Iron sights for trajectory calculations...

[Sooter76]

Here's a bit of an odd question I guess... I'm not quite sure where to ask it so I figure this is as good a place as any.

I'm attempting to use ballistic calculations to get a zero for a couple milsurp rifles I have using a 25yd range. I know with scopes you adjust your calculations off the scope center height and I'm assuming that something similar can be done with iron sights but as I try to work it out in my head it just leaves me lost. I'm thinking I would measure half the barrel diameter subtracted from the the top of the sight blade?

Does anyone know how I would measure my iron sights to figure out trajectory?

Thanks.

 

[FatBoy]

it depends on the sights. What, exactly. are we talking about?

 

[Sooter76]

In this instance I’m talking about a K98 and a Swiss G1911.

 

[Rudy Gonsior]

Are you talking about figuring out the high over bore? You could do exactly what you mentioned, or just use a ruler from the center of the bore to the top of the blade.

 

[sandwarrior]

1. Measure from center-bore to the top of the sight...or center if you use a peep sight (not yours, unless you put on an aftermarket sight)
A. for front sight measure bottom of barrel to top of sight. Turn calipers 90* and measure barrel diameter. Deduct 1/2 barrel dia. from overall height.
B. Do the same for the rear sight at the point the "notch" hangs over the barrel. Hint: remove barreled action from stock.
2. Use the moa formula - sin1/60. But, instead of using 3600, which is 100 yds., measure the inches between rear and front sight. Use that number instead and it will give you how many thousandths of inches of movement needed to move one moa.

i.e. sin(.016666667)=.000290888blahblah instead of finding the movement for 100 yds. which is 3600 use 21" or so which is the linear distance between sights. which equals about .0061" movement to give you an moa of elevation (or windage). Every .006" should give you about one moa change.

Take your caliper and find the sight height changes from original position and each setting should be divided by .006 and that is how many moa you are changing with each setting.

I hope that helped.

 

[FatBoy]

We just got a 100y zero and MV from a chrono, then used scope come ups from JBM (default rifle data) and made the minor corrections at each distance and wrote it down in a logbook. To 750y it's not that much different, you should still be on a full sized IPSC with scope come ups and the right DA. Beyond that might get spicey, especially with surplus. Trick is gonna be verifying the actual movement of your click adjustments. Tall target test at 100 will help with that.

Damn Rangers and SF guys, making shit all complicated. Gotta justify the big bucks I guess

signed: a filthy f'ing leg.

 

[sandwarrior]

We just got a 100y zero and MV from a chrono, then used scope come ups from JBM (default rifle data) and made the minor corrections at each distance and wrote it down in a logbook. To 750y it's not that much different, you should still be on a full sized IPSC with scope come ups and the right DA. Beyond that might get spicey, especially with surplus. Trick is gonna be verifying the actual movement of your click adjustments. Tall target test at 100 will help with that.

Damn Rangers and SF guys, making shit all complicated. Gotta justify the big bucks I guess

signed: a filthy f'ing leg.

C'mon man, gimme a break...it took me years to figure that out And back when I got in, $83 a month was the 'big money'. ha ha. Life was really good when it went to $115.

 

[FatBoy]

C'mon man, gimme a break...it took me years to figure that out And back when I got in, $83 a month was the 'big money'. ha ha. Life was really good when it went to $115.

Brown boot Army, huh? I hear ya. Life was especially good when they took away separate rations when we went to the field. Nothing says, "taking care of your family " like yanking away the grocery money.

As far as the Swede, we have had one on the 1k line, several years back. Guy shot it with the issue scope when SARCO was dumping these 15 years ago. (wish I would have bought a couple). It did OK, mid 150s on a full sized LR-1 with surplus IIRC. Hard to say if it could have done better as I had no history on the rifle or the shooter. Still, a very capable rifle in the right hands. Even more so if they are taking the time to get their iron sight come ups.

 

[sandwarrior]

Brown boot Army, huh? I hear ya. Life was especially good when they took away separate rations when we went to the field. Nothing says, "taking care of your family " like yanking away the grocery money.

As far as the Swede, we have had one on the 1k line, several years back. Guy shot it with the issue scope when SARCO was dumping these 15 years ago. (wish I would have bought a couple). It did OK, mid 150s on a full sized LR-1 with surplus IIRC. Hard to say if it could have done better as I had no history on the rifle or the shooter. Still, a very capable rifle in the right hands. Even more so if they are taking the time to get their iron sight come ups.

Not quite that old...post VN. Jump pay was $83.

But, I know what you mean about taking separate rats away when you deploy somewhere. As an NCO you got it for some reason, When I went to Honduras for a couple months, it was gone from my LES. Then they tried to charge me for meals down there! We need you to sign the meal roster. Bullshit! I never signed that fucker again.