something funny going on

dzander

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Ruger precision rifle .223
77 g sierra TMK bullet, .420 bc G1
chrono'd at 2604 fps
scope zero'd at 100 yards.

KESTRAL says up 1.4 mils for 300 yards , dialed up 1.4 mils

shot paper at 300 yards

group shoots 8" high above point of aim.

new gun to me. Groups .500" 5 shots at 100.

New arc rings and brand new Kahles 624I.

Tall target test next i guess maybe scope isn't tracking or i'm doing something wrong?
 
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dzander

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Caldwell, yes i have 1.9"in the BH in the Kestrel.
I use same Chronograph for my 6.5 creedmoor.
In fact I chrono'd my 6.5 tonight right before the Ruger .223.
I have done this to both rifles before. The speed from the Chrono for both guns was very close to what It gave me in the past. I shot a match last weekend with the 6.5 creedmoor Data. I hit plates from 235 to 1000 yards without elevation issues.
That rules out the Chrono in my opinion.
 

m1match

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Even a big error on your muzzle velocity would not cause you to be 8" high at 300 with a 100 yd zero and 1.4 mils of elevation. No matter what your load in 223, 308 or 6.5 CM, with a 100 yd zero your 300 yd dope would be 1.2-1.4 mils, and your error was on the order of .7 mils, way too much.

Are you shooting at a range with targets at multiple yardages? Is it possible you set your paper at 200 yd instead of a 300 yd ? The difference is just about the amount you were high.

Something isn't right but I'd look at other things before I blame your scope. the K624i is a very reliable scope and a .7 mil error on 1.4 mils of adjustment is almost unheard of.
 
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wade2big

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Wow... can't think of anything but the usual subjects.

BC is off
FPS is faster
Scope tracking has an issue
Parallax

all of them are possible, but very unlikely since you have control group in the 6.5
I don’t know the answer but parallax is never it no matter how many times it is brought up. The BC would have to be cut more than half to get the .75 mil error. Speed would have to be off 400fps or so to be the problem. I would wager it is a scope issue, mounting issue, or zero issue.

Double check your mount OP. Double check your 100 yard zero. Then use the reticle for elevation and shoot a 300 yard group. Next dial the same elevation you held and do the same to compare.

Let us know OP.
 

dzander

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Good points about using the reticle instead if dialing , I thought about that also this morning.
a couple of things

the 6.5 creed is a Remington /Krueger/ Mccrees set up with a 624 I Kahles. It runs perfect. thru same chrono using velocity and plunging in to kestrel and other ballistic apps it dials perfectly proper point of impact.
the Ruger has a different Kahles 624i, actually new within last4 weeks.

I made a tall target with lines every 3.6” , leveled it, leveled gun , laser range finded 100 yards. Gun on bench on atlas bipod bag in rear. Not the best but the error I’m looking for seems pretty Hugh.
good news/bad news is it appears to be spot on . Also dialed 1 mil left and right also appears to be right although I’m looking for elevation error. So I’m ruling out the scope at this point. I really thought that was it .
Also looking at the rear stock setup I found the screw going into the acorn nut that clamps the rod just below the main tube to be loose enough where I could flex the but stock up and down maybe .020” or so.
I cinched it up tight no more flexing I can see. I did shoot a 100 yard group last night at 100 when I was chrono’ing. Group was maybe a .5”, 5 shot group but it was mostly Vertical.
I will shoot at a hundred again then go to 300 with the 1.4 mils , see what happens, maybe with the flex and me, the shooter? Will see. I could also swap scopes as a last resort also.
will go over all the rest of the bolts / mounts before I try again also.
 

Snuby642

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Yea thanks.
I had the wrong scope pulled up for a profile.

Looks like a 200 yard zero whether intentional or not.

Bouncing between mills and moa catches me often since I run both and still think in moa as a default.

Since my 6.5 has an moa.
 

dzander

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The way I see it is .2 mils at 100 yards =.72”. At 300 multiply .72” x3 = 2.16” so theoretically that how high I should have been above point of aim.
since I was off the 8.5 x 11” paper target shots were in a cardboard backer that was shot up a bit . So I’m kinda ballparking the group best guess I was at least 4-5” above target, it was turned so 8.5” was height so somewhere around 8-9” high. I want to say group was around 3.5” best guess. Again I shot a 1/2” group at 100 yds right before I moved to 300.
Maybe that loose but stock rod screw had something to do with the bigger 300 yard group. It should have been around a 1.5” assuming these 77 g Sierra TMK bullets will shoot at 2600 FPS. Next test I’ll be sure to have plenty of paper to catch the 300 yard group. Sierra sight says .420 BC at 2400 FPS +.
I’m going to shoot prone also next time , I shot long range comps that way, Not off a bench like I was testing here. I’ll load enough to try both , bench and prone just for the hell of it.
Maybe I’m letting the gun slide up on recoil that and the loose but stock. Will see. Thanks for the reply’s , id like to get to the bottom of this , no point shooting a .223 match out to 1000 with this garbage I got now.
All groups were 5 shots
 
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Snuby642

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Your sight hight, above bore seems very low.

Did you measure center of scope to center of barrel?

I'm running a 1 inch tube scope fairly low and have 2.7
 

dzander

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I'll check that but I don't think would cause the much error either.
It's 2.38.
Does change come up .1mil. from roughly 1.4 to 1.3.
 
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AKMarty

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My kestrel was worthless until I doped the gun and tuned my rifle-cartridge profile in the Kestrel.
 

Snuby642

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Good that's 1/10th closer.

If it were me I would also reset my turret zero 2/10ths up then lock it down. Return turret to zero mark and see if it holds at 100 next time out.

It all ads up.
 

dzander

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My kestrel was worthless until I doped the gun and tuned my rifle-cartridge profile in the Kestrel.
Maybe I was lucky with the 6.5 Creedmoor.
Using Berger 140 hybrids , got my velocity , plugged data into Kestrel, I'm hitting steel from 235,300,475,450,550,600,650,711,900 and 1000.
Elevation is pretty darn accurate, if i miss over its me , same dope usually hit next shot. the 475-711 i hit if i get the wind right, those plates are in the 6"x6" 8x8" range. 900 and 1000 i'll hit 12 inch to 16" square , again if i get wind right. it seems the kestrel elevations are darn accurate, at least for the 6.5.
I'm hitting about 77% of the time. I'm not that stable, shooting off bipod and rear bag prone. Only been at this 6 months.
 

dzander

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I shot group at 100 prone instead of off bench. Group was on center to .1 low. so it dropped .2-.3 without adjusting scope zero. group .2 right also. So just going prone and finding that loose but stock bolt is all I changed. it was a lot cooler today . Kestrel said 1.35 mills elevation at 300 yards. shot prone at 300 yds, elevation waste center to .1mill low and 3-4 mils right. So either the buttock being loose or i have bad technique shooting off bench.
I notice some guys put a stool behind the bench instead of sitting to the side like i was doing . That way the recoil pad is more like when I'd be shooting prone. That may be part of my issue also.
Coriolis is off not sure about aerodynamic jump. I'll look thru it but I think I got this figured out.
Thanks for all the help
 

Dthomas3523

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How short is the barrel that it’s going 2600??

Also, at 300yds, don’t even bother with kestrel.

6 and 6.5mm dial .8
223 dial 1.0
.308/slow .223 dial 1.2
 

Dthomas3523

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And generally, if you have one of those dialed in like you do, 1.4 for example which is close enough to be on steel and close.......and it impacts either noticeably higher or lower than it should, that is typically indicative of bad zero.
 

dzander

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Did you turn off coriolis and aerodynamic jump in your kestrel?
Actually Coriolis and aerodynamic jump I can't find in my Kestrel.
Spin Drift is what I have off. I have a Sportsman with Applied Ballistics.
I couldn't find the coriolis and aerodynamic jump anywhere ,going thru all the menu options
 

Powder_Burns

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Actually Coriolis and aerodynamic jump I can't find in my Kestrel.
Spin Drift is what I have off. I have a Sportsman with Applied Ballistics.
I couldn't find the coriolis and aerodynamic jump anywhere ,going thru all the menu options
Spin drift is coriolis. Setting latitude to 0 cancels it out. Aerodynamic jump is computed when you have a wind value set for wind zone 1. If you leave it at 0 and put your bullet’s mph value in wind zone 2 it won’t factor aerodynamic jump into your solution.
 

dzander

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ok, thanks.
There is a spindrift on/off in the gun menu if I remember right, I have it off. I had zero'd out the wind 1 and wind 2 values.
 

Powder_Burns

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All that being accounted for, what were your wind conditions that day like? Last weekend my range had a headwind that shifted from 10:30-1:30, all my wind calls from my position were wrong. Kestrel would say 0.3-0.5, actual dope was closer to 1.5mil at 1000 for one shot then 1.0 in the other direction a moment later. But headwind/tailwind will shift your trajectory up and down respectively.
 

Greg Langelius *

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Where the round impacts is a direct consequence of where the muzzle points at the time the round clears the muzzle.

Different shooting positions and supports result in different recoil characteristics. POI's tend to differ as a result.

Is this reasonable consideration here?

Greg
 

Dthomas3523

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Spin drift is coriolis. Setting latitude to 0 cancels it out. Aerodynamic jump is computed when you have a wind value set for wind zone 1. If you leave it at 0 and put your bullet’s mph value in wind zone 2 it won’t factor aerodynamic jump into your solution.
Spin drift is not coriolis
 

Dthomas3523

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Spin drift, coriolis, and aerodynamic jump are three different things.

In kestrel:

Spin Drift can actually be turned off.

Coriolis set lat to 0

Aerodynamic jump set wind1 to zero
 
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dzander

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Where the round impacts is a direct consequence of where the muzzle points at the time the round clears the muzzle.

Different shooting positions and supports result in different recoil characteristics. POI's tend to differ as a result.

Is this reasonable consideration here?

Greg
Thats pretty much my conclusion , it was mainly my poor bench technique and loose buttock .
Without changing anything other than going prone vs bench and snugging up some buttock bolts below is my 100 yard target. Prone I was square behind buttock. POI came down. Grouping wasn't as good as other 100 yard target but there was about a 12 mph wind from say 7:00/8:00.


IMG_1260.jpeg


Now prone again same wind condition 300 yard group dialed up 1.4 mils.

IMG_1261.jpeg