Sorting Pellets for precision

[thomasair]

Wouldn’t surprise me. My 244...and all my other 100y scores were with pellets from the tin.

Think about the purpose of a rimfire tuner. You are basically hanging an adjustable weight to tailor the barrel oscillation to minimize the vertical spread. Rimfire ammo is not particularly tight ES. They achieve tight vertical despite the poor velocity spread because you are timing the exit of the bullet to the upswing of the barrel. Slower shots exit the barrel a little later and therefore are a little higher in the barrel swing. Faster shots exit the barrel a bit sooner in the upswing. These timing differences produce a desirable effect. Get the tune on the downswing and you have a very large vertical stringing.

Fortunately...we get to control the speed of the pellet with an Airgun so we have no real need for a tuner. Ever wonder why a pellet seems to shoot better at a particular speed. It’s not because that’s what the pellet likes...it’s because you found a desirable harmonic timing. Shorten the barrel...and the pellet will like a different speed. Put a barrel band on the barrel...the pellet will like something else. These dang fussy pellets.

Its way more complicated than that...but that’s a nutshell version. You can get tight vertical spreads with loose velocity spreads.



Mike

 

[Chuck-in-Ohio]

I sort pellets by both head size and weight because I can.

Usually in the evening while viewing television with SWMBO, I can sort through a tin or two in short order. She also retires earlier than I do, so I can always find time to knock a tin out then as well.



Now, my justification for doing so may sound like complete malarkey to some, but here goes.



I feel that it instills confidence, and gives me a little psychological boost to know that I have removed every variable that I physically can. This allows me to quickly assess any errant shot in comparison to my wind read and refine my reading ability. If the shot looked good in the scope, and felt good going out, that leaves only me.

Yeah, I know it sounds like some hoodoo BS, but I KNOW in my head that the only variable affecting the pellet flight is my interpretation of the environmental conditions because I have seen to the minimization of all other factors. Plus, I have free time in the evenings...............

 

[oledawg]

I sort pellets by both head size and weight because I can.

Usually in the evening while viewing television with SWMBO, I can sort through a tin or two in short order. She also retires earlier than I do, so I can always find time to knock a tin out then as well.



Now, my justification for doing so may sound like complete malarkey to some, but here goes.



I feel that it instills confidence, and gives me a little psychological boost to know that I have removed every variable that I physically can. This allows me to quickly assess any errant shot in comparison to my wind read and refine my reading ability. If the shot looked good in the scope, and felt good going out, that leaves only me.

Yeah, I know it sounds like some hoodoo BS, but I KNOW in my head that the only variable affecting the pellet flight is my interpretation of the environmental conditions because I have seen to the minimization of all other factors. Plus, I have free time in the evenings...............

I agree completely chuck-in-ohio, shooting, like all competitive sports has a mental aspect to it. 

 

[Chuck-in-Ohio]

Right on oledawg, I am glad that my rambling made a little sense to someone besides myself.



IF that psychological edge was reflected on my cards I would be in tall cotton, but alas, I tend to distribute pellets quite randomly about the bull!!

 

[thomasair]

To get good at anything in the shortest amount of time....triage must be employed. We all have limited time and resources. Making the absolute best use of your time to advance your scores is paramount. That requires very brutal honestly about your own shortcomings...whether that is equipment or skills. You must spend your time and your money on the things that will most advance your scores first. Once you have worked those issues out, you can move on to the next most important on the list.

I am happy I spent the time to do the boring long term testing of head sorting years ago, as it has saved me countless hours that I have been able to apply to other more important aspects of my shooting. Head sorting is so low and insignificant on my triage list that I will never get to it.

Mike 

 

[JungleShooter]

Thank you all for helping me to finally get clarity on this pellet sorting issue that's been bothering me for quite a while.

Thank you, Mike/ ThomasAir!!



I've saved the link to this thread, should I want to revisit the issue again.



I appreciate arguments based on empirical testing — with large enough "sample sizes" (i.e., more than one 5-shot group for each test condition) — even if the test data is not published it's much better than arguments like "Well, what works for me is...."



The psychological aspect feels(!) very valid, Chuck!

And may I add: Sometimes we just like to do airgun stuff — but we feel we can't go shooting AGAIN or any MORE HOURS — as someone would start criticizing us, or because of limitations of weather/ time of the day/ location — so we do airgun stuff that is less "criticizable" or that is more doable within our limitations — but we're still getting do to airgun stuff...!  



Matthias

 

[zx10wall]

I really don’t want sorting to make a difference. I think it’s a pain to do. With that said, I shot a string with my .30 Vulcan 2 after tuning. This string is with pellets that all weighed 44.8 grains rather than the usually variance in weights usually seen from the tin.

To compare some numbers, my usual SD (straight from tin) is 3.8 and ES is 12 as compared to the below string of 1.9 SD and 7 ES (sorted by weight)! Question is, would this tighter performance make a difference on target? I don’t know as I have not tested it on paper. What are your opinions?

Created: 07/18/20 04:10 PM
Description: Vulcan 2
Notes 1: 
Notes 2: 
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 0.043
Bullet Weight(gr): 44.75
Temp: 91 °F
BP: 1014.87 inHg
Altitude: 120.00
# FPS FT-LBS PF
28 855 72.65 38.26
27 854 72.48 38.22
26 855 72.65 38.26
25 855 72.65 38.26
24 855 72.65 38.26
23 856 72.82 38.31
22 858 73.16 38.40
21 853 72.31 38.17
20 854 72.48 38.22
19 858 73.16 38.40
18 857 72.99 38.35
17 856 72.82 38.31
16 857 72.99 38.35
15 852 72.14 38.13
14 857 72.99 38.35
13 855 72.65 38.26
12 858 73.16 38.40
11 854 72.48 38.22
10 859 73.33 38.44
9 857 72.99 38.35
8 858 73.16 38.40
7 857 72.99 38.35
6 859 73.33 38.44
5 854 72.48 38.22
4 854 72.48 38.22
3 858 73.16 38.40
2 857 72.99 38.35
1 858 73.16 38.40
Average: 856.1 FPS
SD: 1.9 FPS
Min: 852 FPS
Max: 859 FPS
Spread: 7 FPS
Shot/sec: 0.1
True MV: 858 FPS

 

[Kim]

zx the improvement in ES may not affect accuracy. Using a benchrest gun with ES about 2% of pellet velocity I once tested vertical POI as a function of variation in FPS. Shooting with a dedicated rest on a solid bench in early morning dead calm (flag tails limp), I did not find a correlation between FPS and vertial POI on a test target. In fact, some of the slowest shots hit higher on the paper than faster shots.

Not sure why this would be - possibly the BC went down with higher velocity.

You could do a similar test with your sorted vs unsorted pellets

 

[Chuck-in-Ohio]

I would think that the lower variance would be more readily apparent at long range.

Long range being @100 and beyond.



Then again, as consistent as your rifle runs with unsorted pellets, any benefit may very well be cancelled by biological error or uncompensated for environmental variables.



Just my thoughts, nothing more.

 

[Centercut]

I really don’t want sorting to make a difference. I think it’s a pain to do. With that said, I shot a string with my .30 Vulcan 2 after tuning. This string is with pellets that all weighed 44.8 grains rather than the usually variance in weights usually seen from the tin.

To compare some numbers, my usual SD (straight from tin) is 3.8 and ES is 12 as compared to the below string of 1.9 SD and 7 ES (sorted by weight)! Question is, would this tighter performance make a difference on target? I don’t know as I have not tested it on paper. What are your opinions?

I plugged your numbers in Strelok Pro and with s True MV difference of 5 FPS, it equates to a 0.2 MOA difference at 100 yards. Could be the difference between a 9 and a 10, or winning and losing. 

 

[Kim]

" plugged your numbers in Strelok Pro and with s True MV difference of 5 FPS, it equates to a 0.2 MOA difference at 100 yards. Could be the difference between a 9 and a 10, or winning and losing."



I would suggest that actual shooting is better than simulations. For example higher velocity sometimes reduces BC, and if so the POI could be lower than lower velocity.

 

[Chuck-in-Ohio]

Slower pellets hitting higher could be an effect of harmonics.

 

[Kim]

Here is one of the studies

https://benchrest.com/showthread.php?97104-Vertical-POI-testing

 

[Centercut]

Huge difference between 25M and 100Y. It’s strange that I was told yesterday when discussing BC that actual drop data wasn’t as accurate as derived speed from a Chrony when determining BC. Now I’m being told that actual data is more accurate that scientifically calculated data. Which is it?

As far as vertical stringing, very easy to check at 100+ yards. Probably not at chip shot distance. But anyway, shoot ten shots at your normal speed then increase that by 10 FPS and shot ten more. Measure the average drop between the two ten shot groups, and you’d have your answer. Which by he way, will correspond with the Strelok Pro derived data since I’ve done this exact test numerous times...

PS., BC changes with only a 10 FPS variance are statistically insignificant. 

 

[Chuck-in-Ohio]

Thanks for sharing that crash course in statistical analysis Kim, the minutiae is sometimes as fascinating, or more so, than the activity itself.



1/4 MOA is nothing to take lightly once you step out a ways in yardage as Mike pointed out.

Has anyone done a comparison similar to Kims at extended range?

 

[thomasair]

Checking BC using poi is the least accurate way and fraught with error.


Pellets rise in a left to right wind....and fall in a right to left. I can’t begin to analyze the variances well enough at 100y to predict their exact behavior. When I attempted to use poi to determine BC at 50y....I had wild variances. 100 and further are surely less reliable.

Harmonics are very much a factor that can make a slow shot go high. I made a post about this already....don’t remember if it was in this thread.

Thats how Rimfire barrel tuners work to eliminate or shrink vertical stringing.

Mike

 

[thomasair]

Here, read this.



http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm



Mike

 

[lhandy]

Although I'm not a competiton shooter. I have shot many thousand's of pellets in my day. Along with many PB rounds down range. I find that when it comes to the magic pellet or bullet. I think has to do more with how square the skirt or bullet tail exit the crown of the muzzle then how tight your ES and SD are. From what I see with how well tuned you guys that shoot competitively have your rifles working. Maybe the magic is in how square the tail exits the muzzle from the magic tin. 

I also know that the best BR shooters shoot flat base bullets not boattails just for this reason.

This is coming from a guy that just likes to shoot for fun.

 

[mmahoney]

@thomasair

Interesting. So basically, I need to be tuning the velocity of my pellets to my barrel and not be looking for a velocity the pellet "likes". If this is the case, all projectiles out of my barrel should prefer the same velocity, correct?

 

[thomasair]

Mike....no, not true. You will not generate the same impulse to the barrel with different pellets, power levels, or levels of tune.

Mike