Ammunition Concentricity Tool...worth the trouble?

[the count]

I am not a competitive shooter, but I like to go for high accuracy. For example, with my Remington 700 in 308, with my best hand loads shooting off the lands I am now at just over 1/2 MOA (~.510" 4 shot groups @ 100 yards). Will this tool get me to 1/4" or so groups?

 

[Art Eatman]

A definite "maybe".

To reliably get on down below 1/2 MOA for five shots takes "a little of this, a little of that". Concentricity is good. Segregating bullets by weight can help. Weighing the brass as an indicator of uniform volume can help. Case trimming. Checking flash holes. I have used stick powders since way back, weighing the charges to right at the nearest granule.

Somewhere in all this happiness you need to reconstruct your benchrest methodology to ensure uniformity and consistency in your shooting.

"Aw, shucks, man, ain't nuthin' to it!"

 

[Slamfire]

To get to 1/4 MOA groups, heck you may be at the limit of some match bullets.

If you want benchrest accuracy, try everything.

 

[TonyAngel]

What you're asking for is a 50% improvement in the size of your groups and your question assumes that your shooting skills exceed the capabilities of your rifle/ammo combo.

If your skills are up to that level, then a concentricity tool can be of help, but you have to remember that putting the tool to use and finding that you are getting an unacceptable amount of runout is going to leave you having the fix the problem. The problem could lie with your bullets, brass or reloading setup.

As a practical matter, you can check for runout by rolling your ammunition across a flat surface, like a sheet of glass (I use a piece of granite) and watching for bullet wobble. Although you won't catch minute amounts of runout, you will see more problematic cases.

I don't use a concentricity gauge and regularly shoot into the .2s and .3s at 100 with my .308, when I shoot for groups. The only guys I know that bother with it are the guys that are serious about benchrest where they have to shoot aggregate scores in the mid teens to even have a shot at winning a match.

If I were you and felt that my skills were not the problem, I'd look to my ammunition and do some fine tuning. For example, what bullets are you using? How far are you jamming them? If you're shooting a stock Remington and loading to reach the lands, you're probably sacrificing too much neck tension to get to the lands. If you are shooting SMKs, I've found that in some rifles, they really like to jump. Reducing or increasing your load by a bit may also get you what you want.

Of course, there's also the chance that a custom barrel with a better bore and tighter chamber will get you what you want.

 

[Ramone]

going down to 1/4 MOA from 1/2 MOA is a long way- far longer than 1MOA to 1/2MOA.

as others have noted, there are a lot more factors to consider- which doesn't throw concentricity off the table, but leaves it a minor factor, especially at 100 yards with .308

 

[the count]

going down to 1/4 MOA from 1/2 MOA is a long way- far longer than 1MOA to 1/2MOA.

as others have noted, there are a lot more factors to consider- which doesn't throw concentricity off the table, but leaves it a minor factor, especially at 100 yards with .308

I see how a multitude of factors are in play here. Until now I always did full length resize but just read how a guy did tests resizing the neck vs full length and how that improved his groups (think he also cleaned the flash hole). So I will do that plus get the Hornady concentricity tool. Will be interesting to see what happens...

@tony angel... i accidentally made some ammo with SMK 175 grain bullets that were a 0.02 jump into the lands and was surprised how well they shot. What kind of jump gave you the best performance?

 

[LeonCarr]

Improving your bench shooting techniques can help shrink groups also. Using a quality front shooting rest and rear bags, using baby powder on your bags to make sure the rifle slides consistently when it recoils, keeping the sling swivel studs off of the bags to keep them from interfering with consistent sliding on the bags, consistent shoulderweld and cheekweld on the stock, and consistent strong hand placement and trigger control.

Notice that I mentioned consistency several times. Consistency equals accuracy.

Just my .02,
LeonCarr

 

[Clark]

Here is a pic of me faking together a concentricity gauge with stuff lying around.
It does work, but it is not as nice as my Sinclair concentricity gauge.

The Sinclair came in a box with fortune cookie fortune, "~~You will probably find that the expander ball is the culprit."

Save $100 on a concentricity gauge.

The answer is to stop using the expander ball pulling through the neck of the brass.

 

[the count]

.
The answer is to stop using the expander ball pulling through the neck of the brass.

But how would the neck be resized without the ball......???

 

[cfullgraf]

Use a bushing style sizing die. You select the proper size bushing that reduces the cases's neck only what is necessary. No expander ball needed.

 

[JustSomeGuyinCA]

Or a collet die.

 

[Otto]

Ammunition Concentricity Tool...worth the trouble?

Only if you plan on turning the necks and that requires more tools.
For an off-the-shelf Remy I wouldn't bother.

Lapua brass and Type S Redding dies are hard to beat.

 

[popper]

If you have a $10K rifle. It doesn't FIX anything, just makes measurements.

 

[ranger335v]

"Will this tool get me to 1/4" or so groups? "

You're already doing quite well. Reducing runout helps but it's very unlikely to take you that far.

Reducing a group by half reduces the area to one quarter, meaning it's four times more difficult to do that than it may appear. Not many rifles - or shooters, or bullets or even scopes - are capable of average 1/4 MOA groups no matter the astonishing claims we frequently see on the web. Far more guys shoot that kind of BS from a keyboard than shoot such groups from a rifle.

 

[the count]

Got the Hornady concentricity tool today. This gizmo not only measures, it also lets you adjust run out by use of a screw. So I was able to correct a couple rounds in a first test from 0.003-0.005 to about 0.001. BTW, is that overdoing it? Is anything under 0.002 good enough?

 

[mitchz]

When I change bullets I always prime, powder and set bullet in half way then chamber it in the rifle. Do this 3 to 4 times and measure each. This will give you an exact seating depth for that bullet in that chamber. And yes concenrticity as best you can. This gives me 1/4'' at 300 yards in my savage
.308 FCPS .

 

[NeuseRvrRat]

This gives me 1/4'' at 300 yards in my savage
.308 FCPS .

LOL

 

[Fat_46]

I own the Sinclair gauge and the TruTool TruAngle fixer. I only use them when setting/resetting my seating die on the press to insure I have everything properly aligned, as close to proper as I can get. Does it improve my groups? Maybe. There is too much other data clouding my interpretation.

My advice(worth what you paid for it) is to concentrate on the basics of accurate reloading:
make sure every case is as close as possible to the one before it.

This means primer pocket uniforming, brass separation by weight, bullet separation by weight, measuring every round for seating depth, watching lot numbers for powder, bullets, AND primers.

In other words - being so anal retentive that you can intelligently eliminate the preparation of the round and concentrate on the shooting of the round.

 

[Ky Larry]

mitchz, please read post #14 above.

 

[cacoltguy]

I've been looking at getting a concentricity tool out of curiosity to see how well I'm doing with bullet runout with my reloads. I was attracted to the Hornady tool because it not only measures the runout but also allows you to correct it. One thing that gives me concern however, is that the Hornady tool seems to hold the case by the rim area and measures bullet run out relative to the case head area. This may or may not give accurate run-out readings. Since most rifle chambers contact the case walls or shoulder area, a v-block design like the RCBS or Sinclair concentricity tool may give a more true bullet run-out reading. The Redding seems to hold the round by the bullet and takes readings from the neck area. This would seem to give more reliable measurements as well.

 

[stubbicatt]

hm

There was a guy in the late 80s or early 90s who sold a concentricity tool. I remember reading his writings on the subject. I wish I could remember his name, but he died, and as I recollect his widow continued selling his tool. It was the first in the business as I recollect.

Anyways. He experimented with runout, and found that if he marked the cases with a sharpie and loaded them all with the same orientation his groups became miniscule. From a certain perspective, taking into account precession, this was quite a revelation. The implications were pretty interesting. He found that the cases which were "out" were banana shaped down the entire length of the case, and oddly enough, if the bananas were loaded in the chamber with the bulge in the same direction he got bughole groups.

I experimented around with his tool, and while the data is long ago lost, I remember duplicating his findings in about 1995 or so.

There is something to this. IIRC, at 100 yards with a 22-250 I had difficulty verifying his findings, but at 200 yards it was OBVIOUS that he was on to something.

I wish I remember his name. But his contributions to the sport in this small aspect were pretty stellar.

Same with the guy who developed the little slide rule device for ranging and windage etc.

Memory is the second thing to go with advanced age and I no longer remember the first thing! LOL.

 

[the count]

@Stubbicat

Interesting post. What do you mean with marked the round with a sharpie and put them all in the same orientation? Did you mean somehow mark the round at the low/high point when using the concentricity tool and then chamber them at the same point?

 

[jim243]

There are so many variables in shooting sub-MOA groups that this post could end up as a book, from neck turning to bullet swaging to adjustable triggers to powder measures to bullet placement in the case, etc...... All will have some effect, but the question of are they worth it? That only you can answer.

If you are a National Championship shooter and get sponsorships worth 100 of thousands of dollars the answer would be yes, otherwise a maybe or no would be more approprate.

As a matter of fact there are 100s of books out on accuracy tuning your loads and rifle, it might not hurt to get one or two of them.

What I find in my reloads is this:

1. Make sure each and every charge of powder is EXACTLY the same right down to the 1/10 of a grain. (Trickle charge or use a electronic dispenser/scale combination)

2. Use a L-N-L OAL gauge to find your Max OAL for the rifle bullet combination and then back off that by 0.050 inches.

3. Full length resize all your cases using a case gauge to eleminate any headspace gaps.

4. Get a trigger job for the rifle or use an adjustable trigger with no creep set to the lowest SAFE trigger pull (1lbs or less).

5. Make sure each bullet is set in the case straight and is not canted.

6. Test your loads on your rifle and find the best balance (of power and bullet weight) for your barrels harmonics.

7. Take your time on each shot don't rush them.

8. Shoot on calm days with very little wind.

All the rest of the work is at your discression and may or may not help.

Jim

5 shot group, and yes you will have fliers but that's you not the load or rifle.

 

[the count]

3. Full length resize all your cases using a case gauge to eleminate any headspace gaps.

This is the only point I will disagree on. Tests have shown that only sizing the neck gives one (me) an edge.