Barrel length on a big 30...

[Ledd Slinger]

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.

Theres another node on the 230s up around 3180-3200 fps. And of course the standard Norma will never see that either

 

[Ledd Slinger]

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

Yeah we do test it, have been for years, and know exactly what our data shows. Ryan knows too.

But once again, where is your data?

 

[FireMedic]

I’ve got lots of data, what would you like?

In the two rifles I’m currently shooting I top out at 89gr of n570 in a 300nmi and 87gr in a straight 300 Norma with 245s. Both around 2950-2975fps in a 26” barrels

Here are the two cases filled with water. Like I previously said, my case is improved more than wheelers .572 at the shoulder and 40deg. Standard 1.5deg lead angle .001 over bullet diameter freebore (pretty standard stuff)

Both of these cases are the same lot of lapua brass.

 

[FireMedic]

I’m not trying to convince someone one way or the other. I could care less what guys choose to build. The 300nmi is cool and I build a lot of them.

It’s a good sell for a builder because I can charge for custom dies and fireformed brass.

But will it make a lot more velocity than a 300 Norma…not in this universe where physics apply.

 

[Evlshnngns]

not in this universe where physics apply.

Maybe your 26" barrels are neutering the 3+ grains of powder capacity.

 

[ISS]

Perhaps it is because you live in a parallel universe...?

 

[LVLAaron]

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.

Totally fair and good context.

 

[Ledd Slinger]

I’ve got lots of data, what would you like?

In the two rifles I’m currently shooting I top out at 89gr of n570 in a 300nmi and 87gr in a straight 300 Norma with 245s. Both around 2950-2975fps in a 26” barrels

Here are the two cases filled with water. Like I previously said, my case is improved more than wheelers .572 at the shoulder and 40deg. Standard 1.5deg lead angle .001 over bullet diameter freebore (pretty standard stuff)

Both of these cases are the same lot of lapua brass.

View attachment 1676091View attachment 1676092

Thats what you are calling data? Come on man! Wheres the load/chrono data and targets? If you are reaching max pressure at 2975 fps with the NMI using a 26” barrel, then your chamber design needs work or your barrels are too tight. Either way, something isn’t right because your NMI is way too slow.

With my chamber, which is nearly identical to Alex Wheelers design, im at 2990 fps using the 245gr with only 88.5gr of N570 and no signs of pressure.

Your chamber may appear to be larger than the Wheeler design on paper, but that must also be a mistake because my NMI holds 109gr of water weight in Lapua brass

Im done here. No sense in continuing to debate a claim that is false. We have TONS of info compiled on this subject with threads on this forum. Maybe go have a good read and I hope you figure it out. Take care.

 

[FireMedic]

Thats what you are calling data? Come on man! Wheres the load/chrono data and targets? If you are reaching max pressure at 2975 fps with the NMI using a 26” barrel, then your chamber design needs work or your barrels are too tight. Either way, something isn’t right because your NMI is way too slow.

With my chamber, which is nearly identical to Alex Wheelers design, im at 2990 fps using the 245gr with only 88.5gr of N570 and no signs of pressure.

Your chamber may appear to be larger than the Wheeler design on paper, but that must also be a mistake because my NMI holds 109gr of water weight in Lapua brass

Im done here. No sense in continuing to debate a claim that is false. We have TONS of info compiled on this subject with threads on this forum. Maybe go have a good read and I hope you figure it out. Take care.

I get my info from my own testing and not parroting what I read on forum threads. It sounds like you prefer the latter.

Nothing in those threads are comparing the 300 Norma to the 300nmi. That’s what we are doing here.

 

[Ledd Slinger]

I get my info from my own testing and not parroting what I read on forum threads. It sounds like you prefer the latter.

Nothing in those threads are comparing the 300 Norma to the 300nmi. That’s what we are doing here.

LOL! Yep thats me!

Im sure your data is true for what you have, but there appears to be a fault somewhere thats restricting the speed of your NMI because should be at least a 80-100 fps gap between anything the standard Norma can do. So your ignorant claims are not fooling us…

Like i said, go educate yourself on the threads where we compiled all this data for years and try to figure out where you went wrong. Good luck!

 

[Ranger188]

What barrel companies are most using?
Krieger or Barlein 5R ?

 

[ISS]

Educate me some more. The HV contour looks good, .90" at 31" length 1.350" shank Bartlein shows on their website.

Talked to Bartlein, they have an order for one of them for Southern Precision. I called them, and left a message. Hopefully, it is mine after they call back.

Yee-Haw!!!!!!!!

 

[FireMedic]

Educate me some more. The HV contour looks good, .90" at 31" length 1.350" shank Bartlein shows on their website.

Talked to Bartlein, they have an order for one of them for Southern Precision. I called them, and left a message. Hopefully, it is mine after they call back.

Yee-Haw!!!!!!!!

I have several Bartlein 5r in stock in both 1.35 and 1.25 shank if you need one. Leddslinger will tell you my barrels are slow though.hahaha

 

[ISS]

Talk to me if you have a 31" or longer 30 cal HV contour with a 9" twist.

I am overloaded with projects in process this month. I got my BRC Borchardt action back from the engraver, another one is at Rod Storeys being fit with double set triggers, and this stuff.

thanks,

ISS

 

[FireMedic]

I have a 31” Bartlein heavy varm 1.35 shank 1:9 5r

PM me if you need it.

 

[ISS]

done

 

[ISS]

Got my HV 9" barrel from a Bartlein dealer. Two parts down, three parts left.

thanks guys!