Boresighting weirdness

[ZeSpectre]

I have a laser boresighting kit that I've owned for a while and used on several rifles and a few pistols. So far it's been extremely accurate with the guns only requiring a few "fine tune" clicks on the scope to shoot point-of-aim.

So the other night I'm helping a guy sight in a Ruger 77/22 WMR with a sweet Leupold scope and we were having a terrible time doing so. I finally resorted to pulling the target in really close and working from there. Once we got it dialed in the scope held true and we were able to nail a nice tight group at different ranges for the next 20 shots so we figured all was good.

Just out of curiosity I stuck the boresighter back in and looked through the scope and the laser dot was WAY off to the right and high?!? Well heck, no wonder we couldn't get it sighted in at first. So I thought "damn, I guess it got banged up or something". However when I got home I stuck the thing in three other rifles I have that are sighted in and the laser dot was dead-bang right in the center of the crosshairs (all done at the same distance).

So then I thought maybe something is weird with that 77/22's barrel, but it was shooting accurately and repeatably after we finally got it dialed in.

I guess no big deal in the end because everything works but I can't for the life of me figure out HOW the laser could be so far off on that rifle and yet the rifle shoots well.

Any ideas???

 

[strat81]

Funky barrel, chamber, or scope mount maybe? I don't know, that is weird.

 

[JustsayMo]

In my experience bore sighting gets you on the paper, usually. How far away or how big that paper is can be the puzzling part.

At our club I've lost count as to how many guys I've heard say "its bore sighted" and then proceed to waste a half box (or more if their really stubborn) at the 100 yard line without even touching the paper.

Experienced guys, bore sighted or not, start at 25, get close or confirm and then move to the longer ranges. Within 6 shots guys are usually pretty close so it saves em money.

Different loads, brands print differently. In my 30-30 the 150's print 6" higher than the 170's. A 170 jacketed bullet just over an inch to the left of a 170 grain cast bullet at 100 yards... In my 45-70 my slower plinking loads print 6" higher than my hunting velocity loads at 50 yards. I'm my 22's subsonics print lower (usually) than the high velocity stuff. I could go on and on but the point is that the same sight zero isn't likely to be the same for all ammo that will feed through the firearm.

My bro-in-law missed a nice buck when he changed ammo brands without rezeroing his rifle... When he checked it afterwards it wasn't even on the paper at 50 yards while his old ammo was right where it should be.

 

[ZeSpectre]

JustsayMo-

I'm usually a "3 shot sighter".

Lock the gun down good and solid and place the target pretty close (30ft or so).

Rough sight w/the laser boresighter.

Then two rounds into the target and if they form a nice tight group I move the crosshairs onto that group (without moving the rifle).

This almost always allows me to now put the third shot right where I want it.

Then I move the target out to desired range and shoot maybe 3-4 more shots to adjust range, verify, (and a couple just for the fun of it) and I'm done.

Not this baby. Had to move it in to about 21ft to get anything on paper and then I could start dialing in the scope.

Good point about the ammo though. I'm gonna call him back and have him drop by with some different ammo and see how that behaves.

 

[rcmodel]

I'd be more interested in the stock bedding. And action screw tightness.

If it's got a lot of uneven forearm pressure on the barrel, or uneven screw tightness on the front or rear screws, there's no accounting for where it might want to shoot, compared to where the laser is looking.

rcmodel