choke and cartridge

[diver682]

Choke constriction is certainly one of the primary contributing factors to pattern but it is also undeniable physics that smaller, lighter projectiles will disperse at a faster rate than larger heavier projectiles….i.e 9 shot will open up faster than 6.5shot.

That’s the reason I’d change shot size at closer ranges in my hypothetical example, given my reticence to change chokes.

And of course that's your choice, I would use the same cartridge size and open up the chokes 

 

[Daz W]

Loads of factors in play that will affect pattern. Choke is just one of them. Cartridge choice is another. Shot "should" be spherical, and fly in a fairly straight direction. Damage to the shot cause it to fly in different directions. More damage to the shot equals bigger pattern.

Just some of the factors:

For the same size shot, recent/pricier cartridges with 5% antimony deform less than older/cheaper cartridges with softer shot ( 0 % or 2%), so give a tighter pattern. Steel shot hardly deforms at all, so gives an even tighter pattern.

The same hardness shot will pattern differently depending upon shot size. Smaller shot receives more damage as a percentage of its surface area, therefore bigger pattern. Also the higher pellet count in 28g of smaller shot gives more opportunity collisions of shot. Hence why there’s also discussions on whether a 24g 7-1/2 patterns better than a 28g 7-1/2. When you start talking 9’s, then even the amount the shot heats up when travelling down the barrel affects the malleability, which is why some shot is plated with nickel or copper.

Plastic wad will pattern tighter than fibre, as the shot is mostly in the shot cup when travelling down the barrel, and not scraping the bore causing more damage.

Choke forces a tighter pattern, but at a cost. It causes a radial pressure on the shot, which tightens the pattern, but as a result causes more deformation to the shot as it’s now all trying to get through a smaller bore at the same time.  Fortunately the effects of the pattern constriction are greater than the extra spread due to deformation of the shot. 

So yes, choke does have a part to play. But not as much as it did years ago, when cartridges were crap.

And of course that's your choice, I would use the same cartridge size and open up the chokes 

Thus decreasing pattern density, and potentially allowing a big enough gap for a clay to pass through? 

 

[diver682]

Loads of factors in play that will affect pattern. Choke is just one of them. Cartridge choice is another. Shot "should" be spherical, and fly in a fairly straight direction. Damage to the shot cause it to fly in different directions. More damage to the shot equals bigger pattern.

Just some of the factors:

For the same size shot, recent/pricier cartridges with 5% antimony deform less than older/cheaper cartridges with softer shot ( 0 % or 2%), so give a tighter pattern. Steel shot hardly deforms at all, so gives an even tighter pattern.

The same hardness shot will pattern differently depending upon shot size. Smaller shot receives more damage as a percentage of its surface area, therefore bigger pattern. Also the higher pellet count in 28g of smaller shot gives more opportunity collisions of shot. Hence why there’s also discussions on whether a 24g 7-1/2 patterns better than a 28g 7-1/2. When you start talking 9’s, then even the amount the shot heats up when travelling down the barrel affects the malleability, which is why some shot is plated with nickel or copper.

Plastic wad will pattern tighter than fibre, as the shot is mostly in the shot cup when travelling down the barrel, and not scraping the bore causing more damage.

Choke forces a tighter pattern, but at a cost. It causes a radial pressure on the shot, which tightens the pattern, but as a result causes more deformation to the shot as it’s now all trying to get through a smaller bore at the same time.  Fortunately the effects of the pattern constriction are greater than the extra spread due to deformation of the shot. 

So yes, choke does have a part to play. But not as much as it did years ago, when cartridges were crap.

Thus decreasing pattern density, and potentially allowing a big enough gap for a clay to pass through? 

If you thinks so ......

 

[Pothunter]

A good 28g no.9 with half choke evaporates Clay's up to 30 yards

 

[Daz W]

A good 28g no.9 with half choke evaporates Clay's up to 30 yards

No reason it shouldn't. Lots of smaller pellets impacting a clay should hit with the same energy as a few larger ones, up to a point. Never shot 9s as I'm  happy with 8s up to about 35 to 40 yards for most birds. Anything edge on at that range might get something bigger thrown at it. Have seen some edgy clays at approx 40 yards change direction mid flight, most likely where they were hit with the pellets, but not with enough force to break the clay. Could have been only one or 2 pellets though.

 

[diver682]

No reason it shouldn't. Lots of smaller pellets impacting a clay should hit with the same energy as a few larger ones, up to a point. Never shot 9s as I'm  happy with 8s up to about 35 to 40 yards for most birds. Anything edge on at that range might get something bigger thrown at it. Have seen some edgy clays get hit with uk8s at approx 40 yards and bounce off. Clay changed direction but didn't break. May have only been hit by 1 or 2 pieces of shot though.

You must have amazing eyesight if you can see pellets bouncing of a clay at 40 yards  :O

 

[chippy]

I used 1/4 as a maximum for 13 years and regularly used cylinder. And all that time I had a low 80s average keeping me at the top end of A class so fairly regularly getting money in A class. For the past 3 year's I've used a 3/4 and full fixed trap gun and my average has gone up a little to 84, I miss more close rabbits and driven but hit more teal and crows but I think it's down to a heavy barrelled gun rather than the choke.

 

[Daz W]

You must have amazing eyesight if you can see pellets bouncing of a clay at 40 yards  :O

Edited my previous message to correct for my questionable eyesight. Hope that suits you

 

[diver682]

Edited my previous message to correct for my questionable eyesight. Hope that suits you

Don't change anything to suit me, if you can see pellets travelling at 1400fps bouncing of clays 40 yards away you have a gift no one else has or some very expensive shooting glasses...... Where did you get them from?