I was chatting with some guys at the club, and they suggested that for a rifle system like the AR a test of 9 shots was more telling than a test of 5.
I tried it, and I really thought it odd how close some 9 shot groups came to the 5 shot groups I did eariler, whereas others opened quite a bit. For example (100 yards):

Black Hills 68 gr match 5 shots
1. 2
2. 1 5/8
3. 1 5/8
68 gr 9 shots
1. 3 3/8
2. 3 1/8

Q 3131A—5 shots
1. 1 5/8
2. 2
10 shot Q3131A (slight counting problem while loading)
1.     2 ½
9 shot Q3131A
1. 2 ¼

Black Hills 52 gr match 5 shots
1. 1 ½
2. 1 5/8
3. 1 3/8
Black Hills 52 gr match 9 shots
1. 2 ¼
2. 1 7/8

The 68 gr BH grew quite a bit, where the others grew less.

For example, between the largest BH 52 grain group in 5 shot and 9 shot is a 40% difference.

The Q3131A? Also 40%.

But the BH 68 gr had a 70% difference in the largest groups in 5 and 9 shots.

What are your thoughts?
Worth the extra 4 shots?

To my understanding, the only reason for five rounds was because that was the magazine capacity of the majority of rifles..

For myself, it does allow fewer holes to shot count on the paper.
As to nine over five, well, why not ten rounds?
Further testing could involve full magazines, and even the use of a 100 round drum, if you want to incorporate sustained fire simulation into the accuracy tests..

It just depends on how you are going to use your rifle, I guess..


Meplat-