Switch barrel build

I only have the Zues, but it is great!

dbow said:

I would like to build a personal version of a Barrett MRAD or AI AXSR. I would like to have 3 barrels, 338 Norma mag, 300 win mag, and a 6.5/6mm variant. I plan to use a Cadex lite competition chassis.

Right now I’m thinking a Terminus Zeus or BAT HR with a WTO switch lug. I know the Zeus QC would eliminate the need for a switch lug but I’m curious if the BAT may be more suited for the large caliber use?

For those who have used both the Zeus QC and the WTO lug, which do you prefer?

If I understand correctly the WTO may add a step when it comes to barrels due to a special cut for the lug?

What am I missing that might cause headaches?

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The special cut for the WTO lug is a non-issue for any gunsmith cutting the barrels on a CNC lathe.

I've done essentially what you're talking about using most of the actions on the market for customers that get an action vise and a barrel wrench. I was kicking around the idea of doing essentially the LaRue approach that is on the Siete since it's dead simple and it uses solid engineering principles. I'm personally not a fan of the idea that set screws are being driven into the shank of the barrel... that's a rabbit hole that I've gone down in posts on this forum previously so I won't make others read my diatribe again here.

The WTO works well enough from what I saw when we did a batch of rifle barrels for a shop in TX several years ago, though I have no personal experience with it on my own rifles.

On my own rifles: I just use an action wrench and barrel vise.

bohem said:

The special cut for the WTO lug is a non-issue for any gunsmith cutting the barrels on a CNC lathe.

I've done essentially what you're talking about using most of the actions on the market for customers that get an action vise and a barrel wrench. I was kicking around the idea of doing essentially the LaRue approach that is on the Siete since it's dead simple and it uses solid engineering principles. I'm personally not a fan of the idea that set screws are being driven into the shank of the barrel... that's a rabbit hole that I've gone down in posts on this forum previously so I won't make others read my diatribe again here.

The WTO works well enough from what I saw when we did a batch of rifle barrels for a shop in TX several years ago, though I have no personal experience with it on my own rifles.

On my own rifles: I just use an action wrench and barrel vise.

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Yeah they work Really well, my Impacts are spectacular. That said I personally hate removing barreled actions and scopes just to change a barrel. especially when it has to happen frequently ( my Zues is a 22 Creed, barrel life is about 650-700 rounds). Set screws are fine, AI has been doing it for decades and been quite successful

I was a massive fan (still am) of the whole AI QC setup until i bought a barrel vise. I've never gotten out a stopwatch but I can swap barrels on my impacts pretty darn fast. Fast enough to really not care about the QC ability anymore. Sometimes i wonder if torquing my AI stuff would be a more consistent approach rather than grabbing it with my paws and saying yep! Good nuff!

I believe I read on here that it was recommended to use a full thread (not QC) barrel for the Lapua and Norma Mag cartridges on the Terminus QC, but it was a few years ago.

300WM and below were no problem. Call Joel Russo and ask. He's a stand up guy.

oldrifleman said:

Yeah they work Really well, my Impacts are spectacular. That said I personally hate removing barreled actions and scopes just to change a barrel. especially when it has to happen frequently ( my Zues is a 22 Creed, barrel life is about 650-700 rounds). Set screws are fine, AI has been doing it for decades and been quite successful

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Why are you removing the scope to remove the barrel?

WB300 said:

I believe I read on here that it was recommended to use a full thread (not QC) barrel for the Lapua and Norma Mag cartridges on the Terminus QC, but it was a few years ago.

300WM and below were no problem. Call Joel Russo and ask. He's a stand up guy.

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One could also put wrench flats on the end of the barrel, in honor of Reubenski

kthomas said:

Why are you removing the scope to remove the barrel?

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I can’t spin the action with the scope (ZCO 8-40) mounted without hitting the barrel vice. The only way would be to grip the barrel way down on the tapered section and I can’t get a great grip there.

oldrifleman said:

I can’t spin the action with the scope (ZCO 8-40) mounted without hitting the barrel vice. The only way would be to grip the barrel way down on the tapered section and I can’t get a great grip there.

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Ah gotcha. That would be annoying.

I would skip the wto. You’ll need to modify the chassis for it and some people experience issues with repeatability and there’s really no need for it

oldrifleman said:

Yeah they work Really well, my Impacts are spectacular. That said I personally hate removing barreled actions and scopes just to change a barrel. especially when it has to happen frequently ( my Zues is a 22 Creed, barrel life is about 650-700 rounds). Set screws are fine, AI has been doing it for decades and been quite successful

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Respectfully, I disagree.

AI does not use set screws into the barrel tenon joint itself. AI uses a collapsing diameter run down using a crossbolt that pulls ears shut in the tenon effectively pre-loading the tenon joint and acting like there is torque imparted to the joint. The screws do not impinge the barrel. The function is quite different. We've seen enough problems with otherwise perfectly good rifle barrels that we won't warranty a barrel if it proves that the set screws were the issue and it's been the issue every time except once. MPA dropped it from their rifles too, same reason.

This is the method I was talking about above:



I've been using ARC's rings and mounts since 2010 and the zero repeatability is best in class, I even wrote an article on it back in 2011 and used 2 scopes shooting the same rifle at 400 yards to show the performance. On and off with a scope is a non issue to me entirely.

kthomas said:

One could also put wrench flats on the end of the barrel, in honor of Reubenski

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Those work great. I have seen the light and have started doing them on personal barrels.

I’ve never had a problem with my zues. I’ve run 6.5cm, 6GT, and 300wsm with it. The set screws are only at 10-15in lbs. Probably easier to just get prefits for a zues than do the WTO route.

So I haven't seen anyone mention magazines yet... has that been solved to get reliable feeding of short action cartridges in LA R700 clones?

That would be the biggest stumbling block in my experience, since most people put a higher round count on their short action barrels than they do their big dong magnums.

bohem said:

Respectfully, I disagree.

AI does not use set screws into the barrel tenon joint itself. AI uses a collapsing diameter run down using a crossbolt that pulls ears shut in the tenon effectively pre-loading the tenon joint and acting like there is torque imparted to the joint. The screws do not impinge the barrel. The function is quite different. We've seen enough problems with otherwise perfectly good rifle barrels that we won't warranty a barrel if it proves that the set screws were the issue and it's been the issue every time except once. MPA dropped it from their rifles too, same reason.

This is the method I was talking about above:



I've been using ARC's rings and mounts since 2010 and the zero repeatability is best in class, I even wrote an article on it back in 2011 and used 2 scopes shooting the same rifle at 400 yards to show the performance. On and off with a scope is a non issue to me entirely.



Those work great. I have seen the light and have started doing them on personal barrels.

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We will respectfully agree to disagree. I find it interesting from a materials perspective that a pair of set screws of such small diameter installed using 10 in/lb could affect a thick barrel tenon. But they are a very well respected action that sells faster than they can make them so by all means don’t buy one

dbow said:

I would like to build a personal version of a Barrett MRAD or AI AXSR. I would like to have 3 barrels, 338 Norma mag, 300 win mag, and a 6.5/6mm variant. I plan to use a Cadex lite competition chassis.

Right now I’m thinking a Terminus Zeus or BAT HR with a WTO switch lug. I know the Zeus QC would eliminate the need for a switch lug but I’m curious if the BAT may be more suited for the large caliber use?

For those who have used both the Zeus QC and the WTO lug, which do you prefer?

If I understand correctly the WTO may add a step when it comes to barrels due to a special cut for the lug?

What am I missing that might cause headaches?

Click to expand...

The recommendation on the zues for a norma mag is a threaded tennon per a gunsmith I asked about one. Threaded vs QC is actually very minor so just get the threaded tennon.

oldrifleman said:

We will respectfully agree to disagree. I find it interesting from a materials perspective that a pair of set screws of such small diameter installed using 10 in/lb could affect a thick barrel tenon. But they are a very well respected action that sells faster than they can make them so by all means don’t buy one

Click to expand...

I don't think the point is that the set screw "affects" the barrel tennon. I believe the point being made is that little set screw providing one small pin point of pressure on a tennon is not enough to adequately retain a barrels zero for sustained precision use, especially in adverse conditions/use.

kthomas said:

I don't think the point is that the set screw "affects" the barrel tennon. I believe the point being made is that little set screw providing one small pin point of pressure on a tennon is not enough to adequately retain a barrels zero for sustained precision use, especially in adverse conditions/use.

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Is the OP going to war with Iran? On my zues I give last little bit of threads a pop when I tighten it and it’s not coming off without a strap wrench.

kthomas said:

I don't think the point is that the set screw "affects" the barrel tennon. I believe the point being made is that little set screw providing one small pin point of pressure on a tennon is not enough to adequately retain a barrels zero for sustained precision use, especially in adverse conditions/use.

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The set screws ( 2 of them) provide a 2 points of resistance that support the larger source of resistance, the barrel shoulder mating to the action. I can’t speak for anyone else but mine had a decent level of friction when I “ hand” tighten the barrel. So,Is it TacOps tight, nah, but when you drive home two additional point sources of friction, well I know mine won’t go anywhere. Now would use mine in a bench rest competition, nah, but it will do really well for itself. That assumes you use quality ammo and a decent barrel to begin with.

I personally hate set screws in almost any application, I've had them fail too many times.

kthomas said:

I personally hate set screws in almost any application, I've had them fail too many times.

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Yeah me too but I check them each range trip. I hate pulling the action from the stock a couple of times a year more. All my other actions are Impacts. I just love hot rodding the 22 creed enough to tolerate them ( never found them loose yet)

Curve ball: I shot my AI AT hand tight without tightening the set screw (clamp) at all and saw no issue on target. Sample size was only 10 rounds on a dot drill.

Is it recommended? No. Do I recommend it? No. Was the barrel still miserable to remove without sticking a wrench on the flats? Yes.

Idk, ive experimented with the switch barrel stuff since I got my first DT SRS a decade ago. Any system that torques against the shoulder can be reliable and consistent. No set screws needed...the question just becomes how much torque on the barrel, and how easy you want it to be to remove the barrel. The set screws are nice insurance if you need to jump out of an airplane though.

I won't be able to test my Zeus until spring at this rate, but I have a feeling I will see similar results: set screws are nice insurance, but torque on the barrel gives us our performance. Curious how well it applies with the short QC tenon.

I've tested 20, 30, and 40 ft lbs of torque using wrench flats. I saw no difference in Poi or accuracy. I no longer use a torque wrench. I just use a crescent wrench.

OP, what if I told there was a super sneaky squirrel, high-speed operator gun that just used wrench flats. It was developed by a semi-govermental think tank called TSWG CTTSO as a proof of concept rifle. Called the CSR. Compact Sniper Rifle. It could be disassembled in seconds and butt-smuggled in a low vis bag but re-assembled faster than an AI quick change. It used a 14.5", 1:8" 308 barrel for dual supers and subs capability. It was made in three variations: the Remington MSR(right before the PSR submission went it's up), the prototype to the Predatobr with it's quick change barrel config(predecessor of the Larues MRGG), and Surgeon (when it was still owned by Preston) developed the best/ third version using the KISS principle. It was just a 14.5" barrel with wrench flats fitted for a 591 action in a Remington RACs chassis that was modified so the front fore end could be disassembled as well.

This is what inspired me for my switch barrel journey. I now just use wrench flats to swap barrels on two TL3's, two Origins, and a Tikka T3. I had an AI...and sold it. Torquing the barrel, even just a little, is superior to add-on clamping techniques. And here's the kicker....it doesn't cost you a thing. Try it out, if you don't like it...by all means buy some gadget. I will say, if you think you need some sort of complex method to swap barrel, the AI method is far, far superior to it's competitors.

The issue is how much smacking around can your barrel withstand. It's pretty common to smack your barrel against a barricade. This lateral shock was wreaking havoc on the BARLOC. It was in vogue a couple of years ago to test your POI shift when your barrel took a smack from something. Dudes were using a 2x4 to smack the barrel and checking for zero shifts. This is where the clamping versions where proving less robust. A torqued barrel is more robust.

Also, I think bedding your action helps tremendously is creating zero retention resiliency.. it's not an accuracy thing. It's about the firm fit of the action beyond just two bolts pulling the action down into a V block surface.