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Article 9 – 2019 (October)

people posing and smiling with shotguns

Russell Mark

Australian Shooter Magazine, Question and Answers

Article 9 – 2019 (October)


Question: I need some advice about chokes and how they pattern before I get a new stock made for my shotgun. I notice that when you pattern your shotguns you advice people to do this at twenty metres. Most of my shooting is at either clays or rabbits where I guess I am shooting them at twice this range. Should I therefore test my shotgun at this distance?

Grant Brayshaw, Mornington VIC


Answer: It is a great question and a complicated one to answer. I am assuming you are referring to a previous article in ASJ where I am patterning a shotgun at twenty metres simply to determine its point of impact percentage above and below the aiming point. I like 20 metres because it opens up even the tightest choke to a point where you can clearly see if the shot pattern is left, right, high or low. In the United States many of the experts will advice you to do this test at thirteen yards, but from my experience I find that some of the tightest chokes really don’t open up their shot patterns wide enough to make a clear and decisive judgement therefore the extra distance caters for the shot shell to open up just enough enough to see its shot imprint on the pattern board.

I am a huge supporter of using a post or a rest to gently lean the barrel against after you have mounted your shotgun in its natural position to your face and shoulder. By using a support such as a post it will take away any human error caused by swaying the shotgun slightly thus giving an incorrect point of impact. I know some great shotgun shooters that are terrible when forced to shoot at a still target. The aid of a support eliminates this problem.

Specifically if you are just concerned if your shotgun is shooting straight then I would suggest testing it at twenty metres firing three shots from the same barrel at the board and then working out what percentage it is in height above or below the aiming point and alternatively left or right. This will give you a starting point to make any changes to your stock or your technique.

If you are interested in what choke you should be using and how the ammunition is performing through that choke at your recognised “killing” distance then of course you should pattern the shotgun at that distance. If you are suggesting that forty metres is the average distance you are breaking your clays or knocking over your game at then if you have the opportunity to check this on a pattern board then by all means try this at forty metres. Because you may be concerned how the shot is performing then do only fire one shot to gauge the shot shells performance. I would suggest at that distance you try either an improved modified (three quarter) or even a full choke. “Open” chokes at that range will require a large pattern board to try and get indication of just how wide your shot is spreading.

A word of warning about comparing pattern-testing results. Try and always compare “like” against “like” when talking percentages or points of impact of a shot pattern. An example of this is simply using a full choke at twenty metres and for arguments sake seeing that the entire pattern hitting above the aiming point. Let’s say the middle of this pattern is twenty-five centimetres above the aiming point and the diameter of the pattern is fifty centimetres wide. This pattern is called a one hundred percent high pattern.

Now lets assume at the same distance of twenty metres we change our choke to “Cylinder” or the most open choke available and all of a sudden our shot pattern is one hundred centimetres in diameter. The centre of the point of impact will still obviously be twenty-five centimetres above the aiming point, but in terms of percentages because of the open choke the pattern will now go from a one hundred percent high pattern to what is called a seventy-five / twenty five pattern. Same shotgun with no changes to the stock and the point of impact will still be twenty-five centimetres high at twenty metres, but the pattern percentages are remarkably different. My point is simply when making comparisons for gun fitting purposes keep the ammunition, distance and chokes the same before you go ordering a new stock for your shotgun.

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