Pellet Weight Difference

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With my .30 I found no difference. Sort a bunch and put the heaviest with the lightest (excluding truly 'wrong' pellets) and shoot them and see if they group any differently than the others.

There can always be a couple rounds that are simply incorrect in some way. Sorting does give you the chance to eliminate those and you put your eyes and hands on each one. But I think those are generally more useful than having the pellets sorted in groups.
 
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MikeAllen said:
How much difference does pellet weight make for the POI at 50 or 100 yards? I'm particularly interested in .25 caliber.
Click to expand...


OK, let's assume that a different pellet weight will result in a different muzzle velocity MV — assuming that the gun is perfectly even in its power output.

Let's assume a 50FPE gun, with two typical .25cal pellets:
(1) JSB Domed 25.39gr | 0.037BC | 942fps MV = 50FPE

(2) JSB Heavy Mk2 33.95gr | 0.046BC | 815fps MV = 50FPE


Let's assume a fairly large weight error of 1.0gr with the resulting velocity offset:
(1) 25.39 ➔ 24.39gr
942fps ➔ 952fps

(2) 33.95 ➔ 32.95gr
814fps ➔ 826fps

Using Chairgun (mobile), the graphs and tables can be adjusted to use the same barrel angle as one of the 4 selected pellets.



🔶 POI Error at 50y:
The 25.39gr will hit 0.1" higher when it is 1.0gr too light (24.39gr).

The 33.95gr will hit 0.2" higher when it is 1.0gr too light (32.95gr).


🔶 POI Error at 100y:
The 25.39gr will hit 0.42" higher when it is 1.0gr too light (24.39gr).

The 33.95gr will hit 0.84" higher when it is 1.0gr too light (32.95gr).

➠ Now, you need to see if you can live with that.


Below a graph that shows the POI error at 100y for the 33.95gr pellet (the 25.39gr is not correctly displayed in this graph).
● green line = 33.95gr
● purple line = 32.95gr = 1.0gr too light ➔ hits 0.84" high



Screenshot_20240906_205048_ChairGun.jpg




Cheers, 😃

Matthias
 
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JungleShooter said:
OK, let's assume that a different pellet weight will result in a different muzzle velocity MV — assuming that the gun is perfectly even in its power output.

Let's assume a 50FPE gun, with two typical .25cal pellets:
(1) JSB Domed 25.39gr | 0.037BC | 942fps MV = 50FPE

(2) JSB Heavy Mk2 33.95gr | 0.046BC | 815fps MV = 50FPE


Let's assume a fairly large weight error of 1.0gr with the resulting velocity offset:
(1) 25.39 ➔ 24.39gr
942fps ➔ 952fps

(2) 33.95 ➔ 32.95gr
814fps ➔ 826fps

Using Chairgun (mobile), the graphs and tables can be adjusted to use the same barrel angle as one of the 4 selected pellets.



🔶 POI Error at 50y:
The 25.39gr will hit 0.1" higher when it is 1.0gr too light (24.39gr).

The 39.95gr will hit 0.2" higher when it is 1.0gr too light (38.95gr).


🔶 POI Error at 100y:
The 25.39gr will hit 0.42" higher when it is 1.0gr too light (24.39gr).

The 39.95gr will hit 0.84" higher when it is 1.0gr too light (38.95gr).

➠ Now, you need to see if you can live with that.


Below a graph that shows the POI error at 100y for the 33.95gr pellet (the 25.39gr is not correctly displayed in this graph).


View attachment 494394



Cheers, 😃

Matthias
Click to expand...
Great evaluation - thanks!
 
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MikeAllen said:
How much difference in pellet weight makes a difference in accuracy/POI at 50 or 100 yards? I know this probably depends on caliber - I'm particularly interested in .25 caliber weight differences and benchrest accuracy. Just trying to eliminate variables!
Click to expand...
a balistic drop calculator might be handy for that or order a tin of JSB's for a variety of weights
JungleShooter said:
OK, let's assume that a different pellet weight will result in a different muzzle velocity MV — assuming that the gun is perfectly even in its power output.

Let's assume a 50FPE gun, with two typical .25cal pellets:
(1) JSB Domed 25.39gr | 0.037BC | 942fps MV = 50FPE

(2) JSB Heavy Mk2 33.95gr | 0.046BC | 815fps MV = 50FPE


Let's assume a fairly large weight error of 1.0gr with the resulting velocity offset:
(1) 25.39 ➔ 24.39gr
942fps ➔ 952fps

(2) 33.95 ➔ 32.95gr
814fps ➔ 826fps

Using Chairgun (mobile), the graphs and tables can be adjusted to use the same barrel angle as one of the 4 selected pellets.



🔶 POI Error at 50y:
The 25.39gr will hit 0.1" higher when it is 1.0gr too light (24.39gr).

The 33.95gr will hit 0.2" higher when it is 1.0gr too light (32.95gr).


🔶 POI Error at 100y:
The 25.39gr will hit 0.42" higher when it is 1.0gr too light (24.39gr).

The 33.95gr will hit 0.84" higher when it is 1.0gr too light (32.95gr).

➠ Now, you need to see if you can live with that.


Below a graph that shows the POI error at 100y for the 33.95gr pellet (the 25.39gr is not correctly displayed in this graph).
● green line = 33.95gr
● purple line = 32.95gr = 1.0gr too light ➔ hits 0.84" high



View attachment 494394



Cheers, 😃

Matthias
Click to expand...
Wow..Sweet write-up...Thank You @JungleShooter
 
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manabeknives said:
a balistic drop calculator might be handy for that or order a tin of JSB's for a variety of weights

Wow..Sweet write-up...Thank You @JungleShooter
Click to expand...
So true about the JSB's! Also true for the FX's (which, yes, are made by JSB). I'm finding the AEA Center Punch pellets to be very consistent in weight. No hesitation shooting right from the tin.
 
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MikeAllen said:
So true about the JSB's! Also true for the FX's (which, yes, are made by JSB). I'm finding the AEA Center Punch pellets to be very consistent in weight. No hesitation shooting right from the tin.
Click to expand...
i did a sorting of 1000 JTS pellets for weight ..i ended up with 2 piles within 1/10th of a grain using a scale to 1/100th and 4 that were under target weights ...none over...super impressed. Did another 1k...same results.
if i had done the same with JSB's ..i'd have 10 piles of various weights
 
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manabeknives said:
i did a sorting of 1000 JTS pellets for weight ..i ended up with 2 piles within 1/10th of a grain using a scale to 1/100th and 4 that were under target weights ...none over...super impressed. Did another 1k...same results.
if i had done the same with JSB's ..i'd have 10 piles of various weights
Click to expand...
JTS and AEA are the same, right? Also, you'd be lucky not to have 20 piles!
 
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A more concerning problem with pellets with a large weight variation is where in the pellet is the extra weight, or the loss in weight, and is it on the centre line or somewhere else? If the weight change is off the centre line it will give an off-centre CG and that can ruin groups, much more than just the pure weight effect.
 
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Ballisticboy said:
A more concerning problem with pellets with a large weight variation is where in the pellet is the extra weight, or the loss in weight, and is it on the centre line or somewhere else? If the weight change is off the centre line it will give an off-centre CG and that can ruin groups, much more than just the pure weight effect.
Click to expand...
I guess that could be the case even if they all weighed the same!
 
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I sorted some H&N 18gr pellets by weight and by head size. I could not see any difference when sorted by weight only. But when I sorted by head size only, the bulk end in the 5.52mm tin. I had very few 5.54mm or the other extreme 5.50mm was even less, sometimes even nothing of the extremes from a tin. My rifle prefer 5.52mm which give the smallest groups and tolerate 5.51mm. The 5.53mm will result in bigger groups and more flyers. The 5.52mm is not immune to flyers but it is less.

Sorting JSB 18gr, again weight did not make a difference. Sorting by head size the bulk is 5.53mm followed by 5.54mm and then 5.52mm and even a few 5.55. Even the 5.52mm is not giving small groups as the H&N unsorted.

When I take the H&N 18gr sorted by head size 5.52mm only and further sort it by weight, I see no difference in group size nor amount of flyers.

I sorted other pellets as well but only give this as an example as this is what I sorted the most.
 
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