concentricity gauges etc

[Swarovski1]

http://www.brownells.co.uk/epages/UK.sf/en_GB/?ObjectID=12314&ViewAction=FacetedSearchProducts&SearchString=Wilson+vld+stem&ICShowAllFacets=1

thanks for the link but the die I use long bullets in is redding.i did have a look for a 6.5 06 forster br seater and it's not listed

[1066]

thanks for the link but the die I use long bullets in is redding.i did have a look for a 6.5 06 forster br seater and it's not listed

 

I think the first thing you should do is see if you actually have a problem with the seater stem you have.

 

Take your seater die apart, push the tip of the bullet you're using into the recess in the stem, if the tip of the bullet makes contact with the stem then you need to change something. If you have the correct stem for the bullet you should see a faint ring round the top where the seating stem contacts the bullet. I think the newer plastic tipped bullets might highlight this problem.

[The Gun Pimp]

I remember Vaughan Cherry turning up at a 100 yard benchrest shoot with his device. He was of course hoping to sell it to us and went round every competitor checking his rounds for run-out - needless to say, he didn't find any!

 

To be honest he was a nice enough guy - but not a shooter. He'd invested in a 'tool that was looking for a job' . I did suggest that he might find a market at Bisley, amongst the Target Rifle shooters who were compelled to use pretty dire military ammo.

[Laurie]

 

I think the first thing you should do is see if you actually have a problem with the seater stem you have.

 

Take your seater die apart, push the tip of the bullet you're using into the recess in the stem, if the tip of the bullet makes contact with the stem then you need to change something. If you have the correct stem for the bullet you should see a faint ring round the top where the seating stem contacts the bullet. I think the newer plastic tipped bullets might highlight this problem.

 

 

Absolutely! It's a particular issue with the heavy (ie long) match bullets in the smaller calibres, but as 1066 says, plastic tips will increase any such tendencies to a mismatch. Having had a few problems in recent years, I thought I'd check the 7mm 162gn AMAX and Berger VLD out in various makes of 7mm cartridge seater dies and found that of those I own, only Forster acommodated the bullets' noses properly. That check didn't include RCBS or Redding dies. Redding used to advise purchase or specifying a VLD seater stem in some calibres at one time, but I have a vague feeling that the company may have made some changes here in recent years given the widespread adoption of VLD type bullets, or very long nose tangent / Hybrid ogive types from Berger.

 

Some die makers still live in the past it seems and think everybody loads round-nose models or short-nose 7R radius tangent ogive types. My reloading room is in chaos right now having a major tidy-up and sort-out, but when I can move a chair back in again, I'll check out various 6.5mm bullets against Hornady's seater die as supplied in the not so distant past for the 6.5mm Creedmoor. Given this is a match cartridge and Hornady itself produces and promotes the use of long-nose, then tipped bullets as per the AMAX model, the results might be interesting.

[Laurie]

I couldn't find 21st Century Shooting's own 'improved' runout gauge last night, but have now. Here's the link:

 

http://www.21stcenturyshooting.com/Concentricity_Gauge.php

 

Note what he says about the inaccuracy of a 'height indicator gauge' system on rotating objects. I'd be interested to hear what the engineers on the forum think of this assertion. Anyway, the pictures clearly show the 'finger' system used in his model, and also the Audette designed NECO.

 

The Audette / NECO was originally designed to measure case wall thickness (from the inside of the case) which Audette found crucial back in the 50s / 60s when there was a lot of poor quality American manufactured brass around. Both Audette and before him, the engineers at Frankford Arsenal (which used to produce the US military's match ammunition) found that any variation in lower wall thickness greater than 0.003" caused the 'banana case syndrome'. Some mid 20th Century American brass and much military ran at much higher figures. Audette marked up cases with thick and thin sides and proved you could predict flyers and their dierection out of the group, also working from the other direction shoot small groups by marking brass and indexing it in the chamber so the thin side say always sat at 6 o'clock when loaded.

 

German Salazar wrote at length on this subject in his .30-06 match loading in his sadly now no longer available Rifleman's Journal Blogspot. He always checked out his long-range match 30-06 brass in this way with an Audette tool. The issue is it seems particularly relevant to traditional long, thin cases such as the -06, and may be one reason why modern short fat designs shoot well - easier to draw the brass 'coin' into a truly concentric form.

 

Later this year, I'm going to see if I can find any such poor quality brass using the NECO gauge and if so do a bit of testing in 260 Rem and 7mm-08 Rem as I have a large number of makes of case for this pair.

 

The point that Salazar and others make on this is that if you have a banana case, you can fiddle around with concentricity gauges until the cows come home, but any such case produces a poor shot even with nil bullet runout. I also saw partial emprical 'proof' of this syndrome in a discussion I read not too many years ago on the US Teams Long-Range Rifle Shooting Forum by one of America's top Fullbore and Palma shooters (ie 308 WIn TR type rifles shot prone + sling). This competitor handloaded all ammo as most such American competitors do, and like many bought Winchester brass 1,000 examples at a time. They were given no preparation / batching other than inspection and rejection of damaged examples, sizing, and mouth chamfering. Every now and then the shooter would get a flier that couldn't be accounted for in his sight picture / let-off etc or by a wind change. (Nice to have that confidence in your ability!) That case was put back in the ammo box the other way round from the rest and on reloading was marked. If it again produced a flier it was dumped on the range there and then - thrown forward into ground ahead of the firing point. It was said that this second bad shot was a relatively rare but not unknown occurrence. Since that time, it's said by American shooters that Winchester brass is generally of poorer quality than it was maybe 10 years ago.

[1066]

I can't really understand why the die manufacturers still list two types of seater stem. A VLD type seater just has a deeper cavity for the bullet tip so could be used as a "universal" seater. It would surely work just as well on a rounder nosed bullet or am I missing something?

[Laurie]

No, I don't think you are Alan. My thoughts entirely. I find it particularly disappointing that the Wilson seaters are fitted with short-cavity stems given their likely use. I've had one or two offers to machine my existing examples deeper which I'll take up in due course.

[Swarovski1]

More great info from one of ukv's guru's.i am sure I've seen that ring around bullets I've loaded.was probaly the 6.5 cal 142gr smks or 140gr amaxs.ive used berger hybrids and vld type bullet but it's been a while since I have.will check some I loaded over Xmas for a ring around the bullet.

[Murph]

More great info from one of ukv's guru's.i am sure I've seen that ring around bullets I've loaded.was probaly the 6.5 cal 142gr smks or 140gr amaxs.ive used berger hybrids and vld type bullet but it's been a while since I have.will check some I loaded over Xmas for a ring around the bullet.

i have a seperate stem for each type of bullet I use. I have a lathe which I use to grind the stems. I simply sacrifice about 6 bullets by putting them into the vice , and use fine valve grinding paste rubbed onto the bullet. I then put my stem in the chuck in the toolpost and push it onto the bullet which is spinning in the chuck. When it is finished there are no marks on the bullet whatsoever. I use light neck tension which helps also.

[Murph]

Murph,sounds OK-but just to be clear,are you saying your gizmo actually improves the precision of your ammo?

I mean,when you load normally,and have 2-3 hou runout thiose cartridges shoot measureably worse than when you use your gizmo torduce this 2-3 though to 1 thou.

If so,just what are two measures,on average...likewise the improvements in ES and SD...a one off never repeated group no matter whether tiny or big tells nothing-only repeatable results can be informative.

And did you get flyers with 2-3 thou.....that really is pretty good anyhow,and would not normally give 'flyers'-ie shots that are clearly much more dispersed than normal.

NIce for you if you can confidently see consistent improvements that are measureable-but somewhat surprising that a reduction from 2-3 to 1 thou is as marked as you imply-though don't actually give measures for.

It's about helping others....with realistic expectations...most have been very luke warm on this when we are in the very low thou's anyhow.

 

 

The " gizmo" as you called it has definitely reduced the amount of flyers. As to the reduction of es and sd. I most definitely put that down to the lee factory crimp die. I have data somewhere which has mv,s es and sd on a batch of 5 bullets with the crimp and without the crimp. I also experimented with different crimp tensions to see which created the best results. 6 thou being the sweet spot. I will put up some of my test results.

[Murph]

 

That's the gizmo there. I use it to check out run out on factory ammo which can be shocking at times. Made it mostly out of brass as I get brass prop shafts off a friend who worked at boats. Then powder coated it to finish. It has told me a couple of times when my dies needed a good strip out and clean. Maybe not to everyone's taste but it serves a purpose.

[gbal]

Murph,'gizmo' is meant neutrally-not a criticism.

 

But you still don't include any data on the group improvements using it.

Yes,factory can be well out on concentricity-but also other things.

An improved concentricity is not the same as a better group....ditto velocity etc,hence my asking if you actually had such evidence. There are posts here that admit as much,though generally with prettty good concentricity already,that was made a little better , but without measureable effects on group.

 

Are you really saying that going from 3 thou to 1 thou concentricity measureably

reduced flyers in your groups.....?

 

gbal

[Murph]

In reply to your query about group size data. No I would not have any hard data on that. The only records I keep are for MV,sd and Es. Any measurements are taken in the field with vernier calipers. The odd target I will keep if exceptional. Most of my targets look like they have been shot with a shotgun as I get good use out of them!. My groups went from .210 down to .160 after I started straightening them, but with no hard evidence who's to say. Maybe another stage in the reloading regime caused a placebo effect who knows. I'm not really one for keeping too much records on anything. That being said I have noticed a difference in the amount of fliers but that is all hearsay without data. My primary goal with this rifle is varminting. An accurate cold bore shot with as little change in poa As I can possibly get with the equipment I have to hand is what I am after ,as well as terminal performance on the quarry I am after.

[1066]

_{There's a video somewhere on youtube showing factory ammo being sorted for concentricity. It was simply a girl rolling several cartridges on a flat surface with the palm of her hand and looking for the wobbly ones - The straightish ones were classed as gold standard and the wobbly ones were silver standard.}

[stu47]

I've only been reloading for about a year and only in .308 caliber, so far. I originally had a set of Lee Dies which produced up to 6 thou run out (even after rotating the case 180 and reseating the bullet in the press) so, believing the Lock n Load hype, I bought one and began spending hours making all 50 of my loads perfectly concentric (according to the LnL). The result - no difference in group size at all when compared with non-adjusted rounds.

I have since been given a set of Redding Competition Dies (birthday present) and run out is near gone but no improvement in group size - far easier to adjust though.

Finally, I was given a MagnetoSpeed Sporter for Christmas (spot the theme here?) And have found no difference in ES or SD between adjusted and non-adjusted rounds. However, these are only my findings, in my rifle, with my hand loads. By comparison Murphs Gauge is a work of art compared to the LnL so it's no surprise he is seeing results from his efforts.

 

Swarovski1 - if you want to try a LnL and your ever up Swadlincote way you can borrow mine.

[Swarovski1]

Ok stu.fanx for the offer and your input on the thread.atb swaro

[Murph]

I've only been reloading for about a year and only in .308 caliber, so far. I originally had a set of Lee Dies which produced up to 6 thou run out (even after rotating the case 180 and reseating the bullet in the press) so, believing the Lock n Load hype, I bought one and began spending hours making all 50 of my loads perfectly concentric (according to the LnL). The result - no difference in group size at all when compared with non-adjusted rounds.

I have since been given a set of Redding Competition Dies (birthday present) and run out is near gone but no improvement in group size - far easier to adjust though.

Finally, I was given a MagnetoSpeed Sporter for Christmas (spot the theme here?) And have found no difference in ES or SD between adjusted and non-adjusted rounds. However, these are only my findings, in my rifle, with my hand loads. By comparison Murphs Gauge is a work of art compared to the LnL so it's no surprise he is seeing results from his efforts.

Swarovski1 - if you want to try a LnL and your ever up Swadlincote way you can borrow mine.

Thankyou stu for your kind comments- murph.

[gbal]

In reply to your query about group size data. No I would not have any hard data on that. The only records I keep are for MV,sd and Es. Any measurements are taken in the field with vernier calipers. The odd target I will keep if exceptional. Most of my targets look like they have been shot with a shotgun as I get good use out of them!. My groups went from .210 down to .160 after I started straightening them, but with no hard evidence who's to say. Maybe another stage in the reloading regime caused a placebo effect who knows. I'm not really one for keeping too much records on anything. That being said I have noticed a difference in the amount of fliers but that is all hearsay without data. My primary goal with this rifle is varminting. An accurate cold bore shot with as little change in poa As I can possibly get with the equipment I have to hand is what I am after ,as well as terminal performance on the quarry I am after.

Murph,thanks for this reply-my only concern is not to mislead inexperienced shooters into considerable expense in pursuit of some holy grails that are in most cases,illusory. This can include 25 fps velocity,small reductions in SD and ES of velocity. While consistency is a virtue,absolute perfection/uniformity is very hard to obtain,and will not generally lead to consistent measureable improvements in precision or accuracy,given that the rifle/ammo is at least reasonable to begin with (that means 3-4 thou run out-reducing it may have a feel good value,but it won't make much difference to groups.

 

I am with you on varminting-first shot cold bore accuracy is the name of that game-and under field conditions all the above apply,but are even less critical-wind error and shooting position will be far bigger factors (what is included under 'accuracy'-the skill to make a shooting solution that results in a hit.That will be much more important than any 'precision'-(rifle and ammo) improvement of .1 moa-even if it was attained.

Incidentally,your .210 groups would podium in Bench Rest ,and your .16s would give you world class wins....I would not worry much about anything ,given that level of shooting -whether or not any golden 'gizmo' has contributed.

 

Pity you don't keep fuller data though;those are the kind of tiny groups that get framed,though very few will ever shoot very many that small.

" It is a capital error to theorise/speculate without data." (Sherlock Holmes)

:-)

 

atb,

gbal

[Murph]

Murph,thanks for this reply-my only concern is not to mislead inexperienced shooters into considerable expense in pursuit of some holy grails that are in most cases,illusory. This can include 25 fps velocity,small reductions in SD and ES of velocity. While consistency is a virtue,absoluteperfection/uniformity is very hard to obtain,and will not generally lead to consistent measureable improvements in precision or accuracy,given that the rifle/ammo is at least reasonable to begin with (that means 3-4 thou run out-reducing it may have a feel good value,but it won't make much difference to groups.

I am with you on varminting-first shot cold bore accuracy is the name of that game-and uner field conditions all the above apply,but are even less critical-wind error and shooting position will be far bigger factors (what is included under 'accuracy'-the skill to make a shooting solution thaat results in a hit.That willbe much more important than any 'precision'-(rifle and ammo) improvement of .1 moa-even if it was attained.

Incidentally,your .210 groups would podium in Bench Rest ,and your .16s would give you world class wins....I would not worry much about anything ,given that level of shooting -whether or not any golden 'gizmo' has contributed.

Pity you don't keep fuller data though;those are the kind of tiny groups that get framed,though very few will ever shoot very many that small.

" It is a capital error to theorise/speculate without data." (Sherlock Holmes)

:-)

atb,

gbal

Maybe it's time to buy a notebook of some sort. It can't do any harm to have some sort of reference point to work off. Only loading for one caliber makes it a lot easier to remember. I admire constructive criticism on any level and if it means "ironing out" any issues on a future date with my loads then I am all for that. I'm going to have to keep some of those targets.

[1066]

I check for concentricity with a homemade gauge but I never try and correct any wobbly ones - I just felt tip the head and use them for initial sighters/fouling shots etc.

 

My thoughts are that bullets with excessive run-out, although they shoot well enough at moderate ranges, will act like bullets with a lower BC at longer ranges i.e. more drop and more drift.

 

A perfectly concentric spinning bullet will surely slip through the air better than a fuzzy lump whose tip is scribing circles round the line of flight.

 

[srvet]

I check for concentricity with a homemade gauge but I never try and correct any wobbly ones - I just felt tip the head and use them for initial sighters/fouling shots etc.

 

My thoughts are that bullets with excessive run-out, although they shoot well enough at moderate ranges, will act like bullets with a lower BC at longer ranges i.e. more drop and more drift.

 

A perfectly concentric spinning bullet will surely slip through the air better than a fuzzy lump whose tip is scribing circles round the line of flight.

 

It strikes me that we are assuming that a non concentric round will result in the bullet exiting the barrel at an angle. Not sure that we can assume this is the case or am I wrong?? You would need to be nifty with a concentricity gauge to measure it too!

[Murph]

I check for concentricity with a homemade gauge but I never try and correct any wobbly ones - I just felt tip the head and use them for initial sighters/fouling shots etc.

 

My thoughts are that bullets with excessive run-out, although they shoot well enough at moderate ranges, will act like bullets with a lower BC at longer ranges i.e. more drop and more drift.

 

A perfectly concentric spinning bullet will surely slip through the air better than a fuzzy lump whose tip is scribing circles round the line of flight.

 

 

That was my train of thought also. Lovely bit of engineering on your comparator. Love the marble base on it. Makes mine look medieval!

[1066]

It strikes me that we are assuming that a non concentric round will result in the bullet exiting the barrel at an angle. Not sure that we can assume this is the case or am I wrong?? You would need to be nifty with a concentricity gauge to measure it too!

 

You're right, I've no idea if a non concentric bullet "straightens up" as it enters the rifling or, if it starts wonky it stays wonky. I'm inclined to think that if it enters the barrel without the axis running through the centre of the bullet, then the bullet stays like that with the tip revolving round the centre of axis during flight - If so, this must lead to increased drag over a bullet running true.

[DaveT]

Surely a non-concentric bullet will engrave into the rifling with some corresponding degree of 'Skew' & therefore deformation which doesn't sound like it would help re drag , accuracy etc.

[gbal]

Guys,intriguing though it might be how much initial non concentricity might be reduced (probably not all) by the bullet being almost swaged thought the bore...and some very exaggerated drawings of bullets yawing wildly down the bore,these are not meassured effects.

 

The question is not about 'fuzzy lumps' gyrating haphazardly through the air( I am happy to accept rifles outshoot muskets) but rather whether an incease in measured concentricity from 3 thou to 1 thou is going to make a measureable difference on target.

Several posters seem to have done the comparison-and are less than convinced.

20 thou to two thou might.....data would be nice.

Who calibrates the concentricity guages...are they as (un) reliable as say chronos,or better....

Anybody checked factory ammo of only modest concentricity and compared it on target with otherwise very similar ammo (same bullet,etc)-though it will be ver difficult to control all the differences with only concentricity differing.

 

 

Just to see where I'm coming from,if it seems implausible-of the top 100 PRS shooters in US (first shot hits on 1-2 moa targets from 200-1200 yards,real life positional and some awkward), only a very few were loading powder by volume,but the rest were about equally split (48 to 47 approx) in using .001 powder scales or .1 powder scales...that is a "huge' difference (x100 precision) but apparently half didn't think it very important....and these are very good shooters.....

 

Maybe a very slight bend in go fast stripes does not affect performance (other than very,very slightly....).

 

:-)

 

gbal