POI changing with light

[stretchman]

These are two different loads shot on different dates at 100 yards.  Has anyone else witnessed point of impact change this drastically do to a change in lighting?

Thanks
Todd

[smylee grouch]

A change in light conditions can for sure change POI but that might not be the case with your targets when you use two different loads and powders.

[yellowhousejake]

Those two loads are really different, I would look there first.

But, yes, light can change your POI. I had a student shooting on a south facing range in the fall one weekend. As the sun moved from the left to the right you could watch his groups shift across the target. A cardboard front sight hood solved the problem and the groups snapped right back to center. There is also two years difference in when you shot those groups, on two different targets.

Pretty rifle, post a picture for us.

DAve

[smylee grouch]

The first 5 shots in one ragged hole overcast sky, went down to check target and walked back, shot a fouling shot into the bank then shot 3 more shots at same aiming point with sun shining through partly cloudy sky. I didn't have my shader with me. I was shooting east and sun moved group up and right somewhat.

[Jeff Murray]

You did not mention what type of front sight you have.  Brass?  Silver?  Both can reflect light and affect your point of aim.  You are shooting some pretty stout charges.  going after bear?

[JHeath]

I second the request for a photo of the rifle!

[stretchman]

Don’t have the best pictures of the whole rifle.  The deer are small in our area of Texas which is obvious when you look at the picture.  I took the rifle in a trade from the late Dave Higginbotham of Lone Star Rifle Company in Conroe Texas.  He claims that the original founder of Hart Rifle Barrels, Charlie Hart made the rifle for himself to take on an Elk hunt in the 1980s.  I will see if I can come up with some better pictures.

[stretchman]

Front sight is iron.  Anyone have some pictures of their front sight shades?  In regards to the loads, the rifle just seems to shoot its best with heavier charges of powder.

[T*O*F]

Your POI will definitely change with light, regardless of what your sight is made of.  There is a reason that most ranges have covered firing lines other than rain protection.  If you have never experienced this phenomena, you can only speculate.

I first noticed it shooting in a match on a bright sunny day.  There were large fluffy clouds drifting over, of the type that cast a shadow on the ground under them.  I was facing south.  When there were no clouds, I was hitting the bullseye.  As a cloud drifted over my POI would drop 3" and hit right 3".  As soon as the cloud drifted past, the POI returned to the bullseye.  When it finally dawned on me what was happening, I shot a 2nd target to confirm.  The results were the same.

[JHeath]

Don’t have the best pictures of the whole rifle.  The deer are small in our area of Texas which is obvious when you look at the picture.  I took the rifle in a trade from the late Dave Higginbotham of Lone Star Rifle Company in Conroe Texas.  He claims that the original founder of Hart Rifle Barrels, Charlie Hart made the rifle for himself to take on an Elk hunt in the 1980s.  I will see if I can come up with some better pictures.

Gorgeous! That's exactly what I planned to do with a jumble of existing parts here from a "flint hawken". Even the same trigger guard. But yours is the real deal -- a Rolls Royce. Mine will be a cobbled together straight-barrel .54. Thanks much for the photos. One of the Tatham/ Board of Ordnance "chiefs' presentation rifles" has that flat trigger guard but slightly rounder for a single trigger.

The glint of sun makes the sight look narrower on one side, or shorter in height, and causes aiming error. You can black the sight, or train yourself to recognize what the sight looks like when side-lighted, i.e. know where the true edge is.

[D. Taylor Sapergia]

You are able to see a 2" bull'seye over open sights at 100 yards?  Your eyes are much better than mine.

[walt53]

Roles Royce is right that’s a beauty, and lots of gun for dear.may be you just need to shot it more .walt

[smylee grouch]

Curious what the rate of twist is.

[MuskratMike]

Like others have said the different powder charges are probably the biggest reason.
The range I shoot at has the sun in the wrong position in the afternoons. I made sunshades in two sizes both out of copper plumbers couplings. I cut a section out that will just "clip" over the barrels. I also take my Dremel tool and round the edges as to not harm the wood or metal. At first they are bright copper colored but soon turn a dark color that I like. have used them for years. I make two of each size, one for the front sight and one for the rear sight.

[Jeff Murray]

You can also make sun shades out of plastic pipe. cut it a little smaller than the width of your barrel at the stock line.  The pressure will keep them on the rifle when you shoot.  Plastic pipe is available at any hardware store.

[stretchman]

Thanks for the photos of the sight shades.  I plan on making one this week.  62 caliber is a little large for less than 100 lb White tails, but it works.   When I got the rifle 20+ years ago I had ideas of going on out of state hunts.  May do that someday, but with two kids in college, Ill have to wait a while longer.

[flatsguide]

The old saying of “ lights up sights up” holds true more so at longer ranges. Mainly for target shooting. If you’re zeroed in at say two hundred yards in overcast conditions and  the sun comes up your next shot will be low unless you “up” your sights.
Cheers Richard
PS Nice shooting!

[Daryl]

stretchman - that is a beautiful rifle.  REALLY Nice. Good groups, too.
I noticed that first target had a tiny bullseye too.
I can see a 4" bull, perfectly at that range, or 100 meters (109yds), but only if I am using double apertures. Over open sights - no way.

[stretchman]

The trick with a 2" black circle is to have it in the middle of a piece 24"x36" white paper.  If I place it on an 81/2"x11" sheet of white paper at 100 yards its hard to make it out, plus there is no reference for your front sight.  With the large sheet of paper the two inch black dot will stand out more than you realize.  I wish  that the targets I have posted were typical 100 yard targets, but unfortunately most of my groups do not look like that. 

[SciAggie]

What a fabulous rifle - I needed to comment just to say that.
Yes, light will definitely affect the way you see the sights. I learned from my BPCR Silhouette days that going from bright sun to overcast would move the bullet impact. For me with aperture sights it would change 2 MOA. Side light on a blade sight will make you center the glare and in general folks shoot "away" from the light.

All that said, since you were shooting two different loads that could easily explain the change in groups.

[yellowhousejake]

Thank you for the pictures! That is a wonderful looking rifle.

DAve

[alacran]

Very nice rifle. Curious about the weight of your rifle. Those are mighty stout loads. Expensive too, only 35 shots out of a pound of powder if you don't drop any.

[Daryl]

It was a "behind the shoulder hit" that broke that little doe's neck.

[D. Taylor Sapergia]

Where'd the pictures go?

[JeffG]

"Sun up, sights up."