Can BUIS zero be approximately verified with a boresighter in my basement?

[PaseMkr]

Hi guys,

I have a dumb question. a number of years ago, during the last gun panic by (post Sandy Hook possibly) I purchased a LWRC M6 SPR MOD 0 carbine. It sat in a safe until now, as I was typically using my SCAR 16 SBR when I would go to the range. I always put optics on my long guns and as a result, I never ever have taken the time to sight in my iron sights (stupid, I know).
Are rifles like LWRCs usually sighted in at the factory if they come with iron sights installed?

I know I will have to verify zero at a range, but since it's winter and I currently don't have access to a hundred yard range, is there a way to do a rough check on the zero using a laser boresighter and a gun vice in my basement? I have about 34ft to work with.

What distance would you recommend sighting in irons at? I typically do my optics at 100 yards, but have recently been wanted to switch my long gun optics to a 50/200 yard zero.

Thanks everyone!
Steve

[jsbhike]

If they were set at the factory at all (unlikely) it would just be for what ever load they used.

In my experience, any kind of bore sighting (I pull the bcg and look at a vertical line in the middle of the bore) is usually just enough to get hits in paper.

Not sure what laser bore sight you are using, but I bought and returned a Simmons arbor in the muzzle type when I figured out the results weren't repeatable at all, even at short range. Turning the arbor with the rifle fixed would move the laser an inch or 2 at about 25 feet which would have been less accurate than eyeballing a line down the bore.

[georgeib]

Steve, in my experience most buis and optics tend to be pretty darn close from the factory. And I'll second that I don't really trust laser bore sighters, so try the eyeball through the barrel method.

[PaseMkr]

Hmmmm. Thank you and interesting. I've been using a Sitelite SL-500 Laser Boresighter.

[PaseMkr]

So if I remove the bcg, stabilize the upper in a vice, make sure it's level, look down the bore at a dot or target on the wall and I only have about 34 ft in my basement, should I use a adjusted target with an offset like the one below or should the bore line and the BUIS both see the dot level that I can see through the bore?

target.jpg

[tb-av]

The bore and sight the same. You are only going to get close anyway. Unless you get really lucky.

Sorry, I read that wrong. Honestly i don't think it will matter, again, you are only going to get close.

Just to be clear... that target you posted is a 25/100 not a 50/200.

So if you aim at the red dot from 25 yards, your bullet will land in the dotted gray circle or hopefully the light gray dot. If you move that target to 100 yards and aim at red dot, it will hit the red dot.
So you can't simulate that in your basement. At least I can't figure how... maybe I'm overlooking something. I suppose you could try to tweak it a bit but if you move your head just a little that could throw it all off. You still have to fire rounds to see where they will land. Also you are only talking about maybe 2.5" from one extreme to the other.

[PaseMkr]

Thanks! Funny thing, looking though the bore and then using the SL-500 laser boresighter matched up perfectly. The front sight post seems WAAAY too high, but windage appears okay from the factory

[georgeib]

Thanks! Funny thing, looking though the bore and then using the SL-500 laser boresighter matched up perfectly. The front sight post seems WAAAY too high, but windage appears okay from the factory

It's going to be too high at 30 feet, so don't worry about it. Just go out and shoot it. You'll be pleasantly surprised at how close it is.

[tb-av]

Maybe they want your first round to go in the dirt instead of sailing over the trees.

[PaseMkr]

Looks better now, after adjustments. Had to bring front post down a lot and move the rear windage. Oddly, to get a good sight picture the rear sight is off center of the housing a bit.
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