Long range groups opening up

[j_unzicker]

HELP. I am shooting right at MOA up through 400 yards. But when I jump to 500 yards my groups open up to abot 10-12" - that's over 2 MOA. Beyon 500 yards, it's the same thing. Is this common? I assumed (barring shooter's error) that if a gun shots MOA at one distance it will shoot MOA at all resonable distances. I am using the 7RM Berger 168 VLD's.

 

[Broz]

What scope? Was there mirage? Do you know how to properly adjust out parallax?

Jeff

 

[rscott5028]

It might help if you can provide a little more information...

Tell us about the
- rifle
- scope
- load data/components
- shooting position/rest

How many outings are we talking about and what kind of conditions were you shooting in?

Also, paper, steel, rocks?

Small samples are poor indicators...

Last weekend, my son did the following...
@100 (1.4 MOAx3 shot)
@200 (.7 MOAx3 shot)
@300 (.67 MOAx4 shot)
@400 (.4 MOAx first 3 shot+1.2 MOAx next 3 shot)
@500 (1 MOA x 8 shot) ...with 1 flyer that opened it up to about 2 MOA

That's similar to what you did. And, you could infer what you want from that data. But, the reality is that it was just one day and the wind was changing. He's been sub-MOA at 900+yds before with this setup. (Sendero, 7mm Rem Mag with 180g Bergers)

 

[j_unzicker]

I'm shooting a Rem 700 BLD 7RM - 168 Bergers 62gr IMR4831, vel. 2875, Remington Brass trimmed to proper length, Fed 215 Primers, COAL 3.32 (this is where it groups best) - Vortex Viper scope 6.5-20x50. I have adjusted the parallax properly, when testing a rifle I only shoot when the wind is 3mph or less without gusting. Shooting from a bench rest. No mirrage. Shooting at a cardboard target. This has happened to me on 3 different outings. And the MOA opening up is not from a flier...all 4 shots are spread all over within the grouping.
It sounds like you maybe implying shooter's error or just shooting variables that make LR shooting challenging. Yet, I can't understand why up to 400 yards is spot on, and just 100 yards more jumps over 1MOA?

 

[Broz]

Are you turning the turrets up in elevation from the 400 to the 500 yard target? If so I would try shooting a 500 yard group with the 400 yard turret setting that produced the moa group. Just in case something stupid is going on as you go up in elevation on the turret.

Canted base? How close to topping out on elevation are you at 500?

Jeff

 

[j_unzicker]

That's a good idea. I'll try shooting at the 400 elevation and hold over for 500 and see if the groups are the same. I don't have a level on my scope, but I leveled it when I mouted it and I really concentrate on keeping it "eyeballed" level (not too difficult on flat land). My scope is high though - 2.2". It is a 30mm tube so I have plenty of elevation left to shoot well over 1000 yards. Funny think is that the pattern seems to have more variance virtically than horizonally. My muzzle velocities, however, are pretty consistant within about 15f/s on all shots.

 

[rscott5028]

I wasn't implying shooter error. Rather, small samples aren't the best indicator.

If you're getting consistent velocities and MOA to 400 yds, you should be able to shoot well at 500 yds.

So, the suggestion of using holdover is a good one to help rule out scope adjustment issues.

I also recommend match primers and Norma brass the next time you need to make a purchase. But, that doesn't sound like the problem here.

 

[Ridge Runner]

put a level on it and shoot a couple groups.
RR

 

[j_unzicker]

Thanks for all the thoughts. I'll try some of these things and report back to you if I pinpoint the cause.

 

[Boss Hoss]

I shoot 1K competition and load development starts at 500yds. There is no way to use results at 300 or 400 and assume 1K. That being said what your ES? Too many variables to discuss because the longer ranges magnify any shooter error by orders of magnitude.

 

[muleyman]

Several years back I had basically the same problem and come to find out it was mostly me. What I found out as I was using a pretty much factory but good shooting rifle is that really MOA is not good enough to hold the groups together at longer distances. Yes it is nice, however with a gun and shooter just holding that standard, any and I mean any variance in the shooter and loads can start to make a big difference in the groups out at distance. I don't know your shooting ability but in my case I was learning basically "How to shoot long range" as I felt and really was a good shooter in close but as the distance grew so did my groups. Just food for thought.........

 

[j_unzicker]

My ES is 25f/s.