View Full Version : NECESSARY Tools for Building an AR-15

June 8, 2008, 07:44 AM
I know this info is probably here somewhere, buried within many threads, but I can't seem to find the simple answer in one place. So please be patient...

I have a Bushmaster all original DCM that's never been fired. I bought it directly from Bushmaster.
But over time, I've decided I don't want to have to worry about corrosion of the barrel (which is why I've never fired it... I just oil it once in a while).

So what I'm doing is to buy (from Bushmaster direct) a 16" Carbine barrel assembly, a naked A3 upper, and the Command Arms CBS6 (FBS-CBSK) telestock to replace the original fixed stock.

I'll buy the tools I need to do this, but I'm hoping someone can tell me only what I "need" to do this because I don't want to put a bunch of money into tools I'll rarely use.

Additional thought:
I'm using the original bolt with the new barrel so I assume I have to headspace them. Do I need just a "no go" gauge or do I need them all?

Thanks all

June 8, 2008, 08:13 AM
Want to sell the fixed stock? I have been looking for one for awhile now.

PM me if you do.

June 8, 2008, 02:07 PM
Receiver block (http://www.armalite.com/ItemForm.aspx?item=EX1616&Category=712d2aa3-e479-4cf2-b707-ac14957399b2%20&ret_url=categories2.aspx?Category=712d2aa3-e479-4cf2-b707-ac14957399b2)
Multi-wrench (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=271183)
Punch set (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=925277)
Hammer (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=297752&t=11082005)
Hollow ground screwdrivers (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=439523)
Also get a small package of silver anti-seize from your local auto parts store for about $2 to prevent the barrel nut from galling the upper receiver threads.

A torque wrench is used in conjunction with the barrel nut wrench to get the 35 foot-pounds minimum torque but not exceed the 80 ft-lbs that can crack or permanently twist the upper receiver.

June 8, 2008, 04:52 PM
Thanks DnPRK, I used to be an auto mechanic by trade and have lot's of leftovers when it comes to tools, so it looks like all I should actually "need" to get are the armorers wrench and the receiver block.

But what about head spacing? I'll be using a different barrel and receiver with the original bolt assembly, so do I not need to re-check the head spacing?

And thanks for the offer, Creature, but my intent is to keep all of the original DCM parts including the fixed stock because I might want to change back and play with some long distance shooting at some point.

June 8, 2008, 10:31 PM
I've been building ARs since the early 1980s and haven't seen a quality bolt and barrel that wouldn't headspace properly. The manufacturing tolerances are pretty tight and while lots of shops sell AR components, there aren't that many bolt and barrel extension manufacturers.

If will make you feel better 223 field gage (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=383456)

Remove the extractor and ejector. Reassemble the bolt into the bolt carrier. Then push the rear of the bolt carrier with your thumb. The bolt should not close leaving the rear of the bolt carrier proud of the rear of the upper receiver.

June 9, 2008, 07:35 AM
I guess what you're saying is that since I'm using all Bushmaster parts, brand new, then head spacing is a non-issue and I don't have to worry about it at all?

June 10, 2008, 08:21 AM
The original bolt is unfired, so headspacing is not necessary. Generally, "marry" a bolt with a barrel, so they wear in together. If you switch back to the DCM upper, get another bolt for that upper. While you're at it, get another lower so you do not have to switch them around. :D Money-wise, you are pretty close to that.


June 16, 2008, 01:14 PM
+1 to what DnPRK said. Tho, I like the vise block that Brownells and Midway sells for around $35. It is molded to the outside of the upper and has a insert to protect the dimensions of the upper. Also, it helps to have a barrel extension socket to attach to the torque wrench. When I was a USMC armorer (M16A days), the torque set was 30#. But specs and metal do change. Just remember the barrel nut only has to be tightened to a line the gas tube notch. The barrel extension is the part needing to be weight tightened. I head spaced thousands of M16s. I only recall 2 that failed. Most problems were bent and worn out barrels...