Load Testing Which Group to Use?

[scsims]

Shooting from the backyard load development range this morning, trying out 175 SMKs out of my 308. I want to tighten up my groups past 600 yards.

Lapua Brass
Fed Match Primers
Varget Powder
175 SMK

I loaded 3 rounds each: Tested at 100 yards:

42gr = 2479, 2509, 2529 fps group = .567"

43gr = 2517, 2605, 2586 fps group = .568"

43.5gr = 2614, 2609, 2622 fps group = 0" one hole barely could tell that 3 shots went through.

44gr = 2646, 2658, 2670 fps group = .9"

44.5gr = 2696, 2684, 2679 fps group = .822 two in one hole

45gr = 2727, 2743, 2744 fps group = .512" two in one hole

I'd like some advice on which I should choose to improve on for 600-1000 yards? I plan on selecting one and loading up more for 200 yard testing.

These are the ones I'm considering..... I like the 3 in one hole but the velocity is a liittle slow for LR shooting?? The other 2 could have been me..... or the some other anomilly.

 

[Browninglover1]

How far can you shoot during load development? I often take the 3 or 4 best loads at a hundred and test them at 300 to see which will do best at longer ranges. For whatever reason, the smallest groups at 100 don't always produce the smallest groups at 300. However, my smallest groups at 300 seem to continue to be the best shooters at the longer ranges.

Also, when I do the testing at 300 yards I load up 7 of each load and shoot groups of 7. It takes longer to test, but it really shows you the accuracy potential of your load. It also gives you the chance to call one or two bad shots and still see how your load is doing with a 5 or 6 shot group.

 

[scsims]

200 yards is all I can do behind the house.... most convienent.

 

[Browninglover1]

In my mind 200 Yards will still give you a decent indication of which will be the best load. If I were you I'd load up 7 at 42.0 grains, 43.5, and 45.0 grains. Take your time when you shoot them and see which one shoots the best.

 

[rscott5028]

I'd load up 10-20 rounds at 43.5 grains and see if the groups and velocity remain consistent at 100-200 yds.

If so, then you won't have any trouble at 600yds.

-- richard

 

[D.ID]

If it is not too inconvenient to test at 600. I would if I were you. Believe it or not I have had one hole groups at 100 that would not stay on a 8x10 at 600. I have also had tolerable but not great groups @ 100 turn into show stoppers at 700.

 

[baldhunter]

That is so true.I've burn pounds of powder and hundreds of bullets looking for the perfect 100 yard group and later find that group really sucks at 200 yards.I think now when I do load development,I'll either just shoot them at 200 yards,or load five for 100 yards and load five for 200 yards and see how they group.

 

[scsims]

I just loaded up 10 of 43.5 and 10 of 45gr last night. I'll shoot them this week @ 200 to see how they look.

 

[Bart B]

I don't think there's enough shots per test group to be meaningful. 3-shot groups are only about 50% reliable to reflect what their load will do all the time.

Shoot at least 15 shots per group. They'll be over 80% meaningful.

Basic rule of meaningful accuracy is to shoot enough shots with a given load so every time you do it, the groups are all the same size. If all the groups of a given load ain't the same size, you're not shooting enough shots in each group for it to be 100% meaningful. So 15 shots per group is good and 20 even better. For example, instead of shooting four 5-shot groups with a load, shoot all 20 shots into the same group.

 

[rscott5028]

I don't think there's enough shots per test group to be meaningful. 3-shot groups are only about 50% reliable to reflect what their load will do all the time.

Shoot at least 15 shots per group. They'll be over 80% meaningful.

Basic rule of meaningful accuracy is to shoot enough shots with a given load so every time you do it, the groups are all the same size. If all the groups of a given load ain't the same size, you're not shooting enough shots in each group for it to be 100% meaningful. So 15 shots per group is good and 20 even better. For example, instead of shooting four 5-shot groups with a load, shoot all 20 shots into the same group.

I basically agree.

But if you're at 3 MOA on your 4th shot, 15 or 20 shots won't make the group any smaller.

-- richard

 

[scsims]

I just shot 7 shots each with each load @ 200 at the back yards testing facility.....

Results:

43.5gr.
2599 cold bore
2616
2617
2611
2617
2595
2598

5 shots went into a .942" group with 2 flyers making it 1.975" group

45gr.
2664
Error
2700
2690
2700
2702
2708

this one shot two .5" 3 shot groups about .5" away from each other with 1 flyer. Group size 1.962".

They are not very consistent in the .5 MOA area but they do stay under 1 MOA. And I know pulled at least 2 of the shots.

After I was done @ 200 I dialed the scope back down 1.75 MOA for 100 yards and the 43.5 gr load put 3 in the same hole again.

I think there is a variable out of wack somewhere that's working against me here. If I can put my finger on it I may be able to hang on to the .5 MOA groups.

Keep in mind that my rifle is a stock Remington 700 SPS glass bedded in the choate stock.

 

[rscott5028]

I hope nobody's in the house or walking around the corner while you're shooting.

 

[scsims]

I hope nobody's in the house or walking around the corner while you're shooting.

That's a storage garage behind the house. Not our main garage....... just like anywhere else when the range is hot, nobody's allowed in the back yard.

 

[D.ID]

I admit I am reluctant to even mention it........but............pulled shots happen but if you have two out of seven or even two out of fourteen pulled shots from the bench with a rear bag. You should probably check your rig. Fine tune the fit. LOP and cheek hight or slop in the bipod. Choate stocks are easily adjusted so don't settle for less than a perfect fit . Just reluctantly thinking out loud.............D