300 Norma Improved 35 degree

[Alex Wheeler]

Everyone seems to think N570 will smoke your barrel in half the time as every other powder. Its irrelevant, if you dont overheat your barrel its a non issue. I dont even consider it hard on throats. Whats hard on throats is shooting too quickly and burning a lot of any powder. Pick your powder based on how it shoots. Thats it.

 

[schw15]

Not enough to concern me with the amount of rounds I will put on the barrel as a hunting rifle. I don't really concern myself with barrel life on hotrod cartridges that move heavy for caliber bullets at such fast speeds. It will never last as long as a 308 win and that's just the nature of the beast. When the barrel wears out, I'll just set it back or get a new barrel.

I understand that I was just wondering because I hear that a lot so thought I would ask.

 

[Ledd Slinger]

Alex is right. Take care with how you treat your barrel during shot strings and it will last longer. Same goes for any cartridge and powder combo.

The one powder that I would say causes premature barrel wear is RL17. I have used it in fast 6.5s. It can cause a lot of premature fire cracking and erosion in the throat even with normal use. But that's not a powder to be concerned with in the NMI. I am on my 3rd 300 NMI build and I have used N570 in all of them. Most of my groups are only 3 or 4 shots fired in rapid succession, then I let it cool. Nothing ive seen with a borescope using N570 causes me any concern with premature barrel wear. I have 150+ rounds on my current barrel and the throat and lands doesn't look any worse off than any other big 30 cal using any other powder. Still looks very healthy.

N570 is very temp stable and produces excellent speeds. For me, the purpose of a 300 NMI is launching big bullets really fast. If I didn't care about running 220-230gr bullets up around 3150-3200 fps, I'd save some cost on powder and build a smaller 300 PRC or something similar. The NMI is made for speed. Just pay attention to your barrel heat and it will serve you well for a long time.

If you intend to shoot the rifle in matches that require long shots strings in hot temps, then the 300 NMI might not be a good choice. So be sure to choose the right tool for the job as well.

 

[schw15]

I usually shoot 5 shot string for load development and practice. But then on some days I will shoot 8 in under 2:30 because that's what the matches are and want to see if the load holds up

 

[schw15]

I'm going to try and buy 8 pounds of n570 and see with the 245s

 

[Ledd Slinger]

I'm going to try and buy 8 pounds of n570 and see with the 245s

Yeah N570 is good for 215gr and heavier so if it doesn't work with the 245, it should work well with 215, 220, or 230.

215gr and lighter seem to work really well in the H1000/N565 burn rate area

 

[schw15]

Yeah N570 is good for 215gr and heavier so if it doesn't work with the 245, it should work well with 215, 220, or 230.

215gr and lighter seem to work really well in the H1000/N565 burn rate area

Might try to sell or trade my 40 plus pounds of n565 haha

 

[schw15]

Shot today my 81.5 load still shot good but sped up more. The pressure issues came back. Look flat to me

 

[Ledd Slinger]

I dont know about loading with that powder, but flat primers are not a clear indicator of pressure. More likely an indicator of excessive headspacing on the FL sizing die. Ejector marks and stiffer bolt lifts are clear signs of reaching pressure.

 

[schw15]

I dont know about loading with that powder, but flat primers are not a clear indicator of pressure. More likely an indicator of excessive headspacing on the FL sizing die. Ejector marks and stiffer bolt lifts are clear signs of reaching pressure.

The load was fine then today bam. Going to test 78 and 79 grains to see.

 

[Darkside]

Neither one of those 2 show pressure.

 

[schw15]

Went back shot 81.5 in first formed brass 2x fired and 3 time fired brass and the last two sets opened up hard avg 3090 sd of 6 so I will try 78 grains and 79 to see if it goes away

 

[tom]

It's not uncommon for the load to need retuned as the brass becomes fully formed for the first few cycles. It's more obvious on these lapua based cases. We usually make brass on a fresh barrel, and barrels are also speeding up at the same time, which will have you chasing your tail a bit. My first 338 lapua improved went from the pet load being 103 to 99 grains of retumbo between fresh fireformed brass, and formed +3... I never realized it was the brass until I needed to make more brass for the same barrel later in life. I had just blamed the barrel seasoning in.

Tom

 

[schw15]

I know there will be some brass growth. This Is a head scratcher for sure for me. I know n565 isn't the fastest but when I back it down to 78 grains I will be 30 nosler loads. My dad runs imr 7977 77 grains 30 nosler 230 a-tip doesn't seem to make sense to me. But if it is powder I will try to get some n570 or sale out

 

[Ledd Slinger]

Just be careful with N570. Small amounts of powder can make significant results on the chronograph. Starting at 89gr, I would work up in no more than 0.3gr increments with an accurate scale until you reach 92.3gr or wherever you see signs of pressure first. If you want to work up a ladder in 0.2gr increments, that's even better. If you are jumping in 0.5gr increments, you could be close to max pressure then jump the next charge 0.5gr and go over pressure. So again, increase charges in small increments.

If you can reach 92.3gr of N570 without pressure signs, that seems to be the magical number for the 215, 220, and 230gr Berger. I always seem to find a good speed node and accuracy there. Also recommend using CCI 250 primers.

 

[schw15]

I have cci 250 but been using fed215. Yes I did do .5 with n565 but felt like I started very low at 80 grains. I appreciate all the help and advice just trying to fix the issue. The rifle shoots great with great numbers. Based on how this pressures out if I get n570 I will start 87 grains to be safe.

 

[Ledd Slinger]

I have cci 250 but been using fed215. Yes I did do .5 with n565 but felt like I started very low at 80 grains. I appreciate all the help and advice just trying to fix the issue. The rifle shoots great with great numbers. Based on how this pressures out if I get n570 I will start 87 grains to be safe.

I love Fed GM215M in some of my other rifles and is usually my "go-to" primer, but I've never been able to get them to ladder worth anything in any of my three different 300 NMIs using N570. CCI 250 has laddered well in all of my NMIs. I've come to a personal conclusion that N570 just seems to react with much better consistency and forgiveness on target with the CCI 250 primer. Use whatever works best in testing of course, but with N570 in particular, I recommend trying the CCI to start

 

[schw15]

I love Fed GM215M in some of my other rifles and is usually my "go-to" primer, but I've never been able to get them to ladder worth anything in any of my three different 300 NMIs using N570. CCI 250 has laddered well in all of my NMIs. I've come to a personal conclusion that N570 just seems to react with much better consistency and forgiveness on target with the CCI 250 primer.

I will see what I can do. I'm gonna try to get one barrel throated longer for these new 245 I just got. Usually in .235 freebore there close to 3.700 oal but mine is 3.650 might have a short chamber issue too because had to cut die off then the new bullet central die camovers pretty dang good.

 

[Ledd Slinger]

On another note, I know some people using H1000 prefer the CCI 250 as well. Since N565 is in that burn rate, I would try a primer swap to the CCI if you do any further testing with N565

 

[schw15]

Will do. Going in morning hopefully to test 78 grains but already primed so will test cci next for sure