Advice on correct impact point - open sights Thompson Black Diamond - The Firearms Forum

wpshooter · 11-16-2012, 12:23 PM

Can anyone give me some INFORMED advice (not just what you might think off the top of your head) about what would be the correct point of impact (i.e. ABOVE the 30 yard hold point) for a 30 yard sight-in range, if I want my Thompson Black Diamond Extended Range to be able to hit dead-on at 100 yards, IF I am using the open sights on the rifle which are fiber optic, red on front and 2 green dots on the back ?

I have a great deal of experience in sighting in rifles that have scopes on them BUT I have practically zero experience with open sights on rifles. I am not going to have a scope on this rifle.

I would be holding on the 30 yard sight-in target point with front red dot in horizontal alignment with the 2 back green dots (or at least the best I can hold them).

Thanks.

Buffalochip · 11-16-2012, 01:10 PM

No one can give you an informed answer without the calibre, powder charge, and bullet weight, and height of sights above axis of bullet. At 30 yds. the bullet is on an upward trajectory because it has to rise to the level of the sight plane. Where it impacts down range depends on velocity and bullet aerodynamics/resistance. You may be able to find a ballistics table online for your particular gun, but to dial it in at 100yds. you need to take it to the range.

wpshooter · 11-16-2012, 06:40 PM

Quote:

Originally Posted by Buffalochip

No one can give you an informed answer without the calibre, powder charge, and bullet weight, and height of sights above axis of bullet. At 30 yds. the bullet is on an upward trajectory because it has to rise to the level of the sight plane. Where it impacts down range depends on velocity and bullet aerodynamics/resistance. You may be able to find a ballistics table online for your particular gun, but to dial it in at 100yds. you need to take it to the range.

Yeah, I thought about that on the way to my deer hunting spot this evening.

I always shoot 90 gr. loose T7 and use 245 gr. areo-tip powerbelt.

The sights on the Thompson Black Diamond are the ones that were supplied with the gun by Thompson.

Thanks.

11-16-2012, 12:23 PM	#1
wpshooter V.I.P. Member Join Date: Jul 2009 Posts: 249	Advice on correct impact point - open sights Thompson Black Diamond Can anyone give me some INFORMED advice (not just what you might think off the top of your head) about what would be the correct point of impact (i.e. ABOVE the 30 yard hold point) for a 30 yard sight-in range, if I want my Thompson Black Diamond Extended Range to be able to hit dead-on at 100 yards, IF I am using the open sights on the rifle which are fiber optic, red on front and 2 green dots on the back ? I have a great deal of experience in sighting in rifles that have scopes on them BUT I have practically zero experience with open sights on rifles. I am not going to have a scope on this rifle. I would be holding on the 30 yard sight-in target point with front red dot in horizontal alignment with the 2 back green dots (or at least the best I can hold them). Thanks. -->

11-16-2012, 01:10 PM	#2
Buffalochip Senior Member Join Date: Oct 2008 Posts: 754	Re: Advice on correct impact point - open sights Thompson Black Diamond No one can give you an informed answer without the calibre, powder charge, and bullet weight, and height of sights above axis of bullet. At 30 yds. the bullet is on an upward trajectory because it has to rise to the level of the sight plane. Where it impacts down range depends on velocity and bullet aerodynamics/resistance. You may be able to find a ballistics table online for your particular gun, but to dial it in at 100yds. you need to take it to the range.