Shots per group

[YutYut]

Gonna send 80 rounds down the tube tomorrow. 3 or 5 shot groups? Why?

[LRRPF52]

3-shot groups don't give you much more than a snap-shot of what your barrel really does. I personally prefer 5-shot groups, and have friends that even prefer 10-shot groups, so go figure. For strictly a hunting rifle where you will make no more than 1 or 2 shots, the 3-shot groups are a relative indicator of what you can expect accuracy-wise.

For higher volume shooting, like half or full-day precision rifle sessions, you will want to see what happens as the barrel heats up. This is where quality barrel steel and high-end craftsmanship shows its worth. For plugging hogs, it probably won't matter either way, but for target-shooting, you'll get an idea of how your pipe deals with heat.

[RStewart]

3-shot groups don't give you much more than a snap-shot of what your barrel really does. I personally prefer 5-shot groups, and have friends that even prefer 10-shot groups, so go figure. For strictly a hunting rifle where you will make no more than 1 or 2 shots, the 3-shot groups are a relative indicator of what you can expect accuracy-wise.

For higher volume shooting, like half or full-day precision rifle sessions, you will want to see what happens as the barrel heats up. This is where quality barrel steel and high-end craftsmanship shows its worth. For plugging hogs, it probably won't matter either way, but for target-shooting, you'll get an idea of how your pipe deals with heat.

Nothing I can add to this.

[YutYut]

Good to go. Ill stick to 3 and throw some 5 in near the end.

[Rambozo]

I typically test loads with 5 shot groups. If a load produces a good 5 shot group in early development, then i will load atleast another 5 to verify groups next range session.

I moved away from 10 shot groups only because its generally the case that poor loads will go south within fewer shots leaving me with unshot handloads. 5 shot groups give an early indication ttowards whether or not its worth loading more of something.

3 shots just arent enough.

[JASmith]

Wikipedia has a section of converting group size to MOA. Unfortunately I lost the precise URL but I've recreated the table.

The correlations are based on statistical calculations for the same rifle and ammunition combination (standard deviations of every shot from center is 1 MOA):

No of shots Size (′/MOA)
2 .................. 1.77
3 .................. 2.41
5 .................. 3.07
10 ................ 3.81
20 ................ 4.45
100 .............. 5.69

Remembering that we are looking at the standard deviation, we can still use this in our normal sense because the proportions are consistent.

So, a way to look at this in our context is to assume that we have a rifle that shoots 1 MOA 3-shot groups. That same rifle/load combination would likely give (5.69/2.41)X1.0 = 2.46 MOA groups when 100 shots are fired.

The scary thing is that a given 3-shot group can be anywhere inside that 2.46 MOA, so a sight-in based solely on a single 3-shot group will have a 2 or more MOA uncertainty in where the true zero is! Most of the time the 3-shot group will be near the center of the uncertainty circle because the shot dispersion largely reflects the bell-shaped curve.

So, do your shooting with 3 to 5 shots as is customary, but verify them by shooting several groups and averaging their centers for the final tweaks.

[YutYut]

my plan is to shoot 5-3 shot groups and then 13-5 shot groups with 80 rounds. That should give a very nice look at what the barrel can do. Just have to do my part.
weather should not be an issue

[JASmith]

my plan is to shoot 5-3 shot groups and then 13-5 shot groups with 80 rounds. That should give a very nice look at what the barrel can do. Just have to do my part.
weather should not be an issue http://www.weather.com/weather/hourbyhour/76226

Darned straight!

Are you planning on posting pictures or just the statistics? I don't know how many folks want to look at eighteen groups, but I think we could learn something from them. If, nothing else, we might be able to see whether that Wikipedia table makes sense and how much the statistical variation makes us think the zero might be wandering.

One thought, depending on whether you plan to have multiple targets or you will replace the target after each group, is to start with a clean backer sheet, and put the target center / aim point in the same position each time. That way you get a natural indication of what the 80 shot group would look like!

Thanks!

[YutYut]

i will post pictures for sure. thats a good idea, i will try and find a clean backer.

[txgunner00]

I load in sets of 5 when I'm working up a new load. After I narrow the field down I'll load sets of at least 10. When I settle on the final load I'll keep records on 10+ shot groups from different range trips. That way I can calculate averages and better predict the loads performance based on environmental conditions. Seems to work well for me.

[YutYut]

Amusing day at the range. Weather wasn't bad 60 degrees with 5-8 mph winds. I used factory hornady 123's. All shots were taken at 100 yards from a bench using a front rest with a rear bag. My scope was a mueller 8.5-25x50 set at x12 for.grouping. Mounted on the Nikon M223.
didn't tighten the rings enough. At first my jaw dropped then realized what was wrong

After getting squared away it shot nothing but sub moa. My 3 shot groups hovered at a 1/4inch every time but when i started my 5 it was this



The first 3 would be dead on, then the next 2 would open up a bit.. I've only been shooting for a little over a year and i know the rifle can do better i just have to keep sending rounds down range til i gain more experience. I would fire the first 3 then start to think. Pretty sure i just psyched myself out overthinking the shots. Im very excited to start my load development. Overall im happy with the rifle. 120 rounds and not a single malfunction. Its a shooter, however the squirrel has to catch up to the nut. Many thanks to the forum members for all the knowledge, specifically LRRPF52 for steering me in the right direction

[JASmith]

I feel your pain.

I had an inexpensive (read "cheap") scope on my .270 a few years back. I'd get the durned thing sighted in, the next time out the zero would have changed and I'd get a group like your first one. Went through, checked the rings, mounting screws, an so on and still got the same results.

Wondered whether it was the rifle. Fortunately I had used "see through" mounts for those few times the scope might be disabled. I used the open sights and promptly got a 3/4" group!

I replaced the cheap the scope with the slightly more expensive Sightron I Mil-Dot. Been happy since, except that that 3/4" group remains one of my best!

[YutYut]

I will be upgrading scopes soon. Looking at a vortex pst but im also looking at a NF or USO. Im debating wether paying 2x as much would be worth it.

[sneaky one]

I shoot hunting bullets in groups of 3-5. In Mn it's a cold one on opening morn, So I try to mimic that--kinda. In April- First shot, of a known wt. class,, say 100 grn.-already sighted in for.., second shot is 3 min. later,, 3 rd. is 8 min. later. Cold bbl. replication , as close as poss.===acap. The odds are= 1-2 shots per deer, should be fine for acc. Iv'e also shot same loads a bit faster in 65-75* heat, to about the same results. My end result, not a sniper here----- is- groups of 3-4-5 will give fine results for us hunters, and paper killers, that don't shoot past 400yds. on purpose. One can hit the target,,, or ,,, not.

[LRRPF52]

One thing with shooting the AR is that it seems more sensitive to positioning than other guns. As long as I muscle it with solid rearward pressure consistently, it will group tighter. This is harder to do with 5-round strings than 3-round strings. A rifle rest with straps can help with that when doing load development.

I learned that hard way with scope mounts/rings with my .270 when I was a kid...got a great zero, then all of a sudden, shotgun. Loc-tite is your friend with scope rings, Blue loc-tite for the ring screws, and red for bases on bolt guns, if not total unitization with welding.

Also, if you do some load development for that stick, you'll find at least a few that shrink the 5-round groups from sub-MOA, to 1/2 MOA.

[earl39]

seems your math is a little off 1 moa=1.047 not 1.47

Wikipedia has a section of converting group size to MOA. Unfortunately I lost the precise URL but I've recreated the table.

The correlations are based on statistical calculations for the same rifle and ammunition combination (standard deviations of every shot from center is 1 MOA):

No of shots Size (′/MOA)
2 .................. 1.77
3 .................. 2.41
5 .................. 3.07
10 ................ 3.81
20 ................ 4.45
100 .............. 5.69

Remembering that we are looking at the standard deviation, we can still use this in our normal sense because the proportions are consistent.

So, a way to look at this in our context is to assume that we have a rifle that shoots 1 MOA 3-shot groups. That same rifle/load combination would likely give (5.69/2.41)X1.0 = 2.46 MOA groups when 100 shots are fired.

The scary thing is that a given 3-shot group can be anywhere inside that 2.46 MOA, so a sight-in based solely on a single 3-shot group will have a 2 or more MOA uncertainty in where the true zero is! Most of the time the 3-shot group will be near the center of the uncertainty circle because the shot dispersion largely reflects the bell-shaped curve.

So, do your shooting with 3 to 5 shots as is customary, but verify them by shooting several groups and averaging their centers for the final tweaks.

[Hoot]

One thing with shooting the AR is that it seems more sensitive to positioning than other guns...snip

It was hard transitioning from highly accurate bolt guns to the AR. With my bolt guns, you had to try hard to make them shoot poorly. Just the opposite with the ARs I have shot. Seems like every presentation flaw you have, contributes exponentially to loss of accuracy in an AR. If I hold mine in a "death grip", it tends to have excellent vertical dispersion, but strings horizontally. That's just me. Also, my experience has been that the smaller the caliber, the more sensitive it is to presentation flaws. My 450b shoots MOA or less at 100 yards almost at will. I can let it practically free recoil, hold onto it lightly, tightly, doesn't matter. Again, just my experience though. If my livelihood depended upon putting my first shot into an X-ring at modest ranges, an AR would be my last choice.

Hoot

[LRRPF52]

It was hard transitioning from highly accurate bolt guns to the AR. With my bolt guns, you had to try hard to make them shoot poorly. Just the opposite with the ARs I have shot. Seems like every presentation flaw you have, contributes exponentially to loss of accuracy in an AR. If I hold mine in a "death grip", it tends to have excellent vertical dispersion, but strings horizontally. That's just me. Also, my experience has been that the smaller the caliber, the more sensitive it is to presentation flaws. My 450b shoots MOA or less at 100 yards almost at will. I can let it practically free recoil, hold onto it lightly, tightly, doesn't matter. Again, just my experience though. If my livelihood depended upon putting my first shot into an X-ring at modest ranges, an AR would be my last choice.

Hoot

I think Tubbs discussed this at-length when he used to shoot an AR10 in competition. I've noticed that the heavier AR's that are built solid, where the rifle feels like one well-balanced tuning fork can get away with less muscling, especially with a lot of rear weight. The Magpul PRS really helps make an appropriate-size AR shoot better, I think, as far as the human interaction with the gun goes. A lightweight gun with a match barrel will have tons of accuracy potential, but you have to work harder when shooting it like a bench queen.

It makes more and more sense to me why DCM shooters stuff those lead weights in their stocks, but I ain't doin' that on a field gun. For the practical field application, the VTAC 2-point quick-adjust sling will be your friend.

[JASmith]

seems your math is a little off 1 moa=1.047 not 1.47

Reference post #6:

I know I've occasionally dropped the zero in the conversion of inches to MOA at 100 yards -- probably because my keys are a bit stiff but that isn't the situation here.

Problem is, there are no ranges or conversions in the referenced post. Everything is MOA to MOA.

[YutYut]

hmmm ok. The ACS is a lighter stock so ill muscle it more next time. Before this AR i had been accustomed to my .300 wby mag. which needs little to shoot 1/2 moa.