The first remedy they ask about is "how do I adjust my sights.
The first such thread on this topic I read this week was from someone shooting 6-8" left with their Sig P238. The manual for the P238 states the following:
Change windage by moving the rear sight either to the left
or right in its dovetail. When you do this, follow the rear sight
rule: Move the rear sight in the direction you want the group
to go. Moving the rear sight 0.020” in the dovetail changes
the point of impact by approximately 3” at 25 yards.
So...I asked this poster at what distance they were shooting....
The answer was seven yards. Without breaking out a slide rule, calculator and some paper and pens I'm going to just go ahead and wager that for a rear sight to be off enough to result in 6-8" of error it would have to be hanging off the slide.
Here it is folks, most people are right handed and when you jerk the trigger or have too much or even too little finger on the trigger, your jerk shots to the left or right...if you have a flinch you'll drop shots low. When you combine the two you get low left, low right etc. the list goes on and on. There's a handy diagnostic target out there on the web that give some helpful hits, but it can't cover all the possibilities of error combinations.
What one needs to do to determine if it's them or the gun, is either properly shoot the gun from a rest in attempt to remove as much shooter error as possible, or let someone that knows how to shoot test fire the gun, preferably both. If after such testing the gun is still shooting left, consult your user's manual regarding how to properly adjust sights, if you are not mechanically inclined, and do not own appropriate sight adjusting tools...like a Ameriglo Rear Sight Tool, you may just want to ask around at your favorite local gun shop & range and see if they have one and are willing to adjust your sights for you. DO NOT TRY TO USE A SCREW DRIVER AND HAMMER!
And maybe, just maybe if your gun is shooting straight from a rest or in someone else's hands, you may just want to check around for a basic marksmanship class.