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Posted: 10/4/2004 8:46:30 PM EDT
[Last Edit: 10/4/2004 10:46:40 PM EDT by TealGunner]
Well, I asked for help, and got nothing. Maybe I wasn't clear, but my dilemna is this:

I want to do my first build. I have a stripped Stag lower.

I want to decide if I should buy a CAR 16 upper kit from model1 or m&a or if I should try and build the entire thing piece by piece.

I'm pretty mechanical and the info here is usually great.

Has anyone here built an upper from scratch, including headspace. I've read quite a bit, but nothing tells me if I could or should try it. I read about chrome lining not being able to shorten if its too long.

Any ideas????
Link Posted: 10/4/2004 11:14:41 PM EDT
Theres a post pinned by at the top of this section by FALARAK. Everything you need on building an AR is there. I'm looking forward to starting my project sometime later this month and the above post is of great help to a newbie.
Link Posted: 10/5/2004 2:23:08 AM EDT
Link Posted: 10/5/2004 4:21:29 AM EDT
Recently built a 20" upper from parts with no problem. Used Bushmater stripped upper, new Bushmaster govt. profile barrell & RRA bolt/carrier assembly. Everything went together smoothly. Just follow the manual & guides here & get the proper tools and you should be fine.

Link Posted: 10/5/2004 4:41:01 AM EDT
Go with a Colt,bushie or RRA barrel, stay away from the no-name or so called FN crap.

If the barrel isn't right, it will be problematic.

No need to headspace, they come pre set, just check it. If you can change your own sparkplugs on your truck, you can build an upper, lowers are even easier.

Good luck
Link Posted: 10/5/2004 6:56:10 AM EDT
About barreling:

I just swapped the barrel on a post-ban colt for a "real one".
I was a bit aprehensive, but actually it was pretty easy.
You do need to get the right tools, with them lined up you should have no problems at all.

One thing which is not mentioned in any of the articles on this site (at least not that I saw) was ensuring that the holes for the gas tube need to be lined up carefully. It is very easy to have the tube end not perfectly aligned inside the upper. To check this you take the bolt out of the carrier and with the gas tube in place, slide the carrier down and watch that as it engages the gas tube there is no significant extra force required to move the carrier, and that there is no perceptible movement of the gas tube.

I lined it up to what I thought was correct and tested - and it was not perfectly alligned. What I ended up doing was finding a piece of metal rod (a drill will do), and as I tightened the barrel nut inserting the rod throuth the lined up holes into the upper hole, them moving it side to side and noting that the movement was not symetrical over the barrel. Slowly and carefully tightening the barrel nut, bit at a time, I arrived at the point where the movement was symetrical over the barrel. I then re-fitted the gas tube and tried the bolt carrier again - this time there was no extra force required as it met the gas tube, and no perceptible movement of the gas tube. Don't just "eyeball" this - its too easy to get a bit of missalignment which will result in wear and possibly poor cycling.

As far as headspacing goes, there really is no adjustment you can make, short of taking a reamer to the chamber. With a new (or good condition) bolt and a new barrel its 99.99% certain that the headspace is correct. There is just the outside chance that the barrel didn't get finished correctly, so you should really check. A set of Go/No-Go/Field gages will cost around $50 - this is cheaper than the bill for surgery if you had the bad luck to have an incorrctly finished chamber. They are easy to use, just drop them in, and try to close the bolt by pushing on the carrier as per the instructions which come with them.

Don't worry about being able to do this - just ensure you buy the right tools and think about what you are doing - it really is straight forward.
Link Posted: 10/5/2004 12:33:13 PM EDT
So, in reality, I could just buy the stripped upper and parts as well as a separate barrel or assembly and just by using the proper wrenches and tools, mount the barrel/parts to the upper? By that I mean that the headspace will be automatic if I do the procedure correctly?

I've real FALARAK's posts and the info is awesome. These procedures are detailed in the USMC tech manual, right?

Thanks for the info
Link Posted: 10/5/2004 12:38:57 PM EDT
The headspace should be fine. That being said, I still spent the money on a set of guages and check the headspace before assembly. Better safe than sorry. IMO

Link Posted: 10/5/2004 12:42:23 PM EDT
i built my first ar from scratch. I even did a 80% lower. if your trying to save money you won't by building it yourself unless you are doing a costum setup. you will need a dpms armorers wrench, a punch set and a receiver block to put in a vice. i think you can get all that at brownells. doesn't take long and the diagrams and instruction on this board can be very help full.



those will help.
Link Posted: 10/5/2004 2:24:52 PM EDT
I would reccommend buying the AR15 assembly guide from Fulton Armory:


It has lots of hints and tips on building an AR15 from scratch from people who have done it a million times, and made all the mistakes there are to make.
Link Posted: 10/5/2004 5:41:53 PM EDT
how much would the headspace be affected if you change out the upper receiver but use the same barrel and bolt?
Link Posted: 10/5/2004 6:30:24 PM EDT
Link Posted: 10/6/2004 4:11:43 PM EDT
thanks, that is releiving.
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