Barrel length on a big 30...

[Ranger188]

You can't tell me that the case on the right isn't sexier looking than the left. LOL

 

[ELR LVR]

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 higherView attachment 1675219View attachment 1675220View attachment 1675221View attachment 1675222View attachment 1675223

What brand carbon wrapped barrel is that you are using?
Excellent accuracy and rather impressed with your 700 yd groupings there.
I've been considering a Carbon barrel but am slightly concerned about barrel walking as it heats up
meaning maybe only good for 3-5 shots at ELR
One thread I read someone got better results with BSF barrels over Proof for this reason
POI only elevated 1 MOA after it heated up where the Proof started to enlarge groupings
Thanks

 

[Matt_3479]

What brand carbon wrapped barrel is that you are using?
Excellent accuracy and rather impressed with your 700 yd groupings there.
I've been considering a Carbon barrel but am slightly concerned about barrel walking as it heats up
meaning maybe only good for 3-5 shots at ELR
One thread I read someone got better results with BSF barrels over Proof for this reason
POI only elevated 1 MOA after it heated up where the Proof started to enlarge groupings
Thanks

That is a hells canyon carbon barrel, 1:9.5 twist, 26”. This is my hunting rifle hence the carbon, and I never shoot more then 5 shots while sighting in or group shooting. Don’t need to kill a barrel on this set up when I got it set it up for moose hunting.

 

[ELR LVR]

That is a hells canyon carbon barrel, 1:9.5 twist, 26”. This is my hunting rifle hence the carbon, and I never shoot more then 5 shots while sighting in or group shooting. Don’t need to kill a barrel on this set up when I got it set it up for moose hunting.

Thanks,
Yeah I was not planning on long shooting strings with a carbon barrel
but given the choice between a simple elevation shift vs group enlargement
I like to know what options I have

 

[Sgt. Brumbaugh]

I have to agree with you, there is absolutely an improvement with the Ackley improved version over the standard 300 Norma. my buddy has found that his ackley improved 338 lapua has significantly less donut formation in the neck/shoulder junction as opposed to his standard 338 lapua, Also the added powder capacity was a welcoming gesture as well. He also noticed a velocity increase of close to 80 fps.

We are talking about two different improved cartridges. No one would disagree that the 338 LAI has substantially increased velocity over the standard 338 Lapua.

 

[Ledd Slinger]

I have talked to a lot of people being disappointed that they didnt go with our 35 degree NMI chamber design over the standard Norma because they can never reach the upper velocity nodes with heavier bullets.

So again, where is this data of shot string records where the Norma runs nearly as fast as the NMI? I bet our NMI speed data with N570 is more than just 25 fps faster than your standard Norma data using whatever powder you choose.

N570 is VERY dense and heavy. Each kernel weighs between .08gr to .14gr depending on the length of the kernel. That adds up to a lot of speed gains pretty fast with the extra capacity of the NMI.

If somehow the sun is shining on a dogs rear end, and you guys are managing to hit 3200 fps with a 230gr bullet in the standard Norma like we can in the NMI using only 27”-28” barrels, then i will secede from this discussion. But i know thats not possible.

You could run a crazy long throat and have barrels spec’d with deeper grooves and wider bore to add extra speed, but then accuracy and consistency may suffer. And the NMI with the the same barrel specs will also run proportionately faster so that doesn’t help your claims.

 

[Mike TackleBerry]

We are talking about two different improved cartridges. No one would disagree that the 338 LAI has substantially increased velocity over the standard 338 Lapua.

Standard 300 Normas are infamous for their donut-creating abilities. Ackley improved with a 35 or 37 shoulder would limit this a lot. The increase in powder capacity is nice and it would make the brass more stable over its lifetime of use by not allowing the brass to flow as easily due to the increased shoulder angle.

 

[ISS]

Mike,

would not the throat erosion mitigate the donut creating issue by increasing the OAL at about the same proportion?

 

[ISS]

Why no love for the 240gr Sierra's in Std or NMI?

 

[SKWERLZ]

Why no love for the 240gr Sierra's in Std or NMI?

Because it’s an older design with a Ho hum BC.

 

[FireMedic]

I have talked to a lot of people being disappointed that they didnt go with our 35 degree NMI chamber design over the standard Norma because they can never reach the upper velocity nodes with heavier bullets.

So again, where is this data of shot string records where the Norma runs nearly as fast as the NMI? I bet our NMI speed data with N570 is more than just 25 fps faster than your standard Norma data using whatever powder you choose.

N570 is VERY dense and heavy. Each kernel weighs between .08gr to .14gr depending on the length of the kernel. That adds up to a lot of speed gains pretty fast with the extra capacity of the NMI.

If somehow the sun is shining on a dogs rear end, and you guys are managing to hit 3200 fps with a 230gr bullet in the standard Norma like we can in the NMI using only 27”-28” barrels, then i will secede from this discussion. But i know thats not possible.

You could run a crazy long throat and have barrels spec’d with deeper grooves and wider bore to add extra speed, but then accuracy and consistency may suffer. And the NMI with the the same barrel specs will also run proportionately faster so that doesn’t help your claims.

you don’t know what you don’t know. Some of us have actually tested this. Several barrels and several thousand rounds of data with different powders.

Sure n570 makes top speeds in a 300nmi, but it also does in a 300 Norma.

Look at wheelers print….his shoulder is less than .006 bigger than a cip spec norma. Open some calipers .006 and hold it up to the light. How much more n570 are you putting in that space. The 35deg shoulder angle is not adding much volume either.

I believe @rhovee has experience with both. I’d be curious for him to weigh in with his experience

 

[SKWERLZ]

You can't tell me that the case on the right isn't sexier looking than the left. LOL
View attachment 1675498

I see you 300NMI!

 

[SKWERLZ]

Sure n570 makes top speeds in a 300nmi, but it also does in a 300 Norma.

^^^^^

 

[Mike TackleBerry]

Mike,

would not the throat erosion mitigate the donut creating issue by increasing the OAL at about the same proportion?

You'd have to cut the throat deeper so you could seat the bullet out farther past the donut, or trim out the donut. The problem with cases like the 300 and 338 Norma is that the brass loves to flow forward due to the shallow neck angle. If your initial load development seats the bullet say .060 past the neck/shoulder juntion and you lose around .004 of erosion for every 100 rds fired then you'd have to shoot over 1500 rds give or take to have enough erosion to allow you to seat the bullet to just past the donut maybe even more but by then the barrel is already shot out and you'd need a new one.

 

[ISS]

Reasonable answer Mike.

I am going to go with the Alex Wheeler NMI design after much thought and reading other's posts in the two threads here. The one is over 5 years old and 36 pages.
A local gunsmith has two NMIs, his and his wife's. They shoot at two nearby 1000yd +/- ranges within an hour's drive, and I have been invited to come and observe. And, also talk with the other shooters. I can start two steps ahead of the curve.

I very much appreciate the wisdom shared here on this thread.

ISS

 

[rhovee]

I have had a few barrels of 300 NMI and 300 Norma. It depends on the bullet you’re trying to run. I shot the 245’s with N570 in both and that bullet likes the 2900-2940 speeds. Both were obtained with 26” barrels. Some NMI barrels will reach a higher node with 230’s in the 3140 area which a standard Norma can not, but this is with some barrels not all. If you drop down to the next node of 3050, then both chambering can run this. The NMI would be at less pressure. Just my experience.

 

[tom]

I was running the 245s 3180ish on my 34" improved. Need to stretch her legs one of these days. I never got to pressure and quit around 3240 on powder ladders day.



Tom

 

[LVLAaron]

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

View attachment 1675105

That doesn't tell the whole story. Metallurgy plays a much bigger role. Alpha 308 brass lasts literally forever compared to 10 firings in Lapua, and they aren't that different looking. I've sectioned almost every 223 casehead I have found, and same thing... you'd be surprised but less metal doesn't mean weaker case necessarily

 

[SKWERLZ]

That doesn't tell the whole story. Metallurgy plays a much bigger role. Alpha 308 brass lasts literally forever compared to 10 firings in Lapua, and they aren't that different looking. I've sectioned almost every 223 casehead I have found, and same thing... you'd be surprised but less metal doesn't mean weaker case necessarily

Old blue bag Winchester 243 brass ran forever and was thin everywhere.
That extra case capacity allowed use of more powder and getting nice speeds

 

[Ledd Slinger]

That doesn't tell the whole story. Metallurgy plays a much bigger role. Alpha 308 brass lasts literally forever compared to 10 firings in Lapua, and they aren't that different looking. I've sectioned almost every 223 casehead I have found, and same thing... you'd be surprised but less metal doesn't mean weaker case necessarily

Very true, but not in this case. Normally ADG brass is excellent and very strong. People were having issues with losing primer pockets on the NMI using the new ADG brass when it came out and Alex told me he thought it was weaker primer pocket construction. I had both brands on hand so I did a cutaway and sure enough, Alex was right.

It’s possible ADG had a bad alloy mixture. And it’s also possible they have already corrected the issue in their Norma brass because they are a good company that listens to customers feedback, but I invested in Lapua brass and never looked back.

Would be interested to see if current production Norma brass from ADG still has the same construction. I have nothing but good things to say about the ADG brass I use in other rifle chamberings.