300 blackout strange bullet impact...

[BadBowtie03]

hey guys I just built a 300 blackout custom AR with a good 16" stainless Wilson match barrel. It is 1/8 twist. Something I think really weird is going on with it though. It shoots really good if you stick consistently to the same ammo...but if you switch its way off. The first ammo is the Remington UMC 115 grain. Second is Southwest ammunition Barnes hunting ammo...110 grain. I originally had it zeroed with the Remington ammo. Then I shot a couple Barnes through it and it impacted about 8 inches to the left. I didn't know why it was doing that. Then I zeroed it with the Barnes ammo and now the Remington impacts 8 inches to the right... strange huh? why do y'all think it has a huge difference windage wise? Ive never seen that before. Thanks.

 

[Mile High Shooting]

Re: 300 blackout strange bullet impact...

Completely different bullet designs will do that. Some guns won't have as much shift as other, but it's not unheard of to have big POI deviations with different ammo.

Put a suppressor on it and you can have similar results.

-Sean

 

[BadBowtie03]

Re: 300 blackout strange bullet impact...

okay good I'm actually glad to hear that! I thought I was going crazy for a few minutes! I was really hoping my build wasnt the problem because I used good stuff. An American defense mount and this brand new 1-4 trijicon Accupoint..

 

[BadBowtie03]

Re: 300 blackout strange bullet impact...

Anyone else had this experience with 300 blackout or tried multiple different kinds of ammo and hadnt had my problem? thanks

 

[stmcelroy]

Re: 300 blackout strange bullet impact...

They probably spin different because of the different bullets designs. One is a standard lead core with copper jacket and the other is a solid copper bullet.

 

[adrenaline junkie]

Re: 300 blackout strange bullet impact...

It's fairly common. I changed a 270 from a 140 gr ballistic tip, to a 140 grain ballistic silver tip. Loaded them at the same time, same powder, primer, case everything. Sighted in with one type, and the other shot groups 2 inchs high, 3 inch to the right.

 

[BadBowtie03]

Re: 300 blackout strange bullet impact...

Thanks for the help guys. I just have never seen it this extreme I guess. The elevation is fine, but the windage is a solid 6-8 inches off. Kind of annoying because I really want to use the barnes bullets for hunting cause they are so deadly and reliable, and I want to use the UMC for plinking cause they are affordable... but they are so different! I guess I could just always hold left about 6" when I want to plink?? Or maybe Dial it in ever time on my accupoint. How reliable do you think this trijicon is for dialing back and forth? thanks

 

[RotARy15]

Re: 300 blackout strange bullet impact...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Badbowtie03</div><div class="ubbcode-body">Thanks for the help guys. I just have never seen it this extreme I guess. The elevation is fine, but the windage is a solid 6-8 inches off. Kind of annoying because I really want to use the barnes bullets for hunting cause they are so deadly and reliable, and I want to use the UMC for plinking cause they are affordable... but they are so different! I guess I could just always hold left about 6" when I want to plink?? Or maybe Dial it in ever time on my accupoint. How reliable do you think this trijicon is for dialing back and forth? thanks </div></div>

Should be pretty reliable. My policy is to keep the weapon zeroed for the "working" load. Whether you hunt 2 legged or 4 legged, zero for that load and dial for the paper.

 

[ksthomas]

Re: 300 blackout strange bullet impact...

As some of the other posts here suggest, there's nothing specific to the 300 BLK regarding this phenomenon. Quite common, and it'll happen in most any caliber. Logical as it may seem that different velocities or different bullet weights would only induce a vertical impact point change, they don't. They shift laterally or horivontally as well. And as you've found, sometimes this shift can be quite pronounced.

Sometimes you get different ammo arriving at the same POI, or with only a slight vertical difference. When you do, just count yourself lucky with that particular combo.

 

[TheShooter]

Re: 300 blackout strange bullet impact...

With a really fast twist barrel, I would think that would exaggerate differences in bullets.

 

[leadbullet]

Re: 300 blackout strange bullet impact...

nothing wrong at all, it is perfectly normal, all rifles are zeroed with their most accurate loads and if you change ammo it will somewhere else.
hope this helps.