Description
Bolt B13 M4 Upper Receiver (Full Metal)
This is a full metal M4 upper receiver from Bolt Airsoft, listed with the reference B13. Bolt is a Taiwanese manufacturer best known for its M4-pattern electric rifles fitted with the B.R.S.S. recoil system, which gives a strong, realistic kick each time the gun fires. Like most serious AEG makers, Bolt supplies the main body parts separately so that owners can repair damage or rebuild a rifle without buying a whole new gun.
The upper receiver is the top half of an M4’s body. It carries the barrel assembly and handguard at the front, and its top rail is where you mount your sight or optic, so a straight, solid upper is important for a rifle that holds its zero.
Why replace a receiver
Receivers usually need replacing after a drop or impact that cracks or bends the metal, after a stripped thread or broken pin hole, or when worn markings and finish mean a rifle no longer looks its best. A replacement is also useful if you are building a rifle from parts or converting one Bolt rifle into a different configuration. Because it is full metal, this receiver gives the same rigid, solid feel as the original.
Fitting
Swapping an upper receiver means removing the handguard, barrel assembly and any rail-mounted accessories, then transferring the barrel nut, hop-up and inner barrel parts to the new receiver. Take care to keep the hop-up unit and inner barrel clean and seated correctly. Bolt’s recoil system adds parts that other M4 designs do not have, so take photos as you strip the rifle. If you are not confident, have the work done by an airsoft technician.
Key features
- Full metal M4 upper receiver
- Bolt replacement part, reference B13
- Ideal for repairing impact damage or worn parts
- Top rail for optics and sights
- Keeps the solid, rigid feel of a metal-bodied rifle
- Useful for rebuilds and custom builds
Compatibility
Intended for Bolt M4-pattern AEGs. Bolt’s recoil-system rifles differ internally from standard M4 AEGs, and receivers from other makers are often not interchangeable even when they look similar, so check your model and compare with your existing upper receiver before ordering. The matching lower receiver is listed separately. Internal parts, pins and screws are not listed as included, so plan to transfer these from your existing receiver.
Care and maintenance
Keep threads and pin holes clean, and use the correct size of hex key or screwdriver so you do not round off screws. A light wipe with a lightly oiled cloth helps protect the metal finish after wet or muddy games; dry the rifle thoroughly before storing it in a case.
Store the battery out of the gun, keep the gearbox and electrical contacts dry, and use good-quality seamless 6mm BBs to protect the hop-up and barrel. If you are not confident working inside a gearbox, have the part fitted by an airsoft technician; a gearbox that is reassembled with a part out of place can be damaged as soon as power is applied.
Who is it for?
This receiver is for owners of Bolt M4 rifles who need to repair a damaged or worn upper receiver, or for experienced players building or rebuilding a Bolt rifle from parts.
Please note: This listing is for the upper receiver only; other parts of the rifle are not listed as included. Always wear suitable eye protection when testing a replica.
