Help for a new shooter.

[iam1964]

Hi,

I am a very new shooter, coming from Scotland my experience with guns is zero!!

Anyway, last year I decided to assemble an AR kit from PSA with a 16” SS Freedom barrel. So far I have been really happy with it and have only shot out to 100 yards with a 1-4 LPVO.

This weekend I decided to test out the 50/200 yard zero theory. I zeroed the sight at 50 yards and then tried it at 200 yards.
It was terrible. The POI was consistently about 7-8” low. I made the adjustment to the sight and then I was hitting the 8” target pretty constantly.

Is it possible that the Tula 55gr ammo was causing this low POI or am I just a really bad shot? Or…. Is there another reason for the low POI?

 

[Coyotefurharvester]

Center of scope to center of bore, really matters in ballistic calculations. Also the 16" barrel will probably result in a lower actual velocity than what the ammo manufacturer claims.

 

[acloco]

No. Trajectory is the demon here. Your copper item is fighting gravity.

 

[Ranger188]

You can't always believe what you read on the internet. LOL
Every AR will be different depending on speed of load and weight of bullet.
You have to test and verify every load. Your shooting skill is probably last
on the list of being the problem. Tula ammo isn't the most consistent either.

 

[ebb]

The 50/200 yard theory works with an ammo of a specific speed and ballistic coefficient with a specific rifle. If your rifle has a shorter barrel, your ammo was slower, your twist was different, sea-level elevation was way higher or lower, and many other variations from the inventor of the theories rifle and ammo your results will be different. glad you are enjoying your 2nd amendment rights.

 

[Retired Grunt]

A 5.56 is supposed to have the same strike point at 25M (Rising) and 250M (Falling), that's why we zeroed at 25M. I use scopes and zero at 100 Yards to easily adjust my DOPE in 100 Yard increments.

 

[NZ_Fclass]

Take a look at the JBM trajectory calculator on the 'net. [ https://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi] It's free and fairly accurate. You can enter all the conditions ( you will need to know the velocity - or a good estimate) and the computer magic will calculate gravity for you. Set your Zero at 100 yds.

 

[jelenko]

Hmmm. With a muzzle velocity of 2960, the bullet should be ~ 3" low at 200 - assuming it's zeroed at 50 yards.
To be zeroed at 50 yards and 8" low at 200 yards, the MV needs to be 2300 fps - does that sound like a possibility?

 

[Bill K]

Run you information regarding your load, bullet, FPS, etc. into the free Hornady calulator site and you will see what you are close too getting in trajectory and adjust from there.

 

[iam1964]

Hi guys thanks for all the info. I bought the Strelok pro app and using the data from Tula the point of impact should be pretty much the same (in theory ).
Using the trajectory validation from the app it tells me that the bullet speed was only 2120 fps. This seems like a massive difference between the published data - does this seem likely considering it was Tula ammo?.

The app does seem pretty accurate though cause when I adjusted the sight for 8” low I was hitting the target pretty regularly (not great grouping but I was happy).

 

[Sebrock]

Hi guys thanks for all the info. I bought the Strelok pro app and using the data from Tula the point of impact should be pretty much the same (in theory ).
Using the trajectory validation from the app it tells me that the bullet speed was only 2120 fps. This seems like a massive difference between the published data - does this seem likely considering it was Tula ammo?.

The app does seem pretty accurate though cause when I adjusted the sight for 8” low I was hitting the target pretty regularly (not great grouping but I was happy).

What you should actually do is zero it at 200 yards, and then you will find that you are pretty close at 50 yards. This worked for me on straight out of the box 5.56 on a 16 inch barrel. The problem with the 50/200 zero is that at the lower distance zero you could think you are dead center but potentially the wind or your grouping or whatever factor caused you to be close enough on paper but angularly grows as you get further out.

 

[iam1964]

What you should actually do is zero it at 200 yards, and then you will find that you are pretty close at 50 yards. This worked for me on straight out of the box 5.56 on a 16 inch barrel. The problem with the 50/200 zero is that at the lower distance zero you could think you are dead center but potentially the wind or your grouping or whatever factor caused you to be close enough on paper but angularly grows as you get further out.

That is a great idea. I will try that this weekend. I’m also going to try it with some 5.56 green tips. Thanks.

 

[Sebrock]

That is a great idea. I will try that this weekend. I’m also going to try it with some 5.56 green tips. Thanks.

And if you hit super high at 50 yards then you know there is something wrong with your ammo or barrel. I would try something else.

 

[Sebrock]

I just ran the math in my ballistic solver and .8 low is exactly right. A 50 yard zero is .8 inches low at 200 yards. A 200 yard zero is only .2 inches low at 50 yards. So you were right on model which is great. The issue is not your shooting, nor the gun. I think the 200 yard zero will work for you.

 

[jelenko]

I just ran the math in my ballistic solver and .8 low is exactly right. A 50 yard zero is .8 inches low at 200 yards. A 200 yard zero is only .2 inches low at 50 yards. So you were right on model which is great. The issue is not your shooting, nor the gun. I think the 200 yard zero will work for you.

Wait, his groups were 8 - not .8 - inches low at 200.

 

[Sebrock]

That could easily be bad shooting then when zerod at 50. I guess a 200 yard zero will help him figure it out. If it’s the ammo then he will hit high at 50. I learned my lesson the hard way on handguns. I was convinced there was something wrong with my gun and it always shot low left. Turns out I was a crappy shot and a tiny movement makes a huge angular difference as you get further out.

 

[iam1964]

That could easily be bad shooting then when zerod at 50. I guess a 200 yard zero will help him figure it out. If it’s the ammo then he will hit high at 50. I learned my lesson the hard way on handguns. I was convinced there was something wrong with my gun and it always shot low left. Turns out I was a crappy shot and a tiny movement makes a huge angular difference as you get further out.

I am certainly not a great shot but when I adjusted for the 8” low I was able to hit the target most of the time.
I really wanted to know if the 50/200 zero was a real thing and if it is, could the Tula ammo be so unreliable that is is underperforming a lot, ie published muzzle velocity of about 2950 fps against calculated muzzle velocity of 2100 fps.

 

[Sebrock]

Could be the ammo if they skimped on powder. Regardless the advise I have always been given is to zero at the longer distance to get it to work properly. Try that first then different ammos. That should help you figure out what is going on.

 

[acloco]

The variety of short yardage/longer yardage zero working, also depends on sight height above the barrel centerline.

Yes? No?

 

[jelenko]

I am certainly not a great shot but when I adjusted for the 8” low I was able to hit the target most of the time.
I really wanted to know if the 50/200 zero was a real thing and if it is, could the Tula ammo be so unreliable that is is underperforming a lot, ie published muzzle velocity of about 2950 fps against calculated muzzle velocity of 2100 fps.

It is a puzzle. For the ammo to be around 2200 fps - even out of a 16" barrel - seems odd. But, being able to keep them on target after adjusted for elevation seems to indicate the ammo.
As mentioned, run another 'trial' - zero at 200 [sounds like you've already got the zero], then shoot at 50 yards.
All that said, how well the 'zero at 50 will be on target at 200' depends on the bullet and it's velocity.
A H75hpbt going at 2800 fps will be ~ 3 1/2 inch low at 200; a H55vmax going 3200 fps will be 1.8" low at 200 yards.
You can 'play' with various bullets and velocities using an external ballistics calculator - like the one at JBMBallistics.com

ETA: With a sight height of 1.5".