POI change brass/steel

A

AssaultTortoise

New member
I am having a weird POI change with my AR. Yesterday I sighted in with normal 223 brass cased 55gn ammo. Once sighted in I switched to a batch of Herters/Wolf 55gn. The POI immediately changed 6" low and 6" to the left. As a test I mixed a mag with one brass followed by one wolf and sure enough each brass round hit the bulls-eye and each steel round hit low and left. Has anyone else experienced this?
 
I guess I will be first to respond.... But my first inclination is that the different POI for each ammo type has much less to do with the material of the case, and everything to do with the total combination of all components and their differences between each ammo type. You didn't provide any detail on the brass cased load.... And I certainly don't have the load data that Wolf uses in their store bought ammo... So with the information given it's impossible to compare differences in primer, powder type/charge, and bullet weight/type.

If all of the other components were identical, I'm sure you would still have some degree of difference in your POI. Of course, since steel cased ammo is not normally reloadable, such an experiment would be problematic.

Hope this helps.

Tom

ETA: on rereading your post I did see where you noted you were talking about 55 grn bullets in the brass case.
 
...my first inclination is that the different POI for each ammo type has much less to do with the material of the case, and everything to do with the total combination of all components and their differences between each ammo type.
Click to expand...
^^^ That ^^^


The fact that one was brass-cased, and one was steel-cased, doesn't matter. All that matters is that it was a totally different load.
 
That makes sense. I always figured if you get a POI change it would manifest itself in elevation change an not effect the windage much. I was lucky enough to buy a thousand rounds or so of wolf pre-panic for $4/20 guess I will have to reserve them for plinking ammo and try to find some more brass to run matches with. Thanks for the insight.
 
I will have to reserve them for plinking ammo and try to find some more brass to run matches with
Click to expand...

Your sights are not adjustable?

If the POI shift is consistent, spin the knobs and call it good. Put it back when you are done.
 
Poi can shift in both windage and elevation because your barrel is whipping around like a light pole in an earthquake. Bullet goes where the barrel happens to be pointed when it exits.
 
Running steel case and brass together can lead to problems, as well as running brass after steel.

http://www.theboxotruth.com/docs/edu18.htm

Could be any combination of type of powder, primer, amount of powder, and steel case letting gas past it and back into the chamber. Basically any time you change the velocity of a bullet out of a barrel you're going to change poi. This is why people suggest trying different types of ammo to see what your rifle "likes" and why reloaders ladder test their rounds for accuracy. Bullet going down the barrel will make the barrel vibrate and where the barrels at in it's vibration will affect where the bullet hits.

http://www.primetab.com/guns/laddertest.explanation.html

During ladder testing you can literally watch a group open and shrink, usually starting large, shrinking, opening back up, shrinking again and opening a third time, depending on how low you start and how high you go. I usually divide the difference in min and max charges by 10, make 5 rounds of each and test, then go back and do another run at 1/2 grain increments starting below and going over the charges I got the best groups from.
 
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