Larger than MOA groups. What would you check first?

[Gun Man Dan]

I’m having issues with my groups being pretty big. I have a 24” shilen SS barrel in 6.5 creedmoor with a 1:8 twist. I shoot out to 100 yards 95% of the time. I do not have a chronograph, but I trust my reloading processs with 140gr Hornady ELD match and 39.5 gr of H4350 powder with CCI primers. Hornady brass that’s been fired 3 times now. I’m getting runout pretty consistent if 4 or 5 thousandths.

I’m at a loss. Where would you look first to make a difference?

 

[markm87]

Strikes me as a very mild output charge. I run IMR 4350 at 40.8, but my H4350 is higher. I just don't have the charge info with me.

Runout seem a touch high, but I'm leaning towards upping the charge. A chrono is a must.

 

[CA_Shooter]

I've run those bullets in the past at a charge of 38.6 H4350 and still got good groups. Well under 1 MOA.

I'd try different bullets though, maybe you got a bad lot

 

[TTE]

What would you check first?​

all screws

 

[Coyotefurharvester]

What shape are the groups ? If you have.eliminated optics, mechanical rifle and rest/bag issues.

 

[Gun Man Dan]

all screws

Good thought. I’ve remounted the scope to be level again so that’s likely not it. Still worth a once over again though.

 

[Gun Man Dan]

What shape are the groups ? If you have.eliminated optics, mechanical rifle and rest/bag issues.

I’ll get 2 or 3 nice ones and then really strange fliers. Other times I won’t group any at all in a 5 shot group.

 

[Gun Man Dan]

Strikes me as a very mild output charge. I run IMR 4350 at 40.8, but my H4350 is higher. I just don't have the charge info with me.

Runout seem a touch high, but I'm leaning towards upping the charge. A chrono is a must.

Is the chronograph a must just to compare velocities? I’m still confused how that info would direct me to how to make my loads better.

 

[ebb]

ignition

 

[nakneker]

I’d clean the barrel, check all the mounts and rings, check the action bolts, just preform a basic check of the rifle. Are you confident in the scope?

I use a bigger charge weight in my 6.5 creedmoors, I get better results. I attached Hodgdon’s load data and a screen shot of Hornadys load data for that bullet and cartridge. I’ve always found a good node that’s easy to tune around 41.5 grains of H4350. Just follow basic reloading practices and start low and work up if you try a higher charge. I’m showing no signs of pressure with Lapua brass, 140s Hornady Match bullets, 210m primers but your rifle may tell you otherwise, be smart…. I use that combo in a Tikka CTR and a Tikka T3 with good results.

Loading without a chronograph really limits a guy as far as knowing where the nodes are, your standard deviation and extreme spread numbers. Running a simple ten shot ladder will help you know where things are, sometimes half grain of powder can make a big difference with your accuracy, SD and ES. You want be in a node, there’s a higher node for both rifles but I’m happy where they are.

 

[JMayo]

Test neck tension.... My groups get wider with tight necks

 

[Gun Man Dan]

Test neck tension.... My groups get wider with tight necks

I use a mandrel at the end of my process before primer so the tension should all be the same.

 

[Gun Man Dan]

I’d clean the barrel, check all the mounts and rings, check the action bolts, just preform a basic check of the rifle. Are you confident in the scope?

I use a bigger charge weight in my 6.5 creedmoors, I get better results. I attached Hodgdon’s load data and a screen shot of Hornadys load data for that bullet and cartridge. I’ve always found a good node that’s easy to tune around 41.5 grains of H4350. Just follow basic reloading practices and start low and work up if you try a higher charge. I’m showing no signs of pressure with Lapua brass, 140s Hornady Match bullets, 210m primers but your rifle may tell you otherwise, be smart…. I use that combo in a Tikka CTR and a Tikka T3 with good results.

Loading without a chronograph really limits a guy as far as knowing where the nodes are, your standard deviation and extreme spread numbers. Running a simple ten shot ladder will help you know where things are, sometimes half grain of powder can make a big difference with your accuracy, SD and ES. You want be in a node, there’s a higher node for both rifles but I’m happy where they are.

I’m going to send it back to Vortex for inspection.

 

[Gun Man Dan]

ignition

I am using older primers I bought before Covid…. Maybe some new stuff would be worth a go.

 

[K22]

Please be specific about " my groups are pretty big". How much large than I moa at 100 yards.

What is your fire sequence. In other words, are you firing a series of shots heating up the barrel?

What bench technique are you using?

My rifle related checklist:

1. All screws tight.

2. Bedding and Free Floating - if not properly bedded and free floated - I wouldn't
expect great groups.

Load issues:

1. Assuming you are using a powder suitable for that cartridge and bullet weight, the first suspect for me is the bullet. Almost always, assuming you have an accurate rifle and mechanically sound scope, when I had load troubles it was the bullet.

2. Never trace a poor load to neck tension or run out. Not saying it can affect group size, but I never found it to be much of an issue.

Cleaning Issues:

Cleaning to bare metal, especially with aggressive copper solvents always created clean barrel flyers and the need, depending on the rifle, to fire several "fouling" shots before POI would stabilize.

Scope Issues:

Rare for me, but I have had some go sound on me. As a last resort, you may want to try another scope if you have one.

 

[Webster]

Good thought. I’ve remounted the scope to be level again so that’s likely not it. Still worth a once over again though.

The scope not being level doesn't affect group size. How good is your bench setup? rear bag, what do you use for a front rest. If you slide the rifle about an inch back and forth on the bags , how does the cross hair move across the target. I have to rotate my rear bag a little to get the cross hair to move vertical. I use a rear bag and a bipod. I have to reset the bag, bipod and gun after every shot. I easily shoot under 1/2". Good enough for GH hunting. I don't think I flinch when the gun goes off based on how I react with a several dud primers. I can see the cross hair move on the target while the gun goes off. I used to shoot small groups with a 7mm Rem magnum. Have somone you know is a good shooter shoot your gun at a few targets. I think a ckeek weld is bad technique on a bench gun. I live in Parma.

 

[RegionRat]

I’m having issues with my groups being pretty big. I have a 24” shilen SS barrel in 6.5 creedmoor with a 1:8 twist. I shoot out to 100 yards 95% of the time. I do not have a chronograph, but I trust my reloading processs with 140gr Hornady ELD match and 39.5 gr of H4350 powder with CCI primers. Hornady brass that’s been fired 3 times now. I’m getting runout pretty consistent if 4 or 5 thousandths.

I’m at a loss. Where would you look first to make a difference?

All of the above advice plus...

For starters, lets check the grounding first... has this rig shot any other load recipe or ammo well in the past?

Are your expectations based on the rig has shot well in the past, or that you would like it to but it never has?

How about the gun's pilot? Have you ever shot this or any other rig where it made you happy?

You mention "flyers" but if they happen all the time they are not flyers. If you can't shoot 20 shots in a row that make you happy, then those are not flyers they are just part of the random distribution within your group that takes more than three or five shots to show up.

Has this rig made you happy in the past with this bullet or a different one?

There is a difference in the approach of an unknown setting when there is no basis versus the one where we know there is ground to be recovered by load development. There is also the process where the driver is still on the steep end of the learning curve.

To narrow down the discussion and get you better help, I would recommend you visit a club or range that has folks that shoot the game that interests you and get yourself adopted. Experienced shooters will be able to diagnose you and the rig better than all the typing in China.

 

[Gun Man Dan]

All of the above advice plus...

For starters, lets check the grounding first... has this rig shot any other load recipe or ammo well in the past?

Are your expectations based on the rig has shot well in the past, or that you would like it to but it never has?

How about the gun's pilot? Have you ever shot this or any other rig where it made you happy?

You mention "flyers" but if they happen all the time they are not flyers. If you can't shoot 20 shots in a row that make you happy, then those are not flyers they are just part of the random distribution within your group that takes more than three or five shots to show up.

Has this rig made you happy in the past with this bullet or a different one?

There is a difference in the approach of an unknown setting when there is no basis versus the one where we know there is ground to be recovered by load development. There is also the process where the driver is still on the steep end of the learning curve.

To narrow down the discussion and get you better help, I would recommend you visit a club or range that has folks that shoot the game that interests you and get yourself adopted. Experienced shooters will be able to diagnose you and the rig better than all the typing in China.

A lot to learn. Sending scope back to Vortex to triple check nothing broke when it was dropped awhile back (seemed fine). Will pick back up after that. Thanks for all of your help.

 

[ebb]

No not even close to what ignition is. Firing pin protrusion too much or too little, weak firing pin spring, dirty interior to bolt body, firing pin or spring rubbing in bolt body, bent firing pin, bolt shroud rubbing firing pin or receiver of rifle, rust, lack of lubrication, Oil that has dried out and is restriction pin movement. And someone that knows way more than I will have a bunch more.

 

[Straightshooter1]

I’m going to send it back to Vortex for inspection.

I use Vortex scopes and had one where the parallax adjustment just stopped working. I called Vortex and they had me send it back. It didn't take long to get the scope back. . . although it wasn't my scope I sent in to be repaired, it was a new scope of the same model. It's been good ever since. Vortex will take care of you!