300 Win Mag and N570

[Iron Worker]

I was shooting 208 ELDms from my new 300 Mag. C.O A.L 3.500. 79.5 grs N570 Fed 215 primers. I was getting over MOA at 100yds, and the EXT spread was 100FPS(2,839-2,942) and SD about 60. That isn't very good. Even so, I could hit the gongs at 300-400 yds. 10" rifling twist Bergara B-14 HMR. What could be the cause?

 

[Dmagna]

I have found that N570 doesn't like to under pressure. You will get crazy numbers until you hit a load that makes consistent pressure. Has done that in my win mag, lapua, prc and others I have used it in. I don't know the barrel length but you should be at 3000 fps with a 208 with a 26" barrel with n570.

 

[Iron Worker]

I have found that N570 doesn't like to under pressure. You will get crazy numbers until you hit a load that makes consistent pressure. Has done that in my win mag, lapua, prc and others I have used it in. I don't know the barrel length but you should be at 3000 fps with a 208 with a 26" barrel with n570.

Thanks,very helpful. 26" bbl

 

[Elk Hunter 338]

If that doesn't tune in get some h1000 and cci 250 mags .. This combo is made for the 300 WM

 

[Iron Worker]

If that doesn't tune in get some h1000 and cci 250 mags .. This combo is made for the 300 WM

I have those component's Thanks

 

[Lefty7mmstw]

v570 is working well in my 300 win with the 200 elx-x, but she's slow... I was only getting 2600 fps from a 24" bbl. I forget the charge but it was Vit. data for a 300win with 200 gr pills

 

[SCVOJTA]

The 2 powders I'm currently playing around with are Magpro and H1000. Both show great promise with Berger 215's and 208's. My ladder test apparently started on the high side of pressure so working backwards from 3100+ fps.
I'd say you should be at least in that 2900+ velocity range.

 

[MTbackwoods]

v570 is working well in my 300 win with the 200 elx-x, but she's slow... I was only getting 2600 fps from a 24" bbl. I forget the charge but it was Vit. data for a 300win with 200 gr pills

Your COAL needs to be at least 3.6" with n570. If you loaded to SAAMI specs, it's going to run slow because you're not getting enough pressure. Seat that bullet out further and fill the case with powder. You almost can't pressure out with n570 in a win mag case. It's a bulky powder so you're going to get powder crunch but I keep going up by .5 until the bullet springs out of the case by .005-.010"

 

[tim1457]

I'm using Reloder 26 with Hornady ELD-X 220gr bullets in a Browning X-bolt Max in .300WM. 26" barrel is averaging 3006 fps.

 

[Lefty7mmstw]

Your COAL needs to be at least 3.6" with n570. If you loaded to SAAMI specs, it's going to run slow because you're not getting enough pressure. Seat that bullet out further and fill the case with powder. You almost can't pressure out with n570 in a win mag case. It's a bulky powder so you're going to get powder crunch but I keep going up by .5 until the bullet springs out of the case by .005-.010"

3.6" isn't gonna happen with my rifles... All 3 are mag. fed and need to stay under 3.4" if not a bit shorter. I'm also running v565 with the same bullet, and it does fine. In fact, I tossed (accidentally) a v565 group and a v570 group at the same 100yd target with 1 of the rifles and it was under moa for 7 shots with 2 loads. The rifle in question is my Savage Impulse 300win with a 6x Sightron on top.
I'll just burn the v570 in another cartridge. v565 is at a few fps under 2700 fps right now in the 300win and I can probably go up; I just haven't worked it.

 

[MTbackwoods]

3.6" isn't gonna happen with my rifles... All 3 are mag. fed and need to stay under 3.4" if not a bit shorter. I'm also running v565 with the same bullet, and it does fine. In fact, I tossed (accidentally) a v565 group and a v570 group at the same 100yd target with 1 of the rifles and it was under moa for 7 shots with 2 loads. The rifle in question is my Savage Impulse 300win with a 6x Sightron on top.
I'll just burn the v570 in another cartridge. v565 is at a few fps under 2700 fps right now in the 300win and I can probably go up; I just haven't worked it.

Makes sense. Yeah a faster burning powder is going to be your friend then. Good luck

 

[Perroe]

3.612 with Berger 215 and n570 is what mine likes

 

[Shane Lindsey]

I was shooting 208 ELDms from my new 300 Mag. C.O A.L 3.500. 79.5 grs N570 Fed 215 primers. I was getting over MOA at 100yds, and the EXT spread was 100FPS(2,839-2,942) and SD about 60. That isn't very good. Even so, I could hit the gongs at 300-400 yds. 10" rifling twist Bergara B-14 HMR. What could be the cause?

What cases? You could also be over pressure. My ES was higher with more N570. Drop it down to the 78 ish range if using ADG. 80ish if using Norma. When you find the sweet spot it will sing, but then you will have eaten your throat and need to adjust

H1000 in the 2850 range is a happy place.

 

[tomcat818]

While loading N570, Berger 215 HT, CCI 250, 26" 8 twist, and 3.595 COAL(Max mag 3.615) I noticed compressed loads @ 79gr. The Hornady seating stem started to leave witness marks on the bullets and pull them out of the cases when retracting. I was using my usual .002" neck tension and had to re-seat several times before getting the CBTO I was looking for which most likely crushed some of the powder. The SDs and ESs went up dramatically from this at 78gr:

Stats - Average	2904.84​	fps
Stats - Highest	2911.62​	fps
Stats - Lowest	2899.53​	fps
Stats - Ext. Spread	12.09​	fps
Stats - Std. Dev	6.17​	fps

to this at 79.5:

Stats - Average	2946.7​	fps
Stats - Highest	2994.61​	fps
Stats - Lowest	2911.1​	fps
Stats - Ext. Spread	83.52​	fps
Stats - Std. Dev	43.1​	fps

Accuracy was good for both these charge weights @ .754" and .833" respectively at 100 yds. However, the hit probability @ 600yds on a 1MOA target drops from 18% to 2% respectively. I've since gone to a Redding Type S Elite die set with a Hybrid Target stem which doesn't mark the bullets or grab them and I can seat them at .002" neck tension.