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*UPDATED*RPR Range Outing #1

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Dumb question here...but did you give the ballistic app the correct height of the sight over the bore?

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Dumb question here...but did you give the ballistic app the correct height of the sight over the bore?

Yes Sir! I measured it as accurately as possible.

 

I have a hunch that accurate BC numbers will likely make the difference, along with pinpoint re-zeroing.

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The BC of the bullet will drop as velocity drops. Why a change from last time I do not know.

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The BC of the bullet will drop as velocity drops. Why a change from last time I do not know.

I think that I'll just have to start over from scratch when the second Chrony arrives. Re-zero @ 50yds, re-chronograph MV, and chronograph velocity @ 100yds, then re-crunch all the numbers corrected for climate conditions.

These slow moving lightweight pills are a challenge to map out with their rainbow trajectory.

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They're not aerodynamic for sure.

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They're not aerodynamic for sure.

Just for snicks, when I'm done figuring out this puzzle I'll run some of the same ammo through my 10/22 with the 1:9 twist barrel to see how a faster twist affects it at longer range. It may be slower at the muzzle due to the added resistance, but could remain more stable when it gets out there.

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Good stuff, LH.

 

Not only are you getting get practice with your scope, trigger control, breathing, ballistic programs, etc,

you are doing it for a fraction of the cost of centerfire.

 

Not to mention the usefulness in being able to regularly plant a .22 LR in some "animal's" ear at

100+ yards, especially if suppressed, is not a skill to be trifled with under expedient circumstances

whether it be for food or another reason. Sometimes discretion is vital.

 

I'd be interested to know what a rifle like that does with the .32 grain high velocity rounds .

The trades offs between velocity and wind drift with the lighter bullet, and, as you said,

transitioning from super to subsonic could make for some interesting log entries...

 

:thumb:

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I'd be interested to know what a rifle like that does with the .32 grain high velocity rounds .

The trades offs between velocity and wind drift with the lighter bullet, and, as you said,

transitioning from super to subsonic could make for some interesting log entries...

John, in my search for BC values I ran across this article that you might find interesting, as it addresses much of what you're talking about....and more.

 

For instance: "The ballistic coefficient takes into consideration the area, length, weight, and streamlining features of the bullet, and is based on empirical testing. It is further dependent on whether the bullet is supersonic or subsonic due to the effect of the acoustic shock wave. That wave is why supersonic .22LR ammo is usually less accurate beyond 50 yards than standard velocity. As the bullet transitions to sub-sonic speed, it passes through its own acoustic wave which upsets its stability slightly."

 

https://1022companion.wordpress.com/2015/02/02/sight-adjustment-part-4-22lr-trajectory/

 

As you can see, there are reasons to stick with sub-velocity ammo and higher BC for the type of shooting that I'm trying to do. I'll likely try some other sub-velocity ammo that may be more consistent, but probably won't shoot any lighter bullets in this pursuit.

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My favorite round is CCI .22LR standard ve!ivory for accuracy in my Ruger 10-22s.

Edited by gshayd
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My favorite round is CCI .22LR standard ve!ivory for accuracy in my Ruger 10-22s.

That has been my experience too. It's the reason I have so much of it.

 

Second Chrony showed up, so I'm going to start my "redo" (re-zero & re-chronograph), then using the second Chrony I'll run my own BC calculations to have accurate numbers to input for dope to dial in at various ranges. It may take a few days to do it all, but I have the time this next week....I just need the weather to cooperate.

 

The newer Chrony is an F1, so the first thing I have to do is make up a remote switch that will enable me to retrieve all the info on each shot. My other one is a Beta, which has the FU button on the face. I have the necessary jack to plug in, so I only need to dig out a momentary contact switch and figure out which contacts to jump to be in business.

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Hit the range hard today!

Re-zeroed and chronographed at the muzzle (3ft as recommended) and @ 100yds.

 

Re-zeroing wasn't really needed, but it basically confirmed my previous zero.

Chronograph indicated an average speed of 1091 @ the muzzle, and 935.1 @ 100yds. Temp was 82°F, pressure was 938.2mBar, and humidity was 62%, making the BC .120 (exactly what CCI claims).

 

Last shot of the day @ 100yds on a 3" target.

qeEcrth.jpg

 

Weather permitting, I'll get back to confirming my dope @ 150, 200, and 250yds in the next few days.

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Good shooting!

Edited by Flesh Wound

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Excellent!

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