Alpex K4 LRF menu item missing help

[Thoburns]

Just tried setting up the balistic calculation and found bullet weight is missing which to me is an essential element. Checked for update and it's on the latest. Anyone experienced this?

 

[WalkedUp]

The Alpex does not account for windage.

 

[mealiejimmy]

None of them do - the ballistic calculator can only handle bullet drop
As for bullet weight - are you telling us you don't know it but you go out and shoot live game????
If you do know the weight, just enter it manually

Cheers

Bruce

 

[Thoburns]

None of them do - the ballistic calculator can only handle bullet drop
As for bullet weight - are you telling us you don't know it but you go out and shoot live game????
If you do know the weight, just enter it manually

Cheers

Bruce

I know my bullet wt and BC but was expecting the scope balistic data menu to ask for bullet wt. Without bullet wt how can it calculate drop?

 

[Thoburns]

The Alpex does not account for windage.

Aware of that it's not wind please see reply to mealiejimmy above. Thanks

 

[WalkedUp]

Aware of that it's not wind please see reply to mealiejimmy above. Thanks

Apologies, I am no expert but believe that the mass of the bullet imparts very little difference in practical ballistics (fall/gravity over typical ranges), the key factors for this being velocity and ballistic coefficient (which itself contains the bullet mass). Bullet mass is needed to calculate wind drift however, but again I may be wrong.

 

[BenBhoy]

I've only ever used a BC on my old pard 008S but that definitely asked for bullet/pellet weight and coefficient

 

[Lateral]

Apologies, I am no expert but believe that the mass of the bullet imparts very little difference in practical ballistics (fall/gravity over typical ranges), the key factors for this being velocity and ballistic coefficient (which itself contains the bullet mass). Bullet mass is needed to calculate wind drift however, but again I may be wrong.

It's a good question, because if it only requires BC & velocity, it would suggest that no two bullet weights can have the BC, and velocity, and I don't believe that to be true ?

I'm sure I've read that you enter the info it asks for, but if the bullet shoots high, or low at say 200y/m, then you adjust the velocity/BC so that the POI is correct.

 

[Ratsbadboy]

It's a good question, because if it only requires BC & velocity, it would suggest that no two bullet weights can have the BC, and velocity, and I don't believe that to be true ?

I'm sure I've read that you enter the info it asks for, but if the bullet shoots high, or low at say 200y/m, then you adjust the velocity/BC so that the POI is correct.

It is more than possible that two or more bullets could have the same BC and velocity, but all those bullets would have the same trajectory which is all the ballistic calculator is interested in.

 

[mealiejimmy]

There appears to be a bit of a debate on this subject with strong opinions on both side
I had a good look at the Zulus ballistic calculator running several ballistic profiles with widely varying pellet/bullet weights and finding that the predicted pellet drop did not change with bullet wight
Against the this YOU Tuber seems convinced that pellet weight is really important


Thoroughly confused

Bruce

 

[Boosh]

Any lump of lead should travel the same trajectory, but the influence of friction changes this. The BC is taking into account the friction due to the shape.
I'd have thought both weight and BC were important in a calculator.

 

[Freightdog]

The mass of the bullet is accounted for in the BC calculation. The mass is divided by the product of the bullets drag coefficient and cross sectional area; hence heavier, streamlined bullets have better BC and fly better.
The BC will tell the calculator everything it needs to know about the bullet to calculate trajectory, the velocity is the other half.
You will always have to tweak one or the other to accurise poi at different ranges. I generally adjust the BC, but whatever works.

 

[Brad93]

If i had a chrono id enter the true FPS and tweek the BC in the scope to get the right amount of drop which means shooting at targets at different ranges and measuring the actual drop to check it corresponds with what the scope is suggesting.