7-300 Norma Mag Improved. IT’S ALIVE!!

[Calvin45]

Yep- 7-33xc. Dies and reamers are on order.

What kind of powder would even be slow burning enough for this monstrosity? Wet US869 blended with coal dust and green wood shavings?????

 

[tacomHQ]

Wait are you being for real here? I was being a facetious troll!!!! . But good lord man….you must keep us informed!!!!

What barrel length you gonna run? 50 inches? .

Did you notify NASA about this rocket?

Real as you can get. Test bed for sure. The current brass for 33xc is the "base" starting point and is projected to be modified significantly to make this a success. It is also a material test bed as 150-200rd life is not acceptable. One of the advantages to our barrel is its cooling capacity: we have some ground to take back. While the barrels are forgiving and very accurate the 4000fps+ has always been the goal.

 

[tacomHQ]

What kind of powder would even be slow burning enough for this monstrosity? Wet US869 blended with coal dust and green wood shavings?????

Fine spherical rubber bits. LOL.

 

[Huntnful]

Got the new 23.5" #5 benchmark on the
7-300. While the over 1lb weight reduction is certainly nice, it's got some pretty good thump to it honestly. Definitely harder to spot impacts. I do like the slightly shorter barrel though. So I'm going to shoot it off and on in this configuration, and when the season gets a little closer I'm going to go back to a heavier profiled barrel at a 24" finish length I'm thinking. I'll hold off on buying anything just yet, until I can fully make up my mind hahaha. But I do like the consistency and performance of the cartridge. So I'll for sure be hunting with it this season!

But it's shooting the 180 ELDM's at 3110fps with 83.5gr. H1000 with an ES of 23fps for 15 shots.

 

[Calvin45]

Real as you can get. Test bed for sure. The current brass for 33xc is the "base" starting point and is projected to be modified significantly to make this a success. It is also a material test bed as 150-200rd life is not acceptable. One of the advantages to our barrel is its cooling capacity: we have some ground to take back. While the barrels are forgiving and very accurate the 4000fps+ has always been the goal.

I won't derail this thread further, will PM for more info!

 

[Huntnful]

I won't derail this thread further, will PM for more info!

Hey I like big cartridges too!! Hahaha

 

[ARlife4me]

I wonder what n170 would do on speed and would add life to the barrel. I want to do a 26-300nmi. It'll be a napalm barrel for sure. Using n170 and n165 it might survive 1k?

 

[Calvin45]

Hey I like big cartridges too!! Hahaha

Alrighty then, never mind!

@tacomHQ when you say "we" and "our"…is this in reference to a particular company or gunsmithing outfit you run or work for?

What kind of modifications are you talking about for the 33xc parent case?

Barrel life of 200 rounds being unacceptable, I'm curious what the plan is to do better than that with a 140+ grain capacity case pushing a 7mm bullet! HBN or some other coating, some kind of special rifling, nitride treated steel, some kind of super alloy barrel material, polygonal rifling, gain twists, or some projectile design that should mitigate wear…?


Of course if this is part of R and D for a new product or procedure and it's your livelihood and you've got investors funding this I understand if one must stay tight lipped about it all. But if you're just a ballistic nutcase experimentalist supreme please do divulge some more details. This project is just fascinating sounding to me.

 

[Phil Rizzo]

Real as you can get. Test bed for sure. The current brass for 33xc is the "base" starting point and is projected to be modified significantly to make this a success. It is also a material test bed as 150-200rd life is not acceptable. One of the advantages to our barrel is its cooling capacity: we have some ground to take back. While the barrels are forgiving and very accurate the 4000fps+ has always been the goal.

.284 Eargensplitten Loudenboomer?
I promise the majority haven't heard that term before or what spawned it,
been a while for Me too.

 

[Calvin45]

.284 Eargensplitten Loudenboomer?

That would be a mere 7-378! This is bigger!

https://i.gifer.com/Od6.gif

I just saw now that indeed a 7mm/33xc reamer is available through pacific tool and gauge. YEEEEEEHAW!!!!

 

[GLRUT]

Wait are you being for real here? I was being a facetious troll!!!! . But good lord man….you must keep us informed!!!!

What barrel length you gonna run? 50 inches? .

Did you notify NASA about this rocket?

I built a couple 7xc from some of my 7-338 lapua improved worn out barrels. I was getting around 3,460 to 3,500 fps with 20n29 with a 195 grain berger 30" barrel. I have a 33" bartlein that will be here in a couple days that I will start from scratch to see what this will do. Just something else to add to the list. Will keep informed.

 

[tacomHQ]

Alrighty then, never mind!

@tacomHQ when you say "we" and "our"…is this in reference to a particular company or gunsmithing outfit you run or work for?

What kind of modifications are you talking about for the 33xc parent case?

Barrel life of 200 rounds being unacceptable, I'm curious what the plan is to do better than that with a 140+ grain capacity case pushing a 7mm bullet! HBN or some other coating, some kind of special rifling, nitride treated steel, some kind of super alloy barrel material, polygonal rifling, gain twists, or some projectile design that should mitigate wear…?


Of course if this is part of R and D for a new product or procedure and it's your livelihood and you've got investors funding this I understand if one must stay tight lipped about it all. But if you're just a ballistic nutcase experimentalist supreme please do divulge some more details. This project is just fascinating sounding to me.

The 33xc, as is, is being used to determine if current projectile design will accomplish specific goals. It will also be used to create another set of data points to determine if we have succeeded in reduced throat/barrel wear. Twist rates will have to change to optimize the projectile. All of our in house guns run large gain twist: of which barrel life is one of the goals. We have been successful shooting the projectiles in our 300Nm (testing for stability) and will continue the projectile test with slower twist rates than currently accepted. We ordered slower twist barrels than can be had on stock guns for the testing (200+gr projectiles). However, the Norma case does not have the capacity to approach our required velocity boundaries. Kind of a "round robin": 33xc, 300Nm, 7mm/33xc.
We are well into other materials outside of 416 with life being a main goal- you need a good base material for coatings to work (Chrome on butter) . The 7mm test is meant to test outside boundaries with enough powder charge to intentionally make tons of heat- then mitigate it. That will be the cartridge design along with the chamber. Rifling will become part of the test- we are testing some specific rifling profiles all with an eye on life. High firing rates in Semi's give a good initial indicator
We are working with David Tubb on the initial phases of the project (the reamer noted...?).
So... a bit tight lipped.

To Huntnful: no wish to high jack your project. A Very appreciated detailed journey.
Would you be willing to share your exact methods of resizing down to 7mm?
In your experience: have you found case values to change with bullet weight fired and powder charge? I have measured some variations when we fire new brass across large velocity changes (1200fps or more) and bullet weights. Chasing SD in this case.

 

[Huntnful]

The 33xc, as is, is being used to determine if current projectile design will accomplish specific goals. It will also be used to create another set of data points to determine if we have succeeded in reduced throat/barrel wear. Twist rates will have to change to optimize the projectile. All of our in house guns run large gain twist: of which barrel life is one of the goals. We have been successful shooting the projectiles in our 300Nm (testing for stability) and will continue the projectile test with slower twist rates than currently accepted. We ordered slower twist barrels than can be had on stock guns for the testing (200+gr projectiles). However, the Norma case does not have the capacity to approach our required velocity boundaries. Kind of a "round robin": 33xc, 300Nm, 7mm/33xc.
We are well into other materials outside of 416 with life being a main goal- you need a good base material for coatings to work (Chrome on butter) . The 7mm test is meant to test outside boundaries with enough powder charge to intentionally make tons of heat- then mitigate it. That will be the cartridge design along with the chamber. Rifling will become part of the test- we are testing some specific rifling profiles all with an eye on life. High firing rates in Semi's give a good initial indicator
We are working with David Tubb on the initial phases of the project (the reamer noted...?).
So... a bit tight lipped.

To Huntnful: no wish to high jack your project. A Very appreciated detailed journey.
Would you be willing to share your exact methods of resizing down to 7mm?
In your experience: have you found case values to change with bullet weight fired and powder charge? I have measured some variations when we fire new brass across large velocity changes (1200fps or more) and bullet weights. Chasing SD in this case.

I think everyone involved in this thread appreciates your added data with the even bigger cartridges, so I don't feel like it's a high jack at all!!

I size the 300 NM brass down in two stages. I chamfer the outside. Then size down once with a .325 bushing. And then the next step with a .314 bushing. That puts the inside case neck around .281-.282. Then I expand with a .2835 mandrel. @Barehandlineman11 sets the chamber up with a nice crush fit as well. But I still seat into the lands, just because.

Honestly unsure what you mean by the changing case values in relation to bullet changes though.

 

[RH300UM]

I think everyone involved in this thread appreciates your added data with the even bigger cartridges, so I don't feel like it's a high jack at all!!

I size the 300 NM brass down in two stages. I chamfer the outside. Then size down once with a .325 bushing. And then the next step with a .314 bushing. That puts the inside case neck around .281-.282. Then I expand with a .2835 mandrel. @Barehandlineman11 sets the chamber up with a nice crush fit as well. But I still seat into the lands, just because.

Honestly unsure what you mean by the changing case values in relation to bullet changes though.

Do you Anneal at any point during your sizing process?