Custom rifle info

[W_Ellison2011]

So I figured I would reach out to the guys on this forum with experience in long range custom rifles. I recently decided the next rifle I am going to build will be chambered in .338 Extreme. Anybody have experience with this cartridge? Any pointers? I am looking at doing it on a savage 110 action with a lapua bolt face and a Krieger 338 barrel. Probably heavy varmint contour with a muzzle break 1:10 twist. Any info would be much appreciated!

[The scout]

You would be just fine with what you described. But benchmark makes very very accurate 338 barels

[Magnum_Willys]

Awesome setup no doubt.  Not sure a Lapua Improved mite not do what you want especially with the new Berger 329 grains

[yorketransport]

This could be a different version of the 338 extreme, but the one I’m familiar with is based on the 505 Gibbs/Cheytac case and won’t work on a Savage.

I have 2 guns chambered for a 338/408 improved variant (SnipeTac, Big Baer, Allen Mag, Rocket, Extreme or any other name for similar designs) and it’s an impressive round but very specialized.

[b23]

This could be a different version of the 338 extreme, but the one I’m familiar with is based on the 505 Gibbs/Cheytac case and won’t work on a Savage.

I have 2 guns chambered for a 338/408 improved variant (SnipeTac, Big Baer, Allen Mag, Rocket, Extreme or any other name for similar designs) and it’s an impressive round but very specialized.

York is correct and unless this is a different version, the 338 Xtreme will not work on a factory based action.

[h20hunter]

What is the advantage if the extreme  ( cue the mountain dew monster truck wheelie 😉) over a 338 lapua or similiar?

[yorketransport]

What is the advantage if the extreme  ( cue the mountain dew monster truck wheelie 😉) over a 338 lapua or similiar?

About 400 fps 

[BULLBLASTER]

What is the advantage if the extreme  ( cue the mountain dew monster truck wheelie 😉) over a 338 lapua or similiar?

About 400 fps 

So basically just a souped up 30-06? 

I’ve always been scared to shoot those big giant magnums... scared of the ballast a bit, but also scared it would ruin me and I’d have to have one! 

[h20hunter]

Just got to googling it.....holy moly thats a howitzer!

[CaNINE]

Is it safe or even physically possible to run this chambering on a savage action? I'd make sure to double and triple check before I pulled the trigger.  You will be generating some extreme pressures.

[W_Ellison2011]

Just got to googling it.....holy moly thats a howitzer!

Im wanting to build a rifle that is 100% capable of 2500+ yard shots. I have a spot in the mountains we ranged at 2670 yards. Really want to build the 338 extreme for that shot and for further possibly.

[W_Ellison2011]

This could be a different version of the 338 extreme, but the one I’m familiar with is based on the 505 Gibbs/Cheytac case and won’t work on a Savage.

I have 2 guns chambered for a 338/408 improved variant (SnipeTac, Big Baer, Allen Mag, Rocket, Extreme or any other name for similar designs) and it’s an impressive round but very specialized.

You are correct that its the same 338 extreme you are thinking of. I have a buddy who built a custom .50 cal out of a 110 action. 7mm rum case necked out and stuffed with a .50 cal barnes bullet. Lots of pressure. He thinks it will work for this but im not wanting to blow myself up lol! He is pushing a 647 gr barnes tsx at 2200-2300 fps. I have never built a rifle chambered for this big of cartridge. Hence why i am asking for other opinions such as yours. I am leaning towards your opinion on this btw.

[Stein]

Is that chart in inches?  As in, hold 100' high and 15' for wind?

[yorketransport]

What is the advantage if the extreme  ( cue the mountain dew monster truck wheelie 😉) over a 338 lapua or similiar?

About 400 fps 

So basically just a souped up 30-06? 

I’ve always been scared to shoot those big giant magnums... scared of the ballast a bit, but also scared it would ruin me and I’d have to have one! 

I hear the 6.5 Creedmoor is just as good. You can barely tell the two cases apart when you stand them side by side.

You are correct that its the same 338 extreme you are thinking of. I have a buddy who built a custom .50 cal out of a 110 action. 7mm rum case necked out and stuffed with a .50 cal barnes bullet. Lots of pressure. He thinks it will work for this but im not wanting to blow myself up lol! He is pushing a 647 gr barnes tsx at 2200-2300 fps. I have never built a rifle chambered for this big of cartridge. Hence why i am asking for other opinions such as yours. I am leaning towards your opinion on this btw.

The rim on a RUM is .540", the rim on a Lapua is .585", the rim on a CheyTac is .640". There isn't enough room to open up a Savage bolt face to even accept a .640" case head, let alone do it safely. Then you run into problems with the barrel tenon diameter and hoop strength, bolt thrust, and most importantly the issue of OAL. You can push a .540" case head pretty hard on a Savage action (I've certainly done that! ) but as case head diameter increases, bolt thrust goes up much faster since it's calculated using the square of the internal case head radius. As you increase your case head diameter in any given action you need to either reduce peak pressures or accept the fact that you're starting to chip away at the safety margin built into the strength of the action. I've personally witnessed measurable bolt lug setback on a Savage bolt head from a steady diet of over pressure loads while working with a wildcat to see just how much performance I could squeeze from a Savage action. I knew it was coming and was watching for it and taking regular measurements, most people don't do that though and can easily get into a lot of trouble.

In my 338/408 rifle (mine's technically a 338 Rocket/Big Baer) my standard load is a 300gr Berger OTM at 3170fps from a 30" barrel. I can crank them up about 75-100 fps faster but at the cost of accuracy and brass life. At 3500' elevation where I do most of my really long range shooting, this load goes subsonic at around 2400 yards. That hasn't stopped me from maintaining 1 MOA accuracy out to 2600 yards which is as good as I will every admit to shooting. The same load from my 20" barrel specialty pistol gives me a velocity of 2875fps which is right in line with what a 338 Edge or 338 Lapua will give with the right load/throat combo. This load will go subsonic at around 2150 yards under the same conditions. While I haven't spent as much time at 2600 yards with this gun, accuracy has still remained in the realm of 1 MOA at 2600 yards despite having gone subsonic 450 yard closer. I'd also look to a bullet heavier than the 265 that they normally push with the Xtreme. With that much case capacity you really need at least a 300gr bullet.

If you want to build something like the Xtreme then go for it, but do it right. It doesn't have to be that much more expensive than building a 338 Lapua with quality parts. I think I'm into my rifle about $2600 without the scope and it's all quality components assembled by a local smith.

Just shop smart and look for deals.

[W_Ellison2011]

What is the advantage if the extreme  ( cue the mountain dew monster truck wheelie 😉) over a 338 lapua or similiar?

About 400 fps 

So basically just a souped up 30-06? 

I’ve always been scared to shoot those big giant magnums... scared of the ballast a bit, but also scared it would ruin me and I’d have to have one! 

I hear the 6.5 Creedmoor is just as good. You can barely tell the two cases apart when you stand them side by side.

You are correct that its the same 338 extreme you are thinking of. I have a buddy who built a custom .50 cal out of a 110 action. 7mm rum case necked out and stuffed with a .50 cal barnes bullet. Lots of pressure. He thinks it will work for this but im not wanting to blow myself up lol! He is pushing a 647 gr barnes tsx at 2200-2300 fps. I have never built a rifle chambered for this big of cartridge. Hence why i am asking for other opinions such as yours. I am leaning towards your opinion on this btw.

The rim on a RUM is .540", the rim on a Lapua is .585", the rim on a CheyTac is .640". There isn't enough room to open up a Savage bolt face to even accept a .640" case head, let alone do it safely. Then you run into problems with the barrel tenon diameter and hoop strength, bolt thrust, and most importantly the issue of OAL. You can push a .540" case head pretty hard on a Savage action (I've certainly done that! ) but as case head diameter increases, bolt thrust goes up much faster since it's calculated using the square of the internal case head radius. As you increase your case head diameter in any given action you need to either reduce peak pressures or accept the fact that you're starting to chip away at the safety margin built into the strength of the action. I've personally witnessed measurable bolt lug setback on a Savage bolt head from a steady diet of over pressure loads while working with a wildcat to see just how much performance I could squeeze from a Savage action. I knew it was coming and was watching for it and taking regular measurements, most people don't do that though and can easily get into a lot of trouble.

In my 338/408 rifle (mine's technically a 338 Rocket/Big Baer) my standard load is a 300gr Berger OTM at 3170fps from a 30" barrel. I can crank them up about 75-100 fps faster but at the cost of accuracy and brass life. At 3500' elevation where I do most of my really long range shooting, this load goes subsonic at around 2400 yards. That hasn't stopped me from maintaining 1 MOA accuracy out to 2600 yards which is as good as I will every admit to shooting. The same load from my 20" barrel specialty pistol gives me a velocity of 2875fps which is right in line with what a 338 Edge or 338 Lapua will give with the right load/throat combo. This load will go subsonic at around 2150 yards under the same conditions. While I haven't spent as much time at 2600 yards with this gun, accuracy has still remained in the realm of 1 MOA at 2600 yards despite having gone subsonic 450 yard closer. I'd also look to a bullet heavier than the 265 that they normally push with the Xtreme. With that much case capacity you really need at least a 300gr bullet.

If you want to build something like the Xtreme then go for it, but do it right. It doesn't have to be that much more expensive than building a 338 Lapua with quality parts. I think I'm into my rifle about $2600 without the scope and it's all quality components assembled by a local smith.

Just shop smart and look for deals.

So what action would you suggest? Your rifle is beautiful btw. Also I will be building this rifle with a buddy of mine. No gunsmith required for us luckily. My issue is beyond the realm of savage and Remington actions... I have very little experience with customizing. I just finished building a custom 300 win mag but that's going to be a competition rifle and fun for 1,000 yards and a mile. I really want something that I can push a lot further for fun.