Re: Ar10
I have used a forward assist a few times on my duty M4 and AR15s, usually from having a dirty gun or not fully racking the charging handle. I use to be a firm believer that you also must have one on your AR308 platform. However, after fiddling with my AR10 at home I have come to the conclusion that under the weight of an AR308 buffer spring their really isn't any reason that under normal circumstances the bolt would not not go into full battery.
Like the guys mentioned above, if the bolt is not fully in battery, something is wrong.