Rifle Scopes Okay, what am I missing here...

[moxford]

ZCO 420 has 35mils of total elevation, so 17.5 each for up/down.

20MOA base + 20MOA mount = 11.63 mils, so I should have a few to spare.

With a laser boresight, I cannot get enough vertical travel to line up (or even get close) at 200 yards.

System is NOT torqued down, so I'm not binding anything.

Ideas?

 

[RobbinsHGray]

Is your 20 MOA base backwards

 

[W54/XM-388]

ZCO 420 has 35mils of total elevation, so 17.5 each for up/down.

20MOA base + 20MOA mount = 11.63 mils, so I should have a few to spare.

With a laser boresight, I cannot get enough vertical travel to line up (or even get close) at 200 yards.

System is NOT torqued down, so I'm not binding anything.

Ideas?

Assuming you have checked that neither your base or your mount is backwards;

A laser boresight is going to be off by a fair bit at 200 yards.
I think you'll have better success if you go back to 100 yards, then put the rifle on a really steady rest, pull the bolt, look down the barrel and have it lined up with a nice big black center of a target then make sure the scope cross hairs point to the same general spot and go from there.

I've never had much success with laser bore sighters at any significant difference, there is just too much room for error in the mounting.
Compared to using the above method, where I can often get the rifle dead on with 3 shots total at 100y and then move out from there.

 

[Olen_4504]

Ditch the laser bore sight

Do what he said ^^^^^

After making sure nothing is backwards

 

[Glassaholic]

Assuming you have checked that neither your base or your mount is backwards;

A laser boresight is going to be off by a fair bit at 200 yards.
I think you'll have better success if you go back to 100 yards, then put the rifle on a really steady rest, pull the bolt, look down the barrel and have it lined up with a nice big black center of a target then make sure the scope cross hairs point to the same general spot and go from there.

I've never had much success with laser bore sighters at any significant difference, there is just too much room for error in the mounting.
Compared to using the above method, where I can often get the rifle dead on with 3 shots total at 100y and then move out from there.

I'm with you W54, I have always used this method (looking down the bore of the barrel) and call it the redneck boresighting method, have always been able to get on paper and zeroed within a few shots. OP, toss that laser boresight and do as recommended here, sight in and zero at 100, there is no need to zero at 200 yards with modern equipment.

 

[moxford]

Mount is integral. 20 MOA base backwards would cancel out the mount.

Ditched the lasers and used the recommended old-school boresight method. Much better and good enough to get on paper next range trip.

Thanks everyone!

 

[Birddog6424]

Haha, I'm even more redneck than some of you...

I pick a spot on the 100 yard berm at our range and shoot at it. When I hit it, I move to paper..

 

[KnowNothing256]

I must be bad at boresighting haha, I’ve spent more rounds than I care to remember trying to boresight at 100y. Now I do it at 25 yards, one single shot to see where I am, then adjust the scope to match my 25-yard dope assuming a 100-yard zero, then I go to 100.

Never fails, which I unfortunately can’t say about my boresighting at 100.

 

[Rob01]

I must be bad at boresighting haha, I’ve spent more rounds than I care to remember trying to boresight at 100y. Now I do it at 25 yards, one single shot to see where I am, then adjust the scope to match my 25-yard dope assuming a 100-yard zero, then I go to 100.

Never fails, which I unfortunately can’t say about my boresighting at 100.

That's what I have done for years but I adjust to make my second shot 1" low at 25 yards so it's real close at 100. And for anyone wondering how to make that adjustment, you use your reticle like a ruler. Says you need to come left 3.2 mils and down 4.9 mils then you dial that on and it's there.

 

[KnowNothing256]

That's what I have done for years but I adjust to make my second shot 1" low at 25 yards so it's real close at 100. And for anyone wondering how to make that adjustment, you use your reticle like a ruler. Says you need to come left 3.2 mils and down 4.9 mils then you dial that on and it's there.

Yep, that’s it for essentially any supersonic centerfire round. I wish I could tell my younger self about this method…

 

[346ci]

I use a cheap muzzle end laser but always at 100yds, gets me on a 8"x11" sheet and use the reticle to measure to center.

The problem with cheap lasers is they are not centered in the bore, can really throw you off at 200yds.

 

[Mike Casselton]

ZCO 420 has 35mils of total elevation, so 17.5 each for up/down.

20MOA base + 20MOA mount = 11.63 mils, so I should have a few to spare.

With a laser boresight, I cannot get enough vertical travel to line up (or even get close) at 200 yards.

System is NOT torqued down, so I'm not binding anything.

Ideas?

So, torque it down. Properly.
THEN try to bore sight/zero it.
Ditch the laser and do an actual bore sight.

 

[Baron23]

I've never had much success with laser bore sighters at any significant difference

Me either....I bought one once, found it impossible to see at any distance, haven't touched it since.

I do as you and other folks do and suggested to me....bore sight peering down the barrel with the bolt out and go from there. Works just fine.

 

[Nik H]

That's what I have done for years but I adjust to make my second shot 1" low at 25 yards so it's real close at 100. And for anyone wondering how to make that adjustment, you use your reticle like a ruler. Says you need to come left 3.2 mils and down 4.9 mils then you dial that on and it's there.

This is what I do as well...works like a charm.

You may have even been the person who told me this when I was starting out with bolt guns several years ago!

 

[Marine52]

You’ve got 40 MOA (11.6 mils) cant on your scope effectively putting your POI way high at 100 Yards. Dial your scope all the way down and shoot it at 25 yards into a large target. a piece of cardboard with 36” height would work. Measure the distance between POA and POI, and then use your ballistic app to determine what your impact will be at 100 yards. I expect it too high for a 100 yard Zero.

 

[W54/XM-388]

You’ve got 40 MOA (11.6 mils) cant on your scope effectively putting your POI way high at 100 Yards. Dial your scope all the way down and shoot it at 25 yards into a large target. a piece of cardboard with 36” height would work. Measure the distance between POA and POI, and then use your ballistic app to determine what your impact will be at 100 yards. I expect it too high for a 100 yard Zero.

I've run S&B 5-25 x56 scopes in 45 MOA mounts and never had a problem getting a 100 yard zero.
40 MOA should still let him do a 100 yard zero just fine.

 

[Rob01]

Yup a scope with 35 mils of travel will zero just fine at 100 in a 40 moa base. Hell it will work in a 60 moa base.

 

[Marine52]

I've run S&B 5-25 x56 scopes in 45 MOA mounts and never had a problem getting a 100 yard zero.
40 MOA should still let him do a 100 yard zero just fine.

Ok yes I see what you are saying. The 17.5 mils is about 60 MOA of play. Plenty. I didn’t read back and was thinking 17.5 MOA.

 

[Aftermath]

First shots out, I use a sled. I aim carefully and shoot carefully 1 shot. I then make sure I am aiming at the original aiming point, clamp the rifle so it's locked into position pretty good and then carefully adjust the scope so that the cross hairs are on the point of impact. I shoot a few more to sure I'm on and make adjustments if needed.

 

[Mike Casselton]

First shots out, I use a sled. I aim carefully and shoot carefully 1 shot. I then make sure I am aiming at the original aiming point, clamp the rifle so it's locked into position pretty good and then carefully adjust the scope so that the cross hairs are on the point of impact. I shoot a few more to sure I'm on and make adjustments if needed.

It's easier than that.
I do it at 100 yards.
Shoot the first shot.
Measure with reticle and re zero.
You should be able to hit a 1" dot at that point.
Shoot a group and fine tune your aim point.
Done.

 

[308pirate]

This is the only laser boresighter I've found that works well enough: https://www.midwayusa.com/product/1008863250?pid=636671

With it I can zero handgun optics at 10 yards and be within 1/2 - 1" of POA at that same distance. I also use it to get a rough boresight at 10 yards (longest distance in my basement) when first mounting a scope on a rifle. I set elevation so that POA is 5-6 mil below the laser reflection on the wall and it will be close enough at 100 yards.

It's a hell of a lot easier than trying to center a black blob through the bore then adjusting the scope without disturbing that alignment