Noob Mounting Red-dot: Looking for Feedback

[Callee]

This is a story of a noob experience trying to mount and zero a red dot. I'm hoping some of you can give some helpful feedback. Thanks!

So i bought this red dot for my marlin 1895.

I'll admit, i didn't put a lot of planning into it. Cabelas advertised a good deal on a vortex spark 2, and i already had a cabelas discount to use, so i really just impulse bought it.

I'd never used a red dot before, i'd only read about them.

I mounted it on the marlin, which was real easy - it just went on with one allan key. I wasn't totally sure where on the rail to put it, so i set it about where i'd expect a scope to be, and it felt good there to me.

Then a buddy and me took it down to the range and tried it out at the 50 yard mark.

First shot, missed the target completely.

So then we aimed high. Still missed.

Aimed low. Still missed.

Aimed right, aimed left. Still missed.

We tried a whole bunch of shots, and just could not hit the target at all, and the back stop made it hard to see where we were hitting.

So i took off the red dot and tried with the peep sight. Hit the target dead on, no problem.

So then we set up the gun on some stands so that the peep sight was aimed right at the target, then i carefully installed the red dot without moving the gun, and then dialed in the red dot. I thought that might at least get us on the target, but no joy. We still missed completely.

Having burned through about a million dollars worth of 45-70, we decided to give up for now.

I didn't think it would be right dialed in right out of the box or anything like that, but i thought it might be in the neighbourhood.

Was that a dumb expectation?

In any case, i decided to buy one of those laser bore sighters i'd read about. I found one on amazon for $50 and ordered it in.

Took it to the range. First i put the laser in my 308 which has a regular scope on it which i knew was already zero'd in nicely.
Looking down the scope, the laser dot was pretty much dead centre, and when i did a test shot, i hit the target dead on.

So then i installed the laser in the marlin, and then started to dial in the red dot to match.
At the start, the red dot was waaaay off. So i dialed it right in, and got ready to fire a test shot.

Since the laser worked perfectly on the 308, i thought i'd have no problem zeroing the marlin. I mean, just stick the laser in the barrel, then turn the dials on the red dot till the two dots line up, right? Easy peasy, right?

Yet my test shot still missed the target entirely!!

I finally took out 8 more target sheets and went down and wall-papered the entire target board!
Then i aimed for the centre target and shot. It hit about a foot low and a 6" to the left.

At least i new where i was hitting!

I worked on dialing it in after that, and within a few shots i was able to hit the bullseye consistently with the red dot.

Then, just for kicks, i stuck the laser pointer back in the barrel, and saw that it was not matched up with my red dot at all.

I then fired a few more test shots, aiming with the red dot, and hit the target just fine.

So the laser pointer didn't seem to be pointing at where the marlin would actually hit.

Yet the laser pointer worked perfect on the 308? So i don't understand that either.

Bottom line, i got it done, but i went through around 50 rounds of 45-70 to do it!

I figured there had to be a bunch of things i could do better next time. Any advice?
Thanks!

[Snider shooter]

Bore siting only gets you close, normally on paper. I have had new scopes that where over 6 feet off. Not surprising what happened. Usually with a new scope I have someone with a spotting scope telling me where the bullets hit. We have sand on our berms so hits are easy to see. Your 308 lining up doesn’t happen often.

[Scotty454]

6" off center left/right at 50 is completely reasonable for a dot that hasn't been zeroed on a gun (That's only 12 MOA, I have red dot optics that have 12MOA dots on them). And depending on the mounting center height of the optic, a foot low at 50 is also pretty reasonable/expected. The laser bore sighter not working was prooobably something not set up right, or something's not right with it (maybe the little centering arbor). They're a little finnicky, but super useful for just getting you on paper. I use then to get close-ish before going to the range, and it always at least gets me on paper.

Muzzle devices are also not great for bore sighting with the type that needs to seat a taper on the muzzle. The muzzle threads on guns are often not perfectly concentric to the bore, and the bore sighter locating on the brake/whatever instead of the crown of the barrel throws them off sometimes.

Start at 25 if you can. 50 is a long ways if you have no idea where you're at, and you'll often/almost always be more than a sheet of paper off of zero at 50, even after laser bore sighting.