Prone And Bipod Change Trajectory...?!?

[RemyBolt 420]

Ever hear something that totally catches you off guard?

 

The wife convinced me not to shoot tonight and instead went for a meal with friends. During the meal one of the guys pipes up about shooting and his amazing air rifle and NV system he's making. My ears perk up.

 

But then I heard something that really blindsided me. He said he has a new PCP, so I asked if he was vetting a bipod. Then the response totally threw me... "Bipods are for fags" (my 'this sounds like bollocks' sense was tingling) then he continues..."And shooting laying down with a bipod changes your zero and trajectory."

 

I was lost for words. He just smirked as if he was the smartest person ever.

 

What happened here? I've never heard this before. I've never experienced this before. .y mind says this is total crap, but I am curious. Anyone else heard of this or is it just poking fun at idiots.

 

Surely an air rifle will shoot the same whether at shoulder standing or prone or seated. The position the shooter is in doesn't magically change the power or trajectory of a pellet.

[pianoman 3,587]

Providing you have your scope set-up to your PCP rifle as perfectly level vertically as you can achieve, it shouldn't make any difference whatsoever with a PCP that is zeroed from prone using a bipod.There is virtually no vibration recoil to affect a shift in zero from one supportive surface to another. Unlike a hefty spring rifle which will deviate slightly as a change from prone to standing shots will alter the weight pressures of the rifle being supported in the hands and a slight change in elevation from low to high. Prone is more supportively secure than standing shots and these changes from prone position, where the scope was likely zeroed from, alters the way the recoil is managed in the aim on your hands..

 

A shift in zero usually, is the result of a shift from your original point of impact (POI) you zeroed your scope at, to a completely new one. It's not so very much to be worried about, The differences are normally slight; only a few millimetres. That is, unless you are shooting at a POI that is further or nearer than your original zero range and switching to a target on a higher plane of angle or a lower one. Because gravity is having a more profound effect on your pellet; especially on a dramatically increased inclined plane; IE. One considerably higher up from a zero established froma flatter ground position for rabbits, say, to corvids and pigeons sitting high up in trees. That's when you need to work out zero-drift if your shooting day is going to encompass shooting at all ranges and elevation heights.

 

Also the precise degree by which your scope reticle is centred to the rifle bore vertically plays a crucial part with defective accuracy estimation at ranges in excess of your set-zero range distance.

 

If your scope is canting over off-vertical true, your shot will be out and in error by that degree of cant-angle your scope is off the vertical-true by.

 

I think, if the scope is too canted over to left of vertical-true, the shot will be shifted to right of target and vice versa at longer-than-zero ranges. Even 5 metres will reveal a marked difference.

 

That's when you need to work out your rifle's drift from zero-true, by test shots at targets of completely differing heights above ground and over different ranges.

 

Really, when you think about it. your zero translates from a precisely realised, fixed point of impact into an average of shot accuracy which you need to understand if you are going to be shooting at all ranges and height elevations in the course of a day's shooting. But I have never heard of a scenario where a bipod alone will affect Point Of Impact from a well set-up rifle and scope. Only the factors I've mentioned above.

 

EDITED TO ADD.

These same factors completely over-rule any successful use of a bipod on a spring rifle. The additional recoil vibration makes shooting a spring rifle off a bipod over the slightest changing distances and elevations an impossible task.

 

Hope this helps.

Simon

Edited May 4, 2015 by pianoman

[jonnie bravo 572]

I can only really see it making a difference on a springer. He's probably canting the rifle differently if he's getting a different zero, or he's not getting his eye alignment right and causing a change in parallax error. That should be the only difference between POI from different shooting positions that I can think of?

[Coypu Hunter 486]

He's full of cack. I've shot a full-power CO2 rifle standing, sitting, supported, unsupported, off sticks, off a bipod. No change in POI whatsoever.

 

If he tried shooting from a bipod and found that the POI had shifted, he was most probably using a different cheek weld/eye alignment.

Edited May 3, 2015 by Coypu Hunter

[RemyBolt 420]

Thanks for clearing that up.

 

That's kind of what I was thinking, but in a much more technical way. I was just thinking "This guy is full of bollocks, that makes no sense" and you've just explained why.

 

Want to explain Canting for me? It's one of those terms I've never come across in shooting.

 

Thank you.

[Coypu Hunter 486]

Thanks for clearing that up.

 

That's kind of what I was thinking, but in a much more technical way. I was just thinking "This guy is full of bollocks, that makes no sense" and you've just explained why.

 

Want to explain Canting for me? It's one of those terms I've never come across in shooting.

 

Thank you.

 

It's when the vertical crosshair isn't perfectly perpendicular to the bore axis, with the result that it makes you shoot like a cant.

[RemyBolt 420]

 

Thanks for clearing that up.

That's kind of what I was thinking, but in a much more technical way. I was just thinking "This guy is full of bollocks, that makes no sense" and you've just explained why.

Want to explain Canting for me? It's one of those terms I've never come across in shooting.

Thank you.

 

It's when the vertical crosshair isn't perfectly perpendicular to the bore axis, with the result that it makes you shoot like a cant.

That'll be me then haha

[David.evans 5,323]

Go back next week for another meal

And if the same lad is there just tell him bo$$ocks

Shooting of a pod can only improve shooting , as long as you don't cannt your rifle

Tell him to tape a sprit level 3foot long to his gun lol

Piano man is bang on again