Duplicate Chronograph results

[Topgun 30-06]

Randy---Thanks for your post and possible explanation! When the OP spoke in decimals, anyone that is/was involved in W&M like I was would immediately think they were referring to a digital device, thus my response. I would suggest that even a cheap beam scale like you referred to would be better that a $20 digital from what I saw and learned about digital devices during my career.

 

[green 788]

since you mention doing an OCW test, I'm assuming you've followed my instructions on my webpage as to how to choose the powder properly... so assuming you've done that, the worst that would happen with a cheap scale malfunction would be you'd blow a primer... no catastrophic malfunction should occur.

just sayin'...

 

[Topgun 30-06]

I wouldn't argue that, other than your use of the word "assume", as I'm sure you know the old saying on that one!

 

[MNbogboy]

I agree that a cheap digital is a castrophy waiting to happen....I have always used beam scales (even in the prototype auto loading scales I built in the eighties)...Accuracy of any scale is the care you put into operation, calibration and maintenance...I have had several beams including a nice 1010 that I used in my auto scales but that one disappeared long ago.....My $11.95(70s price) Bonanza Model C is accurate as I will ever need I can set it to tenths and easily weigh to the a half of kernal everytime....Proper care of the knife and blocks will help it last a lifetime....I had to "stone" the knife once after it was dropped....keep them clean and don't leave bouncing on zero...The nice thing about a free scale is you can trickle slowly up to zero and still read a "kernal"....those magnetic dampened scales will normally not bounce right back into motion after a "kernal" drop once they are laying on zero...Thats why it works best for me to read the "bounce" with a magnetically damped scale.....BTW I had a large electro-magnet that I was able to demagnetize most of the dampening effect on the 10-10...made it far easier for me to maintain precision when I had it.....

Dust on any part of the beam will change its calibration as well as its operation...Keep them covered and make sure they are dust free before use...
Always keep the knife & blocks clean....

Any scale including some of the better digitals can give you "false" readings which are actually stray air movement barely or almost not detectable by a person....This gave me fits for a while when I was younger when I had electric baseboard heat in one of my reloading rooms.....A forced air furnace will make any scale wander no matter what part of the room you are in....

One must also pay attention to the side thrust bearings and the relationship with the beam...Any "stray" drag will affect the reading...When checking calibration with check weights pay attention to this....Use more than one check weight and also check operation at extreme ends of the beam movement.

My need for speed has long past along with my youth and now it seems my joints too...It gets tedious and downright uncomfortable sitting at the bench for hours weighing each load down to the kernal without the help of my automatic powder scale...I am only shooting once or twice a week now (10-20 rnds/session)...So my bench time is only 2 to 3 hours a week.....Hopefully my upcoming hip replacement will cure that....

 

[Topgun 30-06]

Randy---Great post and just yesterday I mentioned a number of things that were in your post on another website regarding beam scales! They will last a lifetime and then some when properly taken care of, just as you mentioned. One of the main things is to keep the beam from swinging freely other than during actual use to keep wear on the knives to a minimum. I didn't know you were having health problems and wish you well on the hip replacement. I'm sure you'll do fine the way they do them nowadays. Are you having it done this summer and skipping the trip out west so you can recover well and be ready for 2013?

 

[rscott5028]

A good digital scale can be pretty precise. But, they aren't cheap.

And, like MNbogboy points out, it's all about the operator. There are a number of issues including air flow, temperature, vibrations, static, drift, etc... that you have to be careful of in order to get precise results.

e.g. Mine sits inside a glass case while in use.

It's a slow process and normally I just use the RCBS Chargemaster which runs about as fast as I can seat bullets.

-- richard

 

[MNbogboy]

I often now wished I would have waited for a tool like the Chargemaster and it's relatives from the competitors to come out...In the days when I did a lot of shooting, it seemed I didn't have the time for reloading like I do now....

Because I love to tinker with electronics/mechanical I built the two automatic scales...Hence I put a lot of time (and hard earned money) into them....They were big, bulky and clumsy all on a wood frame work....They were no more accurate than .1gr at their finest and I could hand weigh almost as fast...The second one with the stepper motors and digital circuitry was a little faster but again .1 grain was best and .15 probably average deviation...The beam scale certainly was much more accurate than the simplified electronic/electrical that fed it.....To build one today would cost an arm and a leg compared to something like the Chargemaster.

I learned quite a bit about beam scales during the development of those early "chargemasters" and I believe those projects definitely helped me become a better hand loader....Albeit if the Chargemaster would have came out before I started those projects I probably would have bought one just because of my impatience then in the reloading room....

As we get older we appreciate the rewards of a job well done...I would bet that my loads seldom, if ever, deviate more than .05gr in powder now...We all can benefit from the great information, theory and advice a person picks up on sites.......By putting our heads together we should be able to stop nothing short of excellence in our shooting and reloading skills....

In days of no internet how was a person supposed to pick up the little "tricks" that make a good job easier.....I fought with powder clumping out the end of my Redding tricklers for years....That straw trick (yes that simple straw trick) never entered my mind till I read it on here a couple of years ago....Wow, what a difference....I use "clear" McDonald's straws I can see those clumps coming before they fall in the pan and adjust my trickle speed accordingly....The best cut on the straw end I found is a slight angle but no notch....I still catch myself scooping out a kernal or two if a clump does drop.....(pretty anal I guess but that's just me)....

Mike, as far as my surgery and western trips...I have been hurting bone/on/bone since last fall but put off going to the doc and getting his diagnosis till after I sent out my apps.....Doctor said take celebrex the day before I go and every day I am out there and he will fix me up when I get back.....The celebrex is pretty spendy almost $5 a pop, I tried it during shed hunting this spring and seems to work pretty good but the hills we have here are nothing like the mountains out west as everybody knows.....We have two for sure hunts planned already for MT....bow hunting for elk in Sept and back there again in Oct and possibly Nov for deer.....I am waiting on my WY draw results at the end of the month but they are both hard draws for both lope and deer so I do not expect to draw even though I might have 3% chance on the deer and maybe 6 or 7% on the lope....Hoping now that I don't draw but if I do I will still go...

I guess we are getting a little off the OPs questions and certainly would like to hear from him again....Also besides the guy I knew who had the little Lee scale is there anybody on this forum with any experience with them?

As far as the "cheap" chrono for the purpose of OCW testing a comparative velocity is really what you are looking for at that time and with proper set-up and reasonable light stability the cheap chrono should serve him well.....I also have had two "cheap" Shooting Chronys and they definitely are accurate as the conditions you subject them too....My sole use is comparative testing during load development...My chrono stand allows me to shade bright sun over the chrono at almost any angle making it very predictable and consistent...Field drop tests at longer ranges can verify your actual MV and my Shooting Chronys so far have been pretty much spot on....

My load development process developed over several decades is very similar to Green 788's method all done at 100 yards initially and then 300 and farther to verify after best 100 yard load is established.....After reading his methods I have hundreds of pages of targets & chrono records to go through to compare to his methods and if they agree and I think they will I might just save a bunch of ammo when I build my next one ( I have a 6.5-06 barrel coming sometimes in July that I am going to try Green's method on).....

Somebody else said that if the OP had results like he said it could be very well that he did everything right...I agree...
Randy

 

[rscott5028]

[...]Somebody else said that if the OP had results like he said it could be very well that he did everything right...I agree...
Randy

True.

And, cold bore hits with lots of tight groups at long ranges under varying conditions will certainly validate that.

-- richard

 

[MNbogboy]

Exactly, Richard....No matter how good the OCW testing is only validation with long range field testing will prove it...It will prove the grouping and the drop test will verify any chrono error...

 

[wallypedal]

I read all this thread and never saw real resolution to the OP's question. Just yesterday I wrote to and received replies from Competition Electronics which made sense. I was asking why I got identical numbers displayed (like 3122 but never a 3123) and why I got the "duplicate" reading semi-frequently. Rather than put my twist on it, here is the quote from Jim at CE:
********************************
"Depending upon what velocity you are measuring, there is a "gap" between displayed readings. Above 1,500FPS the unit will begin incrementing by 2FPS.

The "gap" between velocity readings increases with speed. For instance, at 3,000FPS the chronograph has a gap of 6-7FPS for each count of the internal clock. So if you are getting duplicates at 3,000FPS then your loads are likely within +/- 7FPS of each other. Part of this is due to "rounding of the internal calculations. This translates to about a maximum of .2% error which is part of our 1% accuracy spec."
********************************
I put into bold the eye-opener for me.lightbulb A dup message and reading are within a tolerance range. It also means to me that ES and SD numbers are only within a range as well, so strings should be long if the ES and SD are to be meaningful.
I chased shooting forums looking for similar posts, and never saw this information displayed! Hope it helps somebody before they loose all their hair over it....too late for me!