So, focusing on the spine totally is a good thing for fixing the "laser vs open sights" issues.
However, modern hollow point bullets don't always reach the spine with real bone penetrating power as the bullet expansion has been carefully tuned to fall within the factory metered FBI 12"-16" minimum/maximum penetration levels.
Ammo factories and police departments really don't want lawsuits from over penetration.HOWEVER, my standard cast lead practice ammo (even rounds that were made all soft and cuddly on purpose for teaching my daughter how to shoot well) will penetrate that deep and still break the spine bones.
Cast lead penetrates really really well. And old people
just plain like soft and cuddly shooting as opposed to jacketed expansion harsh type shooting.
Let's talk about what you have got left to do the job after going through the 14" of the soft stuff.
Historically, a cast 45 caliber pistol bullet did the job at circa 850 fps.
Historically, a military FMJ 45acp hardball bullet did the job at 850 fps.
Both weighed around 230-250 grains of lead mass. They did the job by penetrating --- and they did routinely exit the BG's back while doing this.
Now you are in the world of well known 10mm cast lead wide meplat based hunting bullet technology so we will go run by those rules.for a bit.

..... let's go consult the loading manuals
Oh yes, I can do this easily with what I have on hand ........
...... as a matter of fact I already have some hundreds of loaded rounds on hand that were built years and years ago ...... as cheap cast lead practice ammo.