Maybe someone can explain.
My HW100 .20 likes JSB Exact...a lot. I have it zeroed at 35m and the grouping is limited only by the nut behind the trigger.
With H&N FTT and H&N Baracuda the groups look as if a shotgun was used but, at 35m, the groups also print significantly off to the left with centres about 2 to 4 cm left of the bull. I'm curious. I can understand the different weights could result in slightly different elevations and that a poor fit in the bore or bad pellet quality causes groups to scatter but can anyone explain this horizontal shift?
The weather was totally calm with no wind and yes, I am holding the rifle up straight. Targets are taped to a cardboard box sitting on level ground so it is easy to align crosshairs vertically and horizontally.
Last edited by JXV; 22-05-17 at 09:13.
I have also noticed this trend with the S400, haven't tried many different pellets in the R10 yet, so I cant comment there. But for some reason the H&N's group low and right in the S400.
Once zeroed though the groups are similar to the JSB's and AA's, just not quite as tight though. I've written the horizontal movement of groups from different pellets off to basically what my barrel likes or doesn't like.
The H&N's may have different Gyroscopic characteristics, causing the groups to shift either left, or in your case from your barrel, right.
I worked out .... 1 in 12 inch rifling twist, mv of around 860 fps translates to a pellet rotational speed of about 60 000 rpm which seems helluva quick. Any imbalance on that pellet is gonna make it fly all over....but why mostly to one side
Try measuring the H&N versus the JSB Exact. Maybe that's where the difference in performance comes in.
I find this difficult to understand. According to me if there is any horizontal or vertical force acting on the pallet you will never be able to zero the scope. Because it will only continue on the path and get wider.
Why then is possible to zero a scope with different types of pellets at different distances ?
As long as the scope is vertically in line above the barrel, as long as you hold the rifle upright then there should only be vertical rise and fall of the pellet with distance (due to gravity) and any horizontal deflection should only be due to wind .....or so the theory goes. But the H&N pellets ALWAYS shoot to the left in my rifle. Barrel harmonics?
Last edited by JXV; 23-05-17 at 13:48.
Yes I get the impression the Baracudas are smaller. They are a loose fit in the magazine compared to JSB. The FTT is another issue.... lightest pellets but they chrony the slowest.....so they might be a bit tight in the barrel.
Originally Posted by jonratter
The standard .20 barrel in the FAC HW100 rifles like mine is 600mm long and likely to be choked. Could the choke cause this issue?
I will just except it, because I can't wrap my head around it.
Great link...Thanks. Explains a lot.
Originally Posted by Arras
My rifle shoots pretty straight from 20m to 80m with JSB. Only elevation adjustments needed 1 so I think the scope alignment is Ok.
Learned two things I need to do though...
1. Season the barrel with a few mags worth of each particular pellet type before shooting test groups
2. Shoot those H&Ns at various ranges to see if they are spiralling as I suspect
And here's more reading. It may sound like an anal overkill approach but there's a bit more pellet info to glue to your memory.
Pellet preparation guide ~ Air Rifle SA Forums
And from the late guru Mze........
Originally Posted by mze
Last edited by jonratter; 24-05-17 at 09:10.
Agree! Just use what works best and don't lose sleep about the rest, you need to be well rested to shoot good groups...
Originally Posted by McJack