.375 Swiss

[EricB]

Hello again gentlemen, I thought I'd share a new project that I'm working on, and ask some advice. I'm building a safari style rifle out of a Swiss Schmidt Rubin G1911 action for my son as an heirloom piece, but it's going to be in .375 Swiss. (7.5x55 Swiss necked up to .375)
The caliber has already been done, albeit it's called .375-284, dies and a chamber reamer already exist. I've been doing some reading about it, seems like a nice little round.
What I'm wondering is, what would be the best twist rate for this? I'm leaning towards 10/1 but want to make sure before I buy a barrel, as well as a decent length.
Thanks in an advance for any info you have to share!

 

[matt85]

perhaps a twist rate similar to the 9.3x62? i should think your cartridge would be pretty similar, my CZ 550FS in 9.3x62 has a 1-14inch twist according to the website. it definitely depends on what bullet weights you plan on using.

-matt

 

[Adam S]

That sounds like a very cool project! I love Swiss rifles. I'm not trying to second guess you as I'm sure you know much more about it than I do, but what pressure does that cartridge run? I seem to remember reading to avoid shooting newer GP11 loads in a 1911 as it was designed for the relatively stronger K31 action.

 

[Advocatus Diaboli]

Hello again gentlemen, I thought I'd share a new project that I'm working on, and ask some advice. I'm building a safari style rifle out of a Swiss Schmidt Rubin G1911 action for my son as an heirloom piece, but it's going to be in .375 Swiss. (7.5x55 Swiss necked up to .375)
The caliber has already been done, albeit it's called .375-284, dies and a chamber reamer already exist. I've been doing some reading about it, seems like a nice little round.
What I'm wondering is, what would be the best twist rate for this? I'm leaning towards 10/1 but want to make sure before I buy a barrel, as well as a decent length.
Thanks in an advance for any info you have to share!

View attachment 199991 View attachment 199993

I'd call Dan Lilja (Google Lilja barrels). I've called him in the past and he's been extremely helpful with that type of advice.

 

[sestoppelman]

That sounds like a very cool project! I love Swiss rifles. I'm not trying to second guess you as I'm sure you know much more about it than I do, but what pressure does that cartridge run? I seem to remember reading to avoid shooting newer GP11 loads in a 1911 as it was designed for the relatively stronger K31 action.

I had the same thought immediately. The K31 is the stronger rifle.

 

[EricB]

I plan on using bullets around 270-300gr, and I thought about calling a barrel manufacturer,(Lilja is a good one) and asking what they'd recommend.

As for the G1911, it's made for GP11, so I'm not worried about the strength of the action for what I want to do. Yes, the K31 is stronger, but it has weird cuts in the back of the chamber that probably 95% of machinists won't want to mess with. The older rifles don't have this, and are easier to do. (Same as a Mauser, actually. Different thread pitch though)

The Swiss model 1889 is the one with the weak action, the locking lugs are all the way to the rear, whereas the 96/11 and G1911 have them further forward. (See pic above) I have 14 total of these rifles, I'm pretty well versed in them.

 

[EricB]

Oh, and the pressure of GP11 is 55,000psi, I plan on being under that by far, more on the lines of 48,000-50,000psi.

 

[Adam S]

Thanks for the information! I'm looking forward to seeing how it comes out!

 

[EricB]

Me too, working on the parts list right now, trying to find the right piece of wood for a price that won't break the bank. Already have an engraver on standby for when I'm ready for that stage.
When I'm done, I want it to look like this, minus the scope (express sights only) and no take down feature.

 

[Spooksar]

I have a K31 love the gun. Interesting project and cartridge, keep us posted

 

[EricB]

I'd be using a K31 if it wasn't for the weird cuts on the barrel for the bolt. It is definitely a stronger action. I do love my K31's!

 

[Dr Ray]

View attachment 200088 View attachment 200089 View attachment 200090 Me too, working on the parts list right now, trying to find the right piece of wood for a price that won't break the bank. Already have an engraver on standby for when I'm ready for that stage.
When I'm done, I want it to look like this, minus the scope (express sights only) and no take down feature.

Wow what a beautiful rifle - just admire the stock.