AR rebuild

[mosulmp]

I have a XM15 M4 bushmaster A2, and I am looking into changing the upper receiver to a BCM m4 flat top, this is my first mod. to this gun and I am new to this barrel changing mod. and want to know, first what is this M4 feedramp mean? and second how hard is it to switch the barrel.

I have taken a colt armorer course about 2 years ago but I never changed out a barrel. Any advice would be very appreicated. Thank you.

[Ak44]

Wouldn't you just replace the old bushmaster upper with a new BCM upper? M4 feed ramps are cuts into the upper receiver that connect to the ramps on the barrel. It just helps with feeding ammunition.

[5pins]

He talking about replacing the upper only and keeping the barrel.

M4 ramps are cuts in the upper receiver that line up with the feed ramps on the barrel extension.
http://ar15barrels.com/tech/feedramps2.jpg

[Quib]

....................how hard is it to switch the barrel.

I have taken a colt armorer course about 2 years ago but I never changed out a barrel. Any advice would be very appreicated. Thank you.

A barrel swap is not hard at all. Follow the link below to the -23&P and familiarize yourself with the procedure and necessary tooling. A site search will also provide lots of first-hand knowledge on the subject.

:)

http://generalcartridge.net/Documents/TM9-1005-319-23.pdf

[seb5]

The barrel swap is a lot easier than disassembling an A-2 rear sight. Some of the armorer courses priorities are goofy.

[mosulmp]

Thank you to all for all the info. and the pictures were extremely helpful. Thank you