Buckshot for deer?

[Mr. 16 gauge]

I've never used buckshot on deer, either, but I did some playing around with it re: ranges. Talk about a 'rainbow trajectory'!
At 25 yards, pellets usually found their mark, and depending on the load, gauge, choke, ect,. would, IMHO, been effective (most of the pellets in the vitals).
...HOWEVER! At 50 yards, most of the pellets were hitting extremely low on the target, and some were even kicking up dirt in front of the target! At 75 yards, FORGET IT!!!! the pellets were kicking up dirt at less than half way between the 50 yard & 75 yard target.
You said "close range', but didn't say how close. IMHO, I wouldn't use it any farther than 30 yards distant. I would also skip the smaller (#4) buck in favor of the bigger 00, and pattern test your load prior to hunting with it.....I've found that in some instances some things like copper plated shot and buffer can make a difference and really tighten patterns.
Good luck.

[M.T. Pockets]

I've shot a lot of deer with a shotgun, but all with slugs. Trust me, if you hit them with buckshot you would hit them with a slug too. Plus, you'd be using a load that many people use as grizzly bear protection instead of a 00 pellet. Even if most shots are close, a slug would give you range out to 100 yards or so.

I would suggest a shotgun with a slug barrell, it's much more efficient and versatile. You mention that most shots will be close, I've killed many deer at around 25 yards with a slug, works great. It leaves a nice blood trail too, something that buckshot likely wouldn't. I don't mean to hijack this away from buckshot, but I think you'd be happier with slugs.