7-300 Norma Mag Improved

[Article 4]

Jamming the lands. I seat the bullets pretty long and just allow them to seat into the case wherever they come a stop while chambering. Works pretty well. All shoulders were within .001 after forming.


Well just to make things clear, a 28 Nosler is plenty and this is totally unnecessary lol. BUT my reasoning for it is:

#1 Lapua Brass

#2 I was hoping it’d outperform a 28N with Hogdon powders, and lower pressures. Low pressures normally lead to more consistent performance and better accuracy.

It looks like a modest charge of Retumbo in this, will out perform a MAX charge of N570 in a 28N.

Agree, i looked at 28N before building this...case capacity is a key when running overbore magnums and the ratio between bullet a powder should be balanced without causing undue pressure as @huntnful stated.

Also in my experience in most standard length mags, the 300 case allows for more optimal bullet seating allowing more efficient use of a bit more powder at the big bullet weights. Better Ogive to Lands length while maintaining case capacity and not running into compressed load with pressure signs.

I made mine to run the 195 exclusively and the 28N will run it, sure. But the 7-300 NMi runs it better.

 

[kennon.reynolds]

Awesome


Sent from my iPhone using Tapatalk

 

[huntnful]

Happy with the performance of this cartridge. Going to get the smaller 8.5 twist #5 benchmark chambered in it now, and use the Brux for fire forming.


I know this is all so totally unnecessary. But it is fun for me to test shit, and share the info for others that might be interested. Helps keep my sanity during these slower hunting months.

This new barrel is hopefully only going to see H1000 and 180 ELDM’s.

 

[Tyler3288]

Steve never disappoints. Once again, another sick gun shooting small groups!

 

[huntnful]

Steve never disappoints. Once again, another sick gun shooting small groups!

Hahaha thanks man. Just something fun and more of a reason to get out and shoot!

Small groups definitely don’t kill animals, but they’re nice to see when first shooting a rifle!

 

[huntnful]

New barrel is already on the action.

Barrels are chambered as close to each as possible. I’ll be forming brass in the Brux, and then only shooting formed brass and H1000 in the new benchmark barrel. Just going to see whatever bullet likes H1000 the most. Starting with 180 ELDM then maybe 190 LRHT is need be.

 

[huntnful]

An update with the shorter smaller profile benchmark.



At 9.7lbs, recoil does land me about 2 Mils away from the target after the shot though. I can still see the impacts pretty easily though since I was only on 15X. A little weight sure wouldn't hurt and I’ll probably put a heavier barrel on it before hunting season. But we definitely got options now lol. A hair over .1 mil low. Which puts me at a trued BC for the 180 ELDM at .38 G7

180 ELDM
23.5” barrel
83.5gr. H1000
CCI 250
3110 FPS

 

[Quicksilver]

Heck of a group!! What was wind conditions like?

 

[huntnful]

Heck of a group!! What was wind conditions like?

Good enough to kill something out to a long ass ways lol. 4 MPH coming off left rear quarter.

 

[Timberline001]

Happy with the performance of this cartridge. Going to get the smaller 8.5 twist #5 benchmark chambered in it now, and use the Brux for fire forming.
View attachment 681209

I know this is all so totally unnecessary. But it is fun for me to test shit, and share the info for others that might be interested. Helps keep my sanity during these slower hunting months.

This new barrel is hopefully only going to see H1000 and 180 ELDM’s.

Someone has to test everything out. At least that’s my excuse Way too many people give advice when they’ve ever only tried one thing.

 

[huntnful]

Someone has to test everything out. At least that’s my excuse Way too many people give advice when they’ve ever only tried one thing.

I couldn’t agree more man. I don’t really like theorizing. I want to know things first hand. And I try to only give first hand experiences as information.

 

[Timberline001]

I couldn’t agree more man. I don’t really like theorizing. I want to know things first hand. And I try to only give first hand experiences as information.

Exactly, same here.

 

[huntnful]

 

[Diced]

View attachment 685297

That is a VERY dead piggy

 

[Timberline001]

View attachment 685297

Dead dead!!

 

[huntnful]

That is a VERY dead piggy

Dead dead!!

Yeah, he wasn’t walking that one off lol

 

[RockAndSage]

"Guys, guys, seriously...hear me out! Think about it... it'd be a 416 Rigby, but necked down to 7mm."

I absolutely love this project man - very cool cartridge, and eye-popping performance out of that rifle. If you don't mind me asking, where do you even start with getting a custom reamer made, and how much could someone expect to pay for that process?

 

[huntnful]

"Guys, guys, seriously...hear me out! Think about it... it'd be a 416 Rigby, but necked down to 7mm."

I absolutely love this project man - very cool cartridge, and eye-popping performance out of that rifle. If you don't mind me asking, where do you even start with getting a custom reamer made, and how much could someone expect to pay for that process?

Thanks man! JGS reamers will cut you anything you can dream up lol. They are also super helpful! In this specific case, I’d already had several of the Alex Wheeler 300 Norma Improved chambers done. So basically just called them, and them asked for the same case body specs, but with a neck for 7mm bullets.

Then I just used my same sizing and seating die, but just changes the neck bushings out on the sizing die.

 

[wind gypsy]

what are you using for that video?

Curious what terminal performance looked like, was there an exit? Almost got a two-fer there.

 

[huntnful]

what are you using for that video?

Curious what terminal performance looked like, was there an exit? Almost got a two-fer there.

It’s a scope mounted camera called Triggercam 2.1. Pretty cool little device really.

Entrance on the right, exit on the left

Entrance

Lungs