300 Norma Mag AI Shorty Build

[7.62 Gunner]

Thought I'd start a build thread for my 300 NM 40 degree Ackley improved.
My objective is to send 225 ELDMs at 2800 fps from a 19" barrel in a sub 10lb suppressed hunting setup.

I went with a BAT Vesper action, Unknown Munitions bottom metal, Bix n Andy trigger, and a #4 contour 19" 9 twist McGowen prefit (Gasp), with a 1.250" shank.
Still waiting on my Manners LRH.

I had Manson design a custom 40 degree Ackley reamer based on Lapua brass with a .004 crush fit. I added .005 clearance .200 above the web to avoid the "Clicker" issue.
It's throated for the 225 ELDM seated just above the neck shoulder junction.

I got the barrel torqued on and set it in a cheap factory plastic stock for fire forming.
It weighs 7.4 lbs with bottom metal and Nomad LT suppressor, with the March FX 4.5-28×52 and LRH stock it'll be just under 10 lbs.

I fire formed a few cases and dialed her in at 100 yards, I was shocked to see my fire forming loads just stacking in tight.
I needed to fire three cases three times to send in for custom dies, so I worked up to 79 grains with 225 eldms while dialing in the scope.
I went for a group on the third firing and without any cherry picking shot a 3/8" group.
More to come.

 

[Monteria]

Pretty sexy!

 

[FEENIX]

Thought I'd start a build thread for my 300 NM 40 degree Ackley improved.
My objective is to send 225 ELDMs at 2800 fps from a 19" barrel in a sub 10lb suppressed hunting setup.

I went with a BAT Vesper action, Unknown Munitions bottom metal, Bix n Andy trigger, and a #4 contour 19" 9 twist McGowen prefit (Gasp), with a 1.250" shank.
Still waiting on my Manners LRH.

I had Manson design a custom 40 degree Ackley reamer based on Lapua brass with a .004 crush fit. I added .005 clearance .200 above the web to avoid the "Clicker" issue.
It's throated for the 225 ELDM seated just above the neck shoulder junction.

I got the barrel torqued on and set it in a cheap factory plastic stock for fire forming.
It weighs 7.4 lbs with bottom metal and Nomad LT suppressor, with the March FX 4.5-28×52 and LRH stock it'll be just under 10 lbs.

I fire formed a few cases and dialed her in at 100 yards, I was shocked to see my fire forming loads just stacking in tight.
I needed to fire three cases three times to send in for custom dies, so I worked up to 79 grains with 225 eldms while dialing in the scope.
I went for a group on the third firing and without any cherry picking shot a 3/8" group.
More to come.
View attachment 438404View attachment 438406View attachment 438407View attachment 438408

Oh HELLYEAH!

#4 contour 19" 9 twist McGowen prefit (Gasp), with a 1.250" shank.

LOL! I have had outstanding success with my McGowen pre-fit too.

 

[7.62 Gunner]

Oh HELLYEAH!

LOL! I have had outstanding success with my McGowen pre-fit too.

Me too, I put one of their prefits chambered in 7-300 wsm improved on my Tikka action last year, I've shot my best groups with it at 600-1000 yards.
I'm sticking with what works till it doesn't

Did you get that 338 NMI together?

 

[FEENIX]

Me too, I put one of their prefits chambered in 7-300 wsm improved on my Tikka action last year, I've shot my best groups with it at 600-1000 yards.
I'm sticking with what works till it doesn't

Did you get that 338 NMI together?

It is near completion. I had my GS built me reloading and hydraulic forming dies.

 

[7.62 Gunner]

Operation fire form, 30 to go

 

[7.62 Gunner]

Fire forming with 212 eldx, 12" gong

 

[buckbrush]

Fire forming with 212 eldx, 12" gong

Recoil doesn't look bad at all. What is the FF load?

 

[7.62 Gunner]

Recoil doesn't look bad at all. What is the FF load?

Yeah the Nomad does a great job with recoil reduction, I can spot every hit at 550 yards on 15x even with the plastic sps stock.
77 grains Ramshot magnum with the eldm jammed.
I'll do another video with 225s when I get a load together

 

[Monteria]

Recoil does look minimal!

What kind of velocity are you predicting from the 225s and a 19" tube?

I'm planning a 16 or 18" 30-06 suppressor host as a short range compact option, because I already have a 26" carbon six 300prc host for long range. But maybe I can just change the PRC barrel out and kill 2 birds with one stone?

Or maybe I should wait for the form 4 approval and try it out before going crazy?

 

[7.62 Gunner]

Recoil does look minimal!

What kind of velocity are you predicting from the 225s and a 19" tube?

I'm planning a 16 or 18" 30-06 suppressor host as a short range compact option, because I already have a 26" carbon six 300prc host for long range. But maybe I can just change the PRC barrel out and kill 2 birds with one stone?

Or maybe I should wait for the form 4 approval and try it out before going crazy?

Right on which suppressor are you going to run?
I've already hit 2800 with Retumbo on once fired brass, I'll get serious when my dies are done, for now I'm partially sizing the neck with standard 300 NM dies.
Honestly though 2700-2800 is all I need to 1100 yards, my main objective is to run H1000 or Retumbo I could care less about playing the N570 game.

 

[Monteria]

AB Raptor 4 stack and 5" reflex. So really total length will only be 30.7", which may or may not prove to be terrible. I bought the barrel before any intention of buying "my son" a suppressor though.

If you are pushing 225s at 2800 from a 19" tube, I may have to research OALs of the NM to confirm fitiment, then rethink everything.

 

[Monteria]

Just researched it. New case head size... not feasible for me. I'm too deep for that kind of change now.

 

[buckbrush]

Yeah the Nomad does a great job with recoil reduction, I can spot every hit at 550 yards on 15x even with the plastic sps stock.
77 grains Ramshot magnum with the eldm jammed.
I'll do another video with 225s when I get a load together

Leave it in that stock!