Canadian Airgun Forum

When shooting powder burners, we never bothered about twist and drift except at long ranges. Then we shot a lot of groups and just recorded turret settings into silhouette scopes.

I'm shooting Hawke 4-12x50 AO Airmax scopes on my two FX Streamlines and Hawke 4-12x50 AO Vantages on my Kral & HW100KT (now sold).

Our range has strange winds, which play some interesting games with shooting, especially 50 meters to 135 meters.

It has been my impression that the Streamlines shoot increasingly to the right at longer distances but could never completely tie that down.

I've encountered scope rails that were not parallel to the bore and thought maybe that was the case.

Old age is not helping my brain function so hopefully, someone will take pity.

When I have the data in Element Basics, the drift appears to match the calculations. When I reverse the twist from RH 1:16 to LH 1:16, the drift reverses to left, beyond 50 meters seeming to confirm the effects of pellet drift.

Am I on the correct track?
Do RH twist pellets drift to the right at longer distances due to the effects of twist, or is this application calculating for bullets and I'm screwed up by wind?

I read in a Dec 30, 2018, Airgun Nation thread that "Original Smooth Twist is 1 in 16 as Bob said, just be aware that the actual resulting pellet twist rate is much, much less due to the way it is launched in a smooth section of the barrel and then the pellet strips through the rifled section and picks up a small amount of spin. It has been measured at something like 1 turn in 13 _feet_.
".

Someone else said, "I’ve heard 1:30 up to 1:50. So I use 1:40 in my Strelok Pro. I actually don’t think it makes much difference at the ranges and speeds we shoot.".

I may not make it to the range this week and cold conditions aren't ideal for testing so am hoping to nail some of this down so as not to chase my tail too much.

_________________
Slavia 618 .177
Webley Senior .22
Jelly SUPER 4.5 mm
Webley Viscount .177
Kral Mega Marine Walnut .22
Artemis PP750 .22
FX Streamline .22 walnut
FX Streamline .22 composite
FX Dynamic 500 .22

The smooth twist idea is similar to the Paradox rifles of the 19th century for large and dangerous game. In these, the barrels were smooth, up to a reduced section at the muzzles(SxS guns)
that could be equated to choked sections. These were rifled, quite deeply, to grip the super sonic projectile and spin it for accuracy. FX simply turned this over 140 year old process into a more
modern one with their smooth twist.
I was surprised to learn the actual twist incorporated was so slow.

_________________
Best Wishes
Daryl

At my SGC the 100 meters, 50 meters and 22LR silhouettes range is very difficult to shot with air rifle when any "visible" wind movement is present. The ranges are like a low land tunnel between a higher L-R side three lines. The grass is not moving much but the young branches. Also if the air movement is coming from front or rear of me a lot of up/downward push.
I got to a bottom line to build myself a variation of wind flags placed strategically along the distance. Also have a WeatherMeter = wind direction "meter" which I plugged in to my StrelocPro for a real time calculations, placed out to about first third of a distance. It was an improvement but still a windy day is a windy day.
And then I started paying more attention to wind charts. Not much halp at my place to learn but at least to understand what the Strelok does ....
I don't want to bring any chart from the internet, I am sure you able to find yourself that suits you. But what I have noticed that pellets and slugs behave different to air movements.

Ps, misalignment of a scope will show at multiple distances only, if you shooting at a fix really doesn't matter you just sight in for that single distance. But a bubble !!! can also mess with mind. Best to chose a fast moving alcohol filled bubble, more sensitive and shows more if you are on it.

I am shooting .25 pellets from a 1:24 and 1:27 liners, I think the 27 TR is better beside a fact it has a noticeable choke.
Tried the .22 with several twist rates (15.5-16-18-24), but the MRD's not cooperating well @ 100. At 50 really pretty much all capable the same MOA 90%.

_________________
FX Impact MK2 PP - heavy modded
Edgun Leshiy2 - heavy modded
and a lot more scopes with great glass