt gun,groups are always in the .3's or ..4's.In the 308,it seems to gain a small amount,usually .1 or .2 MOA.I no longer even bother to measure the 223,but always measure the 308,25-06 and 280.I'm not a competitive shooter,the only thing I want to do is enjoy shooting the smallest groups possible to a perfect POI.The quest for better accuracy is never ending,and when it's no longer a goal to reach for,I'll have some nice rifles up for sale.

 

[pert near]

How do you correct a cartridge after you find it's out by .004 or .005 ?
Do I pull bullet and start all over and re seat ?

Years back, I read an article where a fellow used a marker to indicate the "high" sides of his concentrically measured rounds. When bench testing he indexed off the mark when placing the rounds in the chamber (i.e. always putting the mark straight up at 12 O'clock). IIRC he swore that this technique proved to be as effective as correcting the run-out. Being a young handloader at the time, I tried it myself but I really lacked the rifle, equipment or technique to make much of a determination.

Perhaps someone more capable here may have tried this before & have come to a valid conclusion.

FWIW

 

[pert near]

I would have kicked this to you in PM, but since you asked - I'll try to keep this brief within each bullet point, so I don't bury the thread, OP, or readers, but a few thoughts on reloading precision ammunition and precision shooting practice, but you know me well enough to know this won't be brief:

• Consistency is king....

• Your precision is only as good as the worst of your ammo, your rifle, and your skill - so be sure you balance these 3 appropriately and be sure your ammo and your rifle are capable of better ammo than you are as the shooter. Crappy barrels won't shoot 1/3moa groups even with precision ammo, and perfect barrels won't do well with inconsistent ammo. If you're shooting factory chambers and factory barrels, there is a high likelihood your bore and chamber are not perfectly concentric, or the axis of each might not even be parallel (not concentric = coke cans laying on two different steps, non-parallel is one can on a flat, one on the side of a hill), or worst, they might be off for both concentricity AND parallelity (it's a word, but it sounds REALLY stupid when said out loud). A buggered crown will never shoot as well as a cleanly cut crown no matter what ammo it is fed. Making perfectly concentric ammunition with cheap FMJ's with inconsistent jacket thicknesses won't pay off either. This is why you often hear guys say neck turning in a factory chamber won't usually make a noticeable difference - because often, you're correcting a thou or two on the ammo, but might be 5 off center in the rifle. Loading powder charges down to the single kernel will not improve precision for a barrel with too slow of twist for the bullet. Very precise ammo can be made on Lee presses and Dies, so don't misconstrue what I'm saying, but be sure you aren't making perfect ammunition and feeding it into a "less than perfect" chamber and bore.

• more.....

If this site would let us vote, I'd put this on the ballot to be made into a "Sticky"....Thanks Varminterror

I especially liked your point number two. As a shooting forum reader/follower (if you're reading this, you probably are too) I come across numerous accuracy questions & numerous accuracy claims. Usually the exact rifle & load is stated. But off the bench accuracy is much more than the rifle/ammo. To detect the effect of small variables in reloading, you must be sure all of the external effects are under control first.

 

[murf]

How do you correct a cartridge after you find it's out by .004 or .005 ?
Do I pull bullet and start all over and re seat ?

no. it may be just as accurate as your .001" runout rounds. shoot it and find out. if it is out of the group you can use it for fouling shots, or practice.

you really don't have to get ocd about this unless you need to shoot half moa (my standard) or better. and this does no good unless everything else in the handloading process is this consistent and precise. it takes a good gun, a good shooter and good ammo to get to half moa on a consistent basis.

luck,

murf

 

[RussellC]

I basically agree, I want use the device to sort of check my work.

If I measure the case (concentricity wise) to a cleaned as is case, then neck size, remeasure, full length resize via body die, adjusting shoulder bump with Redding competition shell holders, remeasure, charge and seat bullet, then remeasure final time.

I think this will show where my work needs improvement. Once that is accomplished and accuracy is following, I can use it as you state, for that final tune for as good as I am going to get with the gun at hand.

Thanks again all,

Russellc

 

[HJ857]

Since this thread looks to be pretty much done, I'd like to ask and somewhat related question to folks that already have a concentricity gauge and know how to use it.

Can anyone test the runout of a round that you assemble "normally" and then measure a round that has gone through a Lee FCD?

I've often wondered if the real value of the FCD is that it makes the bullet seating more consistent. So, I don't mean mashing the collet into the bullet, I use the FCD so lightly that it doesn't feel like it's doing anything at all, but if I disassemble a round, I can see that there is a very slight ring on the bullet where the crimp is.

If this isn't possible, then thanks anyway. I've long considered buying a gauge for this very purpose, but it's never gotten off the back burner...

 

[Varminterror]

I can probably accomplish that test, but I would challenge back - why are you crimping bottleneck rifle cartridges?