twist rate and wind on slugs at 450m /492y in .22

[Ignoto]

Hello guys this is my first post so heres my lack of background in shooting before the actual thread:

English is my second language so bear with me if i anger anyone or lead to misinterpretation.
I started shooting with a maverick VP 600mm in .22 about 1 year ago after watching a relative printing sub moa at 50m with a crown.

After some weeks disassembled the rifle completely and started making parts of my own to complement my needs along the way through cnc machines.

the help needed as a newbie and any comment that enlightens my knowledge about ballistics related to the following topic are welcome:

So like everyone i started shooting longer and longer step by step and now to a point that i am starting to notice that some lighter weight slugs have random behavior at long distances. HN 30gr and 25gr in both .218 and .217 @ around 1050 each to be exact. Groups at 50m were good.

What i noticed is these when exposed to backwind in the order of 5-10km/h or 3-6mph from 300 to 450m tend to poop poi up and down by almost 3mils difference, not right or left.
This does not happen or is much less noticeable with 40gr zan .217

The barrel i am using is a 1:14 fx 800mm providing according to strelok a stability factor of 2 for the 40gr 2.66 for the 30gr and 3 for the 25gr.

My question is could this be related to any kind of instability created by overstabilization or is simply the slug being too light and be carried forward or backward by the wind?

Please notice the wind was measured at ground level and at peak trajectory should be way stronger has it's passing through a valley.

Below is a video shot today with 40gr only to clarify the geometry of terrain but instead with stronger and crosswind conditioned.

 

[steve123]

It seems vertical is affected much more as wind increases when I'm shooting slugs, especially way out there. When it gets to the point I can't hit reliably I get out a firearm instead then the frustration goes away

 

[Ignoto]

With the 40's i can reliably hit the target in fact even with the crazy winds you see in the video if you listen really closely you can hear a hit before the end of the video and with slow wind 3 out of 4 on the day before. The point of the post is to understand what makes the bc drop or the big vertical change in point of impact vertically with lighter weigh ones at such distance

 

[qball]

That is very NORMAL! head/tail wind has high affect on the slugs or pellets, you just can’t see how it affect pellets at that distance because no one shoot them that far. Also it’s almost not possible to have over stabilization at the lowly speed airguns are shooting at.

My question is are you sure your 800mm FX barrel is 1:14????

 

[Ignoto]

I believe you meant vertical deflection am i correct? If so i am aware of that phenomenon and am accounting for it through strelok. Nothing out of ordinary with 40gr slugs and hitting with the same 0.128 BC as all the shorter ranges. What i see out of place is that "lighter" slugs like hn 30 and 25 that up to around 250 ish have stable poi and both have a BC around 0.105 but at this much longer range i find they vary poi vertically (wind from back) i am just wondering if it really is the wind gusting or if the projectile is fighting to reacquire the loop trajectory because of having so much rotation that starts any other issue. I was going to say misalignment with axis of flight path but in a slug the center of mass is at the rear so it would only apply to pellets..
I am just a beginner in this hobby and would like to be corrected if i think wrong in anyway.
I don't get frustrated in missing target only interested and curious to why it happens

Answering your question:
I did not count the grooves but it is what was laser engraved on the liner.

 

[Ignoto]

And by the way vertical deflection from what i learned only applies in crosswind. The video shown is not what i am mentioning it was only to clarify the geometry of the terrain the projectile goes through

 

[qball]

I believe you meant vertical deflection am i correct? If so i am aware of that phenomenon and am accounting for it through strelok. Nothing out of ordinary with 40gr slugs and hitting with the same 0.128 BC as all the shorter ranges. What i see out of place is that "lighter" slugs like hn 30 and 25 that up to around 250 ish have stable poi and both have a BC around 0.105 but at this much longer range i find they vary poi vertically (wind from back) i am just wondering if it really is the wind gusting or if the projectile is fighting to reacquire the loop trajectory because of having so much rotation that starts any other issue. I was going to say misalignment with axis of flight path but in a slug the center of mass is at the rear so it would only apply to pellets..
I am just a beginner in this hobby and would like to be corrected if i think wrong in anyway.
I don't get frustrated in missing target only interested and curious to why it happens

Answering your question:
I did not count the grooves but it is what was laser engraved on the liner.
View attachment 274996

Sorry, was typing on the phone and autocorrect ran amok! LOL! Lighter projectile with lower BC will get blown around by the wind a good amount more so basially BC/wind related or nothing out of ordinary. Even with 1:14 you are NOT over stabilizing or too much spin on a slug, just not possible with airgun speed with slugs. GS factor of 2.6/3 could be a little high, in fact I like to see all my slugs to have stability factor of 2 but not possible with heavier slugs and current airgun barrel twist rate, GS of 1.5 is minimum to get good performance out of slugs/bullets and no different from PB world.

Speaking of which, OMFG!!!! 1:14!!!!! that is so damn awesome! I so want one now! No wonder the slugger with 800mm barrel shot the heavy slugs sooooooooo nice!!!!

BTW if you have the slugger and bought from Utah you need to retune. For some strange reason they shipped the gun with reg at only 135-140 bars, WAY TOO LOW! The tungsten hammer should not be used with reg under 150 bars, it's designed to work with reg set between 160-200 bars! My friend's slugger was spraying slugs till I cranked up the reg to 170 and it's a laser beam with 35 and 38 grain NSA now. Saw someone else had the slugger from Utah air and the gun was printing 2 inch groups at 50 yards, horrible tune!!! For reference Matt Dubber tuned his slugger to 180 bars.



Edit: ideally we want GS factor between 1.5-2, I had slugs shooting very well at GS of 2.5. Never tried GS of 3 as I never had a barrel with enough twist, in theory I don’t see that as a major issue but supposedly can be categorized as too much spin. Now I really want to try the new barrel!!! Sure way to know you have too much twist/spin is the impact hole isn’t round anymore, if it is cookie cutter round then you are fine.

 

[Ignoto]

The minimum gyroscopic stability i could get away was with a pellet liner and tested to 300m accurately was with a 25gr slug measuring 7.9mm in lenght meanning a SF of around 1.

Target at 300m is the one below.

Anything heavier/longer tumbled spreading 2" groups from 50m.

As for trajectory at 450m with zan 40gr i recovered yesterday one after it's impact on a stainless plate and its looking good to my eyes don't think it's out of alignment just yet.

I believe the slugger you are mentioning is an impact mk2. Well i still don't have any knowledge or experience with that gun, i can only speak for the maverick because it's my only girl for now (that's what i always say to her ) but my opinion in that matter is that the more the merrier when it comes to tuning options and that valve travel limiter and trigger system definitely makes my hat drop for the engineering involved. What i am still curious is i the amont of area for airflow around the valve is compared to wildcat mk3 and maverick's i have seen the new m3 blocks being now really "unrestricted" for 9mm so that's my idea of power limitations of these guns.

Don't get me wrong my gun has a heavier hammer, pin probe, weaker valve return spring and 800mm liner with a custom shroud/tensioning. The rest is factory stock-for now

For the hammer i use a carbon tungsten made from grinding a piece from an tunsten endmill with stainless spacers for tuning along reg pressure just because i believe it's better a low speed/high energy hammer for harmonics and vibrations. I used it from 130 to 170bar up to 3 months now. Around 2000 rounds through it.

Warning still did not check the block for wear if overtravel is induced you can damage it!

The FX slug power kit is enough for 170Bars. I tryed out.

I tend to think: where's the bottleneck of the airflow and right next to it is how can i channel the air better?
Clearly from my testing in .22 the valving is not one but airflow can definitely be enchanced(working on it) if comparing to famous youtubers that post results even if it's in a marketing way.
Although i have to thank them for sharing knowledge like Matt's AB101 videos and many more because it really helped me choose the gun and stay with it never feeling i choose wrong out of information.

As for slugs tendency to work on higher pressures i believe it's not entirely the one factor that makes them spray over, i am starting to think through trial and error that it is the excessive air behind them that disturbs it's initial path. So what i would do is mess with a heavier valve return spring if low pressure is wanted. I had my 800mm at 130bar with this heavy hammer and light valve return spring making a valve cycle so long that i could only fly 25gr good with a airstripper. But don't take my word, try out yourself and tell us about it so we may find something cool!

 

[Flintsack]

I’ve only gone out to 300 yards. At that distance if I have wind coming towards me or blowing away I see large vertical shifts on point of impact. 6-12 inches. The same thing will happen with a firearm only on a smaller scale.

You are doing some pretty cool stuff. I don’t even understand most of the lingo going on in this thread.

Please keep it up.

Mike

 

[steve123]

Ignoto, I just looked it up on my ballictic app. If you have an ES/extreme spread of 30 fps - that alone will account for almost 37 inches of vertical spread at 450Y. Add more if your gun is as precise as 1.5 moa at 100Y like most of the better airguns are. Even the BC of the 40 grainers is low compared to centerfires and on the low side compared to a 22rf because of the big hollow point as well as going 100 fps slower than standard velocity ammo. The BC of the 25 and 30 gr slugs must be .085 G1 or so, this low BC gets affected sideways by wind a lot as well as the vertical component. Those light slugs are really petering out at 450Y!

I saw the vertical wind phenomenon yesterday. The wind was low, pretty steady, and from one direction when I shot at 250Y. I hit my coyote steel 15 times in a row before I missed. It's about 19" wide including the head and tail and 7" from belly to back. It was super easy to hit. But last week when it was windy and fluctuating a lot, it was hard to hit, and much of that was the vertical component.

You can think of wind as being compared to a river. There are currents going in different directions, water is ascending, descending, there are eddy's, etc. Then imagine something floating in the midst being carried by every change of....or like a slug going through air.

I've tried shooting my Anschutz 22rf at 500 yards a couple times. 40gr/.17BC at 1070 fps. It's precise enough to hit a 1" spinner quite a bit at 100Y in good conditions. The ES is 30-ish fps with my lot# of Lapua PB ammo and its hard to stay on a 15" round plate in low winds. 1 mph change in wind is 6" of drift and 1 mph change in wind is hardly discernible. Now think of how all the different speeds, pushes, and let offs, that the wind is manipulating the projectile to do during its flight. Winds are like ex wives, lol, hard to deal with!

 

[Ignoto]

I’ve only gone out to 300 yards. At that distance if I have wind coming towards me or blowing away I see large vertical shifts on point of impact. 6-12 inches. The same thing will happen with a firearm only on a smaller scale.

You are doing some pretty cool stuff. I don’t even understand most of the lingo going on in this thread.

Please keep it up.

Mike

Thanks man. I appreciate the kind words. I only mean to share and learn with others through their opinions and certainly more experienced knowledge. If you are struggling with lingo imagine this being my 2nd language and being relative new to shooting and reading one post at first made google my best friend. Although seeing some external and internal ballistic videos helped me. This world has some really cool stuff to be studied

 

[Ignoto]

Ignoto, I just looked it up on my ballictic app. If you have an ES/extreme spread of 30 fps - that alone will account for almost 37 inches of vertical spread at 450Y. Add more if your gun is as precise as 1.5 moa at 100Y like most of the better airguns are. Even the BC of the 40 grainers is low compared to centerfires and on the low side compared to a 22rf because of the big hollow point as well as going 100 fps slower than standard velocity ammo. The BC of the 25 and 30 gr slugs must be .085 G1 or so, this low BC gets affected sideways by wind a lot as well as the vertical component. Those light slugs are really petering out at 450Y!

I saw the vertical wind phenomenon yesterday. The wind was low, pretty steady, and from one direction when I shot at 250Y. I hit my coyote steel 15 times in a row before I missed. It's about 19" wide including the head and tail and 7" from belly to back. It was super easy to hit. But last week when it was windy and fluctuating a lot, it was hard to hit, and much of that was the vertical component.

You can think of wind as being compared to a river. There are currents going in different directions, water is ascending, descending, there are eddy's, etc. Then imagine something floating in the midst being carried by every change of....or like a slug going through air.

I've tried shooting my Anschutz 22rf at 500 yards a couple times. 40gr/.17BC at 1070 fps. It's precise enough to hit a 1" spinner quite a bit at 100Y in good conditions. The ES is 30-ish fps with my lot# of Lapua PB ammo and its hard to stay on a 15" round plate in low winds. 1 mph change in wind is 6" of drift and 1 mph change in wind is hardly discernible. Now think of how all the different speeds, pushes, and let offs, that the wind is manipulating the projectile to do during its flight. Winds are like ex wives, lol, hard to deal with!

Steve, thanks for putting aside the time to calculate the data. I also like the way you put this things comparing it with your experiences so that everyone can make up their ideas and in this specific case your river made me remember the trees and the valley the projectile goes through that may very well create turbulent downfacing air that most likely was carrying the lighter weight ones enough to see it happen. tryed to replicate the same today but wind just wasn't in the same direction. This in itself is probably not the only reason because any small imperfection just magnifies in distance but is definitely a theory to ease my mind.

I though about the speed too and measured fps on shots sent and even tryed slowing them and speeding them up-same happened wich meant to me that it wasn't a speed thing.
30gr BC 0.106

25gr BC 0.104

40gr BC 0.128

I am glad you speak your mind about PB ammo and compare it to airgun projectile BC because it is not a hate competition but sounds to me a less expensive and barrel maintenance mimic for shooter's experience even if with magnified wind effects that to me is a game in itself.

Sure higher speed takes benefit being less time in contact with the elements but what's real fun in airgunning is you can tinker and adapt to improve whatever projectile or ambient to get the best accuracy out of it.

And by the way that coyote steel never had a chance!

 

[qball]

Great work you are doing there!!!

You should check the piston on your regulator. The older regulator has a plastic piston so FX says max pressure is 160 bars. If you have the newer regulator with brass piston then you can go as high as 200 bars!!!

Generally I wouldn’t bother with any slug/barrel combo win GS factor less than 1.3, Berger’s GS calculator will tell you if below GS 1.5 your BC will be compromised a little. I’ve validated their calculations and it is dead nuts on. However slug/barrel combo with GA of 1.3-1.4 can be very accurate, I’ve done it but the BC drops slightly which is easy to adjust for but not as consistent/predicable especially if the tune isn’t super efficient.

You are 100% correct that if slugs don’t shoot well out of the slug barrel it is because of muzzle turbulence which is always caused by low reg pressure. bullets are spin stabilized and slugs even properly stabilized will get distabilized briefly by turbulence just like PB world. This is why I always try to use highest reg pressure I can get away with and make sure the valve closes before the slug leaves the barrel. This means more energy needed to accelerate the slugs up to speed in shorter distance and time aka high reg pressure. Think of this way, just like cars if you need to go faster in shorter distance with a heavier car then you need to up the power by a lot. It boggles my mind that people are so fixated on power and slugs yet on low reg pressure, it’s like trying to win a drag race with a Corolla!

Just today I tuned another friends Impact and in about half an hour I got it to shoot sub MOA at 100 yards and knocking 5 inch gongs at 200 yards with ease. But hey can’t let physics and results stand in the way of some people’s speculations and internet arm-chairing. Many of the same people also accused of Matt and South African guys cherry pick their shots, sadly for them those guys ARE that good. I can closely mimic their results but don’t have permission to shoot pests plus too lazy.

These days I shot so many slugs and tuned so many slug guns for my friends I don’t even shoot my own slug guns hardly anymore. It’s rather boring actually, waiting for more upgrades to take my MK2 to the next level again but that will get boring fast again. Now and in the foreseeable future I’m spending the vast majority my shooting time with sub 12 pellets.

 

[Ignoto]

Great work you are doing there!!!

You should check the piston on your regulator. The older regulator has a plastic piston so FX says max pressure is 160 bars. If you have the newer regulator with brass piston then you can go as high as 200 bars!!!

Generally I wouldn’t bother with any slug/barrel combo win GS factor less than 1.3, Berger’s GS calculator will tell you if below GS 1.5 your BC will be compromised a little. I’ve validated their calculations and it is dead nuts on. However slug/barrel combo with GA of 1.3-1.4 can be very accurate, I’ve done it but the BC drops slightly which is easy to adjust for but not as consistent/predicable especially if the tune isn’t super efficient.

You are 100% correct that if slugs don’t shoot well out of the slug barrel it is because of muzzle turbulence which is always caused by low reg pressure. bullets are spin stabilized and slugs even properly stabilized will get distabilized briefly by turbulence just like PB world. This is why I always try to use highest reg pressure I can get away with and make sure the valve closes before the slug leaves the barrel. This means more energy needed to accelerate the slugs up to speed in shorter distance and time aka high reg pressure. Think of this way, just like cars if you need to go faster in shorter distance with a heavier car then you need to up the power by a lot. It boggles my mind that people are so fixated on power and slugs yet on low reg pressure, it’s like trying to win a drag race with a Corolla!

Just today I tuned another friends Impact and in about half an hour I got it to shoot sub MOA at 100 yards and knocking 5 inch gongs at 200 yards with ease. But hey can’t let physics and results stand in the way of some people’s speculations and internet arm-chairing. Many of the same people also accused of Matt and South African guys cherry pick their shots, sadly for them those guys ARE that good. I can closely mimic their results but don’t have permission to shoot pests plus too lazy.

These days I shot so many slugs and tuned so many slug guns for my friends I don’t even shoot my own slug guns hardly anymore. It’s rather boring actually, waiting for more upgrades to take my MK2 to the next level again but that will get boring fast again. Now and in the foreseeable future I’m spending the vast majority my shooting time with sub 12 pellets.

Thanks man but WE are doing the work, couldn't get the minimal idea why those little slugs were behaving without everyone opinion and certainly wouldn't try it if there weren't people sharing info around forums and youtube.

Glad you mentioned the regulator. Mine is still plastic and pressure is not the problem but instead temperature change. i have created a thread recently about it check it out if you feel like it.

Fx amp regulator pressure shift with temperature

Hi guys, let me tell you right away this is not a reg creep situation. I tested the accurate measure of the digital barometer directly affects the velocity. I use a lot of different weight slugs and pellets and use the hammer wheel on the fx maverick to choose the best speed for each lead. I...

www.airgunnation.com

By the way do you happen to have more info on that new reg piston. More precisely is it a simple swap and is it available yet?

That's a good job to make a rifle tune that puts it sub moa at 100 under half-hour, i imagine your doing it full time by now.. also there's a distinct pleasure in the sound and movements of a gong more even in a small one over distance!
I might make some dynamic steel for plinking at speed shooting whenever time permits because i am missing a 100m target usually use eggs or washers that far.

Since we share the same opinion on muzzle turbulence we can't learn anything new then.

Sub 12 shooting can make some people laugh but is in itself a challenge. I have also a tune for light pellets with this same long barrel and to my surprise gave me a smile when i got back at pellets and saw them work too.

Hate and jealousy was already here when i was born and will pass on through generations.
It's up to grown men to go have a beer and simply ignore it if it arises again.

 

[qball]

Thanks man but WE are doing the work, couldn't get the minimal idea why those little slugs were behaving without everyone opinion and certainly wouldn't try it if there weren't people sharing info around forums and youtube.

Glad you mentioned the regulator. Mine is still plastic and pressure is not the problem but instead temperature change. i have created a thread recently about it check it out if you feel like it.

Fx amp regulator pressure shift with temperature

Hi guys, let me tell you right away this is not a reg creep situation. I tested the accurate measure of the digital barometer directly affects the velocity. I use a lot of different weight slugs and pellets and use the hammer wheel on the fx maverick to choose the best speed for each lead. I...

www.airgunnation.com

By the way do you happen to have more info on that new reg piston. More precisely is it a simple swap and is it available yet?

That's a good job to make a rifle tune that puts it sub moa at 100 under half-hour, i imagine your doing it full time by now.. also there's a distinct pleasure in the sound and movements of a gong more even in a small one over distance!
I might make some dynamic steel for plinking at speed shooting whenever time permits because i am missing a 100m target usually use eggs or washers that far.

Since we share the same opinion on muzzle turbulence we can't learn anything new then.

Sub 12 shooting can make some people laugh but is in itself a challenge. I have also a tune for light pellets with this same long barrel and to my surprise gave me a smile when i got back at pellets and saw them work too.

Hate and jealousy was already here when i was born and will pass on through generations.
It's up to grown men to go have a beer and simply ignore it if it arises again.

LOL! I have a day job, I just happen to have few friends with multiple FX guns that love shooting long range. However, some of them are starting to get bored at shooting 1 inch spinners at 100 yards and added 177 to their collection(I told them before). Once you get the gun to a certain point and learn the wind a little, 100 yards or even meters gets boring.


Brass Regulator piston is available through FX so just call them at least here in US. I got one coming and will order more for my other guns.

The plastic piston is obvious softer so if pushed too hard will creep more especially in higher temp because they get softer with higher temp, main reason I don’t go pass 150 bars in my regulator. Only solution is to upgrade to the brass piston, not sure what took FX so long. The swap is really quite easy, just watch the FX regulator rebuild videos by Ernest, essentially you just need to degas, unscrew the regulator core components, replace the piston and put it back. However, the piston sometimes doesn’t come out easily so you just need to pull it out with small needle nose since you gonna toss it anyways. Careful pulling the components out so you don’t lose a washer.

 

[Ignoto]

LOL! I have a day job, I just happen to have few friends with multiple FX guns that love shooting long range. However, some of them are starting to get bored at shooting 1 inch spinners at 100 yards and added 177 to their collection(I told them before). Once you get the gun to a certain point and learn the wind a little, 100 yards or even meters gets boring.


Brass Regulator piston is available through FX so just call them at least here in US. I got one coming and will order more for my other guns.

The plastic piston is obvious softer so if pushed too hard will creep more especially in higher temp because they get softer with higher temp, main reason I don’t go pass 150 bars in my regulator. Only solution is to upgrade to the brass piston, not sure what to the so long. The swap is really quite easy, just watch the FX regulator rebuild videos by Ernest, essentially you just need to degas, unscrew the regulator core components, replace the piston and put it back. However, the piston sometimes doesn’t come out easily so you just need to pull it out with small needle nose since you gonna toss it anyways.

Thank you