Bore Axis

Bore axis is meaningful when it comes to calculating mechanical recoil/torque, but less so when it comes to felt recoil. Just as with accuracy, I'm convinced that ergonomics is far, far more important for anyone but the top-tier competition shooters.

My wholly unscientific and unsubstantiated theory is that a comfortable grip is one that fills all the contours of the hand naturally, and allows you to position your hands, arms, shoulders, and stance in a manner that dissipates the recoil energy with minimal muscle effort.

If the grip is too big or small, or awkwardly shaped, you've got certain areas that press too tight into your hands, while not getting enough purchase in others. And if the grip shape forces you to take an unnatural stance/form, you end up wasting your energy just holding the gun up, and makes battling the recoil even more wearying than usual.
 
Can you explain this shorter lever?
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Ever play on a teeter totter with a small child, same principle applys.
If the child is far enough from the fulcrum to balance the weight the shorter lever on your side will require less movement on your part than the child.;)

If you don't have enough weight (wrist/hand strength) though, the child will just sit on the ground.
 
Ever play on a teeter totter with a small child, same principle applys.
If the child is far enough from the fulcrum to balance the weight the shorter lever on your side will require less movement on your part than the child.
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Yea I get that. What I don't get is how a higher bore axis allows "the shorter lever on your part requires less movement of your hand to bring it back down." How does a higher bore axis give you a shorter lever?
 
What I don't get is how a higher bore axis allows "the shorter lever on your part requires less movement of your hand to bring it back down." How does a higher bore axis give you a shorter lever?
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your lever is shorter in relation to the longer lever the barrel has when you move the barrel further away from the fulcrum.
I guess I could have said the barrels longer lever since it's the one that changed, but the principle remains the same.
 
I fail to see how a higher bore axis gives you more leverage but rock on.
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Well that's the problem, it doesn't give you more leverage it gives you a greater ratio of movement.

Here, if I weigh more than you the child can sit much further from the fulcrum and I can still control the better hold on the teeter totter better than you could.
 
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marine6680 said:
I took two types of measurements, as there is no standardized way to measure these things.
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While there may be no standardized bore axis measurement, Glock does provide a measurement called 'barrel height' - 1.26" for the G19.

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The picture appears to show that Glock measures from the center of the bore to the most forward part of the back of the grip. I confirmed that by measuring a G19 in the same way and getting the same result.

The most forward point on the back of the grip seems like the proper place from which to measure because that is where the web of the hand n aturally engages the gun, thus becoming the point around which the gun pivots in recoil.
 
If you look at the fulcrum being the top of your hand... Or top of your grip.

Then the higher the barrel, the longer it's "effort arm"... Which means it was do more work.


But levers are not really the best way to look at this. The best way is with a torque equation, as we are talking rotational forces... Levers are somewhat related to this way of thinking.

If the top of your grip is the axis of rotation, the bore hight would be the moment arm.

A simple torque formula is... t=r*F

Or torque equals the product of the Force applied and the distance from point of rotation it is applied.


Seeing that most gun barrels are not at a direct tangent to the point of rotation, there is an angle involved which complicates the equation by making you also factor in the the sin of the angle.

But overall it can be boiled down to the fact that increasing the length of the moment arm, increases the torque applied at the axis of rotation for the same input force.

So if you take pistols of the same caliber, and same grip angle, but of differing bore axis height, then the one with the greater bore height will have a larger torque.


How much does all this matter in practice... That is debatable.

I personally can feel the differences between different pistols. I can as a result shoot some a little better/faster than others. Is the difference so great that I can't shoot the other pistols well... No... Does bore height play a factor in my choices when I purchase... No.

I shoot what I shoot best, whatever the bore height says...
 
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The most forward point on the back of the grip seems like the proper place from which to measure because that is where the web of the hand n aturally engages the gun, thus becoming the point around which the gun pivots in recoil.
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Key word... "seems"


And it is a good hard point to look at, point to, and measure from.

But that is not where the top of your hand sits, nor is it even the highest point your grip is.

Due to both the rounded shape of that area on the frame, the rounded shape of the web of your hand, and the construction of the hand and thumb joint... You get useful grip farther up the radiused area.

Couple in beavertail design, and how it sits against the top of the Web of your hand... And you get a much different point of rotation than the area that glock measures to.


They use that point as I said... As a definable point that is easy to understand.

But my measurements better match the realities of a person's grip on the pistol.

And from what I am seeing, the relationship between those two points that seem to affect the felt recoil more than a simple single bore height measurement would account for.
 
But overall it can be boiled down to the fact that increasing the length of the moment arm, increases the torque applied at the axis of rotation for the same input force.

So if you take pistols of the same caliber, and same grip angle, but of differing bore axis height, then the one with the greater bore height will have a larger torque.
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Thank you. That is exactly how I see it.
 
I take note of how a pistol transmits recoil to the hand and arm. Bore axis height, grip angle, grip ergos, and type of action all affect this. For me, the HK P7, CZ-75, and Beretta 92 (due a lot to its action) all transmit recoil pretty nicely, and straight back into the arm. Sure there is muzzle rise, but it is not as pronounced as some of my other pistols like the Sigs, and 1911. However, that doesn't mean I shoot them any better. I just like the recoil impulse a little bit better.
 
Today at the range I was shooting my M&P next to my VP9. I don't notice much difference between the two bore axis wise, as shown by the numbers here, but if I go to the VP9 from the M&P the first thought in my mind is, "That's a lot more muzzle flip." Same is actually true for going between the P320 and VP9, though not as noticeable of a difference. I wonder how much is this is just my own perceptions.
 
If you know how to hold and pull the trigger properly on a handgun, bore axis means nothing.

The reason people bring it up is to either justify a purchase or bash another brand. I recognize bore axis differences, but I can shoot a semi-auto with a low or higher bore axis equally as well. Give me a high axis Sig or a low bore axis Glock and my groups look the same. Those are only two examples so please don't try and pick at that quote like those are the only two guns I can compare.
 
marine6680 said:
Perceptions... mental bias... it all plays a part.
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I would even go so far as to say that plays the biggest part.

Back when I started researching for my first gun, I rented an M&P and hated it. It felt like it was going to jump out of my hand every time I pulled the trigger, and as a result I was horribly inaccurate with it.

Fast forward about six months later, and I was at the range and started talking to the guy in the lane next to me. We switched lanes, and I got to fire his newly-stippled M&P 9; the difference was night & day to the one I'd rented. The stippling was the only modification he'd made.

Sometime after that, I rented another M&P again just to see if I could shoot it better now that I actually knew how to shoot. Nope. Same problem as before - the grip felt slippery in my hand, and the recoil impulse simply felt sharper than I knew it really was.
 
Give me a high axis Sig or a low bore axis Glock and my groups look the same.
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Bore axis is more about control when firing rapidly... Controlled pairs, etc Shooting for groups is a different thing and bore axis is meaningless then.


Back when I started researching for my first gun, I rented an M&P and hated it. It felt like it was going to jump out of my hand every time I pulled the trigger, and as a result I was horribly inaccurate with it... SNIP...
The grip felt slippery in my hand, and the recoil impulse simply felt sharper than I knew it really was.
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How well you can grip the pistol, and how well controlled it feels plays a big part.

I personally find the grip on the M&P fine... same with the PPQ, but my fiance disliked the PPQ, thought it felt slippery.
 
I notice a difference, it's not much usually. Though my CZ 75 is the best. Combination of the bore axis, grip angle, grip shape, weight, and the nice trigger pull... It all adds up to a pistol I can shoot faster with better accuracy than my others. Though my M&P FS is close behind.
 
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