Revic BR4 help

windypants

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I can't seem to get my ballistic profile trued up for all distances on my BR4. This is for my 30-28N/230 OTM load. My actual velocity is 3107 and the G1 is .364. After truing the drop at 1077 yards, it changed the BC to .354. I've been practicing making wind calls on several rocks at different distances and that setting is dead on at 919, 1077 and 1310, but shoots 1/2 Moa high at 660. If I true it to that shot, all the others will be off. It's a pretty steep downhill shot, but the BR4 automatically accounts for that, right? The 919 yard shot is also downhill into the creek bottom and it's right on there. I just cleaned, fouled and checked the 100 yard zero. What am I missing? I'll include the screen shot of the profile from the app. revic-1.PNG revic-2.PNG

 

windypants

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I took the 25 creed out this morning and shot those rocks. It was right on at 1078, 997, 660 and 926 using the same settings in the app. So the problem has to be in the inputs for the 30-28, but I can't figure out what I did wrong. Anybody have any ideas?
 

Ladd

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I cannot see anything that sticks out in your inputs. Is the scope height really 2-inches from the center of the bore to the center of the scope tube? Not that that would be the reason, only my curiosity. The BR4 does have an internal inclinometer that calculates the angle. Do you have Coriolis turned on or did you true the 230 OTM to 1310 w/o? Remind me what you are using to measure the muzzle velocity?

Also, in your first post you mean to say "G7", not "G1" but I saw in the profile, it is right.
 

Quest1000

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Aaron talked about setting up two profiles on the LRP podcast, one for 800 yards and in and another for over. It was mostly for the ELR Crowd but he did mention the variables above 1k have an impact at on ranges closer. Maybe try trueing your data at 700 and figure the above and below adjustments to a given range and keep that in mind. Just an idea.
 

windypants

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I cannot see anything that sticks out in your inputs. Is the scope height really 2-inches from the center of the bore to the center of the scope tube? Not that that would be the reason, only my curiosity. The BR4 does have an internal inclinometer that calculates the angle. Do you have Coriolis turned on or did you true the 230 OTM to 1310 w/o? Remind me what you are using to measure the muzzle velocity?

Also, in your first post you mean to say "G7", not "G1" but I saw in the profile, it is right.
Oops on the G7--I did enter it correctly, but wrote it wrong. Dislexia maybe. I did carefully measure the scope height with calipers and calculator, but I'll recheck it. I'm going off of labradar velocity. I currently have coriolis, wind drift and aero jump turned on. I've compared these settings on and off to actual POI's extensively and decided (at least for now) that this is more accurate for the distances I have been shooting. Those 650 rounds in three months were all in the name of science:). Until recently, I rarely shot under 800 yards, but when I go elk hunting it will be a meat hunt and I will be looking for an opportunity at a head shot, so I wanted to practice closer ranges. I've played a lot with entering different velocities and BC's to see how that works at different ranges. This profile is most accurate with the actual velocity of 3107 and the BC corrected to .354 from .364. I have found that if you change the BC very much, it really messes with your wind holds. Anyway, I'm trying to get this figured out without shooting a bunch--I'm wanting to save my barrel for the real thing while it's still shooting great.
 

windypants

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Aaron talked about setting up two profiles on the LRP podcast, one for 800 yards and in and another for over. It was mostly for the ELR Crowd but he did mention the variables above 1k have an impact at on ranges closer. Maybe try trueing your data at 700 and figure the above and below adjustments to a given range and keep that in mind. Just an idea.
Wow--that might be a great solution! Simple to do and use just by having two profiles for the same cartridge. I guess I missed that in the podcast. I'll have test it out and report back. Thank you.
 

nuclearmonkey

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Not sure if you own a Kestrel, but you could try trueing with one and see how it compares. I’m unfamiliar with the BR4, but I’ve had very good luck with AB’s custom drag curves. Process is a little different tho than what you describe… You’d pick a target 85-100% of your supersonic threshold, then massage velocity to make up for any discrepancy (making sure to account for any wind holds required). This process would also sort of account for any potential scope tracking issues out to that distance as well. I’m very leery of changing BC to make things play nicely.
 

windypants

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Not sure if you own a Kestrel, but you could try trueing with one and see how it compares. I’m unfamiliar with the BR4, but I’ve had very good luck with AB’s custom drag curves. Process is a little different tho than what you describe… You’d pick a target 85-100% of your supersonic threshold, then massage velocity to make up for any discrepancy (making sure to account for any wind holds required). This process would also sort of account for any potential scope tracking issues out to that distance as well. I’m very leery of changing BC to make things play nicely.
I have a Kestrel 2700, but have only used it to get wind readings to put in the BR4. I have tested extensively and am very confident in the BR4 solutions from 900 yards out to a mile with the G7 trued to .354. I agree that changing the BC much doesn't work. I am going out here shortly to test a short range profile for shots out to 800. I'm going to start with 3190MV/.364BC and true the MV to the drops and see how it works. Interestingly, my 25 creed, with its rainbow trajectory, is perfect out to 1310 just by truing the MV to 2840 from 2860. I haven't shot it much beyond that.
 

windypants

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Wow--that might be a great solution! Simple to do and use just by having two profiles for the same cartridge. I guess I missed that in the podcast. I'll have test it out and report back. Thank you.
Just checked out a hunting profile with 3190 MV/.364 BC. I shot 604 and 797--both had perfect vertical (missed the wind call @797), then I ranged the 660 and 920 yard rocks. 660 was right on at 9.5 MOA and 920 gave a reading that would impact a full MOA low. So if I just switch to the long range profile beyond 800 yards, I'll be confident at any distance I feel comfortable with. Now I can put this rifle out to pasture until its time to go elk hunting. This barrel deserves to get an elk before it retires--it's been a good one! Thanks @Quest1000!
 

Broz

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Be mindful that if mirage is present it can cause impacts to go low or high.

I know you checked zero, but be sure to check it prone if you are shooting prone at distance too.

We seem to be looking for a .5 moa discrepancy.

A solid MV average from a few shots and the Box G7 BC from Berger is usually good to go for me.
 

windypants

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Be mindful that if mirage is present it can cause impacts to go low or high.

I know you checked zero, but be sure to check it prone if you are shooting prone at distance too.

We seem to be looking for a .5 moa discrepancy.

A solid MV average from a few shots and the Box G7 BC from Berger is usually good to go for me.
I've done all my shooting (almost) with this rifle prone as I can't stay on target and spot my shots from the bench. I am aware of the effects of mirage and I have been doing most of my shooting early in the morning to avoid it, but I have shot with mirage enough to know a little about it. It's interesting to note that I also see a 1 click POI shift when shooting at a rock instead of the 1077 yard 12" x 27" white plate (POI is 1/4 MOA lower), just as there is a 1/2 MOA shift (lower also) when shooting at the 4' x 4' papered white target. I put small rocks by the 1077 yard plate to test this many times. That's why I have been shooting at natural targets to practice for hunting.

It's been very enjoyable learning this stuff!
 

Ladd

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You have done a lot of shooting with this 30-28N and it seams like you know it well. The elk won’t know what happened and that is sometimes the best part of long range. That, and seeing them fall on the spot.

 

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