HMB has been around since approx 1996 I believe. It sucked then and ...well it hasnt changed.
The only thing it ever did for me was give me the craps.
THere are studies indicating HMB is good for recovery and muscle gain etc etc.....but the same can be said for just straight leucine which HMB is derived from. Short answer....take BCAA when you train. For 115$ you can buy 5lbs of BCAA lol.....enough for like a half a years daily use.
Or spend like 60 on clear muscle and have nothing happen.
Want a real placebo....HMB is a good place to start.
Also keep in mind the studies used 3+grams and there is 1 in clear muscle per dose. Even if you triple the dose though you wont see any results.
If you already have it....Run a log for us. Dont take anything except the HMB.
Log lifts and endurance and weight.....let me know how it works out

Just for the science.
Also remember...Muscletech makes all of its money selling products that for the most part do very little.
Their 30$ per 3gram creatine for example.....terrible.
You can buy a KG of creatine for 17$ 1000g.