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 stock factory rifle) I have never ever gotten an ABLR to shoot anywhere near MOA for any of my other rifles. And I am talking an arsenal, not one or two guns.

 

[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.

 

[jeepinhntr]

I am just using the G7 ballistics coefficient posted by Nosler and I have confirmed muzzle velocity at 3250 with Magneto speed chronograph. And no i do not believe the strelok pro app will allow ballistics truing. As this is my main hunting rifle I use a zero of 350 yards which gives me a 8" MPBR 4" up and 4" down out to 420 yds. As for maximum hunting distance I've been able call wind and shoot good enough to get cold bore shots on 10" plate out to ~700 yds consistently. I've been saving some money to get a kestrel which I believe will help get me out further.

 

[jeepinhntr]

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.

View attachment 27291

I have noticed some inconsistencies in seating depths and have done just that I will separate them into typically 3 groups load the short snd longs accordingly to BTO and then use the erratic ones as sighters or fowling shots to get consistent data when shooting groups and doing seating depth adjustments. Im about to start work up a my wife's 6.5 PRC and 142 ABLR in a bergara B14 have you done any tests to see what jump the 142's like? I know I probably wont even get to load close to lands as I will be restricted on mag length but just curious what you've found that's a darn nice group

 

[Joec7651]

Try a Berger with full jacket. Maybe the tips do actually deform from heat. I know it’s a different bullet, but if it’s tip related you probably won’t have a sudden drop off with the all copper jacket. This is just my opinion and not pulling it from anything specific.

 

[jimbires]

you could run your info in a calculator and see what it gives for corrections . I like JBM .

JBM - Calculations - Trajectory

jbmballistics.com

 

[xphunter]

First of all, everything ran good to around 1200 yards or to 1100 yards, and then things went wonky at 1200.
For hunting it sounds like you are set, so that is great.

The majority of LR hunters I know don't kill game beyond 1100 yards, yet I know some that do it it on a far more regular basis that most would think.
Joe mentioned the old A-Max problem of soft poly tips. I have no idea if that is it, but it is a possibility.

What direction was the winds coming from?
Could you tell the wind direction at 1200 yards or at 1647 yards?
Was it the same as the earlier shorter range shooting?
Did you have a wind direction change while you were shooting?

Where your 1200+ targets on ridges or hills?

 

[TackDriver284]

I am just using the G7 ballistics coefficient posted by Nosler and I have confirmed muzzle velocity at 3250 with Magneto speed chronograph. And no i do not believe the strelok pro app will allow ballistics truing. As this is my main hunting rifle I use a zero of 350 yards which gives me a 8" MPBR 4" up and 4" down out to 420 yds. As for maximum hunting distance I've been able call wind and shoot good enough to get cold bore shots on 10" plate out to ~700 yds consistently. I've been saving some money to get a kestrel which I believe will help get me out further.

I used to use the Strelok app, and its OK for me out to about 700 yards when I used it many years ago, with little adjustments needed to get good POI. I purchased a Kestrel 5700 a couple years back and it helps tremendously. I use G7 in it and putting accurate details about your bullet, scope height, speed, etc makes it perfect. Capture temps, humidity and wind speeds in the field, then dial it in. I shoot 1200 yards ( my max range at my place ) on 10 inch steel consistently. I'm happy with the Kestrel and I recommend you get one. It helps tremendously and get a good rangefinder. Don't forget about coriolis effect past 1000 yards, but I did not mess with that.

 

[FOTIS]

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

It changes with speed

Ernie is spot on as usual. This is why Sierra, in their 1990's manuals, and even before that, use to list several BC's for one bullet.

 

[JD338]

Ernie is spot on as usual. This is why Sierra, in their 1990's manuals, and even before that, use to list several BC's for one bullet.

The different BC listings were based on bullet speed.

JD338

 

[FOTIS]

Absolutely

 

[jeepinhntr]

Wind was a consistent 10mph 45° tail wind from left to right. I was shooting up a slight hill across a huge flat. Shooting direction and angle did not change much from 700 - 1647yds. I have a bunch of 170 berger EOL I would like to load up for target shooting and would like to test just that if it does the same thing past 1200yds or not.