Barrel length on a big 30...

[Ledd Slinger]

FYI, here is a cutaway i did on my milling mchine of Lapua and ADG brass in 300 Norma Mag. Normally ADG is built very strong like Lapua, but in this particular cartridge, Lapua is much stronger around the primer pocket where you need it most when pushing speeds. No idea why ADG did this in the 300 Norma.

Peterson and Norma brand brass is garbage in the 300 Norma

LEFT: Lapua RIGHT: ADG

 

[ISS]

Thanks.

I am concerned with the Improved version about using quite a bit of accurate barrel life fire forming, and getting the Improved die set. Where did you gentlemen acquire yours?

 

[Ledd Slinger]

Thanks.

I am concerned with the Improved version about using quite a bit of accurate barrel life fire forming, and getting the Improved die set. Where did you gentlemen acquire yours?

You just start shooting while fire forming to zero optics and get your range dopes.
And I would not fireform ALL your brass at once. No sense in that. I usually only have 50 formed pieces at a time. When those wear out, i start using another 50.

But if you must, Whidden makes a hydro forming die and he should still have my specs on file. My chamber dimensions ended up being nearly identical to Alex Wheelers design so if you go that route, my die on file will work for that chamber. Tho John might have Alex’s chamber design on file as well since it was made public a while back

 

[Sgt. Brumbaugh]

I am concerned with the Improved version about using quite a bit of accurate barrel life fire forming, and getting the Improved die set. Where did you gentlemen acquire yours?

I am the team lead for the USMC Scout Sniper Association ELR team. My entire team other than I run standard 300 Norma's, we compare data a lot and I can say there is virtually no "improvement" running the 300 NMI over the standard 300 Norma. We all run long throats (.275) and my improved might run 25 fps faster (max) over the standard Norma's. We have a total of 5 standard Norma's on the team, so lots of different barrel lengths, to compare.

If I had it all over to do again, I would run the standard Norma. If you are going to do the improved, I load up 100 pieces of brass to fire 50 at a time during a range session. I bring a cooler full of ice water and towels and use the towels to cool the barrel down between strings of fire. You can get a barrel that is hot to the touch to cool in a few minutes when you wrap it in cold towels.

Make sure that your fireforming loads are jammed a few .000 into the lands so the brass fireforms correctly. I personally don't like the hyrdo dies, a piece of brass is not usefully fireformed until the shoulder is at the same length as fully fireformed pieces of brass. I can get it there in one fireforming. I use blem 220 SMK's from Midway (.30 cents each) and 93 grains of US 869 (2900 FPS)

When I fireform I will normally try to get some wind call practice in or something more using than just pulling the trigger.

Surprisingly, wrapping the barrel in cold towel does not seem to change the POI much.

 

[Matt_3479]

I run 230 hybrids in my norma with a 26” barrel at 3000-3050fps. Had them up to 3150 with rl33 but this shot so well with n570 I never went higher

 

[ISS]

Jeez, I knew it Brumbaugh! Jarhead! My third tour in RVN we moved from Chu Lai to Danang and took over the 1st Marine Force Recon Bn's AO. We got their hooches, and they were kind enough to leave us a full foot locker of brand new KaBars. Still in the cosmolene!

Seriously, the Corps has always performed well in the field. Force Recon is/was about the equivalent of the Army Rangers.

I was wondering about the benefit of the NMI. I am going to stick with the standard chambering.

What do your rifles weigh? Maybe post a picture one of these days...?

Thank you for your service.

 

[Ledd Slinger]

I am the team lead for the USMC Scout Sniper Association ELR team. My entire team other than I run standard 300 Norma's, we compare data a lot and I can say there is virtually no "improvement" running the 300 NMI over the standard 300 Norma. We all run long throats (.275) and my improved might run 25 fps faster (max) over the standard Norma's. We have a total of 5 standard Norma's on the team, so lots of different barrel lengths, to compare.

Well we’ve been testing this cartridge long before the military ever its greasy little hands in it so i can confidently say that your data is WRONG!

Are you stating that you shoot a NMI and have only compared your ONE single NMI against many other standard Normas to draw your conclusion? Thats very weak and inconclusive. Either your NMI chamber is a poor design, or you have a slow barrel if that has been your experience.

My NMI chamber design holds about a 10gr capacity advantage over the standard Norma and the makes quite the difference when running the slower powers with heavy bullets. The standard Norma cant touch the NMI. I guarantee i can run the same weight bullet well over 100 fps faster than any of the standard Norma rifles you have in your group and i will do it with a shorter barrel and probably still have throttle to spare!

 

[FireMedic]

Well we’ve been testing this cartridge long before the military ever its greasy little hands in it so i can confidently say that your data is WRONG!

Are you stating that you shoot a NMI and have only compared your ONE single NMI against many other standard Normas to draw your conclusion? Thats very weak and inconclusive. Either your NMI chamber is a poor design, or you have a slow barrel if that has been your experience.

My NMI chamber design holds about a 10gr capacity advantage over the standard Norma and the makes quite the difference when running the slower powers with heavy bullets. The standard Norma cant touch the NMI. I guarantee i can run the same weight bullet well over 100 fps faster than any of the standard Norma rifles you have in your group and i will do it with a shorter barrel and probably still have throttle to spare!

Sgt. Brumbaugh knows what he’s talking about. I have burned through several barrels with 300 Norma imp and I’m currently running a standard 300 Norma and 300 nmi 40deg

The improved version pressures out with 2gr more powder and only only runs 25fps faster Maybe. I see more variation between individual barrels than the two chamberings.

The standard Norma has a capacity of 105gr. H20 to the neck. The improved version 110gr

My reamer is about as improved as you’d want to make it also. .08 body taper and 40deg shoulder I don’t think you could make the case 10gr bigger and still have enough body taper for good extraction.

 

[Ranger188]

What diameter and taper barrels are you running with the 300 NM or NMI ?
Will a 1.25 breech dia. work, or larger?