First official 7 mm RM load development.

[Nandy]

After I got all of the little details taken care off I headed to the range to try 2 loads. I shot with separate rest for the forearm (adjustable) and buttstock(sand bag). The chrono is about 40 feet. I cannot get it any closer as we shoot thru concrete tubes.

RL-22 for all loads. This is what I shot:

110 Switch Barrel Action - SAV-2 - Choate Varmint Stock - Leupold VX III 3.5-10x50
Brux (SSS) 7MM RM, 1-9, 26", Varmint Barrel, SSS Brake

Ignore the center target. It was there just for me to make sure I was in paper. The lower 2 shots on that target where shot at target 7.



Date: 9/11/2012
Caliber: 7mm RM
Bullet: Accubond
Grains: 140
200 Yds

String-----Gr.----Grp Size----Std Dev---Ext Spread-----Hi Vel-----Low Vel---Ave Vel----Sht 1------Sht 2------Sht 3
1---------66.5---1.343----------24-------47----------3003------2956------2976------3003------2969------2956
2---------66.8---3.213----------21-------40----------2989------2949------2973------2949------2989------2982
3---------67.1---2.817----------20-------34----------3030------2996------3019------2996------3030------3030
4---------67.4---2.245----------35-------49----------3065------3016------3041------3016------****-----3065
5---------67.7---2.746----------12-------21----------3065------3044------3051------3065------3044------3044
6---------68-----0.547----------20-------35----------3058------3023------3046------3023------3058------3058
7---------68.3---3.556----------25-------49----------3093------3044------3072------3044------3093------3079
8---------68.6---4.137----------17-------29----------3122------3093------3112 ------3093------3122------3122

I would shoot the first cartridge for each load at the pertaining target. Meaning I shot all the loads in the column "shot 1" then the next column and so on.
My best 2 groups are 6 and 4 (if I ignore that high shot). I did have a problem were I forgot to change the string number for the last set of shots and to make it worst the chrono missed one shot. I know my the "shot 1" column is correct so I looked at the numbers and determined that shot 4 on column "shot 2" is probably the one that was missing.





Date: 9/11/2012
Caliber: 7mm RM
Bullet: Speer Hot Cor
Grains: 145
100 yds

Hi Vel: 3044
Low Vel: 2962
Ave Vel: 3004
Ext Spread: 82
Std Dev: 32
Velocity
3023
2969
2989
2962
2982
3044
3030
3037

This shot set was worst as the chrono missed 3 shots. I do have to take responsibility on this group as the chrono was not well aligned. I had 2 test loads to make sure they were in paper, these loads were 66.6 if I recall right then I shot the rest 66.2, 66.5, 66.8 in similar order as the Nosler bullets. I have to guess that the chrono missed one of the test loads but it is hard to tell where was the other shot lost...




My best group is in the .4??" (sorry, I dont have that number handy):



I am going to load those 3 best and see if I can replicate the grouping. Any advise, ideas or positive criticism? I was amazed on how those groups went from open to suddenly tight...

Thanks.

[Nandy]

Is this in the right forum or does it needs to go in reloading?

[Speedrat1]

I've found that most if not almost all load barrel combinations will have sweet spots in the workup. Yes I've seen it many times a 1/2gr difference change a group size from best of the workup, 1/2" to a inch and the next load either size be 2 -3 times as big. Sometimes if you're on the max a combination will tolerate the group will open up even faster or rather larger. If you want my two cents I've switched to never using less than 4 shots in a group test, if I can 5. I've had many, many loads that looked fine at 3 shots but don't back it up with the larger groups. If I can't back it up with a second group of at least as good as the first, I keep working.

[Nandy]

thanks! I appreciate the info. Most of the time I keep it at 3 to keep expenses down then if I like the group I retest... Problem been everytime I retest I dont end up with the same results...