Therefore, the bullet obturates
and stretches the bore, creating a normal force, and friction between bullet and bore.
Just as important, pressure exerted outward by the ball against the cavity wall of the slug causes it to obturate
against the bore in a uniform manner.
The idea behind the hollow base in the .32s and .38s was to make it easy for the bullet to obturate
and fully engrave the rifling at the very low pressures involved.
The lead bullet will obturate
when the gun fires and expand to fill the rifling in the bore.
Single cone 4% taper gutta percha cones (Dentsply) were used to obturate
all the canals (Figure 3).
Very hard bullets also allow some gas blow-by, since they don't obturate
("bump up") as the expanding powder kicks them in the rear end.
It's perfectly normal to see a little but when it's excessive like that we know there wasn't even enough pressure to obturate
the case at all.
Root canal treatment is a common procedure in dentistry for treatment of pulpal and periodontal pathosis.1,2 There can be two approaches to reduce bacterial persistence and reinfection of canals, either dress the canals with antibacterial agents in multiple visits or immediately obturate
the canals in one visit to reduce the space for bacterial colonization.3,4 In past, multivisit approach was opted for endodontic treatment of necrotic tooth and one visit approach was considered as an inappropriate treatment protocol.
One of the advantages of the using a bottlenecked case like the .45-75, rather than a straight-walled case like the .45-60, is the bottleneck cases more fully obturate
in the chamber and eliminates black powder fouling from flowing back into the action.
The sabot fills the rifling and seals the bore, eliminating the need for the bullet to obturate
. This allows the use of hard, jacketed bullets and has allowed a greater range of bullet performance.
Of the loads, the smokeless didn't obturate
the well which isn't surprising and the cases came out with black smudges at the mouth.
A sabot bullet does not engrave the rifling when loading and doesn't need to obturate
to seal the bore; the sabot takes care of both chores, so soft lead is no longer the requirement it once was.
Xenograft granules (0.25-0.5 mm Bio-Oss, Geistlich Pharma, Wolhusen, Switzerland) were used to fully obturate
the conduit and the surgical defect (Figures 11, 12, and 13).
My initial "fun load" of 8 grains of Unique under a 250-grain .45 Colt bullet was accurate and pleasant but did not obturate
the case enough to seal the chamber.
In these instances, iginition pressure is high enough to cause the base of a wad to obturate
enough to seal off the bore during firing.