Need help with understanding my groups

[CoHunter1991]

Question for shooting wizards . Factory ammo shot 1/2 MOA -3/4 for first half of the morning at like 30 degrees.

messed with the optic setting the zero caps and zero stop then shot another rifle . Shot the gun 30-45 min later and groups fell apart. 1.5 MOA

Temp had climbed to ~45 degrees but the ammo was in the shade the whole time. Velocity avg between the two sessions had also climbed 40 fps ….

Seekins element with NF Atacr on it. Chance I messed the scope up setting the zero? I think it has to be ammo based or me. Let me know your thoughts.

Total shots were 26 shots :
11 in first set and 15 once shit fell apart.

Took a minute between each shot and barrel and suppressor were warm but not hot.

Thanks for the help

 

[Bigjay73]

Hate to say it, but it's the shooter. I've shot over 100,000 round in my life and I still have moments where my form falls apart, usually when I have my mind elsewhere. You have a pretty good rifle/ ammo combo going.

 

[TX Trophy Hunter]

I think it was an Erik Cortina where I heard that a fowled barrel can increase velocity because the bullet to barrel seal is tighter so gas can’t blow past the bullet. Im by no means a shooting wiz but something to consider possibly.

 

[CoHunter1991]

Yeah I was worried it was just me as I was Likely more relaxed at first.
I’m not sure about the ammo and rifle combo. It’s Norma bondstrike and it has been fantastic in all other rifles I have. The first 11 rds out of this one grouped so nice that it killed me to see it fall apart. What do you make of the velocity change? Anyway that messed up the accuracy

 

[CoHunter1991]

I think it was an Erik Cortina where I heard that a fowled barrel can increase velocity because the bullet to barrel seal is tighter so gas can’t blow past the bullet. Im by no means a shooting wiz but something to consider possibly.

Okay that makes sense. It was clean prior to the first 11 that grouped well. It probably a bad sign that once the barrel was fowled a bit my groups went down hill. Maybe it’s the ammo my gun doesn’t like. Maybe it was just my shooting also.

 

[TX Trophy Hunter]

Okay that makes sense. It was clean prior to the first 11 that grouped well. It probably a bad sign that once the barrel was fowled a bit my groups went down hill. Maybe it’s the ammo my gun doesn’t like. Maybe it was just my shooting also.

Your second picture has horizontal stringing which I was taught points to the shooter but that doesn’t explain the velocity. What were the extreme spreads on your velocity?

 

[El Jason]

What kind of chrono you using?

Did you start with a freshly cleaned bore?

I’m struggling to see any trend in your groups. One is three shot, then a four, then a bunch. Three shot groups don’t tell you much about the overall accuracy of the rifle. Unless they are really bad then they tell you that.

 

[Addicting]

Your second picture has horizontal stringing which I was taught points to the shooter but that doesn’t explain the velocity. What were the extreme spreads on your velocity?

Velocity is just his barrel warmed up and expanded. 1 min between shots isn’t enough even with a fan blowing down the barrel.

It’s shooter and barrel heat. He goes out tomorrow he can expect the same results.

 

[CoHunter1991]

Total for the 26 shots is 100…. But the ES in each session was about 30. The avg shifted buy 40 fps up

 

[TX Trophy Hunter]

Velocity is just his barrel warmed up and expanded. 1 min between shots isn’t enough even with a fan blowing down the barrel.

It’s shooter and barrel heat. He goes out tomorrow he can expect the same results.

You misread his first post

 

[El Jason]

What chambering in the rifle and how good of a shooter are you?

 

[Wind Gypsy]

Impossible to tell from those 3 groups imo. Iffn I had to guess, it’s a combination of shooter performance and normal distribution over multiple samples.

A tight 3 shot group can lie to you.

 

[Addicting]

You misread his first post

Nope, he shot more rounds on the larger group and gave it a min to cool. Thats not enough and the barrel heated up.

A 3 shot group and a 5 shot are completely different on a thinner barrel. Of course they are going to open up. Combine that with shooter moving ever so slightly or trigger squeeze. This grouping is normal.