Bottles can be great for rectal stretching and conditioning the rectum for more severe abuse.
Some safety issues do exist.
NEVER use glass bottles, Plastic drinking bottles are much safer. Sure, you see females taking glass wines bottles in the asshole, buts it very thick glass. Just dont even try it.
PREP THE BOTTLE: remove any label and wash, retain cap. Inspect the bottle for any sharp edges and removes. CRISCO works best for bottle insertions. Fill the bottles with warm/hot water all the way to the very top and cap. The will warm the bottle and keep it from collapsing on the insertion
BOTTLE TYPES AND SIZE: I found he standard COKE plastic bottle is the best, the 16 oz version for bottle training, and the 1 liter brutalizer version when the asshole is super loose. Here are the sizes that are used.
INSERTION TECHNIQUES: Start small, if you cant start at the 2.7 inch wide starter coke bottle, a plastic orange juice bottle maybe a better start.
Crisco the hell out of the bottle, and slowly insert the fat end. If its real blunt, you might have to "shoe horn" it in sideways to get it past the anal ring. Once past the ring your home free, just hold onto the neck so you dont lose it.
Analboy will start out on the starter bottle if the asshole is not already destroyed. The Assmasters will insert the large bottle, then he will hold it in his cavity for exactly 30 minutes before expelling it from his rectum with no assistance, let the ring do the work. Sometimes the Assmaster may FUCK the LARGE bottle in and out from the blunt end to the skinny part and just keep popping it in and out of his ring for faster rectal breakdown. This is severe asshole abuse and he cant take it for a long period.
OTHER Bottle types:
The pom bottle is a challenge