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 Post subject: .177 trajectory
PostPosted: Mon Aug 13, 2018 8:40 am 
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We choosed 177 cal is for a flatter trajectory.

Isn't it we can suppose the pellet after leaving the muzzle, it's flying a flat trajectory like an extend of the barrel ? I remember someone's comment on a gun ( don't remember what it is) said the pellet just hit what he aimed like a laser...

If so.... I have a question regarding the sights zeroing and the POI changes due to different types of pellets...

I just noticed that while I change to use wadcutter (8gr JSB yellow tin) on a gun which sighted well using the domed pellet (7.8gr JSB express), the POI lowered about 2 inches on target about 8 yards far...

Is that means the pellet not flying on a horizontal flat trajectory if I made the barrel horizontal to the ground while shooting? ( The 'laser' just shoot 2 inches lower...)

In my case, the pellet weight just similar, but the shape of wadcutter just much different than the domed shapes (I tried pointed vs domed before, or domed different brand, weight, no this much differences.... So once I had a tin of mixed Crosman pellets for my 1322 for plinking...)

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 9:02 am 
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Nothing shoots technically flat due to curvature of the world, and gravity. My service rifle, fired a 62grn bullet at like 2800 FPS. It actually would drop as soon as it left the muzzle. And the bullet would rise till the 100m zero, continue to rise and start dropping at 200M it would be the same POI, but than it would start dropping more. So it was a down, up, down.

It might shoot flat for 6M, then it's going to start dropping.

Even velocity effects trajectory. My Kral same pellet, 3 different power settings, 3 different POI. 1000 FPS was high, 800 was dead on, 600, was like 2.5-3" low.

The domes cutting the air better and flying straighter, where the wad cutters are flat and have more Resistance. Slowing them down, and thus dropping faster.

Its like putting your hand out of the window while driving. If you put your palm out, it will push your hands back.. Because all the surface area hitting the wind ( wadcutters ) Where if you put your hand flat ( palms down ) there less surface area. And doesn't pull back as much.


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 9:35 am 
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Actually gravity affects all objects at the same rate.....for bullets and pellets the longer time they take to reach the target...the further they drop....Wadcutters show a lower poi because even though they may leave the gun at the same speed as a domed...pointed...etc....they are still taking longer to reach the target due to wind effect on the shape of the pellet....the more time in the air...the more the drop.

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 9:50 am 
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Alright ~ so actually this is just normal, even just in such a short range, right?

I thought the 'flat' .177 trajectory just 'very flat'... But actually a re-zero when changing pellets is still necessary...

I noticed when I come closer to the target, the POI is lowered too... I didn't understand that before as I thought the pellet should fly a flat way until it lost speed then start to drop... But actually it's dropped due to gravity right away while leaving the muzzle then 'caused by the spinning' (?!) it flies up then drops again when losing speed?

It's so true... Hitting the target is not easy ~ =)



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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 10:27 am 
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YepYep wrote:
Alright ~ so actually this is just normal, even just in such a short range, right?

I thought the 'flat' .177 trajectory just 'very flat'... But actually a re-zero when changing pellets is still necessary...

I noticed when I come closer to the target, the POI is lowered too... I didn't understand that before as I thought the pellet should fly a flat way until it lost speed then start to drop... But actually it's dropped due to gravity right away while leaving the muzzle then 'caused by the spinning' (?!) it flies up then drops again when losing speed?

It's so true... Hitting the target is not easy ~ =)



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If you are hitting 2 inches lower at only 24 feet...no...I would NOT chalk that up to the effects of gravity alone.....unless your wadcutter is travelling at a MUCH slower rate than the other pellet...so it would take longer to reach the target.
Assuming your pellet is doing 475 fps its only taking your pellet about 1/20th of a second to reach the target...a very short time for gravity to affect it.I don't think it would drop THAT much in such a short time being airborne but others could probably do the math regarding time and gravity...

P.S. hitting the target is easy...you just have to adjust for different pellets....gravity is a constant...it doesn't change for each shot you take....its about how much time gravity has to affect an object..in this case a wadcutter on the way to the target....Otherwise yes..it would be a crap shoot if the rate of gravitational forces changed second to second.....

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:10 am 
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So the wadcutter hitting 2 inches lower just because its nose shape?!

Because it was shot fron the same gun, same place, one shot right after the domed pellet... I think I can suppose all other conditions are same...

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:20 am 
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YepYep wrote:
We choosed 177 cal is for a flatter trajectory.



When you hear or read that, ".177 has a flatter trajectory", that's usually only true for those specific circumstances. If they're referencing airguns with a 12fpe limit, then it's true that the lighter .177 pellet has a flatter trajectory because it's being fired at a higher fps to reach that 12fpe limit. Or when comparing .177 vs .22 options for the same air rifle... Many .177 and .22 springers, for instance, share the same power plant. So again, that specific airgun will produce a flatter trajectory in .177 than .22, but only because it's moving quicker out the gate.

Otherwise, as mentioned by others, trajectory is a function of FPS and BC, not calibre.


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:24 am 
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YepYep wrote:
So the wadcutter hitting 2 inches lower just because its nose shape?!

Because it was shot fron the same gun, same place, one shot right after the domed pellet... I think I can suppose all other conditions are same...

Sent from my LG cellphone


You should download chairgun (if you haven't already) just to play around with the numbers. No way that the shape alone drops it 2".

Different pellets can leave the same airgun on a different path. Their fps, how they engage the rifling, the lock-time with that pellet... Thats why re-zero with each pellet...


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:30 am 
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YepYep wrote:
So the wadcutter hitting 2 inches lower just because its nose shape?!

Because it was shot fron the same gun, same place, one shot right after the domed pellet... I think I can suppose all other conditions are same...

Sent from my LG cellphone

I don't know if its because of nose shape....you definitely will see a lower poi if your wadccutter takes longer to reach the target...I don't know the math for figuring out if you should see a 2 inch drop in only 24 feet in 1/20th of a second...

Here is an interesting video showing a bowling ball and a feather hitting the ground at the same time...in a vacuum so its gravity alone affecting the rate of descent....interesting....CERTAINLY then...your two different pellets would ALSO fall
at the same rate from gravity IF they reach the target at the exact same time....Since the wadcutter is only MARGINALLY slower than a round pellet on impact and IF fired at the same fps..then OTHER factors must be accounting for a 2 inch drop..Again .it seems a bit too much drop in too short of time.

https://m.youtube.com/watch?v=9-YNaN-5mnc
Interesting bit starts at 2:30 :D

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:45 am 
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987654321 wrote:
YepYep wrote:
We choosed 177 cal is for a flatter trajectory.



Otherwise, as mentioned by others, trajectory is a function of FPS and BC, not calibre.


So, if we choose a very light weight .22 vs a heavy .177 ( we can have that, right ?!), then, actually their trajectory should be as flat as each other?!

But actually there is hard to see how flat a trajectory will be.... Any experiment can be setup to verify this?


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:48 am 
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987654321 wrote:
You should download chairgun (if you haven't already) just to play around with the numbers. No way that the shape alone drops it 2".

Different pellets can leave the same airgun on a different path. Their fps, how they engage the rifling, the lock-time with that pellet... Thats why re-zero with each pellet...


Yeah, I have chairgun, but found this app will be more useful for high power, long ranger reference... And for 10m or less range, I can only use it to check pellet weight, velocity vs energy...


Sent from my LG cellphone

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


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 11:52 am 
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MyCrosman wrote:



Yeah... So I think it's finally caused be the nose shape and the two pellets actually flying at two completely different path... And it's why I asked at the very beginning, while the pellet left the muzzle, its path actually is not horizontal to the barrel, and is in an angle shooting up or shooting down.... maybe left or right...

Why zeroing the sight, is for matching this specific path to your sights / scope etc....


Sent from my LG cellphone

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HW35 Walnut + Hawke 40mm Scope
2240+14" barrel/Williams peep sight
Camo Chaser long barrel rifle kit
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HW45+Grip panels from Russia
P1322 with walnut forearm


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 12:05 pm 
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I need a beer....I don't drink...but I need a beer... :D

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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 12:36 pm 
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YepYep wrote:
987654321 wrote:

But actually there is hard to see how flat a trajectory will be.... Any experiment can be setup to verify this?


Sent from my LG cellphone


Chairgun :)


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 Post subject: Re: .177 trajectory
PostPosted: Mon Aug 13, 2018 12:57 pm 
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I need a bugbuster edition chairgun for my sub500 guns to shoot within 10 meters ~ lol

Sent from my LG cellphone

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HW45+Grip panels from Russia
P1322 with walnut forearm


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