Shots per group

[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.

[txgunner00]

You shouldn't need to muscle the gun to get to to shoot straight especially if you are on a bench. I spend a few minutes setting my bags up and make sure they are secure and the rifle will track straight in them. After that all I do is provide a back stop. Even when shooting off a bipod and rear bag I still only apply a firm but relaxed grip. There is a technique to accurately shooting an AR and it typically different than a bolt gun. You just have to find what works for you and practice until it becomes muscle memory.

I shot this the other night and I certainly wasn't muscling the rifle.

gren new brass2.jpg

[RStewart]

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.

A service rifle set up for XTC is not something I would want to pack around all day. To balance them out as a consistent shooting platform, most do but a lead ingot in the stock and some put lead ingots inside the foreguard. My competition match AR weighs in around 8 lbs. But, like Hoot says AR platforms have a tendency to magnify anything you do. I believe this is due to the lightness of them.
My 6.5 FPR rifle clocks out at 9 lbs., while my hunting Grendel touches a shade over 7.

[LRRPF52]

These are with my .260 AR built by GA Precision with a Bartlein 5R barrel. I'm still playing around with finding a load for it. If I only shot 3-round groups, the holes would be very small. I have found several 1/2 MOA 5-round loads with it already, most have been the 139gr Scenar and Hodgon's H4831. The two groups on the right are .4 MOA.



Some rifles just shoot for me right off the bat, and others need lots of development. The .260 has shot a sub-MOA group at 700yds in shifting full-value winds, so I know she's a shooter. Look at my post time/date...

[YutYut]

Txgunner Can i ask what target that is?

[txgunner00]

Txgunner Can i ask what target that is?

It's something I drew up on AUTOCad.

[sneaky one]

Wanna make some-sell some?