Pre-fit barrel alignment

memilanuk · Nov 30, 2024

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 · Nov 30, 2024

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 · Nov 30, 2024

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

anon · Nov 30, 2024

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 · Nov 30, 2024

anon said:
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 · Nov 30, 2024

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 · Nov 30, 2024

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

Huckmeat · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

@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 · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

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 · Dec 1, 2024

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

spife7980 · Dec 1, 2024

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 · Dec 1, 2024

memilanuk said:
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 · Dec 1, 2024

kthomas said:
@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 · Dec 1, 2024

spife7980 said:
What stock/chassis is it in?

McMillan A6 adjustable PRS

spife7980 said:
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.

spife7980 said:
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.

spife7980 said:
Triggers not impinging and rotating/lifting the action on the stock?

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

anon · Dec 1, 2024

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

memilanuk · Dec 1, 2024

anon said:
does it mic the same dimension side to side?

Yes

6brshooter · Dec 1, 2024

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 · Dec 1, 2024

memilanuk said:
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 · Dec 1, 2024

308pirate said:
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 · Dec 1, 2024

memilanuk said:
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 · Dec 1, 2024

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 · Dec 1, 2024

memilanuk said:
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 · Dec 1, 2024

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

memilanuk · Dec 1, 2024

JR1200W3 said:
Why wouldn't you just send it back to Zermatt?

That's plan 'A'

JR1200W3 · Dec 1, 2024

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 · Dec 1, 2024

memilanuk said:
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 · Dec 1, 2024

BuildingConceptsllc said:
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.

Matagorda308 · Wednesday at 12:23 PM

Bump for update?

memilanuk · Wednesday at 1:00 PM

Zermatt went thru the action pretty much the same day they got it on their end. From the emails and phone conversations, it sounds like they checked everything out; nothing was out of spec from normal. As an aside, they said it had one of the last few 'gen 1' bolts (whatever that means) so they updated the appropriate parts on that.

Still waiting for the action to get out of 'jail' back on this end. With the holidays... probably won't get it til after the first of the year.

When I get it back, I'm planning to mount up one or both of my nutted pre-fits (both have the nut loctite'd at this point) and check both scopes out again... but with the barrel in a vise, not in any stock. The original bedding job extended up around the barrel nut on the Proof CF barrel, and the current thought is that any change in the position of that nut from one mounting to the next, or to a different barrel nut (like on the NSS/Shilen barrel) might be enough to 'push' or tension things off to one side. Dunno, we'll see. Also, I now have another stock - KRG Bravo gen 2 - that is unbedded to drop the barreled action into and see if the 'problem' persists there.

And just to add another wrinkle to things... the old bore sighter / 'collimator' that I have gave me some weirdness on another gun - one where the barrel/action have never been apart, and I'm *pretty* sure the scope hasn't been off it either - but it was suddenly saying the scope needed dialed way off to one (the other) side. Usually that's mainly a matter of playing with how the spud sits in the muzzle, and getting it to behave consistently. It didn't seem to want to play nice this time, for whatever reason.

I'm sure there'll be a bunch of people that will jump on that and say "See? See? There's the problem all along!" To which I'd say... maybe. Just remember, this all *started* because I was trying to track down a *physical* problem with the gun not holding POA, and not tracking as expected. It was only *after* literally tearing the gun apart and not finding anything that the bore sighter came into play.

If anything... I'm starting to question the Burris XTRiii more than anything else. Things didn't immediately go to hell when I put it on with the NSS/Shilen .223 Rem barrel... but when I swapped the Proof CF 6.5CM barrel back in, and put that scope back on... things went down hill from there. But there remains the question of how/why two scopes and three barrels all 'appear' to point off to the one side, approximately the same amount.

Matagorda308 · Wednesday at 2:10 PM

Keep on keepin on until you figure it out. There are some experts and very good troubleshooters on here, just have to winnow through some BS to get to them. Sounds like you are on the right track. I’m interested in the outcome, not too proud to learn from others and I have several Origin and Solus actions.

I’ve run into issues so many times, I bought a fixed 10x scope and keep it in mounts just to isolate scope issues when troubleshooting rifles. Saves me a lot of headaches but I worked on a lot of rifles.

memilanuk · Wednesday at 2:17 PM

Funny you should mention that... I was thinking the other day that I still have my 'troubleshooter' scope somewhere in the back of a cabinet here somewhere. Laugh if you want, but it's an old SWFA fixed 16x scope that used to get pulled out when my 'good' scopes (Leupold, then later Nightforce) would act up on occasion. Might be time to dust that bad boy off again...

Matagorda308 · Wednesday at 2:17 PM

If you decide you need to move the locktited nuts on the carbon fiber barrel, I’ve used a paint strip gun to control the heat. I haven’t used it on CF. I would maybe consider using one of the big soldering iron “guns” and put the tip against the nut for better control to keep as much of the heat as possible in just the nut.
Good luck and update please when you figure out something.

Matagorda308 · Wednesday at 4:02 PM

I think you are on the right track. Using your head. Eliminate the variables one at a time.
Continue on down the line.

-Swap to the Bravo2 stock. Eliminates or confirms bedding around nut.

-Swap to 16x scope ,w rings hopefully, confirm or eliminate optics and rings.

Doesn’t have to be in that order, swap whichever is easiest first.

Additional-
Take your old scopes off the rifle. Place the objective flat against a mirror and shine a light on the mirror. Look inside, you will see the crosshair and a reflection shadow crosshair. Adjust the scope E & W knobs until the two meet and match. You are now optically centered. Remount the scope. You mentioned a vice, put the barreled action in a vise and bore sight on a target or landmark, check the scope POA keeping in mind the 20 moa rail. If it’s that far off to the side you should be able to see it at 100 yards or more. Repeat with the other scope?

If it’s off to the side, back the barrel and locktite nut off 180 degrees. Look again boresighting and see if there is a shift.

If all matches, put the barreled action and scope back in the original stock and bore sight again to repeat looking for side shift from the bedded nut or bedding job.

Hire a witch doctor.

Sheldon N · Thursday at 10:49 AM

My thought would be that it's far more likely that the pinned rail is out of alignment than there being something wrong with the action body. Machining a square face and square lugs on the action tube is a pretty simple task that is unlikely to go wrong in the CNC manufacturing process.

My guess is that there could be tolerance stacking with the pins for the rail, because those are multiple sets of holes drilled on each part that are supposed to align with the action body centerline. Trying another scope rail would be a good way to check for this.

memilanuk · Thursday at 11:03 AM

I believe they (Zermatt) checked the rail alignment also... actually I think their words were "the squareness of the rail on the receiver body".

But it's a good point, and if I don't find the solution otherwise I'll have to see about borrowing a rail from someone local to try out.

CK1.0 · Thursday at 11:20 AM

I’d pull your barreled-action and then reset it in the stock making sure that the lug is up against the back of the slot by bouncing it on the butt-pad on the floor a couple/few times. Once you are sure the action’s recoil lug is flat up against where it needs to be, torque your front action screw first, then the rear action screw… that could be all it is.

I little while back I thought I had a scope that wasn’t holding zero because my zero changed wildly between range trips, and then I remembered that I’d swapped barrels in a rush and probably just tightened the action screws in no particular order… once I reset my barreled action and made sure to make sure my recoil lug was seated properly and remembered to tighten the front action screw first, voila, problem solved (and I felt like a dumbass lol).

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Pre-fit barrel alignment

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