Pellet Count For Pigeon

[wymberley]

Have a problem with the patterns (far too open) on a new gun which hopefully is being remedied. I've tried many different brands of cartridges - bearing in mind I'm obliged to use fibre - and none are really ideal. As I have several thousand which suit another gun, it's cheaper to sort out the new one than keep on trying others and if/when successful, buy even more. As a confidence check, as by the look of it we're about to get stuck in on the stubbles, what is the consensus of opinion of members as to the minimum average number of pellets required in a pattern with each shot to cleanly kill a pigeon? We know that a pattern does not have a even distribution throughout the proverbial 30" pattern check circle, so to stay with round figures, the number required in the central 20". We're always a bit behind the central UK with the harvest down here and all being well I should have the re-worked gun back in a couple of weeks when things kick off - having said that, the winter barley does look to be almost ready.

Many thanks.

Edited July 6, 2017 by wymberley

[neutron619]

4,000,000.

 

By which I mean, if you're shooting a 12 gauge, stop worrying. It's not marginal and never will be, unless you're going seriously off piste with your choice of cartridges.

 

To help you with your estimations, linearly-equivalent pattern densities for Normally-distributed pellets in a 30" circle, for various pattern circle diameters.

 

Edited July 6, 2017 by neutron619

[wymberley]

Many thanks. And this is probably me being a tad dim and I'm not quite sure what you're saying. Is it that, say, if you have 150 pellets in the 30", then 67 will be in the 20"?

[wymberley]

Thanks again - have spotted your Edit.

It seems I was right to ask. The following assumes (always dangerous) that my understanding above is valid. If we move from the 150 to, say, 170 pellets, this would be within 2 pellets of a 1/2 choked 30gr No 6 shot at 40 yards. I was under the impression that the 20" figure under these circumstances on average would be 96 and not the 76 as indicated.

However, we still don't know the minimum average count to be reasonably certain of killing said pigeon.

[Stonepark]

180 in 30inch is my preferred for pigeon.

 

Split about 100 and 80 in 20 and outer 10 ring respectively.

 

Pigeon is about 6sq inch in killable area and 12 in in non-vital area.

[neutron619]

Not dim, no. I've re-written my post above to make my meaning clearer, since even the way I first described it could have been misinterpreted.

 

The short of it is that you'll have, on average, at least 67 in the 20" circle if you're achieving, on average, 150 in the 30" circle.

 

The long of it is that, as you've observed, the pellet distribution tends toward Normal.

 

This means that, for a single measured pattern, the linear (or "average") pattern density changes as the circle gets larger or smaller. It'll rise for a smaller circle and drop for a larger one. The pattern density measured as a function of the Normal distribution doesn't change, no matter how big or small the circle.

 

When looking at the numbers above, it's important not to confuse the effect I've just described with what the numbers are actually showing. The table above shows the number of pellets one would expect to find in a circle of size X with a fixed linear pattern density, hence it's description as "linearly-equivalent".

 

Essentially, all of the values in each row of the table express a pattern density equal to X pellets per 707in² where X is the 120 pellets, 130 pellets, 140 pellets number.

 

To illustrate:

 

120 pellets / 707in² [30" circle] = 0.1697 pellets per square inch.

53 pellets / 314in² [20" circle] = 0.1687 pellets per square inch.

 

The discrepancy above is due to rounding errors I've introduced to keep the numbers simple, but you see the point.

 

Now to the confounding factors:

 

The linearly-equivalent pattern density value will underestimate the density in a circle smaller than the reference pattern, and overestimate it in a larger circle. This is because the pellets are more likely to be closer to the center of the pattern than the edges, but linear equivalence treats them as though they were equally likely to appear at any point in the circle. This is the basis upon which I say "at least YYY in the circle" - you should expect more than the table predicts.

 

However, this also means that a cartridge which only puts a particular number of pellets into a particular smaller-than-30" circle in the table above is likely to under-perform because the number of pellets expected is skewed lower for smaller circles. The reverse is true for larger-than-30" circles.

 

Ultimately, whether the numbers above represent an under-/over-estimate of 30" circle performance depends on whether one takes the assertions that "XXX pellets in the 30" circle is suitable for YYY game" as a gross simplification to avoid shooters having to do any maths, or merely as a partial simplification that says "a linear density equivalent to XXX pellets in the 30" circle is suitable for YYY game" which would allow for the lower density in smaller circles. I suspect the former, but there's enough wiggle room in all of it to make it somewhat unclear.

 

So how do we get round this "linearization" inaccuracy?

 

We could calculate Normally-equivalent pattern densities which would remove the under-/over-estimation associated with the linear-equivalence approach and give us the true number of pellets we can expect in a given size of pattern circle. There are some problems with this approach too, however.

 

1. The mathematics are more complicated and time-consuming to perform.

2. Densities are more usefully expressed as a number of pellets per unit area; expressing to you that "you need to buy a cartridge producing patterns which match this particular Normal function", expressed as a set of parameters, is even less transparent than what I've already posted above.

3. All of our expectations about cartridge performance are measured against a defined standard - 30" circle performance. There's no reason that this standard can't be changed, but strict mathematical equivalence of the Normal distribution in the context of a 20" or 40" (or other) circle size doesn't necessarily equate to strict equivalence in performance in the field. In short, the 30" circle has a meaning and a purpose connected to killing quarry beyond simply being a convenient unit of area for calculating pattern density. Removing that point of reference may not be safe, even if the mathematics say it's all the same.

 

For these reasons, expressing densities either as linear or function-of-Normal values by themselves is not particularly valuable, particularly when discussing effective pattern area. You really need both to be able to draw mathematically-useful conclusions about pattern performance.

 

For example, if (and I'm making these numbers up) 120 pellets in a 30" circle has the same parameters of the Normal function as 88 pellets in a 20" circle, we can reasonably call those patterns mathematically identical. Expanding the 20" circle to 30" should, probabilistically, result in 120 pellets being contained within it. If 120 pellets in 30" is "effective", then we can say that 88 pellets in 20" is also "effective" (not forgetting what I said above).

 

With this approach, when we get to a real-world pattern, however, we hit a problem. If we want to calculate the effective pattern area, we try to find the largest circle having the same pattern density as our reference minimum. (It's in this way that a 2" .410 cartridge can have any effective range at all.) What do we do?

 

We could calculate via linear-equivalence with our pattern. We hit the problems above - is the real (Normal) pattern density higher or lower than our reference? It's very hard to calculate or say for sure, but you can at least make a reasonable judgement.

 

Alternatively, we could calculate via Normal-equivalence. We will hit one of two new problems, dependent on whether the pattern density is roughly Normally-consistent for the whole pattern, or not.

 

If the pattern is Normally-consistent (i.e. probability of pellet impact can be expressed by a single function throughout), then we can make no comparison of pattern area to effective area this way. We can only really say "it's as effective as itself" because we're expressing the density as a function.

 

Alternatively, if the pattern is Normally-inconsistent (i.e. a blown pattern, without a single probability function) then we can relate the 30" pattern to a larger or smaller area to calculate relative "effectiveness", but in doing so, we have to change the function that describes the pellet distribution in the area adjudged "effective". This is slightly hard to comprehend, but basically means that we're basing our calculation of effectiveness on a pellet distribution that our gun and cartridge may not throw, except for that specific pattern, taken at that range. This will almost certainly misrepresent the performance we will get if we apply it, mathematically, to other ranges and pattern circles.

 

So to conclude - linearly-equivalent pattern density isn't perfect, but it's easy, probably near enough and much easier to understand. Whatever that table above says about 20" circles, make sure your cartridge is putting 20% more than that in the circle and you won't go far wrong.

 

I'm going for a lie down.

[wymberley]

Phew! I think I'll just pattern my gun and go shooting.

[geordieh]

1 pellet in the right place and they fall down dead but they have to be in the right place on the pigeon not the right place in the circle

[Guest cookoff013]

Gaps don't hit pigeons.

[Guest stevo]

Gaps don't hit pigeons.

True but pigeons are not stationary.

 

Anyway what makes you all think that the patten is the same at 10. 20. 30. 40. 50 yards ? It doesn't just get bigger the further it goes out.

 

To prove my point put three sheets of paper at 20. 30. 40. Yard intervals. Use whatever choke you want. And any size shot. And shoot through all three

Your see the patten on first is considerably different to the third one. Your see the patten changes shape as it's traveling along.

This is why I only patten for gun fit.

Edited July 6, 2017 by stevo

[motty]

To be honest I very rarely pattern any pigeon loads. I can't say I have ever had much problem. I have lately been using tight chokes in conjunction with my old favourite ounce of English 7.5s. If I don't try for too many birds over 50 yards, I get good results.

[Walker570]

I don't count, I look for density. My new 410 fibres produce a 24 inch very dense pattern at 35yrds ... now it is up to me.

[dodeer]

To be honest I very rarely pattern any pigeon loads. I can't say I have ever had much problem. I have lately been using tight chokes in conjunction with my old favourite ounce of English 7.5s. If I don't try for too many birds over 50 yards, I get good results.

I've gone the same way. Good fibre 28g 7/7.5 for most winged game through 3/8 & 5/8

[wymberley]

180 in 30inch is my preferred for pigeon.

 

Split about 100 and 80 in 20 and outer 10 ring respectively.

 

Pigeon is about 6sq inch in killable area and 12 in in non-vital area.

Many thanks. That's what I work on - just a few more (nit picking) as I use the traditional (Burrard) vulnerable area which is a tad smaller. I appreciate that it's largely academic for the majority of shots taken, but I just like to make sure there's sufficient to get the job done at my considered maximum range.