Weird Group Issue: Need suggestions

[stattus1]

Looking for some expert help…

I have a Christensen Ridgeline in 6.5 PRC. Long story short it now has a proof 24” barrel with a 1/7.5 twist rate. Also put on an MPR chassis with an area 419 match break. Optic is a leupold vx6 4-24x52.

After getting the rifle back from the gun smith (recommended by proof) with a new barrel I went through their break in.

Groups were all over. Bedded and it got better. Then put in the MPR chassis and it got slightly better again.

Still only shooting at best .64 moa and the Hornady eldm seems to beat whatever I’ve thrown at it so far. It’s just really weird because I get two touching and one way out on every group of 3 shot at 100yds. Proof said to check the bolt lugs for even contact. So that’s next.

Anything else you guys can think of or maybe you’ve seen groups like this before and know what the issue was?? Any help would be greatly appreciated!

 

[Brandon.miller.4]

Impossible to make any assumptions based on 3 round groups. Shoot 10 rounds minimum at one point of aim and post up a picture. The 2 touching with 1 outside is more than likely just small sample sizes telling you lies. I'd bet the group should start to round out with more shots fired.

For reference, a very good shooting hunting weight rifle will often be about 1 moa, or sometimes slightly less. My best shooting rifle is consistently .8moa. Most guns I have worked with tend to fall in the 1 moa to 1.3 moa category. Including handloaded rigs with aftermarket barrels.

 

[sveltri]

Wish I could help, I had the exact same issue on my Savage ultralight. Sold it.

 

[Brandon.miller.4]

This will explain it better than I can.

 

[Wrench]

.65 moa isn't "way out"....it's quite good.....especially for a carbon barrel.

 

[Bubblehide]

Put the scope on a rifle you know is accurate and try it. If you have the same-simular issue, it's your scope. Make sure to degrease properly, quality trusted components, and appropriately torqued.

Yes, to the 10 round groups.

 

[TaperPin]

I‘d change scope to rule that out.
Check scope bases and rings.
Remove the brake to see if if it’s contacting bullets.
What loads are you shooting?
How accurately can you shoot?
Check that the trigger isn’t contacting the stock.
Pull the bolt apart and install a new firing pin spring.
Check the bolt contact.

 

[stattus1]

.65 moa isn't "way out"....it's quite good.....especially for a carbon barrel.

Agreed. It’s not terrible at all. Just seems like it could be doing better and really want to dig in and see what I can find.

 

[stattus1]

I‘d change scope to rule that out.
Check scope bases and rings.
Remove the brake to see if if it’s contacting bullets.
What loads are you shooting?
How accurately can you shoot?
Check that the trigger isn’t contacting the stock.
Pull the bolt apart and install a new firing pin spring.
Check the bolt contact.

Perfect, I’ll work on this and report back.

 

[Wyo_hntr]

Agreed. It’s not terrible at all. Just seems like it could be doing better and really want to dig in and see what I can find.

Shoot a 10 or 15 shot group. If it's within a 1.5 inch group, don't worry about it.

 

[Wrench]

If I were chasing paper, I would be running a steel tube. If I were chasing fur, I would be plenty happy with a consistent 1 moa rig and not wear it out trying to make it what it probably isn't.

I'd spend that time and effort zapping rocks and yotes, learning my gun and enjoying better than mediocrity.

 

[Fartrell Cluggins]

You have a hunting rifle, not a competition target rifle. What I am seeing there is pretty darned good for a hunting rifle.

 

[Rich M]

I do that a lot and it is me.

Try this - set up 4 diff targets (1-2-3-4) and shoot them in sequence (1 then 2 then 3 then 4 then 1 then 2....) 5 times. Then you'll have 4 5-shot groups - betcha they come out tighter than one group you focus all your energy on.

 

[PredatorSlayer]

My guess is the scope is the problem.

 

[Megalodon]

people saying or thinking there’s a “problem” with any of this are pretty damn ignorant.

 

[hereinaz]

That’s not weird. It happens a lot and maybe it’s just the group size. Shoot 10 shot groups.

Could be you. Do the first two touch, then the third is always a “flyer”? Could be you if it is always that way. Other factors would put the “flyer” in different order.

Shoot 10 cold bore shots and look at it. Let the gun cool and it will force you to rebuild your position.

Did you shoot a mono bullet in all your testing? Clean the barrel and only shoot lead or copper, one or the other, don’t mix.

Factory smmo? Walk away happy.

Put a new scope on.

Tear the whole gun down to barreled action with rings off the scope and torque it back properly.

 

[wind gypsy]

Those 3 round groups posted aren't what i'd consider 2 touching and one way out. They are 3 shots randomly distributed as enabled by your rifle's precision capabilities. Its not like a gun is statistically likely to to put 3 bullets all evenly spaced.

You're wasting your time trying to extract info and trouble shoot based on those groups.

This is the table from the video @Brandon.miller.4 posted.


Based on this, if your average 3 round group size was 0.8", groups as small as 0.24" and as large as 1.36" could be expected with nothing else changing. Not "you did your part" on the small one and messed up on the bigger one. That's the real precision capability of gun/ammo when accounting for which 3 random shots were shot in succession.

This thread further illustrates:

How do my 3 shot 1/4 moa groups look?

Here is a group of 11 shots, but I could only legitimately find evidence of 10. It’s .89 moa per the app. Not bad for a gunner like me. Gun is my 6 BRA in the Mini Howa shooting 95 grain VLD hunters. Forgot my chronograph… If I randomly drew any three shots from this group of 10, what are the...

rokslide.com

Shots 5,9,10 could have been shot in succession in a 3 round group. Shots 1, 2, and 7 could have been shot in succession for a 3 round group. Which one is telling you the truth? the answer is both.

 

[Brandon.miller.4]

Ignore the first shot. I was zeroing and made an adjustment before shooting the other 9. As you can see I'd be able to pull 3 round groups that are in the same hole and 3 round groups that are .8" apart. 3 round groups can and will lie to you, as do 5. You start getting a good idea at 7, even better at 10+.


This image is same gun on a different day after scope mounts changed out. If I were a betting man, I'd say that 2 more shots would have most likely opened the group up a bit.

I hope this helps put a visual to the "data" hornady has put out.

 

[hereinaz]

Diagnosing group size and patterns can be like reading tea leaves. You've gotten good explanation why 10 shot groups are more valuable.

The smaller group shot by @Brandon.miller.4 also made me think about something else for you to consider as you diagnose whatever is happening. The better group he posted came after he changed some scope rings. Besides all the the discussion about groups and how the "rifle" is shooting, don't forget about the shooter and how we can make our rifle system easier to shoot...

You could possibly shrink group size just by making the rifle system fit you better and moving the scope to a better position. I know that I can change out a trigger, reduce trigger weight, change to a stock that fits me, or get higher scope rings, and that will change group size. None of that has anything to do with the making the rifle itself shoot better. Sometimes, I do wonder if the patterns we see, like tall groups vs. wide groups is more about the shooter than the rifle, because statistically with enough shots a rifle's distribution would be more evenly distributed. It could be the small influence of the shooter that pushes the rifle into a shape. But, that's a hypothesis I won't test in my lifetime...

And, if you haven't focused on learning and practicing the fundamentals, that is huge in my experience. It can do more than any tinkering with the rifle or load development. Its small things that are different or even run contrary to "the rules." My favorite rule to make fun of is "the rifle should surprise you when it goes off" so you don't flinch... I guarantee that good shooters know when their rifle is going to go off because they have pressed the trigger tens of thousands of times.

I am not an expert shooter by any stretch of the imagination. But, I can often shoot a better group with a friends rifle than the owner. We are at the range, and I hear them complain about how crappy their rifle is and they start talking about selling it and spending money. At that point, I will ask if I can shoot it to see if it has a problem. Most of the times I shoot a small group, and then I let them shoot my rifle, which they can shoot better than their own. Then, my friend will listen to my explanation and sometimes we fit the gun and move the scope right then. I've seen it make .5 to 1 moa difference.

And, I guarantee that there are many, many, many shooters that could shoot my guns better than I can.

 

[Brandon.miller.4]

Diagnosing group size and patterns can be like reading tea leaves. You've gotten good explanation why 10 shot groups are more valuable.

The smaller group shot by @Brandon.miller.4 also made me think about something else for you to consider as you diagnose whatever is happening. The better group he posted came after he changed some scope rings. Besides all the the discussion about groups and how the "rifle" is shooting, don't forget about the shooter and how we can make our rifle system easier to shoot...

You could possibly shrink group size just by making the rifle system fit you better and moving the scope to a better position. I know that I can change out a trigger, reduce trigger weight, change to a stock that fits me, or get higher scope rings, and that will change group size. None of that has anything to do with the making the rifle itself shoot better. Sometimes, I do wonder if the patterns we see, like tall groups vs. wide groups is more about the shooter than the rifle, because statistically with enough shots a rifle's distribution would be more evenly distributed. It could be the small influence of the shooter that pushes the rifle into a shape. But, that's a hypothesis I won't test in my lifetime...

And, if you haven't focused on learning and practicing the fundamentals, that is huge in my experience. It can do more than any tinkering with the rifle or load development. Its small things that are different or even run contrary to "the rules." My favorite rule to make fun of is "the rifle should surprise you when it goes off" so you don't flinch... I guarantee that good shooters know when their rifle is going to go off because they have pressed the trigger tens of thousands of times.

I am not an expert shooter by any stretch of the imagination. But, I can often shoot a better group with a friends rifle than the owner. We are at the range, and I hear them complain about how crappy their rifle is and they start talking about selling it and spending money. At that point, I will ask if I can shoot it to see if it has a problem. Most of the times I shoot a small group, and then I let them shoot my rifle, which they can shoot better than their own. Then, my friend will listen to my explanation and sometimes we fit the gun and move the scope right then. I've seen it make .5 to 1 moa difference.

And, I guarantee that there are many, many, many shooters that could shoot my guns better than I can.

To piggyback off of this I will add that rifle fitment, along with other details you listed do in fact make a big difference. One very overlooked qwerk is the enormous different in stability going from a sling stud mounted bipod to a picatinny mounted bipod. This gets exaggerated even further going from a picatinny to an arca plate. Wider clamp surface=more stability. We are obviously getting in the weeds here but it remains true that if you tailor a system to stability you will likely shoot smaller groups. Ie ever wonder why benchrest guns weigh so much? Why they have such a flat forend? Why they have a truck axle barrel? Weight and surface area matter. You must keep this within reason and keep it applicable to your situation. I don't have any intent to carry a 16lb nrl gun up a mountain. I also have no desire to chase the 6lb all up category. There's trade offs. The groups I posted are from a magnesium chassis gun with a nightforce atacr weighing 11.5 pounds loaded. 10ish pounds is a sweet spot for me that I'm willing to carry for the benefits or long range shooting. If I was a 300 or less shooter like the majority of the hunters out there, there's not a chance in hell I'd have a chassis or a 30 oz Scope. It'd be a short barreled, suppressed, mild caliber weighing less than 8 lbs.

Now that I went off on a tangent, just shoot a couple 10 shot groups and if it puts them in an acceptable group size and this gun is intended for hunting, stop chasing your tail on the 100 yard bench and start ringing steel or rocks at range and have some fun. I promise you won't notice that 1/10 of an inch bigger group size when you miss a rock by 3 feet due to a wind call.