Many times when reading a thread about full auto rifles Ive come across a reference to open bolt operation and how its better than closed bolt operation for full auto.
Depends. Open bolt guns tend to cool better, but tend to have worse-feeling triggers, sear area wear, and poorer first-shot accuracy. Closed bolt guns tend to have have more problems with cookoff of chambered rounds, less cooling, but better triggers and first shot accuracy.
If an open bolt gun uses Advanced Primer Ignition, it can use this effect to operate with a lower recoilling mass for a faster cyclic rate and lower overall weight.
Open bolt guns can be less safe, as all it can take to get one to fire is to jar the bolt to the point where it closes and therefore fires. Common design problem with open bolt submachineguns.
So there's pros and cons and either is a compromise.
Ive searched on here and on the web but I cant seem to find anything that actually tells me what the difference is between open and closed bolt. Can anyone explain this to me?
Open bolt guns when cocked have their bolt open. When you pull the trigger, the bolt closes, chambers a round, and fires as the round is just finally being chambered.
Closed bolt guns when cocked already have the bolt closed. When the trigger is pulled, the firing mechanism *only* moves to fire the round.
With both, upon firing the bolt opens. With open bolt guns, the bolt is held open, whereas with closed bolt guns the bolt closes again.
There are some designs that fire from the closed bolt for the first shot, but subsequent shots are from an open bolt.
Many gun designs have moving barrels as well, just to complicate things.
