What makes shots spread?

[Wrenches]

I've been wondering about that. What is it that makes the shots spread once they leave the barrel?

Let's say from the cylinder bore which is straight all the way. A cluster of shot travel down the barrel and once out of the barrel, why won't they stay a cluster since they all travel at the same speed?

 

[MikeD]

Lots of forces at play.

wind resistence is one.

As the shot is pressed together it is exerting force in directions other than just down the barrel. Once the restriction of the barrel is removed that force is allowed to exert in an outward as well as forward direction.

Shot will also deform causing varying spread as the deformed shot will not travel the same lines as non deformed shot.

Edit: A cyl barrel is not straight per say. The shot passes the end of the hull where it is compressed through the forcing cone and then passes the length of the barrel. Any irregularity in the barrel, some to small to be visibly noticible can cause a change in forces applied to the shot as it passes.

For every action, however small, there is an equal and opposite reaction.

Sent from my Mossberg 930 using Tapatalk2

 

[aksavanaman]

Dare I... Lol

The gasses leaving the barrel expand in a conical manner and since the shot is being propelled by said gasses, will thus act in much of the same way and spread with the gasses.

Bullets on the other hand are stabilized by their own enirtial spin created by the rifling in the barrel, which is why you'll hear much talk about a proper crown on barrels... If it were uneven it would negatively effect the bullets trijectory.

 

[John A.]

That is deep MikeD, but correct.

 

[Wrenches]

That explains it. Thanks.

So you say that the barrel is not always perfect so I would have to shoot it to see how it patterns? So a foster slug have a tendency to not be so accurate?

 

[GunnyGene]

That explains it. Thanks.

So you say that the barrel is not always perfect so I would have to shoot it to see how it patterns? So a foster slug have a tendency to not be so accurate?

Slugs are stabilized via the way they are designed - nose heavy - and actually quite accurate for a non-spinning projectile. Similar to a shuttlecock in badminton. Most will hold a 2-3" group at 50yds, some designs will hold under 2" groups at 75yds.

 

[MikeD]

You should always pattern a gun. Two guns of the same spec, model, etc. will usually pattern a little differently. Same with slugs. That is why some guns prefer one particular type of ammo over another and a broad sample usually needs to be tried to really dial it in.

To further complicate issues these inconsistencies in the barrel and the metal will change as the barrel heats and cools. One of the reasons rifle shooters oft let the barrels cool between shots etc.

 

[LAZY EYED SNIPER]

When you're dealing with slugs there are fewer variables in play.

Sure any irregularities in the barrel will impart certain characteristics on the slug's behavior as it leaves the barrel, but you will be more consistent on target with slugs than with shot. There may be a resulting degree of variation between your point of aim and point of impact as it relates to "accuracy" but assuming there is no extreme variation from one slug to the next, your shot placement should be relatively consistent. My 20" 590a1 puts an entire tube full of foster slugs in the center of a 10" target at 50yd. Accuracy is a fluid concept that changes as you change your ammo, but consistency on target can be achieved by adapting to how the ammo behaves...

 

[Wrenches]

Wow, slugs can be pretty darn accurate after all. The Razorback XTs I have has stabilizing wads so they're more accurate for sure. One and one-eighth oz ought to hit pretty hard going 1600+ fps.

Not that I'm planning on hunting at 50 yards or whatever but using it for SD like a drive by shooting and I'll damage their car for sure.

 

[GunnyGene]

Wow, slugs can be pretty darn accurate after all. The Razorback XTs I have has stabilizing wads so they're more accurate for sure. One and one-eighth oz ought to hit pretty hard going 1600+ fps.

Not that I'm planning on hunting at 50 yards or whatever but using it for SD like a drive by shooting and I'll damage their car for sure.

Some slugs will completely penetrate a 4 cyl engine block. Brenneke is one. Has a harder alloy than most others so doesn't pancake on impact.

Penetration test of various slugs:

http://www.brennekeusa.com/cms/fileadmi ... THD_LE.pdf

http://www.brenneke-munition.de/cms/fil ... mation.pdf

 

[Shotgun Jeremy]

Those winchester rifled slugs will penetrate the block of an older 4cyl engine on a European car. I just can't remember the name of the car.....not so good with foreigners. They also will completely blow through an 80's caddy when shot from 100 yds. Both front doors-no problem.