Be very cautious when using pistol powders in rifles. Low load density can be a recipe for disaster. If the powder fills less than 80% of the case, you have a potential of a Kb (Kaboom). Some will say you should point the muzzle up and strike the stock or side of the receiver before firing to settle the powder toward the base of the case (and against the primer flash hole). I prefer to use a dacron filler to keep the powder positioned properly.
You will likely not get this or any other safe Blue Dot load to cycle an AR because the pistol powder pressures peak too early and will not send sufficient gas pressure down the gas tube.
I would strongly advise against using pistol powder in a rifle unless you are a VERY experienced handloader and are willing to accept a blown up rifle eventually. I blew a Mini-14 up about 24 years ago and stopped the practice of loading pistol powder in rifles cases.
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