Round is tumbling. Either too little of a crimp, or too much or too little powder. If you are shooting plated bullets, it may be too much crimp or too much powder causing the plating to strip and the round to tumble. If you are shooting jacketed bullets it is either too little crimp or too little powder.
If plated...ease up on crimp and see what happens. If still occurring, also reduce charge.
If jacketed, up the crimp 1/1000th and then try upping the charge.
Just remember there is some trial and error when working up a load...take your time, change one thing at a time and you'll get there.
Hope this helps. If anyone else has add'l info i'm sure they will chime in...alot of experience on here...
Not sure if the OP is around anymore, posted the question 3 days ago & hasn't been seen since.
No idea of the distance we're talking about, barrel type (Stock Glock, or aftermarket), ammo used, & so on.
Sometimes the targets aren't secured all the way around, and can flap & twist a bit if there is some breeze up. You can get rounds that mark like keyholes, but it's just a twisting target. Or, high pressure +P handloads, with a too soft lead cast bullet can shear over the bore lands & grooves, & not take a proper rotation.
Or?? Who knows? Not enough information from the OP to do anything other than make SWAGS.