OCW Help 7mm mag 175 smk

[justramit]

I am trying to find a load for my 7mm remington Long range with 175 smk. Is new federal brass just ran through my neck sizer. I seated all loads .020 off of lands to start and went in .4 grain increments from 70 grains to 72.8. My chrony had some errors but this is what I got for each increment shooting round robin at 100 yds. I wasn't real happy with rest I was using and hada little trouble holding steady as I would have liked. Am sure I had a few fliers. I was curious to what you guys would work with after these results I posted target also. I was thinking 70.8 and 72.4 are areas to look around

70g - 2879, 2867, error
70.4 - 2894, 2897, 2926
70.8 - error,error, 2918
71.2 - 2921, 2926, 2953
71.6 - 2965, 2960, 2969
72 - 2953, 2985, 3012
72.4- 2992, 2985, 2977
72.8 - 2983,2985, error

 

[Steel head]

I’m a degenerate neck sized but I’ll be the first to admit it’s often easier to get smaller ES spreads with full length sized brass.


It kinda appears you might have a node at 72.4 to 74.8.
If it was me I’d try 72.6 and see if you get a good ES out of it then do a jump test.
That’s also a fairly reasonable speed.

 

[justramit]

That is kind of what I was thinking I am pretty sure I pulled that last shot on 72.8 and that is why chrony errored too. Kind of thought about trying 72.6, 72.8, and 73 and see what happens.

 

[Dthomas3523]

If those numbers hold up long term, 72.6 and tune seating depth.

Though based on the other numbers, I wouldn’t count on these numbers from 3 shot strings to hold up the same over time.

 

[justramit]

I was kind of thinking about between 70.4 and 70.8 also maybe 70.4 had those two in one hole and am wondering if I pulled the third one. If I did that charge would be pretty close to 70.8

 

[Jordanwickham]

I was kind of thinking about between 70.4 and 70.8 also maybe 70.4 had those two in one hole and am wondering if I pulled the third one. If I did that charge would be pretty close to 70.8

Steel Head and Dthomas are right 72.4-72.8 are the go to based on the information at hand.
70.4-70.8 could possibly be a low OCW node but it's hard to tell with a couple pulls, but the numbers at those loads are all over the place whereas the numbers for the evident high node are actually pretty good.
I would definitely stay with the 72.6 and do a velocity check on 5-10 rounds then seating test.
What powder are you running?
Also in the original post are you saying this is virgin brass?

 

[justramit]

Yes is virgin brass and retumbo, will load up 10 at 72.6 and see what happens

 

[Jordanwickham]

Ok so with it being virgin you may have to tinker with the once fired to get back into that velocity window. Never messed with Retumbo ( never found it in local stores ) of the powders I tried I think the most I got to go in was around 72 gr of RL26. Would have to check my notebook for the 7mmrm it was 72 gr of something @3020.

 

[justramit]

Sierra shows max of 71.1 @3.290. Mine are 3.390 OAL. That is .020 off lands

 

[Jordanwickham]

Sierra shows max of 71.1 @3.290. Mine are 3.390 OAL. That is .020 off lands

Thought 72.8 seemed a little high but as long as you aren't hitting pressure send it.

 

[justramit]

Well I loaded up 10 at 72.6 and did 10 at 70.6 just for the hell of it. Shot both strings with 2 min in between shots and got the following. First shot at 72.6 was cold bore dunno if that would affect velocity that much.

72.6
1. 2952
2. 2982
3. 3000
4. 2998
5. 3007
6. 2976
7. 2994
8. 2991
9. 2979.
10. 2994.

Avg 2987
ES 55
SD 15

Take away first shot
Avg 2991
ES 31
SD 9



70.6
1. 2948
2. 2904
3. 2923
4. 2975
5. 2962
6. 2979
7. 2948
8. 2974
9. 2961
10. Error.
Avg. 2952
ES 75
SD 23

 

[Jordanwickham]

Is this still virgin brass? Or was this once fired? How are you setting neck tension?

 

[justramit]

Is this still virgin brass? Or was this once fired? How are you setting neck tension?

Was virgin brass just ran it through my neck sizer

 

[justramit]

Which way should I go with seating depth these are all .020 off lands

 

[trailrider121]

Late to the party. I noticed in your original target 71.6grs looks like a scatter node. You did what I would have done, 1.5% +/- from 71.6grs, and should put you in a good node. You shown those charges and looks good, don't get hung up on ES, let the target show you down range. Decide if you plan to go with lower or higher node and conduct seating depth test. I like to perform my seating depth test at 100 yards, and in .003" increments starting from jam -.010" . You should find find a couple nodes in seating depth test, and roll with the one that shows 2-3 groups that have same POI. Then test at long range to confirm rifle load. My 2 cents.