Exterior Ballistics Question

W

WinDrummer

New member
Hey folks,
Got a question here for you. I've been out testing my new chronograph with my handloads and some factory ammo and I'm getting some interesting results from Hornady V-MAX's. I'm shooting a Savage Model 12 FCV .22-250 with 1-8" twist. I'm getting good, consistent velocities from my handloaded 60gn Hornady SP's, 60gn Hornady V-MAX's, and a box of factory Federal 55gn SoftPoints, with 5-shot Std Devs in the high teens, low 20's FPS. With the exact same powder load (32.00 +/- 0.05gn IMR 4064) the V-MAX's shoot almost exactly 100FPS faster than the SP's, despite being the exact same weight (Chrono distance 10ft from muzzle). Not sure why this is happening, as they are the same weight and same powder behind them, but at least the target POI impact makes sense, with the V-MAX's hitting a bit higher.

Things get a little weirder when I compare the V-MAX's to the Fed 55gn SoftPoints. Lighter bullet, so the Fed's are shooting 350FPS faster than the V-MAX's - 3735 vs 3386). Despite all this extra speed, the V-MAX's still have a POI higher than the Fed's. My target is at 130yd, and the ballistic calculators I have (Nikon SpotOn and Vortex LRBC) show this not being nearly enough distance for the V-MAX's higher BC of 0.265 to have much impact over the Fed's 0.208.

Any thoughts? I'm running a 50mm objective lens on the scope and have a heavy-barrel rifle so my sight height will be a bit higher than average (no exact measurement, sorry), but I'm not sure if that would account for it. If anyone has a true ballistic calculator (the ones mentioned above work from your POI zero distance and work backwards to give bullet path) and can give an explanation that would be sweet.

Because I'm making the comparison based off 4x 5-shot groups for each bullet, the data was gathered on the same day, I'm getting low velocity deviations, and the gun is holding an average of right around .600 MOA groups on the target, I'm reasonably confident I'm not over-analyzing junk data.

I'd get some information for distances beyond than 130yd but that's the only target/backstop I have set up right now (shooting on my acreage).

Thanks,
Mitch
 
Last edited:
Different bearing surfaces create different pressures so different velocity at same weight.


Different bullets usually hit different places. My 68gr load isn't even on the same sheet of paper as my 55gr load from my .223. The 68gr load is higher though, and 400fps slower.


Faster usually impacts lower on targets for me, not higher.
 
Ditto what was said above. Different loads just shoot to different POI. I've found that changing seating depth can even have a significant effect on POI. Different bullets have very different profiles, so even if they have the same mass, they will have different muzzle velocities. My 215gr Berger Hybrid load shoots just slightly faster than my 208 Hornady BTHP load in my 300 WM, with the same powder charge.
 
Recoil, barrel harmonics, slightly different jacket construction or hardness of the core... Lots of things can cause different bullets to have a different POI. Even the same bullet, different lot#.
 
Thanks for the responses, everyone. I definitely have a lot more to learn, and not ignoring the internal ballistics part of the equation is high on the list.

Out of curiosity since we're on the subject, have any of you tried to tune different loadings to bring their POI closer together? Say for example the purposes of being able to carry two different loadings in the field, such as a short-range and a long-range option, larger-game vs. smaller-game loading, etc?

Thanks
 
Back
Top