Shifting groups

[Rckymtnshooter]

I put together a rifle using a Remington factory barrel and action in a 7mm Rem mag.I put a HS Precision long range hunter stock on it. I initially skim bedded it with with the first inch of the barrel bedded. I wasn't getting the accuracy I wanted and removed the barrel bedding back to the lug. The gun shoots great now with a load using Reloaded 22 and 168 Berger's. EGW 20 moa base, Seekins rings and a Leopold vx6 3-18. The one issue I am having is the groups are shifting left to right. The pictured groups were shot 10 minutes apart with no adjustments. The gun consistently does this, any ideas ?

 

[Barrelnut]

Try waiting 10 minutes between each shot and see what happens. It might be barrel heat. If it's a sporter weight barrel, a 7mm will heat them up very quickly. I have an older Browning 7mm with a sporter barrel and it seems to walk like this if I don't keep the barrel real cool. My would move with only 10 minutes between two 3 shot groups like that. Don't remember it moving quite that much though.

 

[geo4061]

Barrelnut hit the nail on the head. Slow down. I shoot two and then wait an hour before shooting two more.

 

[jimbires]

could it be eye position , scope parallax ?

 

[red dawg]

I tried posting this minutes ago dont know maybe a double, I had the very same thing happen 2 weeks ago, so I totally removed the copper from the bore and my groups didn't move after cleaning! my gun started left and would move to the right slightly for 3to4 trips to the range, but would move only 2 of 3 shots and i asked questions on this site and others as well till I decided to try cleaning, it was the only thing that I hadn't tried

 

[ShootnMathews]

could it be eye position , scope parallax ?

I'll second this one. With maybe a little heat thrown in. I would think if it were heat a lone the group would have also opened up some. Although I guess it did open up just a smidge.

 

[Rckymtnshooter]

I did have a point where I was seeing mirage but don't recall where in the shot sequence. Will both mirage and parallax move a group that much at 100 yards ?

 

[Barrelnut]

Guess it depends on how heavy the mirage is. Barrel heat can cause mirage. If the barrel was causing it, barrel is probably too hot. What was the weather like?

 

[Bart B]

It's normal to have one group shoot to one side from a previous one. Us humans don't always position our bodies exactly the same behind the rifle for each series of shots. The more one's body mass is behind the rifle, the less each groups will shift horizontally.

I've observed this happening in my own tests in different positions sitting at a bench with a rifle resting atop something as I hold it against my shoulder. I shoot about 1 MOA to the right shooting this way compared to zeros obtained in standing free hand or slung up sitting or prone.

 

[Rckymtnshooter]

The mirage was barrel heat. Temperature was about 30. Bart, that makes sense.

 

[cowboy]

I'll suggest something you might consider. Now that you are sighted in - forget about shooting at 100 yds. with a 7 Mag. Repeat your shooting tests at 2-3-400 yds or however far you are comfortable with.

The longer distance results will be much easier to decifer what you actually have going on.

 

[Bart B]

I think he should stay at 100 yards. Further distances will only increase the horizontal spread of any group due to inconsistent cross winds. The accuracy of each group posted may be good enough to warrant all tests at 100 yards. Besides, the angular separation of both would stay the same regardless of range if both were shot the same way for each range in the same conditions.

 

[Rckymtnshooter]

I'm going to put an adjustable cheek rest on the gun. Right now I'm pretty much floating above the stock. The purpose of the gun is for all around hunting including long range so I will deffinately be shooting it at long range. I always felt that I was a pretty decent rifle shot but the more I dig into precision shooting the more I find I have a lot to learn.

 

[Barrelnut]

Good deal. You definitely just took a couple steps forward. A consistent cheek weld is very important. Might also want to try keeping the eye in the same spot by moving into the scope until there is almost no edge ring. Then keep that edge ring balanced all the way around. Those groups did look good, the more I think about it. Barrel walking will usually show up each shot moving in a particular direction, not just groups moving.