Pre-fit barrel alignment

[memilanuk]

So... over the years I've used, removed, installed, replaced a fair few 'pre-fit' barrels - almost all Savage barrel nut style, though. Along the way, via the school of hard knocks, I found out about the joys of barrels... not always pointing where you want them to - as in having to use up most of your windage or elevation (or both) to get the gun zeroed. *Especially* with factory nuts and lugs. Switching to quality aftermarket lugs - surface ground flat and parallel - and aftermarket barrel nuts, with the mating surface machined perpendicular to the axis of the threads, made a *huge* difference. Basically eliminated it, in my experience.

Fast forward to more recently... I've got a couple barrel-nut pre-fits - one a Proof CF, and the other a Shilen, both with aftermarket nuts - and an Origin action. And they both 'point' about 5-6 mils off to the left

I didn't really notice it at first, because the first scope (Bushnell XRSii 4.5-30x) I had on that gun with the first barrel (Proof CF 6.5CM) had a wider range of adjustment, so I never really bumped into the edge of the range of travel. The second barrel (NSS/Shilen 223 Rem) actually points a little less off to the side, so I didn't notice that one either, even when I changed the scope out for a Burris XTRiii 5.5-30x. But when I swapped back to the Proof barrel, I got it zeroed... but started having all kinds of problems with the scope not following the adjustments, or randomly changing POI.

After taking everything apart - barrel off, rail off, scopes out of the rings, etc. - and not finding anything loose, I put it back together with the Burris scope and Proof barrel. Since it'd been completely disassembled, I figured I'd stick the bore sighter on it, and holy $hit I was about 3 clicks off the far left side of the windage travel. Swapped out the Burris for the Bushnell, and while it wasn't up against the edge of it's range, it was definitely way, way further over than I would like. Pulled the Proof barrel and put the Shilen back on. As mentioned earlier, it didn't point *quite* as far over, enough so that the Burris would actually work with it. Barely.

FWIW, both barrels have the nuts (red) loctite'd on, after setting the headspace with the appropriate gauges.

Unfortunately, I don't have a *shouldered* barrel handy for this action to test this out further. Might be able to borrow one from someone local.

I'm *pretty* sure the face of the receiver, the face of the nut(s), and both sides of the lug were as clean as I could get them. Not sure what else might be the culprit as far as pushing both barrels over that far. Or more specifically... I can think of a few things, but I'm really not liking the direction those thoughts are headed.

Curious what else folks here think might be the cause - or the solution.

 

[Huckmeat]

If both are off, maybe the action?

I've only used prefits on AIAX and defiance (no barrel nuts). All have been 1 mil of the prior barrel when I swap.

 

[oldrifleman]

Yeah that sounds like an action issue! I have 4 impacts with prefits and they are all really close.

 

[anon]

If the barrel nuts were not loctited, you could rotate the barrels 180º and see where they point.

Also, what was the vertical deviation?

Interesting coincidence, I just got back from shooting a new Origin with a new Shilen using a NSS ground nut. I did not mechanically zero the scope as I do sometimes when putting new stuff together. Now, I'm wondering.

 

[memilanuk]

If the barrel nuts were not loctited, you could rotate the barrels 180º and see where they point.

Trust me, I'm kicking myself over that right now

I mean, not really, in that having spent years and years faffing about with barrel nuts and go/no-gauges, having the nut 'fixed' once I have the headspace where *I* want it is very, very nice. It's just that in this particular situation, I literally just loctite'd the nut on the Proof CF barrel a couple days before I started clueing in as to what the problem might be. And when I realized I'd just cut off one of my avenues of troubleshooting... yes, there were a *lot* of bad words in the shop that night.

If push comes to shove, I guess I can always heat up the nut on the NSS/Shilen barrel and loose that one up. Not sure I want to do that with the Proof CF barrel until it's ready for permanent retirement - I've seen people mention that putting that kind of heat on/around the carbon fiber is a no-no?

A friend loaned me a shouldered pre-fit to test / see where it 'points', so I'll try that either tonight or tomorrow night, depending on how things go.

what was the vertical deviation?

Not that much. Or more specifically, not enough that I was worried about it, compared to the windage where I was right up against the edge of travel.

 

[supercorndogs]

If you could shim it out 1/4 turn you could see if the zero moves high or low. If it stays way to the side it's probably the action. With two barrels pointing off the same way, it seems that way anyway.

 

[supercorndogs]

Loctite is no problem either, just put some heat to it. It will come loose.

 

[Huckmeat]

Hit the nut and steel on the proof with loctite but don't get crazy with it, the CF will be fine in my experience.

 

[memilanuk]

Well... nuts.

Got home, took the gun apart, pulled the NSS/Shilen barrel off, put the loaner shouldered pre-fit barrel on, put everything back together and... it's still pointing way the heck off to one side.

Both scopes are pointing pretty much the same place as they were on the NSS/Shilen barrel - the Burris XTR III is just off the left edge of travel, the Bushnell XRS ii is way over, but not butted up against the edge. The difference seems to be that the XRS has two full revolutions of windage (20 mil), where the Burris has only one revolution (10 mil)* - at least at this point in the field, sitting on a 20 moa rail.

* I know their website says 15 mil, but I'm getting a couple clicks over exactly one revolution, so...

Also, I checked the lug real quick with a micrometer; it's within a tenth (0.2500-0.2501") all the way around the hoop. I guess it could still not be 'flat', but I'm not really equipped to measure that. Beyond that... it sure seems like it's got to be in the action somewhere

I'll reach out to Zermatt and see what they say, but at this point, for an action purchased in late 2018 / early 2019 I'm not really sure what to expect.

Might just be time to put it back the way it was Originally (pun intended!), with the Proof CF 6.5CM barrel and the Bushnell XRSii 4.5-30x with its gobs of windage, and just leave it alone. Everything was fine (ie blissfully ignorant) until I tried changing the scope.

 

[anon]

I counted the clicks to each side on my scope, old Leupold VXIII 6.5-20 LRT, it is 5 moa off center when zeroed.

 

[memilanuk]

This is a little more than that... but it does raise an interesting question: what's considered reasonable, and what's considered 'too much'?

I ask because I have a Solus on order, and you can be *very* sure that I will be paying closer attention to this sort of thing when it gets in.

 

[ShtrRdy]

This probably doesn't apply but I'll throw it out there just in case. I bought a benchrest rifle off a guy and at some point realized the scope windage was a few clicks off one of the extreme endpoints. To make a long story short, it was the two-piece rings that were the problem.

 

[LR1845]

@memilanuk This is Ray with Zermatt hes a good dude and I am pretty sure if its an action issue he will get you squared away @Zermatt Arms
I had an issue with a RimX action and Ray got me taken care of in a week, I can't say enough good about Ray and his team.

Also like @ShtrRdy said if you haven't tried swapping rings/mount you may want to. I got a smoken deal on a vortex scope in a warren mount off another site...long story short...windage bottomed out left and still had to hold 5 more mils to get on paper...checked the tracking and the reticle moved so threw it in a set of rings and was 2/10s left of center of windage adjustment...then I knew why it was such a god deal.

 

[Char'ed Cuterie]

Is there any chance you have another complete set of Origin optic rail and rings you can try? If something happened to the rail or its screws during the work, even though you've re-torqued it, it might be pointing off to one side or another. Same story with the rings - if you've swapped scopes but not yet swapped rings, could easily be that the rings got damaged somehow along the way.

Certainly let Zermatt take a look at it if they offer to, but if you have another complete set of rail/rings, could be an easy thing to rule out before shipping the action and waiting.

 

[memilanuk]

The XRSii is in Seekins 34mm rings; the XTRiii is in Vortex Precision Matched 34 mm rings (afaik, made for Vortex by Seekins). Somehow the odds of both of them pointing the same direction, the same amount seems... low. I guess I could flip one set around and see if they point back to center, or off to the right. Could it be that easy? God, that would be nice for a change!

The rail is the Origin pinned rail, so I don't really have another pinned rail (99% of everything else in the shop still fits a Savage of some flavor) to test against.

 

[Char'ed Cuterie]

Ok, good info. That seems to be a good alibi for your rings... but does make me start to wonder about that optic rail. I know you removed and re-torqued it, I'm not suggesting it's loose, I'm just worried some part of that system took some damage somehow.

Honestly, if you don't have another rail, it almost doesn't matter if it's the rail or some other part of the action that's not happy. I'd let Zermatt take a look for you and see if they can help.

 

[memilanuk]

The rail was never touched from the time I got the action and put everything together, until recently, when I finally tore everything apart and removed and checked every fastener trying to figure out WTF was going on. So if there was a problem with the rail (or action), it was there before the last few iterations of scope/barrel swaps. There were a time or two, looking back at my notes, that I had to put more work than expected into sighting in the gun when changing barrels/scopes, having to resort to dirt berm impacts to get on paper because it was pointing way off, that sort of thing. Wasn't until I started running out of adjustment, or more specifically, getting erratic movements and/or POI shifts that I started questioning what was going on. Which started this whole trip down the rabbit hole...

 

[6brshooter]

A simple fix would be some Burris rings with the posi alignment sleeves in them. Offset them to gain your windage back.

 

[spife7980]

What stock/chassis is it in?
Can you see if the barrel is evenly spaced in that channel and pointing true and straight?
It’s not free floated and all that jazz, right?
(Assuming it wasn’t custom sanded to fit making centerline determination not possible)
Triggers not impinging and rotating/lifting the action on the stock?

 

[kthomas]

Well... nuts.

Got home, took the gun apart, pulled the NSS/Shilen barrel off, put the loaner shouldered pre-fit barrel on, put everything back together and... it's still pointing way the heck off to one side.

Both scopes are pointing pretty much the same place as they were on the NSS/Shilen barrel - the Burris XTR III is just off the left edge of travel, the Bushnell XRS ii is way over, but not butted up against the edge. The difference seems to be that the XRS has two full revolutions of windage (20 mil), where the Burris has only one revolution (10 mil)* - at least at this point in the field, sitting on a 20 moa rail.

* I know their website says 15 mil, but I'm getting a couple clicks over exactly one revolution, so...

Also, I checked the lug real quick with a micrometer; it's within a tenth (0.2500-0.2501") all the way around the hoop. I guess it could still not be 'flat', but I'm not really equipped to measure that. Beyond that... it sure seems like it's got to be in the action somewhere

I'll reach out to Zermatt and see what they say, but at this point, for an action purchased in late 2018 / early 2019 I'm not really sure what to expect.

Might just be time to put it back the way it was Originally (pun intended!), with the Proof CF 6.5CM barrel and the Bushnell XRSii 4.5-30x with its gobs of windage, and just leave it alone. Everything was fine (ie blissfully ignorant) until I tried changing the scope.

@Zermatt Arms will get you squared away if the issue is on their end. I wouldn't be concerned about that.

 

[BuildingConceptsllc]

@Zermatt Arms will get you squared away if the issue is on their end. I wouldn't be concerned about that.

If, the issue is in the action I agree, they will take care of it. They are fantastic. I'd flip the front and back ring 180 degrees and try it, and then swap the front and back rings, then flip 180 degrees one ring at a time and try that as well.

 

[memilanuk]

What stock/chassis is it in?

McMillan A6 adjustable PRS

Can you see if the barrel is evenly spaced in that channel and pointing true and straight?

The barrel looks generally centered in the channel. Definitely not touching on either side; I can take a 3x5 note card wrap it around the barrel and run it all the way down to the barrel nut with no interference.

It’s not free floated and all that jazz, right?
(Assuming it wasn’t custom sanded to fit making centerline determination not possible)

Not sure what you're asking here.

Triggers not impinging and rotating/lifting the action on the stock?

The barreled action drops in and out of the stock without binding.

 

[anon]

Have you assembled it with the lug in both possible orientations? Or, does the lug mic the same dimension side to side?

 

[memilanuk]

does it mic the same dimension side to side?

Yes

 

[6brshooter]

I've got an origin and I like it. Having said that, the chances of having 2 crooked barrel, or 2 crooked nuts, or 2 sets of bad rings is pretty small. I was always led to believe that tolerance in thread fitment will allow action/lug/barrel shoulder square-ness to keep things straight. If both barrels are crooked in same direction, makes it hard to blame 2 things, vs the 1 action.

 

[308pirate]

Well... nuts.

Got home, took the gun apart, pulled the NSS/Shilen barrel off, put the loaner shouldered pre-fit barrel on, put everything back together and... it's still pointing way the heck off to one side.

Both scopes are pointing pretty much the same place as they were on the NSS/Shilen barrel - the Burris XTR III is just off the left edge of travel, the Bushnell XRS ii is way over, but not butted up against the edge. The difference seems to be that the XRS has two full revolutions of windage (20 mil), where the Burris has only one revolution (10 mil)* - at least at this point in the field, sitting on a 20 moa rail.

* I know their website says 15 mil, but I'm getting a couple clicks over exactly one revolution, so...

Also, I checked the lug real quick with a micrometer; it's within a tenth (0.2500-0.2501") all the way around the hoop. I guess it could still not be 'flat', but I'm not really equipped to measure that. Beyond that... it sure seems like it's got to be in the action somewhere

I'll reach out to Zermatt and see what they say, but at this point, for an action purchased in late 2018 / early 2019 I'm not really sure what to expect.

Might just be time to put it back the way it was Originally (pun intended!), with the Proof CF 6.5CM barrel and the Bushnell XRSii 4.5-30x with its gobs of windage, and just leave it alone. Everything was fine (ie blissfully ignorant) until I tried changing the scope.

Quit wasting time. The front face of the action is not perpendicular to the centerline datum.

Get it faced so that it becomes perpendicular. Pay what you need to pay.

 

[memilanuk]

Get it faced so that it becomes perpendicular.

Not gonna lie... that thought has been percolating through my head the last few days.

The question in my mind is "what will that do to it's ability to take pre-fit barrels?" Better? Worse?

 

[JR1200W3]

Not gonna lie... that thought has been percolating through my head the last few days.

The question in my mind is "what will that do to it's ability to take pre-fit barrels?" Better? Worse?

I've got a spare Origin scope rail laying on the bench I could send out to you.

 

[JR1200W3]

I have a wall of barrels for two TL3 s, an AI, a Tikka T3, and two Origins. The furthest offset I've had is 2.3 mrad. That's 23 total barrels

 

[308pirate]

Not gonna lie... that thought has been percolating through my head the last few days.

The question in my mind is "what will that do to it's ability to take pre-fit barrels?" Better? Worse?

That depends entirely on face runout because that will tell how much length needs to come off the face from the high point to square it up. And it's extremely likely that you don't have an action fixture that you can use to rotate it about centerline to measure it.

Your best bet is to send it off and accept the fact that you might be limited to nut prefits from then on.

 

[JR1200W3]

Why wouldn't you just send it back to Zermatt?

 

[memilanuk]

Why wouldn't you just send it back to Zermatt?

That's plan 'A'

 

[JR1200W3]

As soon as you have some 3rd party cut on it you eliminate any culpability of Zermatts part. And Zermatt has some of the best customer service in the industry. Just let them look at it.

 

[BuildingConceptsllc]

That's plan 'A'

Call Ray tomorrow before you do anything else. My experience as well as countless others is extremely great with Zermatt and Ray.

 

[oldrifleman]

Call Ray tomorrow before you do anything else. My experience as well as countless others is extremely great with Zermatt and Ray.

Not sure why anyone would not make that plan A and B, C, D ect. Zermatt does have a great rep for customer service, they have earned it, take advantage of it.