You make the call: Is my 6mm ARC bolt action a ½-inch gun with factory ammo?

[JAS-SH]

I’d like to think it is, although with an “on average” caveat.

I might be wrong, but I define a ½-inch gun as averaging ½-inch groups at 100 yards. I tend to shoot 3-shot groups because my POA and POI are the same and shots on top of each other can hide the exact POA. That makes it difficult to be precise.

Below is my whole 11x17 target sheet from two weeks ago. The yellow centers on the waterline targets are ¼-inch. On it there are 26 shots total, all in separate 3-inch groups except for the last group which was 5-shots. All shot from the bench with my SEB front rest.

Also, the distance to the target is important to mention. In my case my target distance was 106 yards, not 100. Those extra 6 yards make a difference in dispersion as shown on my calculations at the bottom of the target sheet. The best way to even that out is to convert the results to 100 yards after measuring all the targets.

I also made POA adjustments as I shot the groups. For example, my cold bore group (the single large target at the bottom of the sheet) was quite high – a WTF moment. I looked at my scope and realized I left my scope set .2 mils high from my previous outing . Shooting the waterline targets I used different holds for adjustments smaller than .1 MIL.

I calculated two aggregates – one with and one without the last 5-shot group. I had three groups larger than a 1/2-inch - The second group (first group on the top waterline) was .68”. The sixth group was .6, the other one was the 5-shot group, coincidentally also .68 inches.

The average of all the groups was .455 inches. Converting to 100 for apples to apples at 100 yards, all the groups averaged .429 inches. (100/106 x .455). Without the 5-shot group, the group averages dropped from .42 to .396 inches - numbers at the bottom right hand corner.

If anyone is interested, I’ve attached a PDF of that target sheet, of course with no holes in it.

 

[oldnewguy]

If it were me...

I'd adjust my scope so that my point of aim and point of impact are an inch or so apart. Shoot five, five shot groups. Measure and find average.

 

[TheOfficeT-Rex]

Maybe.

 

[cfulback32]

@TheOfficeT-Rex - What software is that?

 

[TheOfficeT-Rex]

@TheOfficeT-Rex - What software is that?

TARAN 1.1

Props to OP for uploading a good target scan. I just did some quick clicky clicky.

 

[DocRDS]

My guess is the rifle is 1/2 MOA. Unfortunatly we cannot separate the shooter from the rifle. (honestly unless you are a REALLY good shooter no one can)
If I were to guess, I'd say the fliers are you. But of course everyone here shoots perfect every day and we laugh at those who can't cloverleaf cause we are keyboard warriors.

Start shooting longer strings or do Frank's dot drill. I think you have a good load/equip setup. Now go use it.

 

[JAS-SH]

My guess is the rifle is 1/2 MOA. Unfortunatly we cannot separate the shooter from the rifle. (honestly unless you are a REALLY good shooter no one can)
If I were to guess, I'd say the fliers are you. But of course everyone here shoots perfect every day and we laugh at those who can't cloverleaf cause we are keyboard warriors.

Start shooting longer strings or do Frank's dot drill. I think you have a good load/equip setup. Now go use it.

Excellent comment. And I agree. I'm shooting factory ammunition which has a built in vertical component because of it's velocity spread.

So, some vertical spread is inevitable, but shots that go sideways (horizontal), and specifically left of POA is me. How do I know this?

Well, I use a trainer rifle in 22. Mag with a higher end barrel. I just replaced the barrel with another from the same manufacturer because I burned it. About 30,000 shots down that first barrel in 3.5 years or so. I posted a thread in the rimfire forum about this not long ago. Did that help my shooting? You bet! This because my 6mm ARC bolt gun is much more accurate than the .22 Mag but if I'm not careful I will pulls shots left on both rifles. I lucked out on that 6 ARC bolt action big time.

That said, practice doesn't make perfect unless you perfectly practice

 

[JAS-SH]

TARAN 1.1

Props to OP for uploading a good target scan. I just did some quick clicky clicky.

Thanks, I like small 1/4 inch targets at 100. The thick black ring around them is so I can find them with my 7 decades old eyes! After a lot of shots downrange, aim small miss small has worked wonders for me! Makes me concentrate....

 

[Mike Casselton]

Excellent comment. And I agree. I'm shooting factory ammunition which has a built in vertical component because of it's velocity spread.

So, some vertical spread is inevitable, but shots that go sideways (horizontal), and specifically left of POA is me. How do I know this?

Well, I use a trainer rifle in 22. Mag with a higher end barrel. I just replaced the barrel with another from the same manufacturer because I burned it. About 30,000 shots down that first barrel in 3.5 years or so. I posted a thread in the rimfire forum about this not long ago. Did that help my shooting? You bet! This because my 6mm ARC bolt gun is much more accurate than the .22 Mag but if I'm not careful I will pulls shots left on both rifles. I lucked out on that 6 ARC bolt action big time.

That said, practice doesn't make perfect unless you perfectly practice

If your "pulled" shots are always to the left, you'll want to pay more attention to your cheek pressure on the stock.

I'm also seeing some vertical, which you say is because of velocity.
Velocity variations don't have that much effect at 100 or even 200 yards. It will begin showing up around 300.

You either have a small parallax issue or you're changing cheek and shoulder pressure. Maybe both.

Lastly, you'd be surprised how much small amounts of wind will affect your POI.

Short range Benchrest shooters/competitors use wind flags for a reason.

 

[Rio Precision Gunworks]

Agreed with above. Velocity is almost non existent at 100yds. Wind is much more a thing at 100yds than velocity. Since wind can affect the bullet and the target as far as movement.

In general, vertical is going to be breathing, parallax, or rear bag issues. Horizontal is wind, trigger press, cheek pressure, or parallax.

As far as if the rifle is .5 with factory ammo, that's a tough one to answer. It appears that it might be close. The only way to know for sure would be a rail/sled.

 

[Mike Casselton]

Agreed with above. Velocity is almost non existent at 100yds. Wind is much more a thing at 100yds than velocity. Since wind can affect the bullet and the target as far as movement.

In general, vertical is going to be breathing, parallax, or rear bag issues. Horizontal is wind, trigger press, cheek pressure, or parallax.

As far as if the rifle is .5 with factory ammo, that's a tough one to answer. It appears that it might be close. The only way to know for sure would be a rail/sled.

Forgot about the rear bag thing.

Lots of people do the sympathetic release of the rear bag as they break the trigger. It causes vertical, and to some degree a bit of horizontal depending on how much cheek pressure you apply.
It's very hard to diagnose without video.

Another thing with the rear bag is having it set up correctly for every shot.
If the bag is not exactly the same, every time, it will steer the rear of the rifle differently every time it's fired.

 

[JAS-SH]

If your "pulled" shots are always to the left, you'll want to pay more attention to your cheek pressure on the stock.

I'm also seeing some vertical, which you say is because of velocity.
Velocity variations don't have that much effect at 100 or even 200 yards. It will begin showing up around 300.

You either have a small parallax issue or you're changing cheek and shoulder pressure. Maybe both.

Lastly, you'd be surprised how much small amounts of wind will affect your POI.

Short range Benchrest shooters/competitors use wind flags for a reason.

I see you quoted the pulled word. I apologize for the generic term, it can be misleading. I wrote "pull" because I know I was pulling with my firing hand - on the right side of the rifle - my most common mistake. It gets confusing because you can also go left with cheek pressure and I would call that a "push" because that's "pushing" from the left side of the rifle making shots go left. I rarely have that problem because I barely cheek the rifle.

I posted this target specifically because it's not my best. I did not want to cherry pick. I have a lot of software measured 3-shot groups "in the ones" (less than .2 inches). I'll post one or two below...

I also showed all the calculations I do on the range and write them on the sheet before I pack up using a good ruler with 1/16-inch rule that unfortunately leads to instrumentation errors. The measurements are not accurate enough.

I can tell you exactly what I see in some of these groups from experience. Group 2 (first one on the left of the top waterline) is rear bag misalignment.

Now going to vertical - velocity spread WILL show vertical at 100 yards. That's a well known fact that has to do along with velocity, a well clocked barrel bore, barrel resonance and bullet dwell time in the barrel.

You can see velocity vertical in a number of the groups on the sheet, the best example is Group 4. However, Group 6 shows a lot of vertical but it 's not all velocity - the main cause is rear bag sink.

I could go through every group but you get the idea. There is a LOT happening on this target sheet and from experience I can tell what's going on for mostly every single shot. That's also the reason I shoot 3-shot groups. I can get a lot more information from them than from a 10-15 shot "blob" and I do shoot those too but mainly for fun...

Oh, and there was no wind that day.....

Here's a couple of targets in the ones spanning months: