Pre-fit barrel alignment

[Aftermath]

Yeah, if you don't typically zero for 300 meters, it kinda is

If you want to hit the paper at 100, do as I said. You should be looking through the barrel and seeing about a half inch under your point of aim in the scope. A 200 yard zero would be even closer and under your point of aim about a 1/4". 300 yard zero and you should be about a 1/2' high from point of aim in the scope.
I mean. you aren't hitting where you think you should now but think you are off to one side or the other. Aiming the scope at 25-27 yards and then looking through the barrel should tell you if you are off either side, not just above or below.
25 yards is close enough that you should be able to see your aiming spot with your naked eye through your barrel. Not much farther out and it becomes more difficult. Plus, it's a free method and doesn't rely on the misalignment of some bore sight device.
I have swapped to the cartridge lasers. It saves me time and ammo.

This works whether you start with looking through the scope first or the barrel first. In the case of actually using this method to get on paper, start with aiming through the bore and adjust your scope to the point of aim.

 

[memilanuk]

I've done something similar in the past, just usually @ 100yds. Using the right target, one that can be optically centered in the bore like a peep sight, usually gets the job done - the exception being days like last week where the conditions outside were crap. Usually I start with the collimator to at least get close-ish... though that clearly went off the rails, somewhere.

Guess I'll see if I can set something up in the back yard to where I can aim out the shop window without making the neighbors too nervous

 

[memilanuk]

Well... this is interesting.

Finished up night shifts this morning, and rummaged around in the shop a bit. Made up a new small(er) boresighter target, put some fresh batteries in the rangefinder, and found a spot on the back yard fence where I could hang the target at what turned out to be right @ 27 yards.

Set the gun up on a tripod, and using the Arca rail on the KRG Bravo I was able to clamp it in and lock it down pointing at the target. Note to self: I need to find a way to do that with my F-class guns!

So... the first setup was the Origin actions, Proof CF .308 Win shouldered pre-fit, Burris XTRiii 5.5-30x, as that was the most recent combination that I'd taken to the range last weekend. The back of the stock on the Bravo sticks up just enough that it *almost* interferes with doing a boresight like this - makes it a little hard to tell if it's actually 'centered' properly. Anyway, the turrets were centered and zeroed from the last range trip. Looked down the bore and... pointing almost dead nuts center. Huh.

Took the Burris off, and put the Bushnell XRSii 4.5-30x on the gun. Got it pointing at the center of the target, and dialed it back and forth, then zeroed the windage turret. Ran it all the way left, then all the way right, then back to center. It's maybe 0.2 mil right of 'mechanical' zero.

Pulled the scope off, pulled the stock off, swapped the .308 Win barrel for the original Proof CF 6.5CM nutted pre-fit barrel, torqued it on to 75 ft-lbs, and put everything back together.

Started with the Burris again. Had to come about 1.5 mil right to line up. Also pointing 1.5-2 mil high, but I was less concerned about that. Then the Bushnell... maybe 1.4 mil right to get centered, off the same amount for elevation as the Burris.

Some days, with the right lighting/contrast I can get it just right on. Today was not one of those days. Given the level of fuzziness in the bore sighting method... I'd say both barrels were pointing the same place.

I've got maybe 25 rounds loaded for the 6.5 CM barrel at the moment, but plenty of prepped and primed brass. Maybe tonight or tomorrow morning I'll load a few more and head to the range and see how the 'physical' boresighting lines up with actual paper @ 100. Maybe box-test that Burris scope. *Something* was not acting right to begin with, on a couple consecutive occasions, which is what led me down this rabbit hole.

 

[spife7980]

Shoot it on actual paper to actually zero.

Then tape that bore sighter to the paper and shoot it.

 

[memilanuk]

Then tape that bore sighter to the paper and shoot it.

Might have to find a way to stick it out there so I can Hathcock that sum'bitch

 

[memilanuk]

So... more follow up.

Took the gun to the range on the 11th (January), in the Bravo chassis with the Bushnell XRSii 4.5-30x mounted up. Zeroed the scope, shooting nice tight little knots. Then proceeded to box test it - up and right 1.2 mil (about how far it is from the center diamond to the upper right diamond on the red-n-white Champion target), down 2.4 mil, left 2.4 mil, up 2.4 mil, down and right 1.2 mil (back to center). All nice tight little 3 shot groups in the ~0.3 moa range.

Next day (12th), same test, but with the Burris XTRiii 5.5-30x. Group sizes tripled (or more), and definitely did not track, losing about a half mil of elevation and a little windage on the way around the box test. Said fuck it, got an RMA and sent the scope back to Burris.

On the 17th, I'd gotten some new goodies in - an ARC Xylo chassis, and a DNT 7-35x scope - so I took it up to the range to sight in the new glass... and box test it. Again, *that* scope tracked fine, gun shot fine, no problems.

Now, today (Feb. 5th), I get an email from Burris:

Your scope was evaluated through a multi-point inspection process. We have determined that the scope functions properly and is within all advertised factory specifications.

Yah... I have my doubts. I will say that in the past, about 80% of the time when I've sent a scope in (Nightforce, Leupold) for concerns about it tracking or holding zero, it came back with a similar note. But somehow, magically, they always shot 'better'. Even though 'nothing' was fixed...

 

[ShtrRdy]

Oh, man!! Please let us know if the Burris comes back magically healed.

 

[memilanuk]

Well... nuts.

Scope (the Burris) showed up today, while I was at the range playing with a NSS/Criterion 6CM barrel-nut barrel on the Origin. Put the gun up on the tripod, zeroed the turrets on the DNT 7-35x (I'd been messing with loads and then holding off with the tree, so I hadn't bothered slipping the turrets back to 'zero') and checked the bore sight on a target @ ~25m / 27yd along the back yard fence. Checked the amount of windage from stop to stop: 7.4 mil one way, 9.6 mil the other way.

Now the Burris XTRiii 5.5-30x... mounted it up in an ARC M-brace one-piece mount. 34 mm diameter, 0 moa, 38mm / 1.5" height. Leveled the scope to the base, and torqued the screws to the value specified in the instructions (55 in-lbs). Sighted down the bore on the aiming point again, and adjusted the turrets to suit. Once I had everything where it looked good, I ran the windage turret stop to stop. 1.9 mil one way, ~7.5 mil the other way.

According to Burris:

Unable to recreate customer issue. The turrets were not maxed out. The adjustment travel is correct. Recoiled the optic in all directions, there are no loose lenses to cause an image shift. Ran a full test and check, extensively recoiled, the scope consistently holds zero.

Not sure where this leaves me at this point. Anyone want to buy a scope? Maybe trade straight across for a DNT?

Suggestions? Next steps?