7RM Load Development Results – Advice Moving Forward

[Full Curl]

Looking for some advice. I'm not new to reloading but I don't have as much knowledge and experience as many on here do. I had a new carry hunting rifle built chambered in 7RM. Bartlein #3 24" 1:8. I recently started load development for 160 Accubonds pushed by H1000. After a couple OCW tests I have 2 good accuracy nodes… a lower one at 65.3 grains (2,869 fps) and an upper one at 69.0 grains (3,015 fps). At 69.0 the primers start showing the slightest sign of flattening but not much. In the photo, the 69.0 case is on the right and the 65.3 case is on the left. I don't notice any other signs of pressure… although I had the bolt cerekoted and its brand new so still not worn in silky smooth yet and I'm not sure I would notice a little sticky bolt lift?? It certainly shows no signs of noticeable heavy lift.

I have not gone beyond 69.0. Both loads are sub MOA with the 65.3 load having a slight advantage at a solid 1/2 MOA. I was really hoping to find a good node in the 67.5 to 68.5 range like I have with previous 7RM's but it's not there with this one. Looking for advice on what load to move forward with. My goal is to focus on a specific load and that's the one for this rifle. It will be used 80% for hunting and 20% for occasionally banging steel, rarely over 800yds. The rifle should easily outlast me. I'm not sure how "hot" the 69.0 load is, but barrel life, case life, and rifle wear and tear is a consideration. At the same time, I feel I'm sacrificing a lot of the advantages of the 7RM to move forward with an under 2,900 fps load.

Anyway, please talk me through this and what load to move forward with and not look back. Thanks!!

 

[cajun]

Hogdon lists 66 grains of h1000 with the 160 partition at 2839 fps from a 24" as max. They do pressure test their loads. Nosler doesnt list h1000 with the 160 but with the 168 ablr ( different bullet profile ) they show 70 grains with 2993 fps. Trying to read brass and primers is kinda voodoo. By the time you start seeing ejec marks and bolt lift your usually over max. In some rifles that are hard cocking uncocking like a savage bolt lift can be hard to see until it's really hard. I have not used h1000 but with R 26 and the 160 ab we can get close to 3000 but are running it 2950 in my sons rifle.

 

[Full Curl]

Hogdon lists 66 grains of h1000 with the 160 partition at 2839 fps from a 24" as max. They do pressure test their loads. Nosler doesnt list h1000 with the 160 but with the 168 ablr ( different bullet profile ) they show 70 grains with 2993 fps. Trying to read brass and primers is kinda voodoo. By the time you start seeing ejec marks and bolt lift your usually over max. In some rifles that are hard cocking uncocking like a savage bolt lift can be hard to see until it's really hard. I have not used h1000 but with R 26 and the 160 ab we can get close to 3000 but are running it 2950 in my sons rifle.

I looked at both of those and some other bullet brand manuals and max is all over the place. That 66.0 max is listed with a 160NP. Then they list 70.0 as the max for a 162 H-BTSP and 68.0 for a 150NP. I'm not sure how the AB fits in there?? I've always tried to let the rifle tell me but like you said that's voodoo at best sometimes. I wish I had a good accuracy node right there around 2950 or even 2900+ but at 2869 I just feel like I'm shortchanging the caliber's potential. BUT I'm also one who has never loaded at the far leading edge of the pressure cliff just to squeeze another 30fps+ out. I have another stock 700 Rem 7RM that likes 68.5 of H1000 pushing the 160AB and that rifle has 700+ firings of that round on it and still shoots great. I notice bolt lift pressure signs at 69.5 with that rig.

 

[Quintus]

Are these loads on virgin brass?

 

[Bob Wright]

There aren't any pressure signs on your brass. However, it sounds like your rifle is new with low round count. It should speed up over time. If we still had access to Reloder powders, RE23 would get you the speed you're looking for.
So, while you are still loading for that 2950 type speed, changing powders and doing some ladders would show you more potential even as the barrel speeds up over time.
But the other question is, does your bullet's terminal performance at the distance you want to shoot require significantly higher speeds?

 

[Full Curl]

Are these loads on virgin brass?

Yes.

 

[Full Curl]

There aren't any pressure signs on your brass. However, it sounds like your rifle is new with low round count. It should speed up over time. If we still had access to Reloder powders, RE23 would get you the speed you're looking for.
So, while you are still loading for that 2950 type speed, changing powders and doing some ladders would show you more potential even as the barrel speeds up over time.
But the other question is, does your bullet's terminal performance at the distance you want to shoot require significantly higher speeds?

As of right now it has less than 100 rounds on it, including initial break in. I'm sure it'll gain some speed over the next 100 or so. As for the bullet performance at range, I'm not aware of an AB requiring higher speeds, but I'm more interested in moderate speed for gained trajectory performance. I'm not even sure less than 2900 fps would be considered moderate performance for a 7RM?? Maybe on the lower end of it?? I'm not trying to win a race, I just want to capture the full potential of the rifle as best I can with this bullet and powder. If I had a node in the middle somewhere 67.0 to 68.5 I'd probably call it a day there. Accuracy is great with either load, I'm just a little concerned with leaving some performance on the table so to speak with the lower node or risking excessive rifle/case wear and tear with the higher node.

 

[Koda_]

I have not gone beyond 69.0. Both loads are sub MOA with the 65.3 load having a slight advantage at a solid 1/2 MOA. I was really hoping to find a good node in the 67.5 to 68.5 range like I have with previous 7RM's but it's not there with this one.

Your over thinking this. You have a sub MOA load safely at 3000+fps pushing 160gn bullet is a legit 7RM round, run a seating depth test if you want to shrink its group size even more but your already good to go.
Watch for pressure signs though as the new barrel speeds up....

 

[Quintus]

Yes.

I just broke in a 7rm with new Norma Brass. I was running monos with RL26 and got a noticeable gain on the second firing. I also topped out at the first firings first signs of pressure. You may want to play with some of your once fired before you get too set on either of your current options.

 

[Bob Wright]

Yes.

On virgin brass you're developing a load for, you're wasting a lot of effort and material chasing a max load. Once you go to a 1x or greater firing, you'll be in trouble.
Part of the pressure is being used to fireform new brass.
It took me 3 firings and some annealing to fully form the brass I used. Then I had to rework that load to get back into the 2920 fps node where the 180 Bergers like to run.
If you have plenty of brass 1x fired, start back with them and measure headspace first. I bet they have .005 variation across all of them.
This chambering will grow brass about .020 after first firing with a lot of variation. You're not even close to getting this brass settled down for reloading.