Weight sorting Bullets?

ryandpahl

ryandpahl

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I just received my new precision scale in the mail a few days ago. My first test was to weight sort the bullets I plan to use in the upcoming F-class season.

Does anyone else do this? Is it worth the time? It took me about 2 hours to sort this box of 500 bullets for the Pic.

I was surprised at how wide the variance in weight was. 174.88 to 175.52 grains.


Weight Sorting by ryandpahl, on Flickr
 
I hope you slide those off the table like a pharmacist counting ######.

If it were me i would be picking them up off the floor many times. :p

I don't sort as you have done but I will check my bullets, some for hunting some for target. Maybe I will start after seeing what you have for results.

I didn't have as much variance in my SMK's that you have there, my hunting bullets were a different story. Every little bit has to help I would imagine.
 
ryandpahl said:
I just received my new precision scale in the mail a few days ago. My first test was to weight sort the bullets I plan to use in the upcoming F-class season.

Does anyone else do this? Is it worth the time? It took me about 2 hours to sort this box of 500 bullets for the Pic.

I was surprised at how wide the variance in weight was. 174.88 to 175.52 grains.


Weight Sorting by ryandpahl, on Flickr
Click to expand...
One has to consider the implications of such variance to external ballistics to see whether all the trouble is not an exercise in frustration. The very nice layout of the distribution of weights you're showing in the photo is a classic statistical distribution around a central value (peak value) with a longer tail on one side. But look at the numbers: extreme variation of 0.7 gr for a nominal 175 gr bullet, this is nothing! This is a maximum variation of less than 0.5%, which means your standard deviation is around 0.2%! The effect on velocity variation between max and minimum will also be less than 0.5% so the difference in BC and drop even at 1000 m is negligible. Weighing target quality bullets, unless you suspect a production problem, is not worth the time. (And I didn't consider the contribution of your scale to this variation since scales are not perfect either!)
 
If you weight them again you will have slightly differant results, those scales are not as precision as a beam type scale in my experiance. If you were able to see any viable differance on the target it would really be amasing. The differances that you note are tiny!!!! Waste of time in my opinion
 
The scale is a Gempro250. Readability 0.02 Grains, accuracy +/- 0.02 Grains. This is big improvement in precision and accuracy for me, considering I was using a Lee cheapy beam scale (in the background) before. Will it help me shoot better? Only time will tell, but it definately makes weighing things ALOT faster.

I was using the included calibration weight to check calibration during the whole operation. The scale never drifted more than 0.02 grains as advertised. I am very happy with scale.

I have a feeling it was a waste of time, but I plan to use the sorted bullets in a test. Once I have completed load developement I will shoot two 10 shot groups. Group one will use identical weight bullets, group two will use the worst case scenario of heavy vs light bullets.
 
I do this all the time with my cast bullets :D. On a 550gr bullet I sort them into groups that are +/- 0.2 grains. Anything that strays too far from the median gets tossed (remelted in my case).

Chris.
 
gunlaker said:
I do this all the time with my cast bullets :D. On a 550gr bullet I sort them into groups that are +/- 0.2 grains. Anything that strays too far from the median gets tossed (remelted in my case).

Chris.
Click to expand...
Yes, but in the cast bullet case, the variation in weight may signify a void (air bubble) that affects the symmetry and stability of the bullet much-much more than the difference in weight. I guess you're kidding about the +/-0.2 gr variation on a 500 gr bullet because if this is the accuracy you expect just from mass variation, well....Also, it's more likely to create an air pocket toward the base of the bullet, which makes things worse accuracy wise. Jacketed bullets do not have the same problem of air pockets.
 
lots of people weight sort bullets Hell i know a few that weight sort primers. Is there a difference yes if you shoot the lightest and the heaviest in the same string there will be a difference.

The pic shows 13 on the light side use those as blow offs or fowlers.in f class you get 2 sighters and 15 for score try and batch 17 of the same weight per relay this way you can be confident that any particular relay you have reduced or eliminated one more variable.

Best of luck
Trevor
 
Will be interesting to see if you can detect the difference with a 308.
I would think something like a 6mbr would be more sensitive...Hard to say.
Only one way to find out. :D
 
I don't think the weight variation makes that much difference, especially at shorter ranges. I did a quick calculation on a 100 grain .264 bullet at 3600 fps. If you keep the muzzle energy constant (same powder weight), a 99 grain bullet will go 3618 fps. At 100 yards that makes the bullet impact 0.01" higher. At 1000 yards it is starting to get significant for target shooters trying to pull a 5" group. POI will elevate 1.25", but still will not totally blow the target.

I've checked a few Berger and Sierra bullets for weight and calculated standard deviation of weight. Math tells us 99.7% of weights will be within +/- 3 standard deviations. So here are the weight tolerances I got for the 99.7% confidence levels. All bullets were 6mm.

Bullet - +/- 3 Std Deviations
Berger 62 - 0.09 grains
Berger 68 - 0.07 grains
Bart's Ultra 68 - 0.144 grains
Sierra 75 - 0.105 grains

Based on this out of a box of 100 you would expect 0-1 of the Bergers would not make +/- 0.1 grains, of the Bart's 1-2 rejects, and probably 1 Sierra.

Based on the quality of bullets I'm shooting I'm looking at less than 0.001" variation at 100 meters due to bullet weight variation. I've stopped weight sorting, as it appears to be a waste of my time. Even at +/- 1 grain it would still likely be a waste for the distances I shoot.

This said, if the bullet manufacturer cannot keep bullet weight withing +/- 1% you have to wonder what else is changing from bullet to bullet. One significant but virtually impossible to measure variable is the concentricity of weight around the axis, or axial balance. An out of balance bullet will wobble and will be worse the faster the twist of the barrel.

So I think what makes sense is to weigh bullets on a sample basis and just not buy them again if quality does not measure up. I also measure bearing suface diameter and length to check quality, and still sort using those numbers.
 
ryandpahl said:
I just received my new precision scale in the mail a few days ago. My first test was to weight sort the bullets I plan to use in the upcoming F-class season.

Does anyone else do this? Is it worth the time? It took me about 2 hours to sort this box of 500 bullets for the Pic.

I was surprised at how wide the variance in weight was. 174.88 to 175.52 grains.


Weight Sorting by ryandpahl, on Flickr
Click to expand...

Just wondering what kind of scale your using? I use a charge master 1500 combo but wouldn't mind getting a scale that measures to the nearest hundredth. As far as weighing bullets, I shoot 95gr Beger VLD's outa my 6mm and I have tried weighing and sorting and have not seen a difference. I am actually quite surprised on the variance in weight of the SMK's. It was mentioned before that if you have + or - extremes use them as foulers.
 
Ron AKA said:
This said, if the bullet manufacturer cannot keep bullet weight withing +/- 1% you have to wonder what else is changing from bullet to bullet. One significant but virtually impossible to measure variable is the concentricity of weight around the axis, or axial balance. An out of balance bullet will wobble and will be worse the faster the twist of the barrel.
Click to expand...

Ever seen one of Verne Juenke's Internal Concentricity Comparators? I haven't but seems like an interesting idea. The author of the article below had a Remmy 700 shooting in the 2's after checking bullets in the ICC. Who knows?

http://w ww.24hourcampfire.com/reloading.html
 
TargetNorth said:
Ever seen one of Verne Juenke's Internal Concentricity Comparators? I haven't but seems like an interesting idea. The author of the article below had a Remmy 700 shooting in the 2's after checking bullets in the ICC. Who knows?

http://www.24hourcampfire.com/reloading.html
Click to expand...

It appears to be using ultrasonic technology to measure the jacket thickness and detect voids between the jacket and lead core. If it works it probably would help. The other way may be to chuck the bullet, spin it, and measure vibration. However tough to do as bullets get up to 300,000 rpm or so, if I remember right.

The Accuracy Den
 
I def. weigh and sort cast bullets if for my own or others' target shooting, such as benchrest or long range BPCR.....Ben
 
TargetNorth said:
Ever seen one of Verne Juenke's Internal Concentricity Comparators? I haven't but seems like an interesting idea. The author of the article below had a Remmy 700 shooting in the 2's after checking bullets in the ICC. Who knows?

http://w ww.24hourcampfire.com/reloading.html
Click to expand...

Hang onto one if you have it - Vern J has retired from making these units.
 
TargetNorth said:
Ever seen one of Verne Juenke's Internal Concentricity Comparators? I haven't but seems like an interesting idea. The author of the article below had a Remmy 700 shooting in the 2's after checking bullets in the ICC. Who knows?

http://w ww.24hourcampfire.com/reloading.html
Click to expand...

That guy should hang on to that Remington, It sure is a rare one.

NormB
 
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