Tuning Because SOME of us really would like to know

[oldsparky]

Hey Bob and Cole that you. I remember in the past some guys capturing pistol bullets in a saw dust trap they made up. Hey Cole are there still any saw mills up there that may donate some saw dust? I am all ears to hear what you find about obturation.

 

[oldsparky]

Can I ask another question? Do you know if the pellet drop was consistent with the BC? Also do you think the BC would change if all the starting velocity were the same? Just questions. Your data is making me think.

 

[Arzrover]

Since it would require very careful testing of each one individually to determine the drop vs bc, I haven't gone that far yet. My experience so far is that my LabRadar results generally can be applied directly in Strelok or Shooter and need no or very little tweaking.
I DO think that having starting velocity the exact same could change it some. The Tsar comes to mind. It NEEDS to be going slower but is a good example of WHY. It is quite accurate but not good in the wind and very inefficient. It has a hammer preload adjustment but that is at minimum and no stroke or port adjustment. I went way down on reg pressure but maybe I need to go up....endless stuff. I did tweak the Steyr, USFT and Theoben to get them close as practical.

 

[JungleShooter]

Bob and Frank,

I really appreciate all your efforts into running this test.
And that you are sharing the data with us!
This is great!!



I have a question about the BC values.

The published BC values for the .177cal JSB 10.34gr dome are usually quite a bit lower than what the Labradar data of the test shows.
As a matter of fact, most .177cal pellet BC's are usually so low that I simply crossed that caliber off my list....


Would you have any light to shine on this matter?
➔ I'm truly confused and I'm questioning my choice of the .22 caliber over .177 as the Labradar BC's for the 10.34gr are far better(!!) than the published BC's for most .22cal pellets....

Here's what I found:
0.031 ChairGun
0.029 Strelok Pro
0.025 GPC Ballistics Applications

HardAir Magazine curiously lacks the 10.34gr data — but of the 57 pellets they tested in .177cal none gets even close to the Labradars BC's: There are a couple of
0.029 and a couple of
0.025 —
usually by rather heavy pellets — and it's downhill from there.

—————————

On the other hand, the doc in the OP shows the following BC's:
0.039 1x
0.037 2x
0.036 1x
0.035 2x
0.034 2x
0.033 2x
0.030 2x
0.029 1x

—————————

These .177cal BC's are quite a bit better than most .22cal BC's. Which comes as a shock to me as the .22cal are so much heavier (though not necessarily with a higher sectional density).



No critique intended. I'm just confessing my confusion.
And I'm wondering if I should be buying .177cal guns instead of .22....



Thanks, guys. Love threads like this one!

Matthias

 

[Emu]

I am not a professional like you.

But from my empiric findings, it worth for you to look the behavior of NSA .177 cal 12.5 grain slugs in a combination with a Vulcan 3.

Just give it a try..... Your above groups will be a shame. And the Vulcan 3 is much affordable that all the rifles you tested.

 

[Franklink]

Matthias,

I'm intimately familiar with the the trajectory of my USFT from 10-55 yards. As-in, I have shot and verified every single yard in that distance range.

I have a BC value of 0.035 in the Strelok page on my phone for that gun to most closely match actual trajectory. 10.34gr JSBs at an average of 915-920.

I have confirmed BCs with the speed at two distances method to be in the same ballpark.

If the desire is critter killing, the .22/18.13 is the better choice. The .22/18.13 and the .177/10.34 have similar BCs, but the .22 gets there with more authority, mostly because it started with more fpe. So, while their retained energy vs distance plot may have a nearly identical decay rate, the .22 has more left when it gets there because it started with more.