ABLR BC changing at extended range?

[jeepinhntr]

anyone have any issues with bullet drop with ABLR at extended ranges say past 1200 yards? I've got a custom 27/28 nosler running 165gr ABLR at 3250fps and have it sighted in and was testing loads and ranges and was solid out to 745 yds and thought well let's try something around a mile. Found a rock at 1647yds and dialed using strelok pro app and fired with no visible impact. Shot again and again and nothing. Zoomed way out and saw impact of 4th shot about 15 minutes low of target. So I backed back up to 745 and was dead on. Walked out every 100 yards or so until I got to 1200 and was still tracking true with drop data. After 1200 is where the bullet I believe changes BC and turns into a parachute. Is anyone else seeing these results? I know I will never shoot at an animal that far but for practice and plinking I like to stretch the envelope. Kinda has me stumped. I've not got much experience shooting past 1000 yards but just seemed really odd to me if its a bullet construction characteristic or result of design/construction

 

[jimbires]

velocity affects the bullets BC . as velocity drops so does the BC . I've never used strelok . in the strelok ; is there a way to true the BC ? are you using the G7 BC numbers ? did you get a good velocity from a chronograph ? how did you pick the G7 BC number ? if you're using the Nosler BC numbers they are probably high . the little things show up big as you shoot longer distances .

EDIT TO ADD ;

do you have a exactly perfect zero ?
I've shot with guys that sight in 2" high at 100 yards , and call that a 100 yard zero . but it's not .
I've shot with guys that are 1/4 " low at 100 yards and call that a 100 yard zero , but it's not .

could you watch your hits walking down on the target as you walked out the distance ?

 

[FOTIS]

I wish I could offer some opinions and/or advice on this subject but with the exception of a Ruger #1 in 264 Mag (all factory) I have never ever gotten an ABLR to shott anywhere near MOA for any of my rifles. And I am talking an arsenal not one or two.

 

[xphunter]

@jeepinhntr
There could be, a number of different things of why the drops are off, and none of them may be related to your bullet, or any other brand of bullet.
It could be the wind(s) that you had that day, combined with the terrain.
Head and tail and or quartering tail and headwinds, can really mess with your vertical.
If you have some terrain features as well, it can be just that much more.

It could be the internal adjustments of your scope are a little bit off on either the plus or minus side, and those really begin to stack up as you get out there in distance.

Mirage will really mess you up with your vertical as well, because what you know for sure is your target is really just an image.

What if, it’s a combination of one or more of these things?

What is your max distance for hunting big game?

 

[xphunter]

Let me add to what I said in my previous post. Your ballistic coefficient is not a fixed number.

It changes with speed

 

[xphunter]

Four shot group at 100 yards with my 15.9 inch 6.5 PRC rear grip specialty pistol.
142 grain LR AB’s.
Three of them are in a really small cluster at the bottom, and I’m not sure if it was me or not on the one that’s about a half inch off.
I have to confirm that.
I know, from other hunters, that with these bullets, sometimes you just have to separate them by measuring from based to ogive, and then you have some really super accurate loads, but since I only need kill zone out to 500 yards with this rig, I’m pretty close to being finished.