300 Norma Magnum Improved reamer and die release

[E4aker]

Headspace and neck length will be the same regardless of 35, 37, 40deg, etc.. Headspace on a wildcat is usually -.004 on the parent case.

Shoulder angle does not affect seating depth when done properly. The freebore is what affects your seating depth…period

 

[Mad Minion]

Headspace and neck length will be the same regardless of 35, 37, 40deg, etc.. Headspace on a wildcat is usually -.004 on the parent case.

Not sure I'm conveying correctly, forgive me. Let me see if I can say this another way.
I picked a bullet, in this case a 245 Berger, I wanted it to acieve at minimum 3000 FPS, I looked at every 30 cal cartridge with potential to achieve my numbers. The 300 norma mag kept me in the mag. Was available, and others were already doing it.When I looked at the ballistics I would need to modify the case. Being an American and because I can I wanted to shove as much powder in the case as possible, I blew out the case wall and increased the shoulder angle to a point where the bullet would not seat into the powder column at all and still have enough neck left on the bearing surface of the bullet, at least .250 contact. The berger has a long boat tail. To do all of this I also had to maintain the headspace of the 300 Norma case because that would keep it all inside the magazine. What I found crunching numbers, 36.5 degrees on the shoulder would keep the bullet out of the powder. Give me .020 to chase lands and stay in the magazine for the life of this barrel. All without messing with the headspace and still maintain an acceptable amount of bearing surface in the neck. At 40 degrees I had little room to chase lands for the life of the barrel. 30 degrees was un American.
So, to maintain the integrity of my intent a 40 degree shoulder would not work for me.
Hope this clears things up.

 

[E4aker]

I have released my reamer design to the public. Bullet Central will be selling the sizing dies again soon. This one is set up for a crush fit on new Lapua brass and is a compromise for the 230/245 Berger.View attachment 322794

Alex,
I see that you went with a .3083 freebore diameter. What advantage did you see with the tighter freebore over say the standard .3085 that most use. I know some smiths tend to go looser then tighter with the big magnums.

I was curious your thoughts?

 

[Jordan Funk]

Thanks Alex. Just ordered your reamer from JGS.

 

[Alex Wheeler]

Alex,
I see that you went with a .3083 freebore diameter. What advantage did you see with the tighter freebore over say the standard .3085 that most use. I know some smiths tend to go looser then tighter with the big magnums.

I was curious your thoughts?

Im glad you saw that. Thats an error when they re drew the print for public release. I'll have them correct it and change it on anyone thats already ordered one. Its supposed to be .3093"

 

[Alex Wheeler]

I'm just wondering…why not use a 40 deg shoulder?

The main reason is that its a big case and I didnt want to make it bigger. Usually the best case designs are just big enough to do the job.

 

[Jordan Funk]

So, I'm new to this game. I'm building a .300 NMI on a Husqvarna small-ring commercial Mauser for coastal brown bears (I can dream, right?!). I'd like to launch heavy bullets as fast as I reasonably can given the COAL limitations of the '06 length action and I want to stick to a 23" barrel. Can you more experienced guys tell me where I'm going wrong with this project as proposed? I can see an argument that I ought not be using an improved .300 Norma if I'm only using a 23" barrel and a standard '06 length action. Any feedback from you more experienced shooters is appreciated. TIA

 

[waveslayer]

So, I'm new to this game. I'm building a .300 NMI on a Husqvarna small-ring commercial Mauser for coastal brown bears (I can dream, right?!). I'd like to launch heavy bullets as fast as I reasonably can given the COAL limitations of the '06 length action and I want to stick to a 23" barrel. Can you more experienced guys tell me where I'm going wrong with this project as proposed? I can see an argument that I ought not be using an improved .300 Norma if I'm only using a 23" barrel and a standard '06 length action. Any feedback from you more experienced shooters is appreciated. TIA

I don't think you're going wrong. 23" barrel is fine, I run a .338 norms Ackley improved in a 22" barrel. Your issue with heavy bullets will be magazine restrictions if you are running mags. You may want to run some ballistic simulations and look at terminal ballistics of velocity loss from running the heavies versus medium weight bullet.. lighter the bullet the faster she flies and the kinetic energy might be better for closer range shots, but you will want a bullet that doesn't fragment under certain velocities.
My Warbird can shoot 150 gr bullets 3700 fps.. issues is the bullets blow up and I don't get the penetration on game especially for an animal that will fight back. So run 212-215 bullets at 3170..
Anyways do some leg work, pick a bullets and go from there. 23" is fine you will just lose 25 fps per inch give or take

 

[Jordan Funk]

Thanks Waveslayer. In hindsight, I wish I'd purchased a .338 or even .358 barrel. Not too late to do it (I could sell the one I have...at a loss!) but as tme goes by, I'm becoming more and more committed to the .300 NMI. So, what the heck!

 

[waveslayer]

Thanks Waveslayer. In hindsight, I wish I'd purchased a .338 or even .358 barrel. Not too late to do it (I could sell the one I have...at a loss!) but as tme goes by, I'm becoming more and more committed to the .300 NMI. So, what the heck!

I think you picked a solid proven round!!! Run the 215's out of it. I think you're on the right track!!! Stick with it. Just find bullets you want to use on bear and PM me. I'll do some work ups and report what in theory I find and then you can put it to the test at the range. All part of the journey! Then send us pics of a monster

 

[Jordan Funk]

Thank you sir! Saving my pennies as we speak!

 

[Alex Wheeler]

Well, it wont let me edit the thread, this is the corrected print. Anyone with one on order will get the corrected reamer, no need to call them.

 

[Mike D Texas]

Well, it wont let me edit the thread, this is the corrected print. Anyone with one on order will get the corrected reamer, no need to call them.




View attachment 324913

Alex what depth would a 230 Hybrid be at to kiss the lands with this reamer?

 

[Alex Wheeler]

Bullet Central should have dies available in about a week.