Foster style slugs will drop through the average cyl bore of a spec bbl.
Not all bbls being equal, some shoot better that others.
The choke on it also effects the flight & accuracy as it exits. Chokes are not always concentric to the bore nor are they always bored and reamed as part of the bore.
Many less expensive guns have a simple swaged choke where the end of cyl bored bbl is then pushed into a swage die or sometimes rolled to constrict the last inch or so producing a choke . I t can be accurate, but it can be very inaccurate as well.
Full chokes tend to damage the foster type slug as it trys to squeeze thru the restricted opening. But sometimes the spec of the choke and the particular slug match up well and good accuracy result.
Like any firearm, what works well/accurately in one gun may be a flop in another.
Brenneke slugs have a fiber wad attached to the lead slug with a screw.
The slug itself is a bit larger in dia than the average Foster style and meant to be a bore-riding bullet in the Cyl bore .
The attached short fibre wad column is meant to squeeze down and seal & keep the slug centered in the bore. Better accuracy and ballistics are claimed.
Sabots use a small dia bullet or slug in a plastic envelop,,the sabot.
They can be a much lighter weight bullet and therefore higher vel.
The plastic sabot seals and rides the bore of the barrel and if rifled has the same effect as shooting a riffle bullet down a rifle barrel.
But again, one brand of ammo usually does much better than another. Same with your average rifle or handgun.
Ithaca's M37 DeerSlayer used to use a bbl with a slightly smaller spec bore than the standard shot bbl.
That was at the time when the Foster Slug was the most popular. The idea was to reduce the loose fit of the slug to the bore and increase accuracy.
Most said it worked, others disagreed.
I don't know if the small bore idea was dropped after some time in production.
In the 60's & 70's there were a couple of gadgets you could buy, one from Williams Gunsight Co.,,that clamped onto the end of your bbl.
They were simply rifled bbl extensions, usually about 6" in length and made of alloy.
The promise was to impart real stabilizing spin to the Foster slug and 'shoot like a rifle'.
The 'Xtra Lite Slugs' (Hornady I think) use a 300gr bullet inside the sabot.
A regular jacketed soft point rifle bullet.
These reduce recoil from what the regular slug loads can be.
Nice load for anyone a bit recoil shy.
When I grew up, it was 'Slug Only' for big game. So your 12ga shotgun from pheasant season (remember those) became your deer gun.
You were told a '12' was the only gun that would take a deer which of course is non-sense.
But the oldsters stuck to their beliefs and that's what they past along.
A 12ga 'hits harder' after all and a long bbl 'shoots harder'.
No scopes, no extra iron sights. Just the same bird gun with a bead out front now loaded with slugs.
Every one pretty much got their deer and then some.
Sight in & pre season practice was a shot or two a couple days before opening day at a knot on a tree ,, if that.
No wasting ammunition.
