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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 1:09 pm 
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Joined: Mon Aug 08, 2016 7:23 am
Posts: 2633
Location: Somewheres near the Atlantic
All the graphs Ive seen about 177 trajectory all seems to start dropping at around 5M.

Don't need chairgun. Just need to adjust your sights and not worry. I do the old school methods. Paper and pen. Sit at ranges and find out the drop my self. Make a data sheet to my guns.


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 1:19 pm 
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Joined: Thu Oct 04, 2012 10:27 am
Posts: 1062
Location: Thunder Bay,On.
leadslinger wrote:
All the graphs Ive seen about 177 trajectory all seems to start dropping at around 5M.

Don't need chairgun. Just need to adjust your sights and not worry. I do the old school methods. Paper and pen. Sit at ranges and find out the drop my self. Make a data sheet to my guns.


Yeah really....just point...shoot ....adjust...easy...old school is best sometimes... :D

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 1:36 pm 
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Joined: Wed Sep 07, 2016 11:04 am
Posts: 749
Gotta be some reason ft shooters make their own tape rather than relying on factory markings.

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 8:52 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1233
Location: United States
leadslinger; yes everything drops the moment it leaves but what if the trajectory matched the curvature of the planet, would that be considered "flat". Like the ocean is flat yet it is not, so along that mentality ;) Then there's coriolus so really that would only work in either east or west shots, not both. Would it not be awesome to shoot a bullet on a no atmosphere planet and that that sucker orbit at xx inches off the surface for however long? Years? I also recall mention of bullets, especially aft heavy bullets like your example, that would surf the air and not drop and the 33ft/sec like they're supposed to. My guess is any normal bullet (not so much pellets tho) would do that for long shots. If angled up 10 degrees then the bullet will try to stay pointed up 10 even tho the trajectory levels and drops until impact. Surely it gets some surfin action outta that, but how much I don't know. I just remember when I was reading about it the shooters had to factor that in. Basically they had the estimated data based on math, then how much the bullet actually dropped, which were not the same. I'd imagine that's one reason boat tail bullets work a little better than non BT? I'm picturing less drag when in surf mode...

YepYep; I'm sure you know much/most of the following but tmi is better than not enough, or for whoever else that may bennie. Sorry if I'm repeating anyone bc I only skimmed the thread. So; the free program "Chairgun" will do a pretty good job of predicting trajectory and it's an excellent tool to get a visual on what's up w/o having to do it manually over a ton of shots. I believe it'll also do <5m, but I've never tried. Not that much happens in 5M but you could try. Or another way of looking at it is to get really accurate you need to do it manually (old school), but Chairgun gives you a clear picture of what's happening so you have a better understanding and head start when you start doing it old school. Example; the poi being lower at shorter range is shown very clearly. It also factors in scope height which I really like. So as people have no doubt mentioned you always have an arched trajectory (with a pellet, BB's don't count) and the scope only sees a laser straight line. So I sight my scope to match the pellets trajectory, so basically the more fps the further out I zero it. I generally do it one of two ways; one is I'll set it so the pellet hits ~1/8" above the scopes reticle at its zenith, that way the pellet is +-1/8" of the reticle for a good stretch of distance so I don't have to think about holdover much. So lets say 30yrds is zenith, then at 20 and 40 it's spot on, 30 is 1/8" high, and 10 and 50 it's 1/8" low. So close enough for hunting from 10 to 50yrds. Those are just unrealistic example #'s to make a point, but it gives you a "no thinking" window, just point n shoot. Option #2 is actually better, you just have to think: I'll set the reticle to the zenith exactly, then keep in mind that the zenith, lets say 30yrds, is the only point it's on target and I have to know the holdover for whatever distance before or after 30yrds. I'd also like to add that I like my scopes as low as possible, mostly for looks but also bc it makes that 1/8" high/low zone I mentioned longer and less compensation needed when out of that range, like when shooting close. That also applies to the #2 zenith only setting so a low scope is a win win imo. Since you wanted more velocity for flatter trajectory I thought maybe you'd be interested in that. That and getting the most velocity possible with the heaviest, or I should say best BC, pellet you can find. I'm partial to the JSB 10gr and the Baracuda Match. The JSB 8.44 also has excellent BC but may be too fast, the JSB 13.43 is likely too heavy/slow unless you have a magnum, but I don't know what gun you're using. I'd plug in all kinds of #'s into Chairgun so you get a feel for what affects what, by how much.
A lot of people, maybe most, don't sight to the zenith at all but instead to whatever random distance they happen to use. Maybe bc the target says 10M on it they do 10M, or maybe the fence is 12M from the porch so 12 it is... If you sight to 10 or 12M you're screwed when you go out plinkin/hunting bc the pellet will go higher after that 10-12M mark, and the higher you scope sits on the gun the worse that is (assuming 12+ftlb gun since that's what I know). Then whatever lucky animal at 30M is further than the sighted range so they add some holdover, and they miss. It may take a while before they figure this out, and I think most never go to zenith, they just get closer and call it good enough. If you only shoot at 10M then set it to 10M (or whatever fixed dist), otherwise it's a bad idea, imo.
Anything within say 50yards is fairly easy to compensate for drop, <500fps not so much but chairgun will tell you that too ;) The further you go the more drop per Meter you get until at, 100M for example, it's just ridiculous. Plus the further out the harder it is to est dist so shots at say 60-80M+ may be a pot shot first to see where it hits. That's fine for plinking but usually not so good for game, unless it's a Dove, which I recall will just sit there with a "what was that?!?!" expression until you finally make contact.
Chairgun cannot compensate for transonic losses, which start ~890fps and get worse as you go on up to the speed of sound. It causes the BC to get much worse (more drag) but if you're at 925 I spoze you can ignore it, if at 1100 you're screwed and the app will be way off. You shouldn't be shooting at 1100 anyway bc aside from the power loss it also upsets accuracy. Chairgun needs Java and/or NET Framework 3.5? I forget, but it needs something before you can load it and it'll tell you. Then you need your actual pellet wt, BC and velocity. What you don't have you'll need to est. There are BC #'s online, or you can email me and I'll send you the collection I scavenged from the net. Velocity is really iffy if you don't have a crony, if so you'll just have to guess there too but guessing at all these #'s is still better than nothing. As you may know most springer mfg's lie about that velocity so don't use their #, get an avg real user # from me/us. Another note is a heavier pellet (on avg) has better BC so while it's close range trajectory will be worse due to lower speed, it's long range traj will be better. As a result the heavy/better BC pell will travel significantly further than a lighter one, which you can easily test if you have a big lake or dry dusty area to see the poi. Picture throwing a rock vs a shuttlecock which likely has the worst BC of anything meant to fly, excluding a balloon. You can launch that shuttlecock at mach 10 and it's not going as far as the rock doing 200fps. So a 4gr Crosman at 1400fps vs a 10.5gr Baracuda at 850, the 4gr even has more power in this example but the Baracuda will have more range, maybe even more than double the range.


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 9:53 pm 
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Joined: Wed Jul 26, 2017 7:01 pm
Posts: 1676
Location: GTA, ON
Thanks Chevota ~ your reply is very detailed and informative!

One more question... What's the BC means? I noticed I can input this in the chairgun,. but never did so...

I installed the Chairgun in my cellphone, so I don't need any runtime library support for using it....

However so far I think I just used very little of its functions... I used it to compare the energy to choose caliber and pellet weight with all estimated original data as I don't have a chrony... But anyway my guns are non regulated, and shooting for close range ( paper target less than 30m, 'pest control' less than 10m, plinking from 5m to 20m...etc) so I usually just want an easy reference....

I zero my guns use your method #2 to 10m ( maybe just a little bit less than 10 yards as that's the maximum range I can set in my basement... You need a good place to sight in the gun. Once it done, you can start enjoy it, right?). I find that advantage of the low profile mounts by myself... And then I like to use open sights again as no other sights can be more closer than the stock open sights to the barrel, and can give you the maximum useful range of your zeroed point... I like it!

However, I don't have a good eye to aim, so open sights for me, actually bullseye on 10m is 100% guessing already, I am not sure what I see actually... =) so my open sights are for plinking only, shooting a pop can 20m away with my HW45 is very fun ~

And scoped guns are for shooting bullseye or small targets or longer range targets...

Starting this topic is just a suden thought after my current tin of JSB express just coming to finish, and I have a new tin of wadcutter handy on aside then I just put one on and found the POI just dropped unexpectedly.....

Sent from my LG cellphone

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Izzy 46M
HW30 Stainless Steel + Discovery 40mm Scope
HW35 Walnut + Hawke 40mm Scope
2240+14" barrel/Williams peep sight
Camo Chaser long barrel rifle kit
P3+2x20 Kit Scope
HW40+Extender
HW45+Grip panels from Russia
P1322 with walnut forearm


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 Post subject: Re: .177 trajectory
PostPosted: Tue Aug 14, 2018 9:46 am 
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Joined: Mon Aug 08, 2016 7:23 am
Posts: 2633
Location: Somewheres near the Atlantic
Normally people with bad eyes go with optics.

Ballistic Coefficient (BC) is basically a measure of how streamlined a bullet is; that is, how well it cuts through the air.


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 Post subject: Re: .177 trajectory
PostPosted: Tue Aug 14, 2018 10:02 am 
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Joined: Wed Jul 26, 2017 7:01 pm
Posts: 1676
Location: GTA, ON
Similar to the CD ( drag coefficient) for cars?!

Sent from my LG cellphone

_________________
Izzy 46M
HW30 Stainless Steel + Discovery 40mm Scope
HW35 Walnut + Hawke 40mm Scope
2240+14" barrel/Williams peep sight
Camo Chaser long barrel rifle kit
P3+2x20 Kit Scope
HW40+Extender
HW45+Grip panels from Russia
P1322 with walnut forearm


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 Post subject: Re: .177 trajectory
PostPosted: Tue Aug 14, 2018 9:09 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1233
Location: United States
I think leadslinger took a jab at me. I always preferred scopes on rifles but I enjoy open sights too. It's like riding a motorcycle w/o a helmet vs driving a car w/ the windows up. One way you feel part of your environment, the other is half way to watching it via TV. So I'm torn between having to watch thru the scope and hitting whatever itty bitty thing, or seeing it all but only getting close. Like I used to shoot aspirin tabs standing on the fence w/ my FWB 124D, w/ scope I'd never miss, open I could usually get 'em but if I hit the fence it would knock the others off. So the way it ended up for me is none of my air rifles have open sights (excluding Daisy Red Ryder), and none of my pistols have optics. My 22LR has open sights, if that counts bc I basically only use it in place of a pellet gun. Usually for night shooting rats, the sights have glow paint on them...

CD is similar but BC includes weight where CD is just aerodynamic drag. Like if you dropped two ping pong balls from 100M, but one is full of water. CD is the same but BC is not. This is why heavier pells are usually better.

There used to be a BC chart on the H&N site but I don't see it now. I did however notice a simple version of Chairgun:
https://www.hn-sport.de/en/air-gun-hunting/baracuda-177 (bout half way down the page)
Not many options to set but it gives trajectory, speed and power curves (for that pellet) to get that feel for what's going on. Like how the drop at close range is min but 100yrds is drastic. And how velocity and especially power drop faster at first. This one factors in the transonic so if you plug in say 850fps you get the expected velocity/power drop curve, but plug in 1200 and you get a massive drop until it's out of transonic. Note the drop in speed from 0-10yards vs 20-30. This is why it's best to keep it under ~890. I still shoot over that # a lot but I have power to spare and my range is usually close so I don't care and I like the speed. Like shooting misc stuff just to see what happens, like an egg, is best done at max speed from ~1yard. Or trying to punch a hole in a quarter you need a hard pellet (alloy) and a ton of speed. I think it took >1300fps using a Gamo Raptor, which in order to avoid losses I shoot at ~1" away.
Here are some BC #'s from some lost source so no clue how they arrived at the #'s. Can't post a word.doc so I shoved it into a .jpg, so pardon the ugliness. So unknown data like this is iffy bc some will shoot at say 1100fps and take a reading at muzzle, 10, 20, 30 yards, then avg them. Imo they killed it bc the 0-10 is transonic and ruined the avg, we want to know what it is <890... There's also the question of accuracy, like were their cronys spaced accurately? Or worse, did you use one crony and move it? If I had to guess I'd say these were taken with an 18ftlb gun which included transonic #'s for the mid to lighter pellets, but who knows. So unknown but close enough and better than nothing:


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 Post subject: Re: .177 trajectory
PostPosted: Tue Aug 14, 2018 9:32 pm 
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Joined: Wed Jul 26, 2017 7:01 pm
Posts: 1676
Location: GTA, ON
Thanks for the BC data chart ~

Actually there aren't unlimited pellets in the market, and I just thinking why not Chairgun just build in this small data base, and actually put a drop down menu on the pellet name to let ppl choose the pellet they are using, then the app just input all this static data like weight, BC... (Uhh, looks only two?!) for us... That will make it much better and easy to use...

Sent from my LG cellphone

_________________
Izzy 46M
HW30 Stainless Steel + Discovery 40mm Scope
HW35 Walnut + Hawke 40mm Scope
2240+14" barrel/Williams peep sight
Camo Chaser long barrel rifle kit
P3+2x20 Kit Scope
HW40+Extender
HW45+Grip panels from Russia
P1322 with walnut forearm


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 Profile  
 
 Post subject: Re: .177 trajectory
PostPosted: Tue Aug 14, 2018 9:59 pm 
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Joined: Mon Aug 08, 2016 7:23 am
Posts: 2633
Location: Somewheres near the Atlantic
Chevota wrote:
I think leadslinger took a jab at me. I always preferred scopes on rifles but I enjoy open sights too. It's like riding a motorcycle w/o a helmet vs driving a car w/ the windows up. One way you feel part of your environment, the other is half way to watching it via TV. So I'm torn between having to watch thru the scope and hitting whatever itty bitty thing, or seeing it all but only getting close. Like I used to shoot aspirin tabs standing on the fence w/ my FWB 124D, w/ scope I'd never miss, open I could usually get 'em but if I hit the fence it would knock the others off. So the way it ended up for me is none of my air rifles have open sights (excluding Daisy Red Ryder), and none of my pistols have optics. My 22LR has open sights, if that counts bc I basically only use it in place of a pellet gun. Usually for night shooting rats, the sights have glow paint on them...

CD is similar but BC includes weight where CD is just aerodynamic drag. Like if you dropped two ping pong balls from 100M, but one is full of water. CD is the same but BC is not. This is why heavier pells are usually better.

There used to be a BC chart on the H&N site but I don't see it now. I did however notice a simple version of Chairgun:
https://www.hn-sport.de/en/air-gun-hunting/baracuda-177 (bout half way down the page)
Not many options to set but it gives trajectory, speed and power curves (for that pellet) to get that feel for what's going on. Like how the drop at close range is min but 100yrds is drastic. And how velocity and especially power drop faster at first. This one factors in the transonic so if you plug in say 850fps you get the expected velocity/power drop curve, but plug in 1200 and you get a massive drop until it's out of transonic. Note the drop in speed from 0-10yards vs 20-30. This is why it's best to keep it under ~890. I still shoot over that # a lot but I have power to spare and my range is usually close so I don't care and I like the speed. Like shooting misc stuff just to see what happens, like an egg, is best done at max speed from ~1yard. Or trying to punch a hole in a quarter you need a hard pellet (alloy) and a ton of speed. I think it took >1300fps using a Gamo Raptor, which in order to avoid losses I shoot at ~1" away.
Here are some BC #'s from some lost source so no clue how they arrived at the #'s. Can't post a word.doc so I shoved it into a .jpg, so pardon the ugliness. So unknown data like this is iffy bc some will shoot at say 1100fps and take a reading at muzzle, 10, 20, 30 yards, then avg them. Imo they killed it bc the 0-10 is transonic and ruined the avg, we want to know what it is <890... There's also the question of accuracy, like were their cronys spaced accurately? Or worse, did you use one crony and move it? If I had to guess I'd say these were taken with an 18ftlb gun which included transonic #'s for the mid to lighter pellets, but who knows. So unknown but close enough and better than nothing:


Actually I didnt take a jab at you. I was responding to yep.


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 Post subject: Re: .177 trajectory
PostPosted: Wed Aug 22, 2018 9:00 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1233
Location: United States
Chairgun doesn't care, it's a firearm program that by default does pellets too.
They'd have to testing on all these pellets and my guess is they wouldn't even bother doing one. So I'd just use estimates for BC and worry about the other #'s. And/or use that H&N dealie.


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