7-300 coal and chambering question

[Cwballistics]

Hello,
New here. Trying to do some research on a build I am thinking about doing this next year. Main goal is 195 Berger out of 300 or possible 7stw with mausenfield or ARC Nucleus. I haven’t done a custom bolt action before, so when trying to discuss chambering with a few builders, I feel like I’m in a chicken and egg situation. Or maybe the cart in the horse. One is telling me to get the cartridge worked out and chamber to it. The other is basically saying pick a safe length and work out freebore with seating depth. If you don’t know what jump a bullet likes, where do you start the freebore discussion? Also, anybody have any experience with these actions and extended length cartridges. Anyone care to share their oal with the 195s in either of these rounds. Looks like you’ll have a great board here. Thanks

 

[SAP]

Bob Wolfe would probably have some insight. His father designed the 7-300 weatherby. I own one and I was shooting 180 Bergers.

 

[KMart]

Hello,
New here. If you don’t know what jump a bullet likes, where do you start the freebore discussion? Also, anybody have any experience with these actions and extended length cartridges. Anyone care to share their oal with the 195s in either of these rounds. Looks like you’ll have a great board here. Thanks

You are in a conundrum. Just because a bullet likes a jump of .015" in my barrel doesn't mean that it will shoot well jumped .015 in yours. In your rifle it may like .010 jam, .025 jump or more. It is something you will have to work out in your loading, shooting and testing.
Freebore discussions start when you determine how long the bullet will be that you are shooting. Another factor will be if you are magazine feeding or not.

 

[sawcarver]

When I get home I can measure my COAL for my 7-300 win mag that I shoot 195s out of a savage long action. I do know a 195 wont fit in an AICS long action magazine.

 

[Cwballistics]

When I get home I can measure my COAL for my 7-300 win mag that I shoot 195s out of a savage long action. I do know a 195 wont fit in an AICS long action magazine.

Any chance the 3.85” accurate mag will suffice? If not, I guess there is always the 28 Nosler. Sorry for the ignorance. thanks For the help.

 

[sawcarver]

My rounds measure 3.760" with a 195. My AICS mag measures 3.67" inside and I can't put a longer mag in my McRae chassis without taking metal out. If the 3.85" mags fit into your bottom metal then it might work, whats the internal masurement of a 3.85? Gotta be close to 3.75" I would think

A 28 nosler isnt a whole lot shorter than a 7-300

 

[Cwballistics]

My rounds measure 3.760" with a 195. My AICS mag measures 3.67" inside and I can't put a longer mag in my McRae chassis without taking metal out. If the 3.85" mags fit into your bottom metal then it might work, whats the internal masurement of a 3.85? Gotta be close to 3.75" I would think

A 28 nosler isnt a whole lot shorter than a 7-300

Inside dimension of 3.85 mag is 3.755”. Do you know about how close the heel of the 195 is to your shoulder when loaded to 3.760? I figure I can seat my dummy rounds back that far if I have to, and chamber it with .020 jump from there. I guess my hope is that seating it this far back would give me a coal around 3.65 or less.