NSA Slugs without BC- POST YOUR BC

Forums Pellets, Projectiles, Slugs, & Ammo NSA Slugs without BC- POST YOUR BC

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    davidsng
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    I notice some of the NSA slugs dont have a bc listed for them, but most do.  

    Let's list the BC's of the unspecified slugs that we got from our testing. This will save our fellow members some time.

    • This topic was modified 4 months ago by davidsng.
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    davidsng
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    I tested .358 75 grain NSA slugs on two separate occasions.  I got a BC of 0.065 and 0.068 on the two tests.  So around 0.0665 is average.

    UPDATE: I used 20 or shots at 0 yards and at 50 to get the bc.  70 degrees Fahrenheit. Around 65 humidity, and 700 ft above sea level. American Airgun  Classifieds calculator was for the bc calculations.

    Update: Tested with Ataman m2r .35 with a lothar wather barrel.

    • This reply was modified 4 months ago by davidsng.
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    JungleShooter
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    davidsng,

    that's an excellent idea. I have yet to test my NSA slug samplers, but I'm fully committed to measuring and posting BC's. Just yesterday a neighbor said he'd take me to a 120 yard long shooting tunnel with two chronometers, right here at a the local Navy base. Hopefully those chronometers will work with tiny .22 pellets and slugs….  I'm super excited!! 😁

    Suggestion: Some BC calculators are less accurate than others. And all of them will calculate inaccurate BC's if we don't feed them right right atmospheric conditions under which the testing was done.

    So, maybe we could report our BC's something like the following:

     

    .22cal, 33grain NSA slugs.

    Calculator ChairGun

    Weather: 33.22 in Pressure | 68F | 55% Humidity

    Average of 10 shots at muzzle (866fps) and at 75 yards. One chronograph only.

    BC = 0.955

     

    Happy shooting and testing.

    Matthias

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    JamesD.
    Participant
    Member

    JSB Heavy Diabolos in .22 0.364-0.456 ???

    Piledriver .22’s 0.096 same as .22WMR 30 grain but 1250fps slower.

    NSA Almost anything .22 0.97/8-0.1

    VK’s Almost anything .22 0.97/8-0.1

    NSA & VK’s in .25 Slightly lower in same weight as .22’s like 33’s are 0.93-0.96

    .30’s around 0.0456

    .357’s around 0.0665

    Reason I want (3) 257’s: A shorter barrel Raptor almost 28”. 1:14 TJ for 65 RBT NSA .193BC

    Reason I want a 36” Texan in 1:14 same as above but  125-175 ftlbs

    36” 1”OD chrome lined bull barrel 1:12-1:13 for 92-105 grain 257’s .212-??? Testing needs to be done. 95’s @ 950-1015 had 190-205fpe .212BC but I’m only at 700’ASL and 800-950 fps is fine. I’m waiting for that guy who was trying to match BC to caliber. Can anything do it? Maybe a single shot long .177 or .257?

    Feel free to quote, edit, expound on what you’re seeing or reading. 

     

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    davidsng
    Participant
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    Jungle Shooter, JamesD

    Great idea, info.!  I'll update.

    +1 for the great ideas. Thx

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    mtnGhost
    Participant
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    It is important to identify the rifle and barrel used in the tests!

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    davidsng
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    mtnGhost

    It is important to identify the rifle and barrel used in the tests!

    Thanks, will update.

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    AirgunNH
    Participant
    Member

    Not sure how much difference air temperature plays in BC, but for the NSA 36.2 gr 0.25 slug I’m getting a significantly lower BC than the 0.1 reported. 

    FX Impact MKII 700 mm w/ slug liner

    Air temp 36 F

    Altitude 1400 feet

    Muzzle velocity 890 fps 

    velocity at 65 yards 790 fps 

    According to the Pyramyd air calculator, this works out to a BC of 0.069, compared to 0.1 reported.

    (Not sure if it makes a difference, but barrel was very dirty but still shooting 1.5 inch groups at 100 yards.)

     

     

     

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    JungleShooter
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    AirgunNH,

    thanks for the data! πŸ‘πŸΌ

    The JBMBallistics.com caculator allows to enter atmospheric data (with barometric pressure having the biggest effect…). The PyramydAir calculator does not consider atmospheric conditions…. πŸ˜•

    I'm getting a BC of 0.081, with an assumed standard pressure at MSL of 29.92hg, and the G1 drag function (I hope I can attach the screen shot).

    ChairGun (for which I would need my laptop) also calculates the GA drag function, a little more appropriate for airgun pellets.

     

    Why the difference? 

    πŸ”Ά (1) Every barrel is different…. (I hate this reason.) 

     

    πŸ”Ά (2) Errors in the input data produce errors in the output…. E.g.:

    —1 yard  error in the actual range between the chronographs: —> 0.001 error

    —If your barometric pressure (calculated for MSL) was actually not 29.92, but 28.92: —> 0.002 error

    —9 fps total error in the averages of the two velocities (@ muzzle and @ target): —> 0.01 BC error, so instead of 0.080 you'll get 0.090

    This velocity error is "easily achieved" 🀣  (esp. with only one chrono, and using only a small amount of shots)…: Our guns often have an extreme spread of 10fps muzzle velocity, some a lot more. Now all you need is that, by coincidence, the first 5 shots are around 4fps higher than the average MV, and the next 5 shots 5fps lower. There you get a 9fps difference, and that offsets your BC by 0.01.

    —Now, all these possible errors add up….

     

    Thanks for sharing your data! πŸ‘πŸΌπŸ‘πŸΌ

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    davidsng
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    These BC's are just a rough number.  All bc's should be checked/verified in the field before they can be really trusted.  There are too many variables to account for everything. 

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    Airgun-hobbyist
    Participant
    Member

    Not based any formula, but just on my initial FPS readings and my hold over MOA at a 236 yard target, my .30 caliber NSA 50 grain slugs are carrying a .055 BC according to the numbers on Strelock Pro.  This number would likely change, and look better, testing the slug's BC over just 100 yards.

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    Airgun-hobbyist
    Participant
    Member

    NSA .30 caliber 60 grain hollow point slug shooting 883 FPS with 175 yard zero gave a 20.76 MOA holdover at 236 yards, which in turn gave an overall distance BC of .080.

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    JWilson
    Participant
    Member

    NSA 15.5 grn slugs

    Edgun .177 Matador Std

    muzzle velocity 926 fps (30 FtLb)

    .071 BC

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