7-300 Norma Mag Improved

[huntnful]

Spent a little time behind the new rifle. It sure seems promising for a bigger 7mm.

 

[Harvey_NW]

Wicked. Do you jam the lands when forming that, or set a false shoulder?

 

[180ls1]

It looks like it shoots! Whats the real-world advantage of this over a 28N?

 

[huntnful]

Wicked. Do you jam the lands when forming that, or set a false shoulder?

Jamming the lands. I seat the bullets pretty long and just allow them to seat into the case wherever they come a stop while chambering. Works pretty well. All shoulders were within .001 after forming.

It looks like it shoots! Whats the real-world advantage of this over a 28N?

Well just to make things clear, a 28 Nosler is plenty and this is totally unnecessary lol. BUT my reasoning for it is:

#1 Lapua Brass

#2 I was hoping it’d outperform a 28N with Hogdon powders, and lower pressures. Low pressures normally lead to more consistent performance and better accuracy.

It looks like a modest charge of Retumbo in this, will out perform a MAX charge of N570 in a 28N.

 

[Harvey_NW]

#2 I was hoping it’d outperform a 28N with Hogdon powders, and lower pressures. Low pressures normally lead to more consistent performance and better accuracy.

It looks like a modest charge of Retumbo in this, will out perform a MAX charge of N570 in a 28N.

Those are notably faster than my 28 with same bullet and similar powders. Had a pressure spike and locked the bolt up at 3250 while testing.

 

[180ls1]

Similar barrel life?

 

[huntnful]

Similar barrel life?

You know, I really can’t say honestly. I doubt it though. This thing can burn a lot of powder. But potentially a 28 Nosler shooting a max charge of N570 throughout its entire barrel life, could die before this 7-300 shooting a medium charge of Retumbo throughout its entire barrel life.

But I figure if I get 500 rounds that’d be fine. Especially with all the testing I’m doing to get some better parameter and info for it.

Those are notably faster than my 28 with same bullet and similar powders. Had a pressure spike and locked the bolt up at 3250 while testing.

Well that’s a great comparison then for sure! Appreciate that piece of info! What was the powder and charge weight that locked it up?

 

[wind gypsy]

Why H50 BMG for fireforming? Are you aware that H50 BMG has a higher heat of explosion than N570 I.E. might be harder on throats than the reported throat killer n570?

 

[huntnful]

Why H50 BMG for fireforming? Are you aware that H50 BMG has a higher heat of explosion than N570 I.E. might be harder on throats than the reported throat killer n570?

You’re absolutely correct. I only used it because I didn’t want to shoot my H1000 and it was readily available. Definitely not ideal, especially in this circumstance with the already low barrel life. Honestly not the best decision and probably won’t do it again. Trying to save my precious powder, at the cost of my barrel. Catch 22 lol

 

[wind gypsy]

You’re absolutely correct. I only used it because I didn’t want to shoot my H1000 and it was readily available. Definitely not ideal, especially in this circumstance with the already low barrel life. Honestly not the best decision and probably won’t do it again. Trying to save my precious powder, at the cost of my barrel. Catch 22 lol

I used it for quite a few mid 90's grain powder charge loads in a 300 NM before I knew that little factoid so i can relate

 

[huntnful]

I used it for quite a few mid 90's grain powder charge loads in a 300 NM before I knew that little factoid so i hear ya

Haha yep. Another live and learn type of thing. I bought 8lbs of it for fire forming

 

[Harvey_NW]

Well that’s a great comparison then for sure! Appreciate that piece of info! What was the powder and charge weight that locked it up?

87.5gr H50BMG. I had gone up to 89 with CCI250's but I wanted to test Fed 215 and dropped the charge a bit for the test, I got 160fps increase and noticeably more recoil, severe bolt lift. Scared the shit out of me. Tested LRT and N570 and velocity wasn't anything to write home about when I hit pressure signs. That rifle and I did NOT get along.

 

[huntnful]

12 shot .6 MOA group at 108 yards while fire forming.

Here’s a video I recorded on the triggercam of 3 of those 12 shots to show the stability before each shot.

Then a 5 shot group at 300 yards with 180 ELDM’s and 84gr. H1000. Crazy consistent powder.

 

[Tullis94]

You are rock solid in the little video clip! Very very impressive!

 

[huntnful]

You are rock solid in the little video clip! Very very impressive!

It definitely helps with judging accuracy potential. When a bullet doesn’t land where it’s supposed to, at least I can be certain it wasn’t me most of the time lol

 

[blairmckenzie1]

i like how you called it "a bigger 7mm", wouldnt this be the biggest?

 

[huntnful]

i like how you called it "a bigger 7mm", wouldnt this be the biggest?

Hahaha yeah I guess it’s a pretty good sized cartridge . 7 Allen Magnum would be the king though.

 

[wind gypsy]

Probably pretty dang close to a 7 RUM as far as case capacity goes.

 

[Article 4]

Built this caliber in 2019 and loved how it performed. Built on a Defiance action running 195 bergers and Retumbo at 92.2 grains. 26" Proof bbl producing 3340 FPS. Topped with Kahles 624

First photo is 308 next to cartridge
Second is after bbl break and ladder testing, in this is the first 5 shot group
Third is 320 bull, little weak on 5 and 6 but its a true public land bull and I dont pass them like that anymore these days.
Last pic is cartridge next to my 6.5 GAP for reference

Took it to Montana late season hunt at it performed so well! Shot that bull high shoulder at 838 cross canyon and it took about 2 steps and piled up.

Luckily we had a Percheron in camp to help us get this 800 lb bull out. He was a big boy!!

Changed bbl in 2023 and turned it back into a 300 Norma - only got about 670 shots out of that 7mm bbl and wanted to try something different

 

[huntnful]

Built this caliber in 2019 and loved how it performed. Built on a Defiance action running 195 bergers and Retumbo at 92.2 grains. 26" Proof bbl producing 3340 FPS. Topped with Kahles 624

First photo is 308 next to cartridge
Second is after bbl break and ladder testing, in this is the first 5 shot group
Third is 320 bull, little weak on 5 and 6 but its a true public land bull and I dont pass them like that anymore these days.
Last pic is cartridge next to my 6.5 GAP for reference

Took it to Montana late season hunt at it performed so well! Shot that bull high shoulder at 838 cross canyon and it took about 2 steps and piled up.

Luckily we had a Percheron in camp to help us get this 800 lb bull out. He was a big boy!!

Changed bbl in 2023 and turned it back into a 300 Norma - only got about 670 shots out of that 7mm bbl and wanted to try something different

Awesome! Thank you for sharing!!