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

Quicksilver338 said:

Bore scope bore scope bore scope!

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Huntnful said:

So I'm not sure about the jacket failures specific with 4 groove barrels, but I'd imagine this is worst case scenario

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E4aker said:

I think the 9 twist is helping in this regard. Also brux groove geometry is more angled on the sides of the groove compared to other brands….this might be contributing to it also

I know that when I've had bullet blowups it's been in extreme rpm situations and typically happened past 100yds.

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RH300UM said:

I've had 2 brux barrels on my 7-300nmi's both would destroy 180 vlds. I had to use 180 Hybrids to avoid the problems. I've had no issues with the Proof barrels
My sons rifle uses the 180 vlds now with the proof barrel
I use the 195's in my rifle
Also a proof

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E4aker said:

I think the 9 twist is helping in this regard. Also brux groove geometry is more angled on the sides of the groove compared to other brands….this might be contributing to it also

I know that when I've had bullet blowups it's been in extreme rpm situations and typically happened past 100yds.

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RH300UM said:

I've had 2 brux barrels on my 7-300nmi's both would destroy 180 vlds. I had to use 180 Hybrids to avoid the problems. I've had no issues with the Proof barrels
My sons rifle uses the 180 vlds now with the proof barrel
I use the 195's in my rifle
Also a proof

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Huntnful said:

Still obviously learning this cartridge and what charge weight for what bullet weights. So this evenings test wasn't ideal.

I was over pressure on the 190 LRHT's and H1000 in my once fired brass. Which I honestly thought I had enough cushion not to be. I was wrong.

85gr. yielded a bolt click and 3200fps right of the bat

I had 5 loaded at 86gr. for the little accuracy test. I still decided to shoot all 5 because that's what I was there for and it didn't feel that dangerous. Shot just under a 1 MOA 5 shot group at 400 yards. Decent bolt lift for sure, so not ideal conditions for accuracy being that far into pressure. But I did find out that H1000 is really consistent, even in this under filled case, and into pressure.

This is 5 shots at 86gr. H1000 and 190 LRHT's
View attachment 547714

I believe I would have to drop down to 84gr. or possibly even 83gr. to get out of pressure with the 190's. So realistic velocity probably around 3100-3140fps with H1000.


Then I shot the 160 Copper Rose with Retumbo. They shot just over 1 MOA at 400 yards for 5 shots. Also not ideal, since they were loaded in my old 300 NMI that I just necked down for testing purposes.

87gr. 3436fps
88gr. 3460fps
89gr. 3470fps bolt click
90gr. 3523fps heavy bolt lift

5 shots at 87gr. Retumbo
View attachment 547722


Basically we're all just learning this cartridge together lol. Everything is new to me also. So I'm just trying to test and document data for future possible interests in the cartridge.

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RichCoyle said:

What do you think it would do with 130 grain class bullets? I'm thinking of doing one and using 132 grain Hammer Hunter tipped bullets.

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RichCoyle said:

What do you think it would do with 130 grain class bullets? I'm thinking of doing one and using 132 grain Hammer Hunter tipped bullets.

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Calvin45 said:

On that note, if it does die early how about a 7-378 or a 7-33 xc next?

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tacomHQ said:

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

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