Other Why am I getting low ballistic coefficient?

Pellets have an erratic BC change during flight. Air pulse can affect a pellet right out of the muzzle, and any wind deflection or too high speed will also cause wild inconsistencies. Thats primarily why slugs are much higher performing in air rifles, they are much more stable during flight. Remember you are trying to shoot a lead parachute through the air at high speeds that wants to flip around backwards because the center of mass is the opposite of what the projectile wants. Any wind deflection or abnormal flight caused that parachute to try and flip forward, but then the skirt slows down the pellet and it "rights" itself.

So you wont see the same exact numbers as anyone else due to there being so many factors affecting the pellets ballistic travel. Your twist rate, your tune, your speed, your climate, your weather, your elevation, your chrono equipment, your etc.

What's your elevation? I'll be surprised if you're not down near sea level. From similar discussions like this, it seems the trend is that low elevation shooters see much lower BCs than high elevation shooters. And I did indeed read that you plugged in the parameters, including elevation, but I'm of the mindset that the ballistics apps don't quite account for the elevation factor sufficiently.

There's also speeds. Another factor could be if you're shooting projectiles much slower than they were shot at the speeds in the reports to which you're comparing.

What was the wind velocity and direction?
In your face will decrease bc(increase drag) and from behind will increase bc...
Bob

To me, 1,127 feet is low elevation.

As a field target shooter, trajectory is everything. KNOWING impact points at all distances is crucial. So I map out actual impact points on guns I plan to compete with. I live around 5600feet and have shot matches at a location that is very close to your elevation. Comparing trajectory from my house to those low elevation match sites is quite interesting. The net difference is an overall flatter trajectory at my house than at the low elevation matches, the longer shots at low elevation need more holdover/clicks. I have measured BCs at my house and they are always higher than nearly every reported BC I find online, even after plugging in the elevation. I've not yet had a chance to measure at lower elevations, but the difference in real-world trajectory during matches suggests a lower BC at lower elevations.

As Bob said, tailwind/headwind can really mess up the numbers. I once measured the .22/25.4 Monster RD with a BC of 0.074. MUCH higher than normal for that pellet, and that is because it was with a tailwind of gusts in the 18-22mph range. Tailwinds help the pellet retain speed, therefore falsely elevating BC, and vice versa would apply too (predominant winds at my house are tail-winds so haven't personally measured downrange speeds with head-wind conditions).

Also, 945 is probably hotter than reasonable for Hades. BC might actually go up slightly if you shoot them in the 880-915 range. And even if BC doesn't improve, you'll be conserving air if BC is as low as you're finding. When picking up a barrel from him, I once shot over Bobs Labradar and watched a particular pellet have the same downrange speed ( I think the trap was at 50 yards) whether they started at 900 or 960fps. Setting up a gun to push that particular pellet to 960 would have been needlessly wasting air. In other words, 960 was no ballistic advantage with that pellet, and is likely the case with your Hades @ 945.

MushroomPsyche said:

My elevation is 1,127 feet above sea level. I am shooting the 15.89gr Hades at 945 FPS and the NSA 17.5gr at 888 FPS. In my case, there are 3 apps that all corresponds with each other, JBM, Strelok Pro, and the Applied Ballistics app that the Sig rangefinder uses. As was stated above, it might very well be all the other factors such as twist rate, tune, and projectile velocity.

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Published pellet BC is based at their peak which is usually somewhere in the 800fps range. If you are starting in the mid 900s your actual muzzle BC is pretty low in comparison. This is why shooting a pellet faster may actually increase the effect wind has your shot. Slugs on the other hand are probably at their peak closer to the 1000fps range but don't hold me to that. Here's a graph for JSB pellets BC.

Sqwirl57 said:

This is why shooting a pellet faster may actually increase the effect wind has your shot.

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Anything above about 860 fps will start to have more wind drift with speeds slower than 2000 fps or so. My memory may not be correct on the 2,000 fps.

Notice the green line in RSterns graph above.....

.22/25.4 Monster RDs, their BC hasn't peaked out at the 790 at which the line stops. Mr. Sterne must not have shot them faster in this comparison.

From slow twist polygonal barrels, I've found the best BC from the 25.4g Monster RDs to be north of 950fps. Compared to most wasp waisted (Diabolo) shaped pellets, the .22/25.4 Monster is a rule breaker.

Franklink said:

Notice the green line in RSterns graph above.....

.22/25.4 Monster RDs, their BC hasn't peaked out at the 790 at which the line stops. Mr. Sterne must not have shot them faster in this comparison.

From slow twist polygonal barrels, I've found the best BC from the 25.4g Monster RDs to be north of 950fps. Compared to most wasp waisted (Diabolo) shaped pellets, the .22/25.4 Monster is a rule breaker.

Click to expand...

I was curious about that myself. Thanks for adding that bit of info