Physics of shooting a rifle - Page 14

stagpanther · April 11, 2024, 08:22 AM

To get a bullet to cross the line of sight at 5 yds--you'd need a pretty heavily canted rail I would think.

tangolima · April 11, 2024, 10:14 AM

The cheapy lpvo with 30mm tube on the AR had no problem doing it. 2.5" at 5yd is 50 moa, which is quite a bit indeed.

For the rem 700, 1.5" at 5yd is 30moa. The scope was an old redfield with 1" tube. No problem either.

No canted rail in either case. Probably the scopes were about to max out.

-TL

Sent from my SM-N960U using Tapatalk

tangolima · April 15, 2024, 11:43 AM

In order to bore sight a rifle that doesn't allow looking through the bore, mini 14 for instance, I have struggled with different methods; mirror, reflector etc.

Then it hits me. Why am I doing this? To get on paper, is it not? I just pull in the 24"x24" target really close, say 10yd. Fire one shot with sight right on the middle of the target. I will have to really screw up not to be on paper. Adjust turrets to put poi under poa by amount equal to sight height. Fire another shot to confirm. Push the target back to 100yd and fire again. It will be on paper.

That's how I bore sight without sighting through the bore. It always work. Why don't I do it for all guns? I could. But it involves calling the range cold to move the target. I only do that when I have to.

-TL

Sent from my SM-N960U using Tapatalk

tangolima · April 21, 2024, 06:06 PM

Let's try another light one in optics, shall we? It is actually based a discussion on other forum. There they were discussing shift in poi caused by phoria. The op had such medical condition that his eye ball shift slightly when the other eye was covered. He noticed significant poi shift when shooting with both eyes open or one eye closed.

Members were perplexed. Everyone scrambled to do his own test. I believe it is parallax. What think you?

Say it is a FFP scope with 100yd fixed parallax. The reticle in the tube is located 8" in front of the shooter's eye. The target is at 50yd, so there is parallaxing going on. If the shooter's eye shifts 0.01" to the left, which direction will the reticle appear to shift in his field of view? If he adjusts his aim to realign the reticle and target, the poi will shift. By how much?

-TL

Sent from my SM-N960U using Tapatalk

georgehwbush · April 21, 2024, 07:33 PM

both my ar's 10 and 15 are zeroed at 100yds and both will hit low at any shorter range (ANY SHORTER RANGE) so the 100yard mark is the first crossing of the trajectory and line of sight, that's from imperical testing not just calculations.

now it should be noted that the sights are 2.5 and 2.75 inchs above bore respectively. and the speed of projectile matters too.

tangolima · April 21, 2024, 11:05 PM

Quote:

Originally Posted by georgehwbush

both my ar's 10 and 15 are zeroed at 100yds and both will hit low at any shorter range (ANY SHORTER RANGE) so the 100yard mark is the first crossing of the trajectory and line of sight, that's from imperical testing not just calculations.

now it should be noted that the sights are 2.5 and 2.75 inchs above bore respectively. and the speed of projectile matters too.

100yd is indeed near the apex that touches the line of sight. It is dictated by the tall sight height.

-TL

Sent from my SM-N960U using Tapatalk

stagpanther · Yesterday, 08:04 AM

Is this different from simple right/left eye dominance hard-wired into sighting especially for those who are accustomed to shutting the left eyelid (reverse if you are left dominant)?

tangolima · Yesterday, 09:48 AM

I'm not 100% sure, but it is a medical abnormality.

https://medical-dictionary.thefreedictionary.com/phoria

-TL

Sent from my SM-N960U using Tapatalk

stagpanther · Yesterday, 09:55 AM

In my experience this is normal unless you are accustomed to training your brain to sight in with both eyes open.

tangolima · Yesterday, 11:19 AM

I managed to train myself to shoot with both eyes open. The major difficulty to overcome is seeing 2 targets. Sometimes the "wrong target" is picked to put the sight on. With enough practice, somehow the target seen by the non-dominant eye disappears and replaced by peripheral awareness.

But I think phoria, what the op of the discussion was diagnosed of, is different. There isn't dual vision. The dominant eye just perceives the target differently when the non-dominant eye is covered. There wouldn't be a diagnosis if it was normal, I think.

-TL

Sent from my SM-N960U using Tapatalk

April 11, 2024, 08:22 AM	#326
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,784	To get a bullet to cross the line of sight at 5 yds--you'd need a pretty heavily canted rail I would think. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

April 11, 2024, 10:14 AM	#327
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,824	The cheapy lpvo with 30mm tube on the AR had no problem doing it. 2.5" at 5yd is 50 moa, which is quite a bit indeed. For the rem 700, 1.5" at 5yd is 30moa. The scope was an old redfield with 1" tube. No problem either. No canted rail in either case. Probably the scopes were about to max out. -TL Sent from my SM-N960U using Tapatalk Last edited by tangolima; April 11, 2024 at 10:33 AM.

April 21, 2024, 06:06 PM	#329
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,824	Let's try another light one in optics, shall we? It is actually based a discussion on other forum. There they were discussing shift in poi caused by phoria. The op had such medical condition that his eye ball shift slightly when the other eye was covered. He noticed significant poi shift when shooting with both eyes open or one eye closed. Members were perplexed. Everyone scrambled to do his own test. I believe it is parallax. What think you? Say it is a FFP scope with 100yd fixed parallax. The reticle in the tube is located 8" in front of the shooter's eye. The target is at 50yd, so there is parallaxing going on. If the shooter's eye shifts 0.01" to the left, which direction will the reticle appear to shift in his field of view? If he adjusts his aim to realign the reticle and target, the poi will shift. By how much? -TL Sent from my SM-N960U using Tapatalk Last edited by tangolima; April 21, 2024 at 06:24 PM.

April 21, 2024, 07:33 PM	#330
georgehwbush Senior Member Join Date: July 14, 2023 Location: down town USA Posts: 144	both my ar's 10 and 15 are zeroed at 100yds and both will hit low at any shorter range (ANY SHORTER RANGE) so the 100yard mark is the first crossing of the trajectory and line of sight, that's from imperical testing not just calculations. now it should be noted that the sights are 2.5 and 2.75 inchs above bore respectively. and the speed of projectile matters too. __________________ If you are not sure where your bullet will stop, then don't send it!

Yesterday, 08:04 AM	#332
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,784	Is this different from simple right/left eye dominance hard-wired into sighting especially for those who are accustomed to shutting the left eyelid (reverse if you are left dominant)? __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

April 15, 2024, 11:43 AM	#328
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,824	In order to bore sight a rifle that doesn't allow looking through the bore, mini 14 for instance, I have struggled with different methods; mirror, reflector etc. Then it hits me. Why am I doing this? To get on paper, is it not? I just pull in the 24"x24" target really close, say 10yd. Fire one shot with sight right on the middle of the target. I will have to really screw up not to be on paper. Adjust turrets to put poi under poa by amount equal to sight height. Fire another shot to confirm. Push the target back to 100yd and fire again. It will be on paper. That's how I bore sight without sighting through the bore. It always work. Why don't I do it for all guns? I could. But it involves calling the range cold to move the target. I only do that when I have to. -TL Sent from my SM-N960U using Tapatalk

Yesterday, 09:48 AM	#333
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,824	I'm not 100% sure, but it is a medical abnormality. https://medical-dictionary.thefreedictionary.com/phoria -TL Sent from my SM-N960U using Tapatalk

Yesterday, 09:55 AM	#334
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,784	In my experience this is normal unless you are accustomed to training your brain to sight in with both eyes open. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

Yesterday, 11:19 AM	#335
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,824	I managed to train myself to shoot with both eyes open. The major difficulty to overcome is seeing 2 targets. Sometimes the "wrong target" is picked to put the sight on. With enough practice, somehow the target seen by the non-dominant eye disappears and replaced by peripheral awareness. But I think phoria, what the op of the discussion was diagnosed of, is different. There isn't dual vision. The dominant eye just perceives the target differently when the non-dominant eye is covered. There wouldn't be a diagnosis if it was normal, I think. -TL Sent from my SM-N960U using Tapatalk