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.

http://i305.photobucket.com/albums/nn215/nandy_temp/20120911_145636.jpg

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.

http://i305.photobucket.com/albums/nn215/nandy_temp/20120911_145636_grp6.jpg

http://i305.photobucket.com/albums/nn215/nandy_temp/20120911_145636_grp4.jpg

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...


http://i305.photobucket.com/albums/nn215/nandy_temp/20120911_145620.jpg

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

http://i305.photobucket.com/albums/nn215/nandy_temp/20120911_145620_grp1.jpg

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...