What did I miss

[Bob Kingsbury]

Shooting groups with a 6PPC this am. I shot 4 groups with 2 different
powders. Wind was very light, about 2mph from 3-9 o'clock and
seemed steady.Very Light mirage was present and tgt movement was
in all directions more as a wiggle than a direction. In each group
the shots kept falling lower and lower. The next group would begin
in the same place as the first shots in previous groups. then down they came. This amounted to 300 verticle at 100. I would have thought that
those conditions would be pretty good. With all four groups doing the same
, I'm sure there is something I don't understand

 

[Joe Krupa]

It's heat coming off the barrel.

Even if you are using a mirage shield strip (which is almost useless unless it encompasses the entire bell of the scope in very light to dead calm) the heat causes the sight picture to rises in very light conditions. We continue to hold down to compensate for the rise in the picture.

This is very easy to see on a rail gun without a mirage shield. You can shoot your gorup and when you're done, sit there and watch the crosshairs fall back down to the original POA as the barrel cools off.

When the wind blows decently well, the heat is being blown off the barrel and has a lessoned affect to the sight picture. I get a lot of grief for this, but I use an old target taped to the barrel and the bell of the LCS scope (harder to do with the older 36X's with the parallax adjustment on the bell). I haven't had a dropped shot in years since using this in a dead calm and very light air.

 

[jackie schmidt]

Bob

Even in really cruddy mirage, you will always get a certain time where the sight picture is dead on.

When testing your loads, be willing to wait on this. Of course, this is not always an option in match shooting, where the clock is ticking.

Joe made a good point, aiming at a different spot each time can wreck havoc on groups. But it sounds like your Rifle just is not in tune.

I know that shooters get tired of hearing that answer, but in my opinion, most of the problems encountered by shooters is not the bags, it's not the scope, it's not the mirage, it's not that you doubled with someone, or a whole host of reasons that shooters lament as to the cause of problems.

It is, more times than not, the simple fact that the Rifle just is not working. We don't like to admitt this because it is probably the most difficult item to fix.......jackie

 

[Bob Kingsbury]

I keep on learning

Thanks Joe,
I think your dead on, Yesterday, I took the shears to my mirage
shield and made it narrower, was 2 1/2 inches wide , I cut it to an
1 1/4. Now its in the trash. Thanks , your the man

 

[Steve Lee]

Joe...that's interesting and I didn't know that. I was under the impression that if you shoot fast, barrel heating would not have time to reach the outside of the barrel.

At the same time I wonder if wake turbulence from the preceding shot might affect the sight picture.

 

[JJ-IA]

Not discussed here much but changing ambient light intensity can cause havoc too.
Some days carefully watching the broken cloud cover for a consistent lighting condition is as important as reading the flags, or messing with the powder measure.

 

[gt40]

Even if you are using a mirage shield strip (which is almost useless unless it encompasses the entire bell of the scope in very light to dead calm) the heat causes the sight picture to rises in very light conditions. We continue to hold down to compensate for the rise in the picture.

This is very easy to see on a rail gun without a mirage shield. You can shoot your gorup and when you're done, sit there and watch the crosshairs fall back down to the original POA as the barrel cools off.

When the wind blows decently well, the heat is being blown off the barrel and has a lessoned affect to the sight picture. I get a lot of grief for this, but I use an old target taped to the barrel and the bell of the LCS scope (harder to do with the older 36X's with the parallax adjustment on the bell). I haven't had a dropped shot in years since using this in a dead calm and very light air.

Do you mean like I use in the picture? I cut it shorter away from the end of the muzzle because the blast would blow it off the scope and split the plastic tube.

"Aim small miss small",

gt40

 

[Bob Kingsbury]

Gt40

GT40
Wow, even the bench has a mirage shield
Mom will be mad, you got that from the crib