300NM/300LMI/33XC?

[MagnumManiac]

G'day all,
I am having a conundrum that I cannot persuade myself what direction to go.
I am re-barreling my custom 338-416 Rigby Improved in the new year. I got an awesome deal on 2 blanks in unfinished length of 34", both are 1:8.5" twist and should finish at 32" minimum.
So, the other barrel is going to be put on a different rifle. The action has already been sourced and chosen, it's a Borden.
So my question is what cartridge will benefit me the most.
I do not care if I end up at a single shot, what I really want to know is if the 33XC really is that much faster/efficient over either of the 33Norma Mag or 338 Lapua Improved.
The 33XC is already at the same level as my own custom 338-416 Rigby Improved, so I know what to expect with that, but unsure where to go from here.
Your opine is very welcome, even if you want to steer me into a repeater, which the action currently will be setup for.

Cheers.

 

[FEENIX]

The XC is a lot longer than the LM (https://www.petersoncartridge.com/t...november/peterson-cartridge-introduces-33-xc/) and would make a pretty bad arse .33 cannon.

The 33XC (eXtra Capacity) has (140 gr of H 2 O capacity) while approaching 130 grains of useable powder capacity yet leaving the .393" neck unfilled (for bullet seating as it should be) – depending on the powder density and drop-tube length. Both the 33XC and 37CXC are based off of a .580" bolt head.

 

[adam32+P]

Don't overlook the Lazzeroni Titan...

 

[MagnumManiac]

The XC is a lot longer than the LM and would make a pretty bad arse .33 cannon.

I am actually slightly ahead of the XC with my own designed 338-416 Rigby Improved….unfortunately I made a bad choice on throat length with the original reamer, this has been revised and a new reamer made. I get about 3g more capacity than the XC as it is now.
I realise the differences in case length, but am wondering if there is an efficiency deficit going with the XC, maybe the smaller fatter cases are where it's at?
I peak at 3200fps with a 323g HBN coated CNC turned solid.
It gets about the same with most 300g pills too.
Have been using the 265g ABLR due to the barrel being very tired and the throat looks like a dried lake bed…LOL.

Cheers.

 

[MagnumManiac]

Don't overlook the Lazzeroni Titan...

Without export/import permits, I cannot get Lazzeroni brass here…..so that's out of my reach. I could make it I guess if I really had to.

Cheers.

 

[FEENIX]

I am actually slightly ahead of the XC with my own designed 338-416 Rigby Improved….unfortunately I made a bad choice on throat length with the original reamer, this has been revised and a new reamer made. I get about 3g more capacity than the XC as it is now.
I realise the differences in case length, but am wondering if there is an efficiency deficit going with the XC, maybe the smaller fatter cases are where it's at?
I peak at 3200fps with a 323g HBN coated CNC turned solid.
It gets about the same with most 300g pills too.
Have been using the 265g ABLR due to the barrel being very tired and the throat looks like a dried lake bed…LOL.

Cheers.

Stay 338-416 Rigby and make a wiser choice on throat this time. LL, sorry mate, I couldn't resist. My gunsmith loves his 33XC.