Strange Bullet Impact... Windage difference is huge!

[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.

And has anyone else experienced this or tried multiple different types of supersonic ammunition in their barrels? thanks

[Whole Bunches]

At what distance are you shooting?

[BadBowtie03]

I was zeroing at 100 yards. A guy on another forum was saying how bullet design can have a big impact on how the bullet flies...

[BadBowtie03]

Any opinions? Why is it soo much? Can barrel harmonics affect it that much?

[Bullystix]

Quality of optic? Quality of mount?

[Magos_Mal]

Very interesting to hear. I'd not expect quite as large a change for the 5gr weight difference and going from jacketed lead to solid copper.

If possible, try to get the Barnes load for their 110gr bullet (they are currently offering until around christmas a rebate, so bonus for finding some) and seeing if perhaps its the powder/velocity/whatever affecting the point of impact, I'd also think to get some of the 125gr Remington match ammo to see what happens with those in comparison.

Aside from just different loading and cartridge characteristics, the only other thing that pops to mind would be barrel break in, and how many rounds you've run through it yet.

Bullystix:
If he adjusted his point of aim to match the new ammo's point of impact, and it shifted the previous ammo's point of impact the same distance to the opposite direction, that would show that the optic is most likely not at fault, as POA/POI is consistent when sighted for that ammunition.

[BadBowtie03]

Trijicon accupoint 1-4 tr24g and an american defense mount. Good stuff. I dont think that's the problem.

Thanks for the help guys. And yeah I want to try different ammo and see which of these is way off... thanks.

[rjacobs]

Can barrel harmonics affect it that much?

Barrel harmonics typically affects vertical dispersion, not horizontal as you typically have "barrel whip" that goes up and down and different loads affect when the bullet exits the barrel at its point of whip if that makes sense.

[rem_pss308]

I do a lot of gun work for people on hunting rifles. I have seen some rifles shoot close to the same impact with different weight bullets ( 150g, and 130g ).
and then I have seen guns who are all over the place. shooting as much as 6" of when just changeing name brands and using the same weight bullet.
Each barrel is different, and acts differently. Find what your gun likes the best and use it. or keep a log of where each type of ammo hits, and you can make a scope change before shooting.

[jwb47]

its not his barrel and its not his scope . the solid copper bullet is alot longer than a traditional bullet of the same weight . the ballistic coefficient is also very differnt . most of the time the faster the barrel twist and the closer you get to maximum charge the better they tend to shoot. like I said before in the other post I responded to the barnes bullet is a horse of a different color and going on my past experience with 5.56 , 308 and 458 socom I am not suprised at all with 8 inches of difference.