300 Norma vs 300 Norma Imp

[Gamesniper19]

The 300 PRC is derived from necking down the 375 Ruger case which was also developed by Hornady and has been around for quite some time now. The 6.5 PRC is just a shortened necked down 375 Ruger. Though the 300 PRC is very slightly smaller than the Nosler Jeffrey cases, it is very close in performance. PRC will push 215gr Berger to 3100 fps just like the Nosler.

I run the 375 Ruger necked down to 338 cal (338-375 Ruger) for a long time. Long before the PRCs came into being. It can hit over 3000 fps with 250gr Berger bullets from a 26" barrel and very accurate. So rounds based on the 375 Ruger case are no slouches by any means especially when you consider that factory ammo for the 338 Lapua using 250gr bullets is listed at 2850 fps. And now with ADG and Lapua making PRC brass, the 300 PRC or variants from that case are a good choice for a powerful and accurate long range round.

Here is a photo of my 338-375 Ruger case necked up and fireformed compared to a virgin piece of ADG 300 PRC brass on the left that I use to make the rounds.
View attachment 296257

Take it one step further. 6.5 GAP on L and 7-300 NMi on R

 

[LeddSlinger]

Take it one step further. 6.5 GAP on L and 7-300 NMi on R

Big pass for me on a 7mm-300 Norma. The 28 Nosler is bad enough at scorching barrels pretty fast so I'm sure that one would be really bad. Although I bet speeds would be impressive, I don't like having to retune rifles as often as I'm sure that case would require. The 300 NMI actually isn't too bad on the lands once the barrel is broke in. And with the High BC 220gr Berger ripping at 3200 fps, there's really not much more I would ever need for the level of long range shooting I do.

I do have 200 pieces of ADG 6.5 SAUM brass and waiting on a reamer for an improved design we drew up on the SAUM case with 40 deg shoulder and some other modifications. Have a bunch of Berger 140gr and 144gr on hand for testing.

 

[Gamesniper19]

Big pass for me on a 7mm-300 Norma. The 28 Nosler is bad enough at scorching barrels pretty fast so I'm sure that one would be really bad. Although I bet speeds would be impressive, I don't like having to retune rifles as often as I'm sure that case would require. The 300 NMI actually isn't too bad on the lands once the barrel is broke in. And with the High BC 220gr Berger ripping at 3200 fps, there's really not much more I would ever need for the level of long range shooting I do.

I do have 200 pieces of ADG 6.5 SAUM brass and waiting on a reamer for an improved design we drew up on the SAUM case with 40 deg shoulder and some other modifications. Have a bunch of Berger 140gr and 144gr on hand for testing.

I hear you. To each their own and your SAUM idea sounds cool although speaking of barrel burners - more powder and more speed out of an already very fast cartridge. I know GAP says the 4S will last 2500 rounds but I am not so sure. Have about 300 or so through mine and with a 140 berger I get 3190 FPS and everything it has hit has dropped stone dead on the spot. Will be cool to see what you get out of your updated model

I built the 7-300 NMi as strictly a hunting rifle. 70-100 rounds a year and if I kept it long enough - 10-13 years of barrel life, I am good with that. I love making wildcats and learning all I can about them through tuning and building. It makes my brain happy! More range days you say? Yes please!!!

 

[L.Sherm]

1,000 Accurate rounds out of a 7-300NMI
Hmmm that might be a stretch, 600 to 800 on a 28 Nosler if its taken care of is the Norm. I bet after 800 on a 28 the barrel is completely toast thats about .080 or more throat wear which is a ton.

 

[Huntnful]

1,000 Accurate rounds out of a 7-300NMI
Hmmm that might be a stretch, 600 to 800 on a 28 Nosler if its taken care of is the Norm. I bet after 800 on a 28 the barrel is completely toast thats about .080 or more throat wear which is a ton.

I wish I would have kept better, exact data on my 28 Nosler. But I'm right around 600 rounds +-50. Throat erosions is quite a bit, and I've babied it. No long shot strings ever, and always letting it cool down. It still shoots the 180 VLD targets and 169 Hammer Hunters into 1/2-3/4 MOA pretty consistently. But I feel like its day is coming soon based on how far out I need to seat bullets now.

BUT, I also believe the hammer bullets will extend the accuracy period quite a bit. They don't care much about jump and they're pretty long (for the weight) with a fatter Ogive. So while my 180 VLD's don't even reach the throat any more while staying in the neck of the case, the 169's seat .200 into case neck still at the point of jam. And then I seat them .100 deeper.

So what really causes the accuracy to fall off? Is it not being able to seat the bullets far enough out for the accuracy node anymore? Or something else?

 

[L.Sherm]

I believe its a combo of things.
One thing to take into consideration as your throat wears is jacket integrity of your bullet.
Its my main reason why I dont spin bullets no more than necessary

 

[Huntnful]

I believe its a combo of things.
One thing to take into consideration as your throat wears is jacket integrity of your bullet.
Its my main reason why I dont spin bullets no more than necessary

Great point! Another + for the mono bullets as well. I do believe I'll finish out this barrel with the hammer bullets and see how they perform on game this season as well.

 

[.222 ND]

There is no free lunch with fireforming. I did enough of it to know that I don't want to do it anymore.

 

[L.Sherm]

Doesn't bother me one bit, ive fireformed 1,000's in my sage rat calibers and done right they can be very accurate.
Hunting rounds same thing, I dont get serious about load development anyway untill minimum 75 rounds down a new barrel so its perfect time to fireform or go the hyd. Forming die route.
After there AI'd you will spend alot less time trimming cases which i despise.

 

[LeddSlinger]

I hear you. To each their own and your SAUM idea sounds cool although speaking of barrel burners - more powder and more speed out of an already very fast cartridge. I know GAP says the 4S will last 2500 rounds but I am not so sure. Have about 300 or so through mine and with a 140 berger I get 3190 FPS and everything it has hit has dropped stone dead on the spot. Will be cool to see what you get out of your updated model

I built the 7-300 NMi as strictly a hunting rifle. 70-100 rounds a year and if I kept it long enough - 10-13 years of barrel life, I am good with that. I love making wildcats and learning all I can about them through tuning and building. It makes my brain happy! More range days you say? Yes please!!!

I shoot 3209 fps with the 140gr Berger in my 6.5 Remington Magnum (26" barrel, 59gr RL26). At about 3230 fps the crappy Remington primer pockets start giving out. Never have gone full throttle with it because I know the Remington brass won't take it and the brass has always been very hard to come by. If ADG or Lapua made brass for the 6.5 Rem Mag, I wouldn't change a thing. It is very accurate and really fast. Just as fast as many larger cases yet burns less powder so also very efficient.

BUT, the 6.5 Rem Mag is a barrel burner like the rest of the fast 6.5 rounds so I'm used to it. I have already burned out one barrel with that round. My son and I both have one. They are strictly hunting rifles and we don't shoot them much because I know they won't last much longer than a 28 Nosler.

Yes the SAUM improved version will be faster than the GAP 4S, but that's not the main reason. I want to do the 6.5 SAUM Improved because the brass won't stretch and need trimming as often and having ADG brass will be a big advantage over the Remington brass I am currently forced to use in my 6.5 Rem Mag.

 

[Gamesniper19]

I wish I would have kept better, exact data on my 28 Nosler. But I'm right around 600 rounds +-50. Throat erosions is quite a bit, and I've babied it. No long shot strings ever, and always letting it cool down. It still shoots the 180 VLD targets and 169 Hammer Hunters into 1/2-3/4 MOA pretty consistently. But I feel like its day is coming soon based on how far out I need to seat bullets now.

BUT, I also believe the hammer bullets will extend the accuracy period quite a bit. They don't care much about jump and they're pretty long (for the weight) with a fatter Ogive. So while my 180 VLD's don't even reach the throat any more while staying in the neck of the case, the 169's seat .200 into case neck still at the point of jam. And then I seat them .100 deeper.

So what really causes the accuracy to fall off? Is it not being able to seat the bullets far enough out for the accuracy node anymore? Or something else?

Yeah, I guess the only way to find out how long the barrel will actually last is to get it there. Even if it is 800 +/- rounds, that is quite a bit out of a big heave magnum that not many people are gonna wanna shoot 40 times on the range in one sitting. I know I wanna quit after about 20 LOL

Had a thought though around fire forming. If I did get to 800 and started to lose accuracy, my brass would probably need to be replaced about that time too. Might make sense to buy new brass and fireform in the old chamber to save the new barrel a bit. Doenst matter from a throat perspective cause gonna re measure COAL in the new barrel anyway but having 200 round of brass and then ladder and load testing, might save 250 rounds in new barrel life.

 

[LeddSlinger]

Yeah, I guess the only way to find out how long the barrel will actually last is to get it there. Even if it is 800 +/- rounds, that is quite a bit out of a big heave magnum that not many people are gonna wanna shoot 40 times on the range in one sitting. I know I wanna quit after about 20 LOL

Had a thought though around fire forming. If I did get to 800 and started to lose accuracy, my brass would probably need to be replaced about that time too. Might make sense to buy new brass and fireform in the old chamber to save the new barrel a bit. Doenst matter from a throat perspective cause gonna re measure COAL in the new barrel anyway but having 200 round of brass and then ladder and load testing, might save 250 rounds in new barrel life.

Yeah people do that all the time. It's a great practice for breaking in new brass without sacrificing barrel life

 

[Gamesniper19]

I shoot 3209 fps with the 140gr Berger in my 6.5 Remington Magnum (26" barrel, 59gr RL26). At about 3230 fps the crappy Remington primer pockets start giving out. Never have gone full throttle with it because I know the Remington brass won't take it and the brass has always been very hard to come by. If ADG or Lapua made brass for the 6.5 Rem Mag, I wouldn't change a thing. It is very accurate and really fast. Just as fast as many larger cases yet burns less powder so also very efficient.

BUT, the 6.5 Rem Mag is a barrel burner like the rest of the fast 6.5 rounds so I'm used to it. I have already burned out one barrel with that round. My son and I both have one. They are strictly hunting rifles and we don't shoot them much because I know they won't last much longer than a 28 Nosler.

Yes the SAUM improved version will be faster than the GAP 4S, but that's not the main reason. I want to do the 6.5 SAUM Improved because the brass won't stretch and need trimming as often and having ADG brass will be a big advantage over the Remington brass I am currently forced to use in my 6.5 Rem Mag.

Yup makes sense.
I am running a 24" PROOF bbl on ADG brass as well. My initial ladder had the top node at 3230 with 63.0 grains but was starting to show pressure and at 61.7 grains I was upper middle of a 15 shot ladder and dead on with accuracy node. George at GAP insists it will last 2500 rounds in that node....guess Ill have to keep shooting it to find out - woo hoo SEND IT!

But wait, this is a 300 NMi string - tapping out on the GAP track

 

[Alex Wheeler]

Fireforming is a good thing. You need at least 100 rounds on a barrel before you start tuning. Fireforming is a good way to do that without running it hard. Even if its a non improved case you still need to fire form virgin brass.