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Posted: 3/5/2007 7:21:06 AM EDT
| What sort of 3 shot groups should one expect to be getting out of a milled gun w/open sights at 100 yards from a bench rest? Assume barnaul or golden tiger steel cased ammo. Thanks |
The reason I'm asking this is because I finally got to shoot from a rest this weekend and didn't do well at 100. It was windy so maybe that had something to do with it (30-35mph gusts) but man was I horrible. So I'm trying to get a handle on just how horrible I did. Most of my shots were quite far apart, as in 8" easily. |
1MOA is 1 inch at 100 yards therefore 6MOA would be six inches at 100 yards. At 200, it would be 12 inches. Is 6MOA really standard for an AK though? I know they aren't as accurate as AR's but I expected them to be around 4MOA. |
6MOA would be roughly 6+" at 100yds. If the dispersion was mainly horizontal then the wind might be a factor, maybe an inch or a little more. If the dispersion was mostly uniform then the wind is not to blame for it. At 100yds the time of flight is so low that wind would have to be outrageous to really effect POI much. Some rifles just don't shoot well. I have an SKS that simply can't hold a paper plate at 100yds. I have a FAL that can do 2" easy from a bipod. I also have an AR that shoots about 3MOA at best and one that came hit dimes at will. |
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Well at 25 yards 3 shot groups were around 1" max. distance apart. Sights were @ 100m. I left the sights @ 100m and when shooting at the paper 100 yards distant the groups were in the far upper left corner of the paper. And it wasn't a real tight group either. I'm more inclined to blame myself than the gun. I'll be pretty disappointed if an $800 rifle can't hold a 3" group from the bench at that distance. Gross. |
Well, that sounds like your gun is probably capable of around 4 MOA with that ammo then. Using iron sights I find it's very common for my groups to open up at longer distances. My eyes just aren't that good and I have trouble seeing the target clearly enough at more than 100m to shoot to the best of my abilities. Also, AK sights are very poor when it comes precision shooting. It could also be the gun, the ammo or a combination of the two though. Unstable bullets or inconsistent velocities will produce groups that get exponentially worse at greater distances. One trick I have found for shooting long range groups with iron sights is to line your sights up with either the upper or lower edge of the target depending on whether your rifle is shooting high or low at the range in question. The straight line on the paper will give you a better reference for keeping your front and rear sight in perfect vertical alignment and the corners of the target will help you to center the rear sight horizontally. Using this technique and a decent rifle I can shoot 2" groups at 100 yards with open sights. That might not be match grade accuracy and I'm sure others can shoot better, but it ain't that bad either. It's not something that you're going to do with an AK in 7.62x39 shooting Barnaul ammo with stock iron sights though and anyone who tells you otherwise is either lying or deluded. If you really want to see what the rifle is capable of, you'll have to scope it and try a variety of ammunition to see what it likes best. If it does end up shooting 3MOA it's a keeper. AK's aren't tackdrivers, they're combat weapons that are made to go bang everytime under the worst conditions on earth. AK's in other calibers, notably 5.56 and 5.45, will ussually produce better accuracy though. A 5.56 AK that shoots 3 MOA isn't anything special at all. |
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Regarding crosswind deflection, here is a simple formula to calculate the deflection due to a crosswind. z=w*(t-X/v0) z is the deflection w is the wind speed t is the flight time of the bullet to the target x is the distance v0 is the muzzle velocity I prefer ISO units, velocities in m/s; time in seconds, X,z in meters The only unknown parameter in the above formula is the bullet flight time (which you may find in manufacturers tables). For your example (I assumed a bullet mass of 100 grain) I calculated t = 0.106 seconds for X = 100 m. with v0 = 1000 m/s and w = 5 m/s this ends with a side deflection of 10.4 mm. Yes, a 35 mph crosswind would make a significant impact on accuracy; even at 100 yards. AK47 MOA accuracy with no wind averages 5. AK74 averages 2.5. One reason the CCCP dropped 7.62X39. |
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I think that it is impossible to tell what the problem is at this point if you do not have any confidence in your shooting skills. Go on a calmer day, bring a variety of ammo and try different ones. Try resting it on the receiver in front of the mag and make sure the mag is not moving around. Concentrate on that trigger squeeze but most of all concentrate on that front sight. Practice dry firing- keeping that front sight centered, a hair to the right or left and you are way off at 100 yds. AKs take practice, those sights are really close together. Once you get the group size tamed down some re-adjust the front sight to a 100 yd target. A little off at 25 yds is a lot off at 100. Also, it could possibly be the rifle. I fired a butthole stocked SA 93 Bulgarian when they first came out and it patterned like an improved cylinder choke. There are at least a few lemons out there. Happy blasting |
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LOL I wonder what Arsenal would say were I to call them up and tell them there is something wrong with the rifle because it shoots like crap.  I think I'm going to have to go out on a nice calm day with no wind and start over again. Another thing that could be affecting this is that I have corrective lenses and even with them they still can't correct 100% for the astigmatism in my right eye. That might be a factor. I dunno. |
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Hey buddy, Be patient with yourself and have fun. Do you have access to another rifle that is scoped and known to be accurate? Try that rifle out to see where you are with that set up. Try the AK at 25 yards and work your way out to a longer range. A 35 mph cross wind will throw you off at least 3 inches at 100 meters. |
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