I haven't seen a lot of info around on 7MM-300 with H1000 so I'm posting my data.
The usual disclaimer, this load works well in my rifle. It might be dangerous in yours.
I had my rifle barreled by LRI especially for the Berger 195 EOLs. They used a "no turn reamer" with a final neck diameter of .313. My COAL is WAY past mag length at 3.735. I have .005 jump.
The ingredients:
Norma 300 Win Mag brass
H1000
Federal 215M primers
Berger 195 EOLs
Redding 300 Win Mag bushing die
Redding TIN bushings; .330, .325,.320, .315, .311
Case lube of your choice
Redding 7MM Mag seating die.
Powder:
I chose H1000 because it works well with 300WM, 7-300 and 338 Lapua. I don't want to have to keep a a bunch different powders.
Brass:
I was advised by mijp5, in this post, to neck down in .005 increments. That worked out well. https://www.snipershide.com/shooting/threads/7-300-win-mag-questions.6878762/#post-7017273
I checked all the brass for dented case mouths. Any dented cases were run through a lubed 30 cal mandrel before necking them down. I wanted to start with a perfectly round mouth. I lubed the case mouth each step. In theory you don't need to do that with TIN bushings but I wanted to be as gentle as possible with the brass. I started with a .330 bushing. My loaded neck diameter is .313 so my final bushing is.311. That gives me a nice .002 neck tension. 5 sizings was a chore but I am getting .0015 runout with the final product.
The unfired cases looked funny, see post above, but looked completely normal after the first firing.
Seating:
I had no issues seating with the 7MM Mag die but I wouldn't mind getting a Forster 300 Win Mag with the 7MM stem.
Charge:
I read as much as I could find before I started. There was not a lot out there for 7-300/H1000. I took some 7MM Practical info from Nathan Foster at Ballistic Studies. (Note, he uses STANDARD primers, not magnum.) I'm not sure why but he is a smart guy and I'm sure he has his reasons. I want the load to work in cold weather so I started lower using magnum primers.
I did ladder tests, starting at 71.6 and working up to 73.8.
There is a nice node at 73.8 (2967 FPS) but I wouldn't go there again. The first firing was perfect, no pressure signs. When I was testing velocity on the second firing I got sticky bolt lift and loose pockets. It's possible that I had a carbon ring but I am done experimenting. Barrel life is short enough with this round and making the brass is a pain in the ass. 72.6 seems accurate enough. The fliers were me, I could feel it as i yanked the last 2.
I should be getting low to mid 2900s. That should get me out to a mile fine. I will post exact speeds when I am finished with my temperature/velocity tests. I will post brass and barrel life when I have more data.
Cheers,
JBC
The usual disclaimer, this load works well in my rifle. It might be dangerous in yours.
I had my rifle barreled by LRI especially for the Berger 195 EOLs. They used a "no turn reamer" with a final neck diameter of .313. My COAL is WAY past mag length at 3.735. I have .005 jump.
The ingredients:
Norma 300 Win Mag brass
H1000
Federal 215M primers
Berger 195 EOLs
Redding 300 Win Mag bushing die
Redding TIN bushings; .330, .325,.320, .315, .311
Case lube of your choice
Redding 7MM Mag seating die.
Powder:
I chose H1000 because it works well with 300WM, 7-300 and 338 Lapua. I don't want to have to keep a a bunch different powders.
Brass:
I was advised by mijp5, in this post, to neck down in .005 increments. That worked out well. https://www.snipershide.com/shooting/threads/7-300-win-mag-questions.6878762/#post-7017273
I checked all the brass for dented case mouths. Any dented cases were run through a lubed 30 cal mandrel before necking them down. I wanted to start with a perfectly round mouth. I lubed the case mouth each step. In theory you don't need to do that with TIN bushings but I wanted to be as gentle as possible with the brass. I started with a .330 bushing. My loaded neck diameter is .313 so my final bushing is.311. That gives me a nice .002 neck tension. 5 sizings was a chore but I am getting .0015 runout with the final product.
The unfired cases looked funny, see post above, but looked completely normal after the first firing.
Seating:
I had no issues seating with the 7MM Mag die but I wouldn't mind getting a Forster 300 Win Mag with the 7MM stem.
Charge:
I read as much as I could find before I started. There was not a lot out there for 7-300/H1000. I took some 7MM Practical info from Nathan Foster at Ballistic Studies. (Note, he uses STANDARD primers, not magnum.) I'm not sure why but he is a smart guy and I'm sure he has his reasons. I want the load to work in cold weather so I started lower using magnum primers.
I did ladder tests, starting at 71.6 and working up to 73.8.
There is a nice node at 73.8 (2967 FPS) but I wouldn't go there again. The first firing was perfect, no pressure signs. When I was testing velocity on the second firing I got sticky bolt lift and loose pockets. It's possible that I had a carbon ring but I am done experimenting. Barrel life is short enough with this round and making the brass is a pain in the ass. 72.6 seems accurate enough. The fliers were me, I could feel it as i yanked the last 2.
I should be getting low to mid 2900s. That should get me out to a mile fine. I will post exact speeds when I am finished with my temperature/velocity tests. I will post brass and barrel life when I have more data.
Cheers,
JBC
