AR noob questions on receiver i am holding right now

[coyote1911]

Ok I have had this Bushmaster lower receiver for many years but I have yet to match it to an upper receiver. It is a model XM15-E2S in .223. I installed the internals myself.
I am pretty noobiefied when it comes to this subject but...

Two questions: What is this small hole and large hole buisness and which one is mine?

Next question: I saw some M16-A1 uppers for sale at sarco http://www.sarcoinc.com/m16.html I thought this would be kinda neat if i could put an m16 upper on this bushmaster lower and have it work right away (semi only of course). Is this possible?

[JE3146]

Perfectly legitimate question.

You have a small hole upper.

A while back, Colt plagued the civilian market with large hole lower and upper receivers to make the civilan AR's imcompatible with their LEO/Military variants(which had small hole). Companies like Bushmaster, RRA, Olympic, DPMS, and many man more all have small hole lowers and uppers.

If that upper is a smallhole upper, then yes it would work. I looked but couldn't find exactly what you were looking at.

Take note you'll need the following for an AR to function.

A complete lower, a bolt carrier group, a charging handle, and barreled upper receiver.

:up: goodluck and keep us posted on how it turns out.

[thedaledoe]

hmm.. that upper comes with a "cocking handle" :rotflmao:

[Ne1]

Get this A1 upper. It's a new colt small hole upper so it will fit the bushmaster lower with no problems. Everyone recommends them. You'll need to buy a bolt, bolt carrier and charging handle separately though.

http://www.cdnninvestments.com/arsp1upnewco.html

[coyote1911]

That clears up alot for me thanks JE3146! I will definately keep that link in mind Ne1 and I will let you know how it turns out though it will be a while before I can get everything together.