.284 / 6x47 Switch Barrel Build

[walkabout]

We have just finished the first loads through this FMJ Firearms custom build we finished last week.
This is a switch barrel build, using shouldered Bartlein Barrels with flats milled near the muzzle for torquing.
In .284 Win & 6 x 47 Lapua, with a 300 Norma Barrel looming. 
Bighorn TL3 Long Action
Bartlein Barrels
XLR Industries Evolution Chassis
March 5-40x52 Scope
Tier One scope mount
Tier One Moderator
Cerakoted in a 3 colour camo.
First groups were very encouraging.
Another near identical build is in progress.

 

[shooter83]

Beautiful. Love the xlr chassis system. I have the element and absolutely love it. 1/4moa all day long without the heft you get with AICS.

[silent_varmintor]

that is one beautiful rifle, i really do like this chassis system a lot.

[Hobbit]

What a great set up .... and action specifically

I am interested in a multi calibre rifle in Long action built around a Big Horn and probably a PSE stock as a lighter weight option

Can I ask the following:

1, How easy is the barrel switch?? I have an AXMC and even with the 300 WM to 308 it is super easy, I use a cyclist torque wrench to be exact with the barrel pinch bolt but it is the work of minutes with no other tools and the mag housing insert is beautifully made and easy to use - do you need a vice for the Big Horn?

2, How do the magazines and feeding work in the action - 300 Norma Mag to 6x47 is superb flexibility but on top of the bolt head with what do you need to do with the mags/ mag housing

Thank you

[baldie]

I don't believe Bighorn do a .338 bolt head ?

Thats what the .300 Norma uses.

Paddy would know.

Just checked, the biggest they do is magnum [ie .300 win mag/7mm rem mag etc ]

didn't think they did. Its only a .700 diameter bolt. Bit weedy for a lap mag sized head.

[Hobbit]

On 10/12/2018 at 1:08 PM, walkabout said:

We have just finished the first loads through this FMJ Firearms custom build we finished last week.
This is a switch barrel build, using shouldered Bartlein Barrels with flats milled near the muzzle for torquing.
In .284 Win & 6 x 47 Lapua, with a 300 Norma Barrel looming. 
Bighorn TL3 Long Action
Bartlein Barrels
XLR Industries Evolution Chassis
March 5-40x52 Scope
Tier One scope mount
Tier One Moderator
Cerakoted in a 3 colour camo.
First groups were very encouraging.
Another near identical build is in progress.

 

I may be mistaken but thought the 300 Norma used a 338 LP case

[Hobbit]

Either way would be good to hear from someone on the ease of barrel change and mag length/feeding qestions

thank you

 

[baldie]

The .300 norma magnum is a .338 LM based cartridge. or .416 Rigby, before the real pedants kick in.

Barrel changes are simple on the bighorns. i do mine in the shop, but it would be no problem to do them with a Davidson type barrel vice fixed to whatever was handy.

Bighorn even do their own action wrench which is rear entry, and clears the ejector lug. i have them in stock.

Bighorns feed as slick as snot. They are controlled round feed.

[Hobbit]

Very helpful - thank you

if the barrels in question have been custom fitted to the specific action and head spaced in this process can you, after this process, continue to swap out these barrels without recourse to head space gauges?

[Hobbit]

I saw this for the proof research switch barrel rifle - quite a palaver compared to the AXMC - which I am increasingly appreciating

Do you need to change the bottom metal on the Bighorn?? are there any implications for what you can do with bedding on the TL3? does it need to come out of the stock?

 

[baldie]

You can only realistically run cartridges in the magazines they were broadly designed for, eg short action and long action in their respective mags.

I would think there is some crossover, as in the Gun of Walkabout's as pictured here.

I'm sure he will tell us, but the .284 and also a 6x 47 should be able to both feed from a l/a 300wm magazine, with suitable lip manipulation.

much past that, eg a 300 norma from a 338LM mag, and you wouldn't get a 308 width case to work. You would then need different magwells/bottom metals etc.

The TL3 works as a conventionally bedded switch barrel, just fine. The action face is quite large in diameter, so a decent diameter blank can be used, which gives a good wide shoulder. Providing this shoulder is cut squarely and very cleanly , there  are usually no headspace problems, providing the headspace hasn't been cut stupidly tight, or stupidly slack.

The video shows the savage barrel nut system in use, and its a good system.

Using a gunsmith headspaced barrel does away with that, you simply screw them on and off, and 60-70 ft/lbs would be plenty with a well shouldered barrel, allowing easy non Herculean effort required in the field.

The use of a rear entry wrench negates stock removal completely.

[Hobbit]

Extremely helpful, thank you!

[Catch-22]

Baldie is right with needing seperate SA and LA lower units if wanting to run something long like a .300NM and shorter, like a 6x47.

Take a look at the Eliseo RTM chassis systems. I built mine on one for this very reason. I literally unscrew the front action screw and I can swap the lower unit from SA to LA. At the same time I loosen 4 bolts holding the foreend hand guard to expose the freeloating barrel, stick it in a barrel vice, place an action wrench up the backend and hey presto...barrel off. Then same in reverse. 

Granted it's not as quick as the AI quick change system but I have zero need to do a barrel swap in the field.

Overall it takes me about 5 mins in total to swap barrels, bolts and lowers.