Into the left side of the receiver.
Depends on the rifle- some do not HAVE a bolt catch. On the AR15 family of rifles, it is the left side of the receiver.
Screws?There are no screws on an AR15 bolt, a pin secures the assembly
The serial number and possibly on the bolt.
Depends on the model
Please tell me how to install the bolt in a Remington Model 512
First do a full functional clear, eject the mag, rack the bolt/carrier to eject any casing. Next fully clean the gun. Check for broken or weak parts in bolt/carrier, gas system, and buffer system. Use quality ammo. If it still doesn't then take the gun to someone who knows how to work on ar15 rifles.
The process is different for a Mark1, #3, and a Mk 4#1 or a Mk5 carbine. The Enfield has a bolt catch that must be released to withdraw the bolt. For the Mk3, open the bolt, and flip the bolt catch UP (it is on the right rear of the frame). When vertical, bolt can be withdrawn. For the Mk 4 and Mk 5, open bolt, flip rear sight up, depress bolt catch (right side, near bolt head) draw bolt back until under the catch, and release catch, which will turn bolt head up. Continue turning bolt head until vertical, then withdraw. This site has some excellent information on a number of surplus firearms, including the various Enfields: http://surplusrifle.com/no5/rifledisassembly/index.asp
Bolt it to the frame.
When the bolt is pulled back there is a catch on the left side of the bolt. Using a small screw driver or Allen wrench push the catch forward and down. this allows the bolt to pass. the tool must be inserted from behind the action.
If you catch on spark of a lightning bolt, it can give electricity to the world for a year.
These are simple bolt-on parts, there is no special procedure to install them.
Try AR15.com Try AR15.com