hornady concentricity tool

308Loader · May 13, 2020, 05:32 PM

Any one useing this tool? Thoughts or conserns? pro-con V/S others?

My OCD said I should have this tool. Both my 308's shoot clover leafs at 100yrds and sometimes at 200M when I do my part. Many of the other caibers I load for will do similar. Chaseing the one hole group I thought I might try this tool and see if their is any improvement. Have been tweaking some previously loaded rounds to cut bullet runout.

worth the time? havent shot any yet.

Bart B. · May 14, 2020, 07:48 AM

Bullet runout gauges are useful. If runout is less than 1% of bullet diameter, that's good enough for 98% of all rifles. They don't position cartridge's bullets to the dial indicator like cartridges align in the chamber to center bullets in the bore but such is life. A given cartridge will have different runout values across all of them.

What's the size of your biggest groups? Those are the ones that best define shooting system accuracy (SSA). SSA = ammo + rifle + human.

I ask because one-hole groups (less than .010 MOA extreme spread) are more luck than perfection.

The most accurate centerfire ammo shoots 5-shot cloverleafs at 100 yards up to 3/10ths inch extreme spread in accurate rifles shot free recoil untouched by humans except for a finger on a 2 ounce trigger. The smallest 100 yard benchrest group on record is .0077 inch but the lucky shooter holds no other records and isn't a top ranked one.

Group shooting is much like shooting craps. You'll average 7's but seldom, but equally as often, get boxcars or snake eyes.

In closing, remember we always do our part for every round fired because we are aiming the rifle and firing the ammo we acquired and chose to shoot.

BJung · May 14, 2020, 08:21 AM

Those are good groups.

I own a Sinclair Concentricity Tool and like it. I use it for sorting my brass and reloaded cartridges.

I think the tools are all about the same. Just make sure your case spins flat on the V-block.

hounddawg · May 14, 2020, 10:25 AM

Since I removed the expanders on my full length sizing dies 90% of the time mine sits on the shelf. I check all my match loads just for the OCD factor

Bart B. · May 14, 2020, 10:45 AM

Quote:

Originally Posted by hounddawg

Since I removed the expanders on my full length sizing dies 90% of the time mine sits on the shelf. I check all my match loads just for the OCD factor

A good thing to do. But the die neck needs to be honed out to a couple thousandths less than loaded round neck diameter. This gives about .001" interference fit of bullet to case neck which about perfect.

Otherwise, bullet jackets get scraped peeling off copper unbalancing bullets. Bullet extraction/pull force is also higher and has a greater spread.

Metal god · May 14, 2020, 11:12 AM

Do you turn your necks ? I don’t and I can’t load a concentric round if my life depended on it . I’ve done minimal testing with standard dies , bushing dies , with or with out expanders , standard seater and competition seater and nothing gets my concentricity at or below .002 consistently and I still get the .005 or .006 in there . My concentricity gauge is my most disappointing tool to date . It shows I’m doing something wrong I’m just not sure what that is . I’m afraid to buy a neck turner because if that doesn’t fix it I’d Likely curl up in a fetal position and cry myself to sleep .

That all said means I should have bought the Hornady rather then the Sinclair because the Hornady allows you to fix your concentricity issues .

Bart B. · May 14, 2020, 11:34 AM

For most 30 caliber cartridges, you can gently grip the case neck in a 33 caliber bullet puller collet then push the case head such to straighten the case neck. A little practice and you'll get excellent results.

I've done that with great results; Lake City arsenal match ammo, especially. It has runout to .007" or more

Dave P · May 14, 2020, 11:49 AM

While we are talking OCD: I use a 12" square floor tile (ceramic) to roll eacch fully prepped case accross the surface.

It is pretty easy to see and hear a lopsided case. If your case is thicker on one side vs the other, this could make you believe that it wont release the bullet evenly.

My approach to making perfect ammo, was to do every thing possible to the case and bullet, and powder. Trim necks, ream flash hole (inside and outside) weigh each case,etcc, etc.

Then I would back off on some of those steps, and see if accuracy was reduced. I found that a lot of that work did not show up on my targets. Oh well.

hounddawg · May 14, 2020, 12:45 PM

Quote:

Bart B.

A good thing to do. But the die neck needs to be honed out to a couple thousandths less than loaded round neck diameter. This gives about .001" interference fit of bullet to case neck which about perfect.

Otherwise, bullet jackets get scraped peeling off copper unbalancing bullets. bullet extraction/pull force is also higher and has a greater spread.
Bart B. is online now

easier just to use bushing dies and a chamfer tool, plus I have found .003 interference fit gives me the best performance on every cartridge I load for. But that is for a different thread, no need to derail this one

Bart B. · May 14, 2020, 01:04 PM

At Sierra's California plant match grade rifle bullets were tested at 100 yards shooting 10 shot groups with bullets right out of the final die forming the ogive. They were seated ih unprepped commercial cases full length resized in gelded dies with necks a couple thousandths under loaded round's neck diameter. Primed cases had thrown charges with up to 3 tenths grain spread.

Best quality 30 caliber match bullets tested sub 2 tenths inch after another. Bullet runout under .003 inch on those measured.

Very straight bullets and case necks is about 10th on the list of requirements for consistently tiny cloverleafs. One holers are 99% luck.

Bart B. · May 14, 2020, 01:11 PM

Quote:

Originally Posted by hounddawg

easier just to use bushing dies and a chamfer tool, plus I have found .003 interference fit gives me the best performance on every cartridge I load for.

Then the resized case mouth diameter is 003" smaller than bullet diameter.

That's okay if bullet jackets aren't scraped.

Metal god · May 14, 2020, 01:17 PM

What happens if the bullet is scraped ? Does that cause it to yaw as it’s released or something ? I’d think swaging down to bore diameter then screaming down the barrel would scrape the bullet up pretty good and likely make those Surface scrapes from seating disappear ??

I ask because I’ve pulled some bullets I’ve loaded and they were scraped up pretty good but was never sure if it was from seating or pulling , maybe both .

hounddawg · May 14, 2020, 01:55 PM

excellent point MG, when that bullet exits it ain't near as perfect as when it went in. But a bench rest type will argue neck tension and pull tension factor and all that. Anyway what Bryan Litz found was no scraping until about .005 compression in his experiments.

Back to topic I do think concentricity is important but figure once you have your case prep right the necks will be coming out of the die with the necks straight. It takes a lot to bend that neck, the Hornady lets you tweak the bullet into alignment for the ones that are not. The Sinclair does not. I have used both, and own a Hornady. I think I prefer the Sinclair although I do not own one, I borrowed a friends for a week to see if it was worth buying in addition to my Hornady. I decided that the Hornady works well enough for my needs. Sinclair is the best made piece of gear though.

Bart B. · May 14, 2020, 02:13 PM

Quote:

Originally Posted by Metal god

What happens if the bullet is scraped ? Does that cause it you yaw as it’s released or something ? I’d think swaging down to bore diameter then screaming down the barrel would scrape the bullet up pretty good and likely make those Surface scrapes from seating disappear??

I ask because I’ve pulled some bullets I’ve loaded and they were scraped up pretty good but was never sure if it was from seating or pulling , maybe both .

If jackets have copper peeled off, that'll unbalanced them. It happens regardless which way bullets move in case necks. It also lets gas escape unevenly around their heel where the peeling starts upon exit from the muzzle. With bullets spinning 150,000 to 250,000 rpm, that matters and the bullet jumps off the bore axis from centrifugal forces. There's a couple thousand or so psi behind the bullet as it exits. If the bullet path is 1 inch out the muzzle puts it .00015 inch off the bore axis, it's already going about 1/2 MOA away from where the direction a well balanced bullet will go.

Good quality barrels with 10 to 15 microinch finish and less than .0001" spread in bore and groove diameters ss well as very uniform rifling twist rates scrape the least copper off bullet jackets. And shoot bullets most accurate.

Where does the copper wash in bores come from?

Why do some barrels need several fouling shots embedding copper in them to the point where no more scrapes off and better accuracy prevails?

Standard deburring tools leave a sharp edge inside case mouths that'll scrape copper off bullets. Remove its sharp edge and round it off with a bronze bore brush spinning in an electric drill going into then back out of case necks.

Metal god · May 14, 2020, 05:06 PM

Bart , Thanks I'm following you now . Peeling or removing of materials having an effect on flight makes perfect sense . What about scratches where if any material was removed it would be microscopic amounts ?

How do you think these bullets would fly ?

I was worried this may be getting off topic but I think I can dovetail it right back to concentricity . If surface scratches cause out of balance bullets . I'd think your bullet being perfectly concentric to the bore as it enters would be absolutely paramount . My thinking is if the bullet starts to swage down even the slightest bit off center . That would squeeze material from one side of a perfectly balanced bullet to the other side or move it at least somewhere other then where it started . Making that once perfectly balanced bullet unbalanced once it left the bore ??

308Loader · May 14, 2020, 05:28 PM

wow, thanks for all the replys.

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. I dont shoot competiveally, I just enjoy the quiet time in my head before the shot breaks, the focus or slight meditation.

The reward is shooting better than the guy with a $2000 rig on the next bench, not that he knows i am watching his groups also.

I must be doing something right in my process, most of the rounds i have passed through the new gauge are about 3-4 maby5 thou out. A few are more few are less. I do like the fact that I can push them in to the 1.5-2 range with this tool. The polimer tip on the push screw is suspect, only 50 rounds in and it looks squished.

Plan to shoot some this weekend. Some "fixed" with the tool, some not but not too far out of alignment, and some of the ones the tool says are 5+ out of whack to see for my self what improvements I may have gained. The hard varieable to guage in this will be the shooter.

So far im only looking at bullet alignment base to tip. Measureing about a tenth infront of the mouth. I havent looked at the mid case or web or neck of a new sized case. I havent neck turned any cases, supose that will be the next set of tools in the jurny down the rabbit hole.

Bart B. · May 14, 2020, 05:43 PM

Metal god, where did you get those scratched bullets with black sealant on them?

308Loader · May 14, 2020, 05:50 PM

MG, what is all the goo at the back of that bullet?

Metal god · May 14, 2020, 05:56 PM

Those are 77gr smk pulled from 223 Rem Federal gold medal match factory ammo . Yep I was surprised they had sealant on them as well .

old roper · May 14, 2020, 06:24 PM

Easy shoot small groups.

http://bulletin.accurateshooter.com/...-nbrsa-record/

Bart B. · May 14, 2020, 07:49 PM

I'm convinced the most common cause of crooked rifle bullets in reloaded cases is the sizing die's expander ball bending case necks as it's pulled out.

Resize 10 fired cases with an expander ball and 10 more without. Measure case neck run out at the mouth on them.

BJung · May 14, 2020, 11:48 PM

I have a few comments.

I use an RCBS hand operated neck turning tool and it's fine with me.

If my loads are not concentric, I make sure that wherever it's highest, I mark the casing and face all of the same cartridges in the same direction. Before turning the neck, I also mark which side of the neck was thickest

I once read that to reduce bullet runout that I would partially seat my bullet, then rotate the cartridge 60 degrees, seat the bullet further, turn the case another 60 degrees, and continue doing so until the bullet is completely seated. I took this as gospel but have never tested it to a bullet that was seated without rotating the brass. I just haven't tested it yet. Comments here?

Last, I haven't thought much about the scratches but if that's a problem, why not just use some Imperial Wax?

Bart B. · May 15, 2020, 08:24 AM

I doubt those scratched bullets pictured will cause accuracy problems. They're probably uniform all the way around. That ammo has to pass Federal accuracy tests.

Lubrication inside case necks won't stop the scratching. It's softer than brass therefore easily pushed aside.

Meanwhile, the details involved that give erroneous readings. Any runout in case body diameters where it rests on the gauge will be transferred to the dial indicator. Consider what happens to a cartridge whose bullet is perfectly aligned with the case axis.......

If the case body rear touch point (pressure ring?) is 2 inches back from the front point (next to the case shoulder?) and the indicator touch point on the bullet is 1 inch forward from the body touch point near the shoulder that has 0 runout, for every .002" runout on the rear touch point there's .001" runout on the bullet.

If the rear case touch point has 0 runout but there's .002" runout on the front case touch point, there's .003" runout on the bullet.

When the round is fired, the case shoulder is well centered in the chamber shoulder and the front touch point on the case body touches nothing. Only part of the case body that might be touching the chamber is the pressure ring.

Read post #15 in

https://thefiringline.com/forums/sho...dicator+runout

Bart B. · May 15, 2020, 02:27 PM

Quote:

Originally Posted by 308Loader

MG, what is all the goo at the back of that bullet?

That's a sealant used to water proof the case to keep powder dry. Typically used on military ammo, never seen it on commercial ammo.

Nathan · May 16, 2020, 07:46 AM

A run out tool is valuable in my experience. Sometimes a die can jam up weird in the threads and create excessive runout, IME. This can usually be fixed quite quickly.

The Hornady tool is no good, IMO. Let me explain. When looking at an object and taking data on it, the most important thing is that the part be held by the datum structure. Then the critical points are measured.

The Hornady holds the bullet tip. Not only is the tip not a datum point, but looking at bullet manufacturing, you will see it is where manufacturers put their variation. That will always create bad data.

May 14, 2020, 07:48 AM	#2
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Bullet runout gauges are useful. If runout is less than 1% of bullet diameter, that's good enough for 98% of all rifles. They don't position cartridge's bullets to the dial indicator like cartridges align in the chamber to center bullets in the bore but such is life. A given cartridge will have different runout values across all of them. What's the size of your biggest groups? Those are the ones that best define shooting system accuracy (SSA). SSA = ammo + rifle + human. I ask because one-hole groups (less than .010 MOA extreme spread) are more luck than perfection. The most accurate centerfire ammo shoots 5-shot cloverleafs at 100 yards up to 3/10ths inch extreme spread in accurate rifles shot free recoil untouched by humans except for a finger on a 2 ounce trigger. The smallest 100 yard benchrest group on record is .0077 inch but the lucky shooter holds no other records and isn't a top ranked one. Group shooting is much like shooting craps. You'll average 7's but seldom, but equally as often, get boxcars or snake eyes. In closing, remember we always do our part for every round fired because we are aiming the rifle and firing the ammo we acquired and chose to shoot. Last edited by Bart B.; May 14, 2020 at 08:24 AM.

May 14, 2020, 08:21 AM	#3
BJung Senior Member Join Date: December 5, 2019 Posts: 773	Good Groups Those are good groups. I own a Sinclair Concentricity Tool and like it. I use it for sorting my brass and reloaded cartridges. I think the tools are all about the same. Just make sure your case spins flat on the V-block.

May 14, 2020, 10:25 AM	#4
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	Since I removed the expanders on my full length sizing dies 90% of the time mine sits on the shelf. I check all my match loads just for the OCD factor __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek

May 14, 2020, 11:12 AM	#6
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	Do you turn your necks ? I don’t and I can’t load a concentric round if my life depended on it . I’ve done minimal testing with standard dies , bushing dies , with or with out expanders , standard seater and competition seater and nothing gets my concentricity at or below .002 consistently and I still get the .005 or .006 in there . My concentricity gauge is my most disappointing tool to date . It shows I’m doing something wrong I’m just not sure what that is . I’m afraid to buy a neck turner because if that doesn’t fix it I’d Likely curl up in a fetal position and cry myself to sleep . That all said means I should have bought the Hornady rather then the Sinclair because the Hornady allows you to fix your concentricity issues . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again . Last edited by Metal god; May 14, 2020 at 05:13 PM.

May 14, 2020, 11:34 AM	#7
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	For most 30 caliber cartridges, you can gently grip the case neck in a 33 caliber bullet puller collet then push the case head such to straighten the case neck. A little practice and you'll get excellent results. I've done that with great results; Lake City arsenal match ammo, especially. It has runout to .007" or more Last edited by Bart B.; May 14, 2020 at 12:38 PM.

May 13, 2020, 05:32 PM	#1
308Loader Senior Member Join Date: August 24, 2014 Location: Minnesota Posts: 639	hornady concentricity tool Any one useing this tool? Thoughts or conserns? pro-con V/S others? My OCD said I should have this tool. Both my 308's shoot clover leafs at 100yrds and sometimes at 200M when I do my part. Many of the other caibers I load for will do similar. Chaseing the one hole group I thought I might try this tool and see if their is any improvement. Have been tweaking some previously loaded rounds to cut bullet runout. worth the time? havent shot any yet. __________________ Just a dude with stuff.

May 14, 2020, 11:49 AM	#8
Dave P Senior Member Join Date: August 16, 1999 Location: North Florida Posts: 1,346	While we are talking OCD: I use a 12" square floor tile (ceramic) to roll eacch fully prepped case accross the surface. It is pretty easy to see and hear a lopsided case. If your case is thicker on one side vs the other, this could make you believe that it wont release the bullet evenly. My approach to making perfect ammo, was to do every thing possible to the case and bullet, and powder. Trim necks, ream flash hole (inside and outside) weigh each case,etcc, etc. Then I would back off on some of those steps, and see if accuracy was reduced. I found that a lot of that work did not show up on my targets. Oh well. __________________ I think this country is screwed.

May 14, 2020, 01:04 PM	#10
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	At Sierra's California plant match grade rifle bullets were tested at 100 yards shooting 10 shot groups with bullets right out of the final die forming the ogive. They were seated ih unprepped commercial cases full length resized in gelded dies with necks a couple thousandths under loaded round's neck diameter. Primed cases had thrown charges with up to 3 tenths grain spread. Best quality 30 caliber match bullets tested sub 2 tenths inch after another. Bullet runout under .003 inch on those measured. Very straight bullets and case necks is about 10th on the list of requirements for consistently tiny cloverleafs. One holers are 99% luck.

May 14, 2020, 01:17 PM	#12
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	What happens if the bullet is scraped ? Does that cause it to yaw as it’s released or something ? I’d think swaging down to bore diameter then screaming down the barrel would scrape the bullet up pretty good and likely make those Surface scrapes from seating disappear ?? I ask because I’ve pulled some bullets I’ve loaded and they were scraped up pretty good but was never sure if it was from seating or pulling , maybe both . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again . Last edited by Metal god; May 14, 2020 at 05:09 PM.

May 14, 2020, 01:55 PM	#13
hounddawg Senior Member Join Date: March 1, 2009 Posts: 4,232	excellent point MG, when that bullet exits it ain't near as perfect as when it went in. But a bench rest type will argue neck tension and pull tension factor and all that. Anyway what Bryan Litz found was no scraping until about .005 compression in his experiments. Back to topic I do think concentricity is important but figure once you have your case prep right the necks will be coming out of the die with the necks straight. It takes a lot to bend that neck, the Hornady lets you tweak the bullet into alignment for the ones that are not. The Sinclair does not. I have used both, and own a Hornady. I think I prefer the Sinclair although I do not own one, I borrowed a friends for a week to see if it was worth buying in addition to my Hornady. I decided that the Hornady works well enough for my needs. Sinclair is the best made piece of gear though. __________________ “How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek Last edited by hounddawg; May 14, 2020 at 02:12 PM.

May 14, 2020, 05:06 PM	#15
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	Bart , Thanks I'm following you now . Peeling or removing of materials having an effect on flight makes perfect sense . What about scratches where if any material was removed it would be microscopic amounts ? How do you think these bullets would fly ? I was worried this may be getting off topic but I think I can dovetail it right back to concentricity . If surface scratches cause out of balance bullets . I'd think your bullet being perfectly concentric to the bore as it enters would be absolutely paramount . My thinking is if the bullet starts to swage down even the slightest bit off center . That would squeeze material from one side of a perfectly balanced bullet to the other side or move it at least somewhere other then where it started . Making that once perfectly balanced bullet unbalanced once it left the bore ?? __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

May 14, 2020, 05:28 PM	#16
308Loader Senior Member Join Date: August 24, 2014 Location: Minnesota Posts: 639	wow, thanks for all the replys. 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. I dont shoot competiveally, I just enjoy the quiet time in my head before the shot breaks, the focus or slight meditation. The reward is shooting better than the guy with a $2000 rig on the next bench, not that he knows i am watching his groups also. I must be doing something right in my process, most of the rounds i have passed through the new gauge are about 3-4 maby5 thou out. A few are more few are less. I do like the fact that I can push them in to the 1.5-2 range with this tool. The polimer tip on the push screw is suspect, only 50 rounds in and it looks squished. Plan to shoot some this weekend. Some "fixed" with the tool, some not but not too far out of alignment, and some of the ones the tool says are 5+ out of whack to see for my self what improvements I may have gained. The hard varieable to guage in this will be the shooter. So far im only looking at bullet alignment base to tip. Measureing about a tenth infront of the mouth. I havent looked at the mid case or web or neck of a new sized case. I havent neck turned any cases, supose that will be the next set of tools in the jurny down the rabbit hole. __________________ Just a dude with stuff.

May 14, 2020, 05:43 PM	#17
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Metal god, where did you get those scratched bullets with black sealant on them?

May 14, 2020, 05:50 PM	#18
308Loader Senior Member Join Date: August 24, 2014 Location: Minnesota Posts: 639	MG, what is all the goo at the back of that bullet? __________________ Just a dude with stuff.

May 14, 2020, 05:56 PM	#19
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	Those are 77gr smk pulled from 223 Rem Federal gold medal match factory ammo . Yep I was surprised they had sealant on them as well . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

May 14, 2020, 06:24 PM	#20
old roper Senior Member Join Date: June 11, 2007 Posts: 2,155	Easy shoot small groups. http://bulletin.accurateshooter.com/...-nbrsa-record/ __________________ Semper Fi Vietnam 1965 VFW Life member NRA Life Member

May 14, 2020, 07:49 PM	#21
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	I'm convinced the most common cause of crooked rifle bullets in reloaded cases is the sizing die's expander ball bending case necks as it's pulled out. Resize 10 fired cases with an expander ball and 10 more without. Measure case neck run out at the mouth on them. Last edited by Bart B.; May 14, 2020 at 07:56 PM.

May 14, 2020, 11:48 PM	#22
BJung Senior Member Join Date: December 5, 2019 Posts: 773	A few comments I have a few comments. I use an RCBS hand operated neck turning tool and it's fine with me. If my loads are not concentric, I make sure that wherever it's highest, I mark the casing and face all of the same cartridges in the same direction. Before turning the neck, I also mark which side of the neck was thickest I once read that to reduce bullet runout that I would partially seat my bullet, then rotate the cartridge 60 degrees, seat the bullet further, turn the case another 60 degrees, and continue doing so until the bullet is completely seated. I took this as gospel but have never tested it to a bullet that was seated without rotating the brass. I just haven't tested it yet. Comments here? Last, I haven't thought much about the scratches but if that's a problem, why not just use some Imperial Wax?

May 15, 2020, 08:24 AM	#23
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	I doubt those scratched bullets pictured will cause accuracy problems. They're probably uniform all the way around. That ammo has to pass Federal accuracy tests. Lubrication inside case necks won't stop the scratching. It's softer than brass therefore easily pushed aside. Meanwhile, the details involved that give erroneous readings. Any runout in case body diameters where it rests on the gauge will be transferred to the dial indicator. Consider what happens to a cartridge whose bullet is perfectly aligned with the case axis....... If the case body rear touch point (pressure ring?) is 2 inches back from the front point (next to the case shoulder?) and the indicator touch point on the bullet is 1 inch forward from the body touch point near the shoulder that has 0 runout, for every .002" runout on the rear touch point there's .001" runout on the bullet. If the rear case touch point has 0 runout but there's .002" runout on the front case touch point, there's .003" runout on the bullet. When the round is fired, the case shoulder is well centered in the chamber shoulder and the front touch point on the case body touches nothing. Only part of the case body that might be touching the chamber is the pressure ring. Read post #15 in https://thefiringline.com/forums/sho...dicator+runout Last edited by Bart B.; May 15, 2020 at 10:08 AM.

May 16, 2020, 07:46 AM	#25
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,333	A run out tool is valuable in my experience. Sometimes a die can jam up weird in the threads and create excessive runout, IME. This can usually be fixed quite quickly. The Hornady tool is no good, IMO. Let me explain. When looking at an object and taking data on it, the most important thing is that the part be held by the datum structure. Then the critical points are measured. The Hornady holds the bullet tip. Not only is the tip not a datum point, but looking at bullet manufacturing, you will see it is where manufacturers put their variation. That will always create bad data.