Charge Weight Accuracy

[Blue Haze]

So for those of you who shoot F Class or long range benchrest... How accurately do you weigh your charges? How much better do your numbers get?

 

I currently weigh to 0.1 gr on a Lyman Gen 6 - I drop 0.1 gr light and trickle up to mass. SO in reality I can be anywhere within a 0.1 gr window.

 

I am considering getting a 'better' scale to further improve charges - was thinking of a Gempro 250, or mabey an AD&T 120 if you can justify its really worth 3x the cost.

 

I currently achieve around 35 fps ES with SD of about 11 fps - I would really like to half those numbers.

[Chris-NZ]

I'd say you're better off focussing on brass prep/ neck tension issues rather than chasing better scales. That will probably yield better ESs that going to the nearest kernel in powder.

 

And yes, an AnD is DEF better than a Gempro. Its zero will not wander unlike any strain gauge-based scale.

[Andrew]

I'd say you're better off focussing on brass prep/ neck tension issues rather than chasing better scales. That will probably yield better ESs that going to the nearest kernel in powder.

Absolutely. 100% correct~Andrew

[Re-Pete]

Neck tension consistency and case prep +1................and I think you'll be lucky to find an electronic scale under 3 grand that'll consistently and accurately weigh to 0.1grains with zero drift............

 

(I used to routinely weigh stuff to 4 decimal places as an analytical chemist, and I still use an old 3 decimal place mechanical balance for my reloading)

 

RePete

[VarmLR]

I've found that variations in charge (as above) matter far less than neck tension, but still can't kick the habit of being fastidious about charge weights! I load to within 0.1gr (tuned RCBS 10-10). I know it's possibly a waste of time being so finicky but regard attention to detail in general as being a good thing for ammo consistency.

[Webby]

Agree completely re neck tension and case prep etc but feel that powder weight also important. I have just purchased A&D and as a result have a gem pro and dandy/omega tricker that I would like to sell. Gem pro stops wandering if you leave switched on and don't change the room temp a lot whilst using it. I did find that it takes a while to settle if you switch on and expect to use it straight away! Apparently german Salazaar says 1 kernel varget = 1fps and he weighs so accurately that he cuts kernels in half! That seems a bit OTT!

[Re-Pete]

What's meant by a "tuned" RCBS 10-10..............can you weigh faster with it?

 

RePete

[Andrew]

Apparently german Salazaar says 1 kernel varget = 1fps and he weighs so accurately that he cuts kernels in half! That seems a bit OTT!

Nutz.~Andrew

[VarmLR]

What's meant by a "tuned" RCBS 10-10..............can you weigh faster with it?

 

RePete

 

I believe that our USA friends would use the term "Accurised". As I understand it, someone competent in improving beam scale accuracy has fettled it to make it more sensitive and repeatable. I bought it from someone who had it done by a respected UKV member. All I know is that it will reliably show the difference that a single kernel makes when viewed using a little webcam aimed at the pointer and my laptop screen. You can see the pointer move when adding a single kernel from the trickler. You could probably do it yourself by simply cleaning and honing the beam pivot bearings, cleaning off the beam, cleaning the magnet faces and generally paying attention to anything needed to free up the motion, but I bought mine already done and periodically just clean everything.

[n8ess]

Really interested on your comments regarding case prep and neck tension. Could someone elaborate on the best way to improve both. I am particularly interested on how you optimise neck tension. This maybe a separate topic on its own but l would appreciate your comments.

 

N8ess

[gbal]

Re-Pete- pretty much exactly as Varm LR says-the magic touch just smoothes everything up (agate contacts?whatever);repeatability is excellent- redump the same powder weighing again,it's the same; I'd agree with 1 to 2 kernel precision,though you need good level eye (or screen) to get it to 1 kernel.

It does damp a bit faster than an untuned scale,but only a very few seconds (cleaned magnets) but it is reassuring,(as is the repeatability!) It's -for me- a very cost effective upgrade.

 

On seating,the K&M (wilson hand die) arbor press has a Belleville and whistle thingy,and can take a dial which measures seating tension,so at least rounds can be batched. Wilson dies are no compromise,either.

 

Webby, German Salazar really should be uniforming the length of the kernels first...so that half is the same...but do read his AccurateShooter article on uniforming the fine hole through the kernels-obviously it should be a standard hole,must be very satisfying,though tricky technically.....and do check the date of publication-its 2012,April,very early in April....the first,as I recall (and therefore I read it as a very subtle satire on OTT/OCD borderline behaviour....that does no harm.... :-)

 

.

 

gbal

 

ps I've found that ensuring the standard cylindrical diameter of the kernels should be considered,though it's not that easy to do,compared to a cut length and boring a hole. Perfection comes at a price; and there may be therapy costs.

 

There may also be ultra fine discrimination dial guages for the K&M......must be,but not must have...yet. :-)

[Re-Pete]

All sounds a bit "anal" to me............I've had sessions where the ES has been 40+, and the rifle (6BR) has put 13 out of 15 shots into the V ring at 300yds. (300m target face)

And others where the ES has been in single figures, and the pattern looked like a 12-bore at 25 yds.

One thing is certain (in my world): Inconsistent neck tension and bullet jump affect the poi more than + - 0.1 grains of powder.........

 

RePete

[gbal]

Consistent powder measure;neck seating tension; neither are very expensive to get prettty good.

Annealing helps neck seating tension,can cost a bit to do well.....

 

Tuned powder scales will get to a couple of kernels-that's .05g (good untuned scales can get .1g).and maybe the magic 1kernel ( 'magic' does not imply we 'need' 1 kernel =1fps precision,but it can do no harm,and by 1000+ yards,effect is probably less than an inch(?...no handy beermat to figure it out).**

Neck tension-very good dies and tension measurer (to batch) -as Wilsons and K&M dial arbor press.

 

 

Just a word on ES generally: like most descriptive stats it's 'useful',but limited....

 

I'm with Re-Pete but just consider his finding-simply because it's on this thread and relevant data:

 

13/15 shots were V bulls,'despite' ES of 40fps ( we 'want' single figures).However,

 

just suppose 13 of those 15 had identical (or very close) MV,and there were two outliers-differnt MV...

 

(13 were 3200fps,one was 3180 and one was 3220,which give ES 40) AND the V bulls were the 13 with 3200 fps.....

 

that would strongly support low ES......

 

( a very small ES batch that shoots rubbish means some other factor is awry-nowhere near a node,eg)

 

Now ,we hardly (n)ever get the actual shot POI related to actual fps per shot....understandably....though it would not be too hard to record after each shot ( target hole and magneto reading)....that's velocity,probably powder related....not neck tension...

 

point is that ES is a crude measure,identifying only the dispersion of the two most extreme scores,but saying nothing about the consistency of the others.

SD is better,but still vulnerable ( eg to an extreme score.....rather like a 'flier')

 

Stats don't lie...but can be misinterpreted.

 

 

** next table had a spare " Litz lager" mat,so here are some ballistic sips:

 

% hits on a 5 inch gong;accurate wind reading and ranging; .5 moa 308 175 @ 2600:

 

MV SD 10 fps 400y 99% 500y 93% 600y 73%

 

MV SD 15fps 400y 99% 500y 91% 600y 67%

 

MV SD 20fps 400y 99% 500y 83% 600y 55%

 

Clearly,it would matter more if the target was smaller;even so, by 500y differnces are emerging....cheers!

 

gbal

[VarmLR]

I agree with gbal here. Whilst large ES doesn't automatically indicate a wide spread of MV from a batch, it can indicate just ONE that is way off the average for the rest, the combination of ES with SD (either on their own only tells part of the story so are of limited use unless expressed together) is a useful and meaningful indicator.

 

I agree that neck tension, and runout, start to become very important in tightening groups up the further out you shoot, and are a major factor. It still doesn't hurt to be "anal" as some put it on the more minor factors that, after all, are easy to sort out with little more care needed in the reloading process.

 

I start with the brass, cleaned, de-primed and inspected. I then clean my dies using brake cleaner spray (basically IPA in a mix with other solvents) and a few cotton buds to ensure there's no junk in there which could damage the dies or brass or affect consistency.

 

The brass, before de-priming/sizing is also annealed every 3rd firing. I feel that this is enough without needing to do it every firing as the SD seems to be kept in single figures.

 

One thing many perhaps discount is to try different primers. I have some BR primers here which I may try for some of my hotter, more compressed loads, but generally, I've found that the CCI primers give adequate consistency, perhaps not as good as going the BR primer route for competition standard. That, to me, is more dependant upon load and chambering.

 

The powder charging is an area where achieving accuracy is simple enough, so I do it. Charge thrown, checked on the (tuned) beam scale and adjusted to within a kernel or two of the same beam point indicator each time. Takes seconds so worth it.

 

Finally, the seating. I am not especially happy with the standard Lee bullet seater as it seems to vary the seating, especially with more "pointy" tipped bullets, so I check every one to ensure they're all within a few thou of where I want them to be and no more. The Lee manages plus or minus 2 or 3 thou. Whilst I'm seating them, I turn the bullet half way, or sometimes a third way (3 times) during seating which may help seating concentricity.

 

I seem to manage single figures using this regime and haven't tried it with more variance on charge, as there's little point if I'm in no hurry loading. Works for me and happy so far with my 600 yd groups. Will be trying 900 next month to see if I can manage to keep them tight, but my reading of wind has yet to be developed to upper echelon levels which will take time! (years I suspect).

[Andrew]

Neck tension and uniformity of ignition. The two top factors in my book. I uniform primer pockets and deburr flashholes. I seldom weigh / trickle a charge (because I have a superb powder dispenser) but I do strive for absolute uniformity in my brass and pull weight of my bullets. Cutting a kernel of powder? Nonsense.~Andrew

[VarmLR]

Neck tension and uniformity of ignition. The two top factors in my book. I uniform primer pockets and deburr flashholes. I seldom weigh / trickle a charge (because I have a superb powder dispenser) but I do strive for absolute uniformity in my brass and pull weight of my bullets. Cutting a kernel of powder? Nonsense.~Andrew

 

+1

[Martin52]

I posted the comments below on another forum recently in response to a similar question. I would add that I use a Lyman Gen 6 for the first powder dump, then pour it across to the A&D and trickle with the Omega/Dandy.

 

I have a Gempro 250 and an A&D, I bought the GP first.

The 2 scales are different in terms of build and performance - the GP is a strain gauge scale, the A&D is a magnetic force restoration scale.

Both will weigh a powder charge to within 0.02 grains, about 1 kernel of varget.

However, should the charge be underweight the GP will not respond as well to trickling as does the A&D.

With the GP you may need to remove the pan to add a few kernels (e.g. by tweezer) and then re-weigh until you get the desired weight. You can also add kernels without removing the pan however the "work around' is to then tap the pan lightly with tweezers to permit the scale to re-weigh once the extra kernels have been added.

The GP may also drift a little and you will need to hit the Tare button.

With the A&D, this scale will respond well to trickling, it senses each kernel drop into the pan and registers accordingly.

Eventually I found the extra steps with the GP frustrating and I bought the A&D. I do use the GP occasionally mainly for static weighing of projectiles and brass.

If time is not an issue for you then the GP may be OK.

If you prefer to a time efficient solution then the A&D is the way to go, link it to a Dandy/Omega trickler or the automated system that is mentioned elsewhere on this forum.

[gbal]

Mr Salazar's Kernel Kalkulations need to be Konsidered in their fool Kontext-the article was published on April 1st.

 

However, a much reduced kernel size would expedite loading the 50BS wildcat.

 

This is the 50cal Browning case,necked to fire a standard Singer sewing machine needle.

 

It has to be loaded (mini) Kernel by Kernel,and takes quite a while,even with surgical grade tweezers.

But with only two and a half shots before the barrel is toast,what's the rush?

 

gbal

[Andrew]

Mr Salazar's Kernel Kalkulations need to be Konsidered in their fool Kontext-the article was published on April 1st.

 

However, a much reduced kernel size would expedite loading the 50BS wildcat.

 

This is the 50cal Browning case,necked to fire a standard Singer sewing machine needle.

 

It has to be loaded (mini) Kernel by Kernel,and takes quite a while,even with surgical grade tweezers.

But with only two and a half shots before the barrel is toast,what's the rush?

 

gbal

~Andrew

[Re-Pete]

Try weighing a kernel of Wildboar.............

 

RePete

[Brillo]

When I was getting really picky about charge weights, and on a day when I had nothing else important to do, I decided to weight a batch of powder and count the kernels. On average there were 6 kernels to 0.1 grains of Varget, and nearly double that of N140 or RS52.

If you assume a charge weight of 46 grains for a .308 load that makes (on average) 2760 kernels per charge (over 4600 for N140).

 

So, does one kernel make a difference? I think not. But I'll still follow my meticulous loading regime. I can't help it.

 

Now, before anyone says "you need to get a life" it was either count kernels or watch Emmerdale at that time. What would you choose?

[VarmLR]

I once weighed a Pine Kernel if that counts?

[John MH]

From the 'mind set' approach to shooting if you think something helps it probably will even if there is no physical evidence that it does. It's one of those things that you can park at the back of your mind when you are concentrating on your sight picture and trigger squeeze.

[Webby]

I seem to have inadvertently started quite a humorous note to this thread! Keep it up guys my skin is thick up to a point! Don't have time to visit that often I am too busy halving kernels and trying to drill through the centre!

[Blue Haze]

Common Webby, drilling the hole really is a bit amateurish... You need to broach then ream and lap it.

 

Get with the club.