9 "3 shots" Groups at 302 Yards.

[Eaglet]

For my 300 RUM I got different components loaded 27 rounds using 9 different loads from 89 gr. of Retumbo to 95 gr. of Retumbo. 210 gr. Berger. Powder and bullets I did not change. I did change brass to Nosler brass, Primes to CCI-250 instead of fereral. I seated the bullet 0.015 into the lands. First time ever the action screws had been torqued using a torque wrench, also I used a cheek piece on the stock which does help a whole lot.
All 27 bulles in 9 "3 shots" groups shot at 302 yards averaged 0.667 MOA's which is 2.11" at 302 yards. Not so good... Well is a factory 300 RUM... is the same as saying 0.7" @ 100 yards... remember, that's an average of 9 different charges. The smallest group was 89 gr. @2924 ft/sec which grouped 1.2" at 302 yds. = 0.397" @ 100 yards. Because I'm quite low on muzzle velocity this is what I decided:

Please notice that the 1.5" group line touches the graph in two different places, at 90.9 gr. and at 91.7 gr. Half way in between would be about 91.3 gr. having a plus or minus 0.4 grains to keep my groups at 1.5" or less at 302 yards. My aim is to get closer to 1.0" at 300 yards.

Any coments, thoughts, ideas etc. are very welcome.

 

[edge]

Since a picture is worth a thousand words, you owe us 9 thousand

While I agree with your logic, a picture may show a flaw.
I often see VERY horizontal groups or VERY vertical groups, and even though they may be larger than other groups, a slight change in hold or something minor may make the groups exceptional.

edge.

 

[Eaglet]

Since a picture is worth a thousand words, you owe us 9 thousand

While I agree with your logic, a picture may show a flaw.
I often see VERY horizontal groups or VERY vertical groups, and even though they may be larger than other groups, a slight change in hold or something minor may make the groups exceptional.

edge.

I get your meaning! That's a lot of words I think I'll give you the pictures...

The reason the graph looks the way it does, is because I shot the group of 89.0 gr. and the group of 90.0 gr. twice, and I included it in the graph just to see how weird it would get.

 

[philny1]

RUM

You didn't mention what rifle you're using.
I'm getting some very similar results with a Rem M700 LSS in 338 RUM. This rifle's been tinkered with a bit. Working with one bullet, the 225gr AccuBond. I'm hard headed I guess, just can't bring myself to use the Sierra match bullets for hunting. I have a load of 99gr RL-25, this is giving me an avg vel of 3218-3175 fps with a spread of 31 and 20 fps respectively depending on which lot of sorted Rem brass I'm using. Also with 92gr of RL-22 she is clocking 3117fps with a spread of 21 fps.
At 300 yds acuracy is about identical to yours with some groups flirting with 1" and most 1½"-2½". Actually it doesn't open up that much at 400 Yds. And hitting the plate at my farthest yardage--750yds is not a problem.
So many groups are teasers, two tight with one out a bit. Of course I have to factor in that the nut behind the gun may be kinda loose at times.
Sorry no pics.
Great post.
Phil

 

[edge]

Eaglet, I see most groups as little triangles, but some are two very, very close and then one shot away from the group. Have you tried two shot groups to eliminate heat?

Another trick is to shoot at three different targets, especially if you can see the holes. If you see two hole next to each other the third shot may have extra tension.

Impact is also skewed. Impact appears to be slightly High and definitely Left with the exception of 90 and 91 grain loads. Barrel harmonics or conditions??

I don't have answers, just observations

edge.

 

[Eaglet]

Phil,
I Can't belive I did not say it was with the 300 RUM Sendero.
Thanks!

 

[Eaglet]

Thanks Edge,
Definately gives me some ideas. We'll see what happens!