Author Topic: 1st Chrono use for load development, does this look right?  (Read 817 times)

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Offline Red Dog Leader

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Firearm
• My CZ pistol/rifle model is: SP-01 TAC
• The caliber of my CZ is:  [9x19 Luger]
• My CZ has the following changes: stock
• I use this CZ in the following ways:  general plinking, 1 steel plate match...and want to do more...
• I want ammo accurate at:  7- 25 yards for my clubs plates.
Components
• I've been reloading for months/years:  15 years
• Fully describe the maker, weight, and type bullet:  Xtreme.. 124gr RN
• Powder (brand name and load range):  N320
• Primer:  CCI SP
• My Cartridge Over-All Length is:  aiming at 1.135", with results from 1.133 to 1.137]


Reloading Equipment
• Press brand and type:  Lee Classic 4-Position Turret (just got a AutoBreech and want to start using it full time)
• Dies:  Lee 4-die set]
• Scale:  Gempro 250/ FA digital/LEE beam
• Powder Measure:  Lee Auto-Drum
• Do you have access to a chronograph ?  Yes

Other Info
• Exactly what is your load data and where did you get it ?  VV manual, this site, Lyman/Hornady manuals
• Where are you located ? NW Indiana

Problem Area


Well thanks to this site I'm determined now to make better "crafted ammo"
Hence I recently bought a Chronograph (Cheepo Caldwell, which might be my problem?) and following guidelines on this site did a load workup of the N320/CCISP/124RN Xtreme @ 1.135 (push & plunked) All the same cases.
Charge weights of 3.8 to 4.2.  10 each. Used LEE autodrum to get close, then trickled up on GP250.

So, yesterday got to range at 10 AM, sun up over left shoulder, chrono ~12 foot from table. Partly cloudy. 75 degs. Used pistol rest/MTM
 
My problem (or is it? never using a chrono before) is I had velocities all over, or extreme spreads it seems to me looking over other results posted here for chrono use...

10 shot strings for 4.0/N320 low of 915 to high of 1056. AVG: 1035, SD of 13.3, ES of 33

10 shot strings for 4.1/N320 low of 970 to high of 1058 AVG: 1019, SD of 31, ES of 86

So, how do I improve these numbers?
Better chrony?
Better loading techniques?

All help is greatly appreciated...

Red
« Last Edit: June 10, 2018, 09:49:58 PM by Wobbly »

Offline 1SOW

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Re: 1st Chrono use for load development, does this look right?
« Reply #1 on: June 07, 2018, 02:49:33 PM »
Hard to say but can offer some suggestions:
Chrono set up:   put the chrono about 9' from your shooting position. Put a very small target at about 8-10 yards.
Adjust the chrono height so it is LEVEL and "aimed" directly at that very small target (or adjust target position as needed). I shoot from a rest/range bag/rolled up towel so the pistol stays level with the chrono.
The top of the chrono should be level and not tilted.  I paint two rings on each of the sun screen rods to SHOW where I want the bullet to travel LEVEL as it passes the light sensors.  If you shoot at any  angle  other than level and aligned with the chono across the sensors the DISTANCE INCREASES and gives a false reading.
Early in the morning or late afternoon/evening may be a problem.  Indirect or screened light is needed to get accurate readings across the sensors.  Cloudy or when the sun is high improves the angle of the light hitting the chrono sensors.  Shading the chrono can fix that.

Ammo:  I also use the Lee Turret Press with the Lee carbide  4-die set with  the older powder disc system. 
Sounds like you use a good load system.  I usually drop 10 loads and weigh that and then divide by 10.  When it's very close,  I then weigh just a few sample loads untill I have confidence in the drop. Then I 'press on'.
I believe using same headstamp cases makes "MY" bullet seating more consistent.  Small OAL differences don't have a significant effect on your your readings.

Without more info,  I would guess the chrono set up may have played a roll in the wide spread results.

Hope this makes sense.
« Last Edit: June 10, 2018, 09:53:17 PM by Wobbly »

Offline Red Dog Leader

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Re: 1st Chrono use for load development, does this look right?
« Reply #2 on: June 07, 2018, 04:22:41 PM »
Hard to say but can offer some suggestions:
Thank you sir, will do.
just started to re reload these rounds again...

Offline IronicTwitch

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Re: 1st Chrono use for load development, does this look right?
« Reply #3 on: June 07, 2018, 05:04:23 PM »
I had the same results with my Caldwell.  Put the sunshades on (if was afternoon, sun was higher in the sky) and got much less spread.

Offline Earl Keese

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Re: 1st Chrono use for load development, does this look right?
« Reply #4 on: June 07, 2018, 05:31:58 PM »
I had a similar result Monday testing Gallant 135gr loads for the first time. It's funny, I've had good results with pistol loads, and errors with my 6.5 Grendel. On Monday the Grendel rounds worked fine but the spread on the pistol rounds was horrible compared to previous sessions. I was surprised, because these were sorted by headstamp and charges weighed individually on a beam scale. There is a learning curve. . .

Offline 1SOW

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Re: 1st Chrono use for load development, does this look right?
« Reply #5 on: June 08, 2018, 12:12:35 AM »
P.S.  If you follow these CHRONO guide lines for pistols,  you won't SHOOT your chrono.......mostly.  Ask some members here... O0
If you use it for rifles,  be sure you allow enough clearance for scopes/tall iron sights. Your scope may show great alignment... right into the chrono face.

One thing about the LEE beam scale:
It can be very accurate and consistent.  It can also be a pain in the butt to get precisely zero and hold it.
I used mine for years, before I bought the Dillon OHaus balance beam scale.  It is EASY to zero and holds consistently if the scale is level and unmoved. Want to know how many particles of n320 weigh .1 grains?  Or what your bullets weigh? O0 

Just saying it's something to consider to make your reloading life easier.   
« Last Edit: June 08, 2018, 12:27:40 AM by 1SOW »

Offline skin

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Re: 1st Chrono use for load development, does this look right?
« Reply #6 on: June 08, 2018, 12:25:48 AM »
 Are the primers seated all the way to the bottom of the primer pocket? I have seen swings in velocity because primers weren't seated to the bottom. I use a hand held to seat primers, you can feel the primer hit the bottom.

Offline 1SOW

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Re: 1st Chrono use for load development, does this look right?
« Reply #7 on: June 08, 2018, 12:32:02 AM »
skin,  on the turret or a rigid single stage press you can feel the primer bottom out.  I think I've had two primers(FEDsp) that didn't seat right due to something in the primer hole obstructing the primer( and caught it).

Offline skin

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Re: 1st Chrono use for load development, does this look right?
« Reply #8 on: June 08, 2018, 12:53:10 AM »
 Did not know that. My rcbs is hard to tell if you're crushing the primer or if it's bottomed out, hence the hand primer.

Online tdogg

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Re: 1st Chrono use for load development, does this look right?
« Reply #9 on: June 08, 2018, 02:34:33 AM »
Red dog,

The gem pro is a great scale for the money but it doesn't respond well to trickling powder.   Are you trickling then lifting and resetting the powder pan to get your weight? Are you letting it warm up before using it?  I always verify it returns to zero after dumping the powder too.

I'm guessing it wasn't variability in your powder charge since n320 meters well (so I've heard,  if it's anything like 3n37 that meters like water).  How much were your trickling up?

I use a Caldwell and it seems to be better/ less finicky than the pro chrono I used to use.  I try not to setup with a light angle where one sensor is shaded and the other isn't.  Either both are shaded or both have direct light.

I do all pistol load development at 10yds with the chrono at 6ft (rifle chrono moved out to 10ft).  Do you best to level it to the angle your shooting and try to keep your shots from string to string centered in the same area over the sensors.   If you have to move the target,  the shooting rest,  or the chrono to make that happen just try to be consistent.

My final thought is to ensure the battery is fresh.   I've had chronos do some weird things with a weak battery.  Oh and just put extra batteries in your range bag now so that when you forget to turn it off your next development session won't be wasted (I some how keep forgetting to turn mine off).

Cheers,
Toby

Sent from my SM-G950U using Tapatalk


Offline Red Dog Leader

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Re: 1st Chrono use for load development, does this look right?
« Reply #10 on: June 08, 2018, 05:51:49 AM »
thanks all for the replys...

Offline Red Dog Leader

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Re: 1st Chrono use for load development, does this look right?
« Reply #11 on: June 08, 2018, 05:58:33 AM »
Red dog,

The gem pro is a great scale for the money but it doesn't respond well to trickling powder.   Are you trickling then lifting and resetting the powder pan to get your weight? Are you letting it warm up before using it?  I always verify it returns to zero after dumping the powder too.

I'm guessing it wasn't variability in your powder charge since n320 meters well (so I've heard,  if it's anything like 3n37 that meters like water).  How much were your trickling up?

I use a Caldwell and it seems to be better/ less finicky than the pro chrono I used to use.  I try not to setup with a light angle where one sensor is shaded and the other isn't.  Either both are shaded or both have direct light.

I do all pistol load development at 10yds with the chrono at 6ft (rifle chrono moved out to 10ft).  Do you best to level it to the angle your shooting and try to keep your shots from string to string centered in the same area over the sensors.   If you have to move the target,  the shooting rest,  or the chrono to make that happen just try to be consistent.

My final thought is to ensure the battery is fresh.   I've had chronos do some weird things with a weak battery.  Oh and just put extra batteries in your range bag now so that when you forget to turn it off your next development session won't be wasted (I some how keep forgetting to turn mine off).

Cheers,
Toby

Sent from my SM-G950U using Tapatalk


Yes sir, warmup, LEDs by bench, no drafts, anti vibe pad and lifting pan
I am going to pay attention to sky/light conditions better next time
Going to bring my scope mini bubble levels next time

Batts fresh and spares in bag.

Thanks, Toby

Offline Red Dog Leader

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Re: 1st Chrono use for load development, does this look right?
« Reply #12 on: June 08, 2018, 06:01:34 AM »
Red dog,


I'm guessing it wasn't variability in your powder charge since n320 meters well (so I've heard,  if it's anything like 3n37 that meters like water).  How much were your trickling up?



Was a W231 and WST user prior to N320. N320 is the most consistent powder from the Autodrum I've ever used, remarkable...

Offline IDescribe

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Re: 1st Chrono use for load development, does this look right?
« Reply #13 on: June 08, 2018, 07:17:14 AM »

10 shot strings for 4.0/N320 low of 915 to high of 1056. AVG: 1035, SD of 13.3, ES of 33

10 shot strings for 4.1/N320 low of 970 to high of 1058 AVG: 1019, SD of 31, ES of 86


Your first obvious problem is that the numbers you reported are not correct:

915 to 1056 is an ES of 141, not 33, and your SD should be MUCH higher than 13.3
970 to 1058 is an ES of 88, not 86

So there's that.  ;) 

This is oversimplified (because I lack the knowledge to talk about this in anything more than simple terms ;)  ), but basically, how it works, the sensors "observe" the space overhead, and when something (like a bullet) disrupts the space over the front sensor, it starts the timer, and when that object disrupts the space over the back sensor, it stops the timer, and uses the distance between the two sensors and the time it took to cross that distance to calculate feet per second.  Pretty basic, but because the distance between the two sensors is short, minor differences in how/when the sensor is triggered can produce significant differences in the calculated velocity.   

SO... if for example, some light reflected from the nose of the bullet triggers the a sensor before the bullet is overhead, the sensor is effectively seeing the bullet early, and precision declines significantly.  So light matters a lot.

With a chrono, diffused light is better than direct light.  Cloudy days are perfect, so long as there's still enough light for it to function, but if there's not enough light, you'll just get failures to record shots, so you would know.

I don't use the sky screens at all.  If it's an overcast day, they're unnecessary, and if it's a clear day, I set up a target stand in an adjacent position to cast a shadow across the entire chrono.  This negates the issues of direct sunlight, which are supposed to be cured by the skyscreens, which I have personally found to be only marginally effective.  I have a buddy with the same chrono as I have, and after I explained to him the why of what I do, he went out and bought a picnic/beach canopy, like a tent without walls, and he just erects that over the chrono every time he uses it, and when he told me what he had done, he was very excited at how much his numbers had tightened up.  Pretty smart.  I've thought about building a doghouse to mount my chrono in and shoot "through" but that canopy is probably just as effective.

To combat direct sunlight, some people will color the tips of the bullets to reduce light coming off the nose.

So... I use a ProChrono Digital, which uses the same basic type of optical sensors your Caldwell does (who knows, possibly identical, sourced from the same supplier -- you never know).  I have found that the more reflective the surface of the bullet, the less precise the chrono readings are.  To that point, jacketed is more reflective than lead or coated lead, plated is more reflective than jacketed, and XTreme is the most reflective plated bullet I've used, as shiny as a brand new penny.

Angle of light has an impact.  I can't guarantee that my tricks and techniques will translate exactly to anyone else unless they're shooting at the same latitude I am with the ranges oriented in the same direction.  I would imagine if I were doing this somewhere else in the country, or in the same spot but facing a different direction, that some of my techniques in chrono use would become more or less effective.

You might also want to weigh charges individually to make sure your problem isn't in the powder drop.

Do you leave powder in the hopper between loadings?  That increases drop to drop variation.  Always empty the drop after a loading session and start fresh each session.

And wipe down your drop with an anti-static sheet.

AND STOP using plated bullets.  They're not best at anything.  ;)

Offline IronicTwitch

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Re: 1st Chrono use for load development, does this look right?
« Reply #14 on: June 08, 2018, 10:40:06 AM »
Good idea to put a target stand next to the chrono to remove direct sunlight.  I hadn't thought of that.  Thanks!