Help with boresighting

[bolus]

Sorry if this sounds stupid, but if you just put a shim under one end isn't that going to tweek the scope.

that's a good thought. But I see tons of info on shimming scopes online.

by the way. ACE has brass sheets for shims in a multisize pack for 0.001 to 0.005

 

[Ura-Ki]

Did the rifle come with this mount installed? Does the rifles specs call it out as a -20 moa mount? Likely the rifle was sold with this as a convenience as most would opt to install one any way! if so, that would account for such a large amount of scope dope to get a zero. I would start over with all the info posted here, bring every thing back to factory specs and re check for a zero. Like posted before, you would be about 10 to 12 in. off true bore center. With that in mind, dope in 1/2 that, and see where you are.

 

[Ura-Ki]

I hate shims!!! You spend that kind of money for rings and bases, only to have to shim to get it perfect. Not going to happen! I would use shims only to tell me how much I need to remove from the front end of my mounting system to get it to zero. Scopes these days, combined with the really good mounts you have should be able to take shimming, but to me, this is just a band aid. Over time, it may bend your scope tube, or worse, it puts uneven tension on your receiver and could cause consistency problems!

 

[Member 34319]

I've done up a lot of scopes on a lot of different set ups, mine and others, and never have I had to shim anything to get anything to line up at the distance your talking about.

Just a few more thoughts on the matter and I'll leave it be.

I feel you on wanting to save money on 50cal rounds, but I don't think shimming it will help if your already off by so much at this little of a distance. I would try to ensure that the brake wasn't causing the laser to shoot off coarse first before adding shims to the equation.

Especially since your only at 17 yards, if I read that paper correctly. In my head, the brake or laser have to be the culprit. No way can I see shimming your base or rings being needed if your guns barrel and scope can not line up reasonably at 51 feet. That almost certainly tells me the brake is angling the laser off coarse to be that far off so close.

On another note, once you get that bad momma jamma up and running let me know. I'll take you to a place to stretch her wings out.

 

[bolus]

The rail was installed at the factory and is both pinned and bolted in place. It should be a 0 MOA rail. no slant was advertised. The height of the rail is also identical front to back.

But looking it over I found this. little over 0.005 gap at the front of the rail and no gap at the rear. so the front of the rail is higher.



so that explains at least part of the problem. The laser and brake could explain the rest.

On another note, once you get that bad momma jamma up and running let me know. I'll take you to a place to stretch her wings out.

Thanks for your help. I got a few of these for when it is set up

 

[Member 5605]

I'm going to step out on a limb...

I've never used a laser boresight tool.
Can you pull apart the rifle so you can look down the barrel? Center barrel on target, put scope where you want it. I've been able to sight a new rifle in once with 4 rounds. Average is 8.

That rail gap looks rather large. Could be a culprit.

2.5" is centerline of bore to centerline of scope?

 

[bolus]

I'm going to step out on a limb...

I've never used a laser boresight tool.
Can you pull apart the rifle so you can look down the barrel? Center barrel on target, put scope where you want it. I've been able to sight a new rifle in once with 4 rounds. Average is 8.

That rail gap looks rather large. Could be a culprit.

2.5" is centerline of bore to centerline of scope?

Yes the scope height is 2.47"
with the 50 I see the entire target looking through the bore at 17 yards. I know it is going in the right direction but that's about it.

I reinstalled the rail and got the gap down to about 0.002" and it reduced the sight problems.

So I'm putting this down to the precision of how the rail matches with the upper receiver. Considering this is the budget upper receiver from tactilite, Im not too concerned. Just as long as it does not explode on me.

 

[Member 5605]

Yes the scope height is 2.47"
with the 50 I see the entire target looking through the bore at 17 yards. I know it is going in the right direction but that's about it.

I reinstalled the rail and got the gap down to about 0.002" and it reduced the sight problems.

So I'm putting this down to the precision of how the rail matches with the upper receiver. Considering this is the budget upper receiver from tactilite, Im not too concerned. Just as long as it does not explode on me.

Thanks for that. I've been thinking a bit on this since you started the post.

I wasn't thinking about a .50" hole, spending time at ARPC helping 'hunters' sight in rifles I've looked down many bores to find feet of difference at 50y.


If you ever need a place to shoot... Look me up. I'll gladly take you out to the range down here since there are no restrictions on .50's.

 

[Velzey]

Is there a size large burr around on of the holes or possibly the end have a burr from milling then they anodized over it.

 

[Member 34319]

After posting that gap on the mount. That likely is your culprit.

Sad, though entry level 50. Still not cheap. I would expect better than that type of tolerance.

Sounds like you got it worked out though.

 

[bolus]

After posting that gap on the mount. That likely is your culprit.

Sad, though entry level 50. Still not cheap. I would expect better than that type of tolerance.

Sounds like you got it worked out though.

Perhaps I should have waited the 9 more months for the upper end model. It does have a Criterion Barrel which I've heard good things.

 

[PaulB47]

Sorry if this sounds stupid, but if you just put a shim under one end isn't that going to tweek the scope.

I have used shims before and am not bothered by them other than the extra work they require. Sometimes manufacturing does not do a perfect job for us. You need to pay big bucks to get perfect.

However I think you need to do it right. I can't imagine how anybody can slap a $100 scope in some rings and just tighten it down, never mind a $1000 scope. Especially when shimming, you certainly do need to lap the rings (which pretty much makes vertically-split rings impossible, even though I like them otherwise). Also when shimming you should bed the base to the action. This assumes the shim goes under the base, not above it; it never occurred to me to do it any other way. I often use a pop can but Brownells has shims too.

Also when mounting scopes I like to get a roll of the old-fashioned cloth electrical tape and stick a piece of it in the ring bottoms. It's sticky on both sides so your scope will definitely not slip in the rings.

You do have to use a little trig to figure out how thick to make the shim, unless you want to do trial & error (tough if you are bedding). Or you can just use proportions, since it is similar triangles.

 

[B5Ben]

Get one of these if you can find it. I have used a buddies on many occasions and just realized as I was finding a link, that they are discontinued. I will have to be very careful with his since it wont be easy to replace.

http://www.midwayusa.com/product/675745/leupold-zero-point-bore-sight

I was on paper first shot at 100 yards or more last three rifle/scope setups. Cant beat that if you are looking to save ammo. Good luck on your 50 @bolus!

 

[PaulB47]

Better yet, refer to your ballistics program. It should tell you where the bullet strike is at any range. One shot at 20 or 30 yards (assuming you are careful with it) should be all you need to get on target at 100.

 

[P7M13]

Better yet, refer to your ballistics program. It should tell you where the bullet strike is at any range. One shot at 20 or 30 yards (assuming you are careful with it) should be all you need to get on target at 100.

+1

I have a laser bore sighter, never use it. To me, it's one of those things that should have a calibration on it.
Bolus, you are extremely experienced on setting up firearms, I'm sure you've tried the following?

1. Set your rifle up on a gun vise, and completely level the scope rail in the cradle.
2. Use your ballistics program to see where same trajectory point for your 200 yard zero is (~30 yards?)
3. Measure out that distance
4. Set a structure on that point (I use a ladder)
5. Look down the bore and identify where you should hang your target. I use a 1/2" diameter fluorescent dot for my bore sight target.
   
6. Hang a plumb line and establish vertical for your crosshairs
7. Zero your scope cross hairs on the fluorescent dot.

I do the above for 100 yards and I'm usually within 3" of zero. I then zero, and stretch it out farther.

 

[bolus]

+1

I have a laser bore sighter, never use it. To me, it's one of those things that should have a calibration on it.
Bolus, you are extremely experienced on setting up firearms, I'm sure you've tried the following?

1. Set your rifle up on a gun vise, and completely level the scope rail in the cradle.
2. Use your ballistics program to see where same trajectory point for your 200 yard zero is (~30 yards?)
3. Measure out that distance
4. Set a structure on that point (I use a ladder)
5. Look down the bore and identify where you should hang your target. I use a 1/2" diameter fluorescent dot for my bore sight target.
   
6. Hang a plumb line and establish vertical for your crosshairs
7. Zero your scope cross hairs on the fluorescent dot.

I do the above for 100 yards and I'm usually within 3" of zero. I then zero, and stretch it out farther.

Thanks, I dont have a 100 yards on my property though. There is a wall on the other side of the street 1/3 of a block away that is ~100 yards from my living room and I did use the boresighter to that wall. But I have to be careful pointing a 50 cal (upper, not thr complete rifle) down the street since my neighbor is a D bag (he once called the police because my step daughter was playing with the cat with a laser pointer and they told the police we were pointing sniper rifles at them)

 

[P7M13]

Thanks, I dont have a 100 yards on my property though. There is a wall on the other side of the street 1/3 of a block away that is ~100 yards from my living room and I did use the boresighter to that wall. But I have to be careful pointing a 50 cal (upper, not thr complete rifle) down the street since my neighbor is a D bag (he once called the police because my step daughter was playing with the cat with a laser pointer and they told the police we were pointing sniper rifles at them)

D-bag is right!
I meant to do the 100yd at the range. I guess that defeats your save ammo objective. D'oh!

 

[tac]

Reading all this farting around with shims and so is is making my brain bleed.

Soooooooooooooooooooooooooo, try this -

1. Set up a four-foot square piece of paper at 100 yds, with a 1" black dot in the exact centre.

2. With your rifle set up on front and back bags, sight through the barrel and get the black dot in the middle - your eye will do the centering from you.

3. Without moving the rifle, adjust the crosshairs onto the black dot.

4. Fire ONE shot at the target.

5. Put the crosshairs back on the black dot - they will have moved when you fired the rifle - and then, WITHOUT moving the rifle, move the crosshairs to the new bullet hole.

6. Fire another shot at the black dot - I bet a penny to a pinch of parrot poop that you are pretty much on target.

This has worked for me for the last sixty years, and saved me mucho dinero.

tac

 

[Member 5605]

I'm lucky.... That roof vent from my kitchen island is 101 yards.