Nomercy448

We're mid-season for deer and I'd like to change scopes on my deer rifle, but obviously don't want to miss time in the field by spending time sighting in at the range.

I was BS'ing with a friend last night about it and he mentioned a technique he uses that he learned from a guide some-odd years back. I can't find any flaws in the logic, and he swears he's done it several times with perfect results, but I'm skeptical whether it's a fluke, or if it's the real deal...

Taking a rifle that has been live-fire zero'ed, he puts a target on the wall of his morton building at 100ft, and centers the crosshairs in a rifle vise on the bullseye. Then he puts a laser boresighter in the bore and marks on the target where the boresighter laser lands. Then he removes the scope, and installs the new scope. He sets the boresighter again on the previous reference mark, then zero's the scope to the bullseye.

He swears it's dead on every time. Logically, I can't see a flaw in it; the bullet should fly the same path away from the boresighter line every time, so if the crosshairs on the new scope are set to the same deviation from the reference point, it will still have the same POI, correct?

He also said that when he takes a scope OFF a rifle, he takes a target and makes a laser reference mark, in case he'll put a new scope, or even THAT scope back on the rifle. He hasn't "re-sighted" any of his rifles from scratch in years. He just uses this technique and then takes a few groups to verify he's on target. He said he replaced his 15-20shot "from scratch" sight in method with this method, plus 3-6 shots.

I'm too skeptical TODAY to try it, but I do believe I might spend some time after season swapping between scopes at the range and seeing how well this technique really works...

So is this a fluke, or is that legit? Has anyone ever heard of this technique before?

Wingbone

It sounds like good system to me. In an emergency, I'd trust it. In a non-emergency, where I had time, I'd follow the procedure and confirm with shooting.

homers brother

I don't see the principle here as anything new, we've been using lasers to align crosshairs with the axis of the bore for awhile now. What's novel is the idea of "proofing" a boresight with refinements from actual shooting. This might be particularly useful for those who might find reason to question (as a result of impact, etc.) the validity of their zero without making a trip to the range. In a sense, use traditional boresighting to "get you on the paper," shoot and refine your zero at the range, then "reverse boresight" on a target at a repeatable distance - making no adjustments on the optic and simply recording where the laser hits the target and then filing the target for later use as described above.

Obviously, ammunition variance (lot-to-lot or switch to something else) will compromise the "proofed" information, so probably necessary to record ammunition information on the reference target as well (brand, bullet weight, velocity, BC, etc).

Todd1700

It should work but the paranoid side of me would never let me hunt until I had actually fired it for confirmation. LOL!

homers brother

Nor would I. My understanding of the OP's description is that this method would not eliminate shooting, just reduce the number of shots potentially required.

huntingkidPA

it worked for me. i had mine laser bore sighted at 25 yards. it was dead on. i moved to 100 yards. about a half inch low, made one adjustment and it was hitting perfect. i think it will probably save you a lot of rounds and time sighting it in.

GTOHunter

I think it should work rather well...as mentioned a few real life shots are needed to verify the new scope is On-Target.Another thing I do at the Shooting Range is to have my Rifle in my Caldwell Lead Sled....I shoot at my target dead center starting out at 50 yards...if the bullet impact is down and to the left I simply hold my crosshairs where I aimed dead center and adjust the cross-hairs down and to the left where the bullet hole impacted/hit...then I shot again dead center on the target and see where I'm hitting.....usually I cut down on wasting bullets and the Rifle is dead on,then I resume shooting out to my 100 yard target!

Nomercy448

My buddy swears that the "confirmation shots" are always on target, and he only shoots to verify, rather than actually sight in. He said he'd be confident hunting it (to reasonable ranges, south of 400yrds at least) even without shooting it.

I'm going to spend a while at the range after season with different scopes and different rifles and see how it comes out.

Nomercy448

And there it is, Ridge ladies and gentlemen, always the voice of reason.

I knew there had to be something simple I was over looking. Once I read this I thought about the crossing X's diagram and it all came together.

On the other hand, I'm fairly curious that a guy could do this same work up at 100yrds (for a 100yrd zero), rather than the shorter range, and it'd work better, even for different scope heights, rings, etc. I.e. at 100ft, it doesn't necessarily prove that your reference has any bearing on 100yrds, since your crossing X's aren't related. At 100yrds, I think the variability between crossing X's would be moot, so even if the scope were higher, they'd still cross at 100yrds (but then you'd have more dramatic "scope drift", per usual with any tall scope).

Dang, I was really hoping this wouldn't just be a fluke. I'm sure my buddy was using the same rings and bases, just dropping new 40mm scopes in the cradle, so he was "getting lucky" that the height and scope position wasn't changing much if at all, which is why it worked for him.

jeepkid

Why not just shoot it? Isn't that the point off having all these "toys", to use them? Unless your shooting custom bullets at $3 each, whats the big deal of shooting 10-15 rounds downrange?

But, I would like to see how your tests turn out...