Spin Drift

[Pandur_HR]

Nice discussion. i learned a lot.

I tweaked the Strelok Pro.
- Barrel twist rate changed to left hand.
- Pellet lenght shorten to get SF 1.85

Now, calculated POI match with true POI on my targets archive.

BTW I found bug in Strelok Pro. When you have a left hand barrel it will calculate POI correct. But Magnus is displayed reversed in statistics.

One day I will try to tweak Chairgun for Windows. I need Cd values from it. I plan to modify one of Lapua custom drags to JSB 18.13 drag.

Then I would be ready for N.U.A.H 200m attempt.

Just I need to find a range. Shooting range I am using is designed in a way that .22LR is stopped by a 150m bank. Bullet will hit bank or fenders above.

That is valid for me too. I cannot shoot over 150m bank.

So, 200m with a springer will be even more difficult then I tought. Maybe for me impossible (no suitable range).

PS
On 200m, my spin drift + Corriolis is 12 cm, I need perfect calculation, or I might end in a situation that I don't know where my misses are. I am not going for one hit (continue shooting until one hit). But for 5 grouped, I need to know my POI. Especially is it left or right of target.

[Pandur_HR]

I rechecked the scope alignement and cant one more time, all was OK.

I just ordered weather station (I was planning to buy one anyhow).
So, when I have a good day with accurate and precise groups, I can messure wind down the range and check is it causing shifting to left or not.

https://weatherflow.com/weather-meter-for-shooting/

Products as labradar are not usefull to me.

https://www.creedmoorsports.com/product/4013/chronographs

.22 pellet they will track up to 60yd, and max is 130yd. I shoot further.

Due to the nature of job I am doing, I will not be able to shoot for some time (month or two). But I will continue on this. Pellet ballistic is full open for scientific work, and I find that interesting.

PS
Too bad, I do not have powerfull and precise PCP, it would be faster and easier. And for me, due to laws, it is not trivial to buy.
Nevermind, I will continue with a springer.

[BackStop]

I noticed it first time while shooting for N.U.A.H and blamed Hawke shims alignement at first

https://www.gatewaytoairguns.org/GTA/index.php?topic=151557.0

After that scope was realigned multiple times.

At the end I bought adjustable mount and aligned all perfect.

Pellets are in perfect fit with rifling. The one on picture hit the metal plate at 144m at 12 mph wind 3-6 o'clock. It hit it straight and deformed correct, rifling is visible. Stability is excellent.

What caliber is that pellet?
Thanks!

[Pandur_HR]

Don't think that springers cannot shoot precise and accurate on long ranges. Well, not submoa groups, that they can't. But they can be sufficently precise and accurate to estimate is it POI left or right, and aproximatly for how much.

Picture 1. Sample of precise but not accurate group at 157.5 yd with 12 mph wind in 3 o'clock

Picture 2. Sample of accurate but not precise group at 159.5 yd with wind 10 mph 9 o'clock.

I was not lucky so far to have a calm weather for more than 2-3 shots. Sample is on a picture 3.
Two near the center (accurate and precise) are on a calm weather. Two on a bottom-left are with a strong crosswind in 3 o'clock.

Picture1


Picture2


Picture3

[Pandur_HR]

I noticed it first time while shooting for N.U.A.H and blamed Hawke shims alignement at first

https://www.gatewaytoairguns.org/GTA/index.php?topic=151557.0

After that scope was realigned multiple times.

At the end I bought adjustable mount and aligned all perfect.

Pellets are in perfect fit with rifling. The one on picture hit the metal plate at 144m at 12 mph wind 3-6 o'clock. It hit it straight and deformed correct, rifling is visible. Stability is excellent.

What caliber is that pellet?
Thanks!

JSB .22 18.13 gr

[BackStop]

I noticed it first time while shooting for N.U.A.H and blamed Hawke shims alignement at first

https://www.gatewaytoairguns.org/GTA/index.php?topic=151557.0

After that scope was realigned multiple times.

At the end I bought adjustable mount and aligned all perfect.

Pellets are in perfect fit with rifling. The one on picture hit the metal plate at 144m at 12 mph wind 3-6 o'clock. It hit it straight and deformed correct, rifling is visible. Stability is excellent.

What caliber is that pellet?
Thanks!

JSB .22 18.13 gr

Thanks!
That there is darned pretty!

[Pandur_HR]

It hit the metal plate with 9-10 fpe according Strelok.

[BackStop]

It hit the metal plate with 9-10 fpe according Strelok.

I was going to say WOW!  But then I thought about what I usually shoot at.  Not metal targets.
Usually, it is 10 meters indoors (shoot down my central hall) into a box stuffed with newspapers.
Outside can be from 20 to 60-70 yards/meters, but usually just 20 to 50.
However, I am still indoors shooting out of 2 windows... 10 feet back in the house.

Anyway, I don't think I have ever seen a pellet that I shot look like that.
I'm afraid the neighbors would get upset if I started shooting "dinging" metal targets.
It is not legal for me to shoot in the city limits.  I am not even sure that shooting inside my house
is technically legal.
However, I am going to rid my property (they are getting under the house) of Chipmunks, Squirrels
and any other vermin that invade or damage my property.

[Pandur_HR]

When I shoot 25m, I use metal pellet trap. Pellets are torn appart after hit, looking as melted led.

[BackStop]

When I shoot 25m, I use metal pellet trap. Pellets are torn appart after hit, looking as melted led.

You must be shooting a LOT faster than I do.
Any in case, thanks for the replies!

[Pandur_HR]

Last chrono with JSB .22, 18.13gr

[BackStop]

Last chrono with JSB .22, 18.13gr

I stand corrected.  Although I am shooting .177, I am sure I have not seen expanded pellets like
that simply because I never have the chance to shoot at a flat, hard target such as steel.
Really enjoy your posts, even though some of it is over my head.
Thanks for the reply!

[Bill G]

Ivan, You have probably already checked for what I'm going to mention, you seem very thorough. I may have been reading through material lacking maximum attention, I have lots of distraction at the moment. 
Have you checked to see if the barrel is clocked to accommodate any slight bend or deviation? this may not be an option for your rifle. I have had an issue a long while back that had me completely stumped. It was way back when I first got into Air rifles and I had one with a very slight bend over the length of the barrel. IIRC, it was .003" over ~20"( .076mm over ~500mm).  Some one suggested that I rotate the barrel around the bore axis and observe the pellet impact. There the problem was, plain as day.  I oriented the bend to disperse in the vertical and shot placement became extremely predictable from then on.  since then, If I barrel a gun, I always indicate the barrel to expose not so good imperfections. I then mark accordingly and install appropriately. If I missed this detail, excuse my lack of attention.

Bill

[Pandur_HR]

Ivan, You have probably already checked for what I'm going to mention, you seem very thorough. I may have been reading through material lacking maximum attention, I have lots of distraction at the moment. 
Have you checked to see if the barrel is clocked to accommodate any slight bend or deviation? this may not be an option for your rifle. I have had an issue a long while back that had me completely stumped. It was way back when I first got into Air rifles and I had one with a very slight bend over the length of the barrel. IIRC, it was .003" over ~20"( .076mm over ~500mm).  Some one suggested that I rotate the barrel around the bore axis and observe the pellet impact. There the problem was, plain as day.  I oriented the bend to disperse in the vertical and shot placement became extremely predictable from then on.  since then, If I barrel a gun, I always indicate the barrel to expose not so good imperfections. I then mark accordingly and install appropriately. If I missed this detail, excuse my lack of attention.

Bill

Did a laser check, look OK. (Beam, center to center, and there should be no deviation all the lenght).

I check it from time to time (for vertical bend). It is a magnum springer, with extra cocking effort.  And I am not weak. :-)