Why does a load shoot two separate goups??

[FishDFly]

I have read and found by personal experience that wetter/tighter patches shoot higher. Looser/dryer patches shoot lower.

Atmospheric pressure changes can cause groups to shift up and down. High pressure causes groups to go up and low pressure causes groups to shift down.

Need to take a hydrometer with you to the range and watch it carefully between shots.

Grouping right and left is caused by the deviation from shooting right or left of true north. Need to take a compass with you and adjust your target so it faces exactly true north to get your shots centered on the target..

 

[Grenadier1758]

While @FishDFly's suggestions won't stand up to critical thinking, some of the other suggestions may gave some merit.

Lead, being non magnetic is not effected by the earth's magnetic field.

Air pressure changes far too slowly to justify needing a barometer to read and make sighting adjustments.

Relative humidity may be responsible for fouling build up, but fouling in the bore can be mitigated by loading procedures. The dampness of the patch will have more effect than relative atmospheric pressure.

@Steel Guitar, you need to ensure all the conditions for each shot are consistent. This means all the components, powder charge, propellant, projectile, lubricant, sight picture and hold. Avoid prelubricated patches.

Do you have cataracts? Floaters?
Do you have minor issues seeing the sights?
Have you put a diopter (peep hole) on your shooting glasses to improve the sight picture?

 

[Salty]

Yeah I probably got it backwards or upside-down. Sometimes it happens with me

I kept confusing it also. The way it was explained to me is that a wet patch is tighter and thus prevents gases from escaping around the ball. More push on the ball. Higher trajectory.

 

[Steel Guitar]

Thanks again for all of your help guys! I learned a lot. I've had catarack surgery on both 15 years ago and see better.

 

[waksupi]

Ya know, if you are using pillow ticking, and don't line the stripes up directly at the center of the target, your shots will go the direction of the stripes!

 

[Grenadier1758]

I use #40 cotton drill cloth. There's no stripes to align with the target.

 

[Chuck Tiller]

Since this two group phenomenon is happening with more than one rifle, we need to put aside issues with rifles and look at procedures. What are the procedures that Steel Guitar is following between shots. Is he using prelubricated patches that have deteriorated during storage? The result of having two distinct groups rule out most of the situations that open up groups. Deteriorating patches normally result in a pattern. Weight variations would have a vertical line of impact. Are there two different thickness of patching that is in use that Steel Guitar is using for several different rifles? What's common between those instances where several rifles shoot into two groups? What variations in shooting procedure occur when the two groups are observed? Is there a clump of

Steel Guitar needs to set up his shooting table so that every shot is being shot using identical procedures and components.

Marking the range rod.

 

[olskool]

the problem has been mentioned several times here. it is several things, you are picking the gun up to reload, that in itself changes everything. then you reposition the gun ever so slightly in a different spot every time. the light changes, the load is tamped harder or softer than the last, you flinch maybe, the gun is canted, the balls are not a consistent weight, it goes on and on,,,,,,,,,,,,,,,,,,,,,,,,,

 

[ChuckJonesWagon]

the problem has been mentioned several times here. it is several things, you are picking the gun up to reload, that in itself changes everything. then you reposition the gun ever so slightly in a different spot every time. the light changes, the load is tamped harder or softer than the last, you flinch maybe, the gun is canted, the balls are not a consistent weight, it goes on and on,,,,,,,,,,,,,,,,,,,,,,,,,

How do you not pick up the gun to reload?

 

[Grenadier1758]

Hmm, @Chuck Tiller has added another step on the consistency check. The ball needs to be set to the same position on the barrel as seen by marking the rod. There could be the notorious crud ring building up and preventing the ball being set to same depth every time. That will show up as a change in elevation.

 

[olskool]

How do you not pick up the gun to reload?

LOL, you don't, that is my point, everything you do matters if ever so slightly. it all adds up. I learned that by handloading for the last 57 years,,,,,,,,,,,,,,,,,,,,