No, both of these methods are attempting the same thing though. Both are attempting what is sometimes called a "parallel" zero or an "infinity" zero.
By zeroing to an offset, you are literally trying to achieve a parallel zero. By zeroing to the reticle at some distance farther out like 400yds, 500yds etc. you are approximating an infinity zero.
Mathematically a parallel zero and an infinity zero are the same thing.
Besides a parallel or infinity zero there's also a "convergent" zero which would be if we zeroed exactly to the center of our day scope reticle at 100yds. Depending on how far out you are typically ranging, this could work. As has been mentioned, if you have a 1.5" offset between the center of the reticle and the center of the ranging laser aperature on the gun, and you use a convergent zero at some distance, then your offset on the gun is 1.5" your offset at 100yds is 0" and your offset at 200yds is 1.5" and your offset at 300yds is 3.0" etc.
So while zeroing your reticle to the laser at 500m is attempting to approximate an infinity zero, its actually, in theory a convergent zero (as has been mentioned). That said, for distances inside 1000m the error (in theory) never exceeds the offset on the gun at the starting point.
And no you can't see the offset at 400yds or 500m or 1000yds from the gun. BUT, I have done this by sending one team member down to the target, he can see the offset, since he's right there and radio back to the gun to direct the adjustments to the LRF. This of course requires safe-ing the gun
... but we've done this several times. If you believe you will be ranging small objects beyond 1000yds, then I'd say this is worth doing and we once did this at 1000yds with a guy down there at the target, but this is not always (usually) worth doing IMHO.
For most critter control activities, which take place inside 500yds/meters, there's practically no difference between a convergent zero at 500yds/meters and a parallel zero at 500yds/meters.
I zero the vis laser to the reticle at 415yds at night with 14, because that's the distance I have a mineral feeder I can see from right outside the house and that's plenty accurate enuff for what I do. I've been able to range and kill a yote at 509yds with a radius zeroed to the reticle at 415yds and that's good enuff for me.
So now you're either totally unconfused - or even more CON fused !!!
