Was at Angeles today to practice. I used the same load I've been using since last year: .308 175g SMK, 42.2g Varget, 2.805" OAL. I prepared 50 rounds, each dispensed with a Chargemaster and verified with a 505 beam scale. This would be the 3rd time the brass had been reloaded.

After clearing some dots, I reconfirmed DOPE from 600 down to 200 yards. Temperature at 10am was 68, DA 2400. Ballistic AE's soft dope trajectory was spot on at every distance. By noon, temps had risen to 74, DA at 2787. I hadn't shot for an hour or so while helping Robojet collect dope. Rifle was on the ground in the shade all day, same with the ammo.

I updated the change in temp and DA into the app. The dope trajectory appeared unchanged. However, none of my shots were on target. I had to reduce drop at every distance to get back on target (example: -4.6 reduced to -4.3 @ 600 yards). When I trued the app with the new hard dope values velocity was corrected from 2607 to 2684 fps! This huge jump in calculated velocity makes me think I did something wrong updating the app. I chrono'd this load previously at 2619 average (in colder temps), but 2684 fps seems high to me.

I understand that velocity is gonna rise with increased DA. But I expected the app to update the trajectories accordingly. Was I supposed to do something else besides just updating temp and DA in the app before recalculating trajectory?

Thanks,
Jeff

Could be your load.

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In the face of a crisis, a failure to act is the first act of failure.
There are no stupid questions, just stupid people asking questions.
Sweat saves blood, blood saves lives, but brains saves both.

Firstly you can't check a CM with a 505 stop wasting time.

Sounds like you fucked something up in the app. Let's find out...

The DA is not going to change at ASR to matter don't bother updating it from now on.


I would bet you have some type of powder temp turned on, check that.

Did your hard dope differ from the morning? I should not. If so, you have a mechanical or shooter issue. If not, error in the app settings. Restart from baseline and don't worry about it



Sent from my iPhone.

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Team GAP, Shooter #7
Draining squares and banging steel

Charles, I guess the only thing I know for sure is I left the range with two sets of hard dope for distances of 200-600. In almost every previous shooting session, with the load I've been using, the soft dope calculated assuming a velocity of 2607 has generally been good enough to hit the steel. Your chronograph gave me an avg of 2619, and you thought the deviations it measured was due to the CM error rate of +/- 0.3g, or a mistake on my part prepping the brass.

We did have some tail winds today, maybe that was it, but it was only 5-10 mph and it really wasn't noticeable.

I'm going to give my FDAC card for 2600 fps a try next time I shoot. If it's good enough it'd be less hassle than messing around with ballistic.

Tail Winds? You're over thinking it....... In some way, shape or form, it's you.

_________________
In the face of a crisis, a failure to act is the first act of failure.
There are no stupid questions, just stupid people asking questions.
Sweat saves blood, blood saves lives, but brains saves both.

I can accept that. I just looked back at my hard dope records in my logbook. On average, it matches the FDAC card I have for a 2600 fps 175g SMK. I've got hard dope for DA between 2000 and 4000. The discrepancies vary by .1 at most out to 600 (most of the numbers match right up), so for simplicity I think I'll print up a card based on the FDAC, 100 to 1000 yards in 50 yard increments. A column for DA at 2k, 3k, and 4k. We'll give that a few tries and maybe I can just use the app to fill in some gaps for less common distances.

And yeah, I'm tired of thinking about this stuff.

Do you remember what the mirage looked like when you were gathering both sets of hard dope? Sometimes a boiling mirage will give you weird elevation changes, allegedly more so with a scope or post sight than aperture sights. It is also a great opportunity to get a solid wind zero.

Did you check Parallax?

I'm guessing you have the powder temp feature turned on as well...

What is this powder temp feature and where can I find it in the app?

You said you were shooting from 200-600.

Did you re-check your 100 yd zero when you were having the discrepancies in your dope?