Concentricity Musings

[ggibson511960]

Like many reloaders I have a concentricity gauging rig complete with runout dial indicator. I must confess that I have used it little after coming to the conclusion that loaded ammunition found to have "excessive" concentricity went bang just like its more concentric stuff. You can surmise that I don't load for gilt edged accuracy. I have begun to wonder if it is possible to straighten cartridges found to be crooked. Brass is one of the more malleable metals and it would seem feasible to find the maximum axis of runout, slip the round into any old round hole and bend straight. Even a partial push into a resizing die would seem to improve neck to side wall concentricity and alignment. Has anyone tried something like this?

 

[Krogen]

I haven't tried to correct rounds with excessive runout. Instead, I found that good dies can help avoid the problem to begin with. Not all of my dies qualify as "good" though. With those I found significant improvement by seating a bullet part way, rotating the case 1/4 turn and seating the bullet a bit more and repeating until I've turned the case a full turn.

The greatest improvement I've observed using this method was with a 300 Blackout. I didn't think too much about runout when I set out to develop loads. It was frustrating to say the least. I figured I had bought a .30 caliber single-pellet shot gun. One day a round rolled across my bench. The tip of the bullet clearly showed extreme runout. On the runout gage, I got something like +/- 30 thou runout. When I fixed that problem, I got much better results. I think the .300 Blackout is particularly prone to runout troubles. At least with my setup, it seems to be. I think the long bullet, short neck for caliber and short case conspire to create runout.

Just my 20 m$. YMMV.

 

[scooter123]

It's pretty pointless to attempt to "straighten" an assembled cartridge. Because as soon as you set off the primer that case is going to conform to the Chamber. If you have cases that are a bit wonky the problem for that lies with the Chamber it was fired in.

BTW, I have a Ruger Scout Rifle in 308 and have tried all the tricks to try and improve it's accuracy. I've used fire formed cases that chambered tight enough that there was about 5 lbs of drag on the bolt handle. Didn't do diddly for improving the accuracy. It's your basic battle rifle with 2 MOA accuracy and the only way to effectively change that accuracy would be with a new custom barrel.

On the other hand I have an AR-15 with a Gibbz Arms Side Charging upper with a precision Shilen barrel that will shoot under 0.3 MOA. Yeah, cloverleafs at 100 yards. The only thing I do to build the ammo for this rifle is trickle every charge to weight, use Lake City cases. Varget powder, and use a 68 grain Hornady BTHP. I don't check for concentricity, I don't sort the cases by volume, I don't weigh the bullets and I don't use a 300 dollar super precision die set. Actually I use plain old Lee Rifle Dies.

 

[Ivan the Butcher]

To answer the OP's question, Yes, Hornady made/makes a tool that you can make ammo more concentric.

Will that make a difference? I don't know!

I use a press that it parallel and perpendicular, on most target rifle I use dies that center the bullets in the cartridge's mouth. I get sub .10 MOA groups on several test groups.

I own the RCBS tool for concentricity, but don't use it for that.

What I try to achieve, is ammo fit to the chambers neck! (I full length size even target and varmint ammo.)

At my club, there was a man with lots of money. He bought very good rifles and shotguns. He had some of the best loading equipment money could buy! He checked his concentricity and it was some very low number! Yet, his Dakota rifle in some wiz bang cartridge seemed to group 2 " at 100yards from a rest! At one point we decided to shoot each others rifle. He shot my Ruger No 1 in 218 Bee (with an inexpensive 4-12 scope) off my rest and got a 5 shot group in the 1's (between .100 and .200" centers), and all he could do was complain about how terrible the trigger was. (It was the same factory setting it came with) I shot his Dakota Wiz Bang (with a Zisse scope) and had 5 shots at 100yards in the 2's. It wasn't the ammo, the gun, the angle of the sun or any other correctable cause. It was an unrepairable attitude between his ears! He was convinced his ammo and gun were no good!

When I lose confidence in my equipment, I never shoot well! All the loading tools and gimmicks, make me shoot better, because I have made the perfect ammo. (and I never set out to disprove that!)

Ivan

 

[rockquarry]

I'm not generally gadget-oriented, but bought a Sinclair concentricity gauge more than ten years ago. It's the least used tool on my bench. If I have an accuracy problem with a rifle, cartridge concentricity is the last thing I'll check. So far, I haven't been able to blame any accuracy deficiency on a lack of concentricity. That's certainly not to say it can't happen, because it does.

Like many others, I suppose I've been fortunate in having good dies, good presses, and a basic yet adequate knowledge of sound handloading practices.

 

[M29since14]

Good ammunition should unquestionably shoot better than not-so-good. That seems obvious. I was curious about the runout thing, so I bought a Hornady gage and did a series of experiments with it. With my rifles and marksmanship, I came to two conclusions.
1. Just buy the best brass you can, and take care of it.
2. If you find a piece of brass that consistently has objectionable runout after loading a couple times, set it aside.

One of the problems with “trueing” loaded ammunition was that if it sits for a while, it may return to close to its original condition. I set aside a series of .300 Winchester target loads with excessive runout and corrected them to less than 0.002”. (Considerably less. ) Then I set them aside for a week and rechecked them. Most had returned to close to their initial condition - a few as much as 0.007” TIR. Another problem is that in “bending” the rounds to achieve the desired TIR, one may be screwing up neck tension.

I like nicely made dies. Yeah, it hurts a bit to buy them, but I like working with them, and I do believe I can load better cartridges easier with them.

The bottom line for me, I do not often sort my ammo with the runout gage - but I do it once in a while. I’m still a little on the fence. Sorting to identify bad rounds is one thing. “Correcting” them is another. I just save the bad ones for foulers.

 

[Mike0251]

I have extensive use of the Hornady concentricity tool and use it for 6.5cm and .308. What I have learned is that using my Forster FL dies on the Forster Coax press is that almost all rounds come out within .005 or less to start with and occasionally a very few at .010. Some come out at .001 and I do not try to tweak those. All the others do and brought back to .001. It takes very little time to make these changes as I know how much to turn the adjusting knob based on the amount it is out and usually get it on the first tweak.

Now does it add value? Well my 6.5cm reloads are at .25" MOA with one hole out of a Ruger Precision Rifle and eggs or golf balls at 300y are not a challenge lol. If nothing else it provides me with knowing I have uniformity across all cartridges and I've done my best to ensure that. This also includes a very accurate OAL with a .015" jump to bullet ogive for the CM and a .002" press fit of the bullet (no crimp). As for .308 out of the same type of gun model I'm at less than .44" MOA but I'm still working on powder charge/FPS/accuracy. Fast is not always your friend as I have learned.

I do not use this tool for any other rounds such as .223 etc. Just the two mentioned above. I love long range shooting including 8" steel at 1000y with CM and enjoying the new .308 development. Retired, have plenty of time to devote lol.

 

[Ruger 13]

I think it’s a gimmick!

 

[STORMINORMAN]

I genuflect to those who can tell (appreciate and need to) when their reloads are that perfect...

When mine go bang with regularity, hit near where I'm aiming (well, close enough!) without any drama... I'm a happy camper!

If I had gotten into this 30 years ago, if my eyes were still good enough to be competitive, or if we had varmints (or critters?) aplenty maybe I'd be more concerned...?

Right now I am still attempting to determine what "works" with safe regularity for the multiple calibers I try to get out and shoot as much as I possibly can. When my latest attempt to reload 300 Blackout for a pistol I built wouldn't go through the LEE Ammo Checker I found it wasn't my faulty OCD reloading technique: it was the bullets themselves that were out of spec!

And, after almost a year, Midway graciously agreed to take them back for a refund!

A lesson learned the hard way: check the bullets for size before you start.

Cheers!

P.S. When I say multiple I really mean many! I can only say it is a lot of fun, I wish I had started earlier and had more time ahead to be able to concentrate my efforts on the degrees of accuracy some of you can achieve.

 

[Cdog]

On many rifles I’ve been very detailed with my loading.

Uniforming every aspect of each round I could. I have one of the Hornady concentricity tools. I’ve used it, but I don’t even have it on my bench now. I can measure and straighten a bit. As for better groups, it’s not something I’ve seen to be worthwhile.

 

[zeke]

Have never tried to straighten loaded rounds. Having read numerous older loading manuals, learned one principle a lot of them had in common. That was assuring the sizing die was squared up (in line) with the shell holder. Most of them emphasized using a washer on top of the shell holder and pressure to square up the die and hold it there while tightening the lock ring. Have taken to using a fired casing from the rifle/pistol instead, as this aligns the dies chamber cut directly with the upward force the press exerts. IT COSTS NOTHING to try, and can be done on any standard single stage press. Every die i use (rifle/pistol) gets "squared up", by some method.

The second most factor was using a quality competition bullet seating die (mostly rifles). Now a days, this does involve some expense. Of the commonly available ones Redding works the best for me, and Bonanzas coming in second. If they are still available without the micro adjust, they are considerably cheaper.

Rarely do i use a full size expanding button on the sizing die. A comp seating die keeps a boat tail bullet aligned without it. This can be affected by how far down your sizing dies takes the neck dia, and for some calibers have the "s" dies with different size bushings. If i do use an expanding button, it is allowed to "float", and self center in the neck. This limits it from pulling the neck out of alignment after it is sized.

I do not own a concentricity "tool", but roll a loaded round across a flat surface. My goal is to see no "wobble"

Everybody's needs are different, and take the above for whatever it is worth to ya.

 

[Ivan the Butcher]

I see to points I would like to endorse.

1) Quality and type of bullet and amount of lead (Bullet Jump). Different bullet nose designs behave differently! Of my 5 favorite long range rifles, most shoot best with Zero jump. That means every different shaped bullet of the same weight has a different COAL! Cheap bullets have inconsistent lengths. A friend loads 6.5x284 and uses Sierra 140 MK. The company has 3 die sets that form the bullets. He buys bullets by the 500 & 1000. Before he loads any of them he separates them using a Comparator. he sets up 4 bowls and gets roughly 1/3 of the bullets in each bowl, oddballs are used for fireforming or other cartridges.

I have seen this gun shoot 5 shot groups of 3/8" at 800 yards! (I was shooting this gun once and got 3/8" at 300 yards, My friend was mad that I was teaching his gun bad habits!)

2) Quality seating dies. I like the self centering die that Redding uses best. It was invented (I think) by Bonanza. I was buying Bonanza's in the early 80's without the micrometer in 264 Win Mag and with them got 1/2" groups at 400 on dad's farm. I use them for bolt actions only in 223, 22 BR, 22-250, 6 PPC, 6x284, 264 Win Mag, 308 Win, 300 Win Mag & 338 Lapua. I would never have spent all that money if I couldn't get them to work. I believe the Co-AX Press is the best! (Bonanza's or Forrester's, defiantly not Caldwell's!) But I use a very old Rock Chucker Supreme and a 2007 Redding T-7 and get ammo that shoot's well. The operator is always my group's problem!

Not a main point, Accuracy is elusive! The standard of accuracy is variable, You only "Need" enough to kill that varmint or outshoot the next guy! But we constantly attempt for perfection! Industry standards are huge! Personal standards are expensive!

Your second worst enemy is the wind! Your worst enemy is between your ears!

Ivan

 

[Racer X]

I am a complete novice at reloading, but I took a reloading class from a master. We used a single stage press, range pick-up brass and I don't recall the bullet manufacturer. But used RCBS dies. 223/5.56 brass. When we were done, we tested our loads on a runout set-up, and we were less than half the runout than Hornady Match 223 69 grain loads out of a sealed Hornady Match box.

Unless you are a high powered long range competition shooter with a bolt gun, probably won't matter.