AR-15 Bolts

[ChipOnShoulder]

I recently bought a spare bolt for my Bushmaster M-4. Does anyone know if stock bolts are interchangeable? An example would be if I am out at the range and the bolt face shatters. Can I just drop the new bolt in, or am I going to have to replace the entire bolt/carrier/firing pin package?

[BRanger91]

The bolts are basically interchangable. You can most likely go to a gun smith or shop and they will have go/no gauges to verify. Some people think they are very sensitive but I have never found that. Hell do you think the bolts in the arms room are all the original? I know that those gwet screwed with. However, if you have your bolt just explode or shatter, im guessing you have some other problems too.

[1st Ranger]

I will have to disagree with BRanger91. AR-15/M-16 bolts are not a drop in item, they need to be headspaced. Redoing the headspace is not that hard a task, but it needs to be done! Is there a possibility that if you dropped in a new bolt that it would be so close to the old one that you wouldn't need to re-headspace it? Yeah, but its not worth the risk and the chances are very slim. While it is very true that many M-4s in the arms room have had their bolts replaced, but they all were re-headspaced before leavin the shop. With a un-headspaced bolt you could run into such mundane problems as your bolt not seating or locking, to the more serious problems like your ifle firing out-of-battery, which could end your day at the range in a bad way. Ask H8 what its like to have an M-4 explode on you. It happened to him while we were in Germany in 2000.

1st

[Saltbitch]

While it is very true that many M-4s in the arms room have had their bolts replaced, but they all were re-headspaced before leavin the shop. 1st

This is a fact; learned it the 'hard way' while working in the 3/75 arms room for a stint.