Modifying an AR-15

[Phantom Warrior]

I recently purchased a Bushmaster AR-15. You can get all the details here. In summary, I got the 20" A2 style with Realtree camo furniture.


I'd like to swap the 20" barrel for a 16" barrel and swap all the furniture for straight matte black. I'm new to ARs, so I'm not clear on all the small parts. My questions are as follows:

1. Can I just buy a 16" barrel or do I need all the small parts that come with it? Don't I have those already?

2. What kind of handguard do I need if I buy just the 16" barrel?

3. Can I just buy a black stock or do I need the gas buffer and springs? Those are already on the rifle, right?


Any help would be appreciated.

 

[TechBrute]

1. Buy a complete barrel assembly, with the Gas Tube, Front Sight Base and Delta Ring assembly already on it. They'll swap right out with the right tools.

2. Carbine or M4. You can also get rails, free floats, etc., but Carbine Length is the operable term.

3. If you already have a standard A2 buttstock, then all you need is the stock. The existing tube, springs, etc, should be GTG.

 

[444]

As was mentioned, you can't just swap out the barrel with another barrel due to the gas system. One is a rifle lengtn gas system and the other is a carbine length gas system. All you need however are the barrel and the gas tube.
Of course you are going to need a barrel wrench, a torque wrench, and an action block to swap out the barrels.

 

[Phantom Warrior]

Mmmmm, carbine length gas system. Veeeery innnteresting. Ok, I'm looking at some used stuff, so that's why I'm asking. What is the minimum I could get away with? Could I just buy the barrel and the gas tube and use the other parts I have already?

 

[TechBrute]

One clarification:

To swap the barrels, the most trouble-free way is to buy a complete barrel with FSB, gas tube, delta ring assembly, and barrel extension already in place. If you get a barrel without a FSB, there are all sorts of headaches with trying to match up a standard pinned FSB with a new barrel. If you get a barrel without the extension, you have to worry about headspacing. Most AR barrels come the way I've suggested.

 

[TechBrute]

By not buying an assembled barrel, you are only going to save yourself maybe $20. You'll cause yourself more than $20 in therapy trying to get the front sights set up. Once you've seen it, you'd understand.

You will need a different length gas tube. They are $8.

 

[Phantom Warrior]

Fsb=??

 

[cordex]

FSB=front sight base

 

[TechBrute]

Sorry.

Thanks, cordex.

 

[Phantom Warrior]

Alright, so I need a fully assembled 16" barrel or I'll regret it. Hmmmm. Thanks for the advice guys.

 

[Harry Tuttle]

heck, buy a used 16 inch upper and do the 2 push pin upgrade

keep the 20 inch upper and in 6 months buy another lower

 

[jefnvk]

+1 on Harry

Buy a new barreled upper, less B/BC/CH. Since your other upper is relatively new, take the B/BC/CH out of the old upper, put it in the new one, and sell the old upper, making back most of your money. You shouldn't have a headspace problem, but if you are worried, get a gauge. It will be much easier than removing the barrel off your old upper, and putting a new one on. Plus, you won't have to buy the action block or armorer's wrench.

 

[Phantom Warrior]

*** is a B/BC/CH? I'm considering just the barrel because that would be cheaper. And in a month I join the Army so I'm not planning any gun purchases (i.e. another lower receiver) any time soon.

 

[DMK]

*** is a B/BC/CH?

Bolt / Bolt Carrier / Charging Handle (the bolt and bolt carrier are an assembled unit in your rifle)

To do a barrel swap, you need at minimum:

Parts:
- a barrel assembly (they almost all have a front sight assembly unless you are getting a match barrel)

- A carbine gas tube (use the roll pin from your other barrel that you're keeping)

- Carbine handguards

Tools:
- Receiver block

- Barrel Wrench

Parts you will be reusing:

- Delta ring assembly(although the new barrel might come with these parts)

- Gas tube roll pin

- Front sight post

- Front sight detent

- Front sight detent spring

- Flash suppressor (if so equipped)

- Bolt/ Bolt carrier (the only expensive part)

- Charging handle


If you get a complete upper, it will only cost you about $150-$200 more for the upper receiver depending on whether you use an A2 or flattop upper, but then you don't need the $50-$60 in tools. You also should get a new bolt/ bolt carrier assembly. Swapping once is OK, but cosntantly swapping the bolt back and forth between uppers will cause excessive wear on the locking lugs and increase headspace over time.

What I would do is buy a new complete upper, keep your bolt, bolt carrier and charging handle, then sell your old upper. That way you don't need to buy any tools.

And yes, buy just the stock itself. You can use your existing buffer tube and hardware.

Visit the Equipment Exchange at www.ar15.com You can buy used parts there, trade you parts of others and sell your old stuff.

 

[TechBrute]

Bolt/ Bolt Carrier/ Charging handle.

 

[Commissar Gribb]

IMO it would behove you to just get a 2nd upper. This way you can swap back and forth any time you like and it's very simple to do. why would you go to a 16" barrel anyhow? the 20" is more accurate and IMO the 16" on a solid stock looks god ugly.

 

[Phantom Warrior]

DMK,

THANK YOU for the detailed explanation. That was exactly what I needed. I know what the the Bolt/ Bolt Carrier/Charging Handle is (the acroynym threw me), but I didn't realize what all was involved with a swap.



Commissar Gribb,

I'm starting to agree w/ you on the upper. Now I just have to pull together a few extra $100 bills to pay for the upper. As to why, I LIKE the 16" on a solid stock. I handled one last fall and loved it. It feels better balanced to me and I like the over all look of it much better. Plus it's handier than the 20 inch.

 

[TechBrute]

IMO the 16" on a solid stock looks god ugly.

Phfffft...

 

[Harry Tuttle]

what i dislike about the 16 inch barrel, is that bayonets mount 1.5 inches to deep

 

[jefnvk]

what i dislike about the 16 inch barrel, is that bayonets mount 1.5 inches to deep

Midlength, my friend.

For $295, you can get a 16" upper, minus B/BC/CH (sorry for throwing you off there) from Del-Ton: http://www.del-ton.com/detail.aspx?ID=472

Or for $309 from J&T: http://webcats.net/store/merchant.mv?Screen=PROD&Store_Code=J&Product_Code=1APBU&Category_Code=BU

Or for $405, if you prefer to stick with Bushy: http://www.bushmaster.com/shopping/uppers/pre-ban/bura2b16m4.asp

For $320, you can get a midlength from M&A Parts. It is a RRA upper, with the handguards stretched a bit longer, giving you a longer sight radius and correct bayonet mounting. Still 16" though: http://www.mapartsinc.com/productsDetail.asp?id=225

If you upper is a practically new Bushamster, I'd imagine you could come close to making up all your money back on the swap out. Maybe even a bit more.

 

[TechBrute]

I didn't want to complicate the issue, but since the cat's out of the bag...

Middies RULE!!!

 

[DMK]

why would you go to a 16" barrel anyhow? the 20" is more accurate

Granted, the carbine has a shorter sight radius, but barrel length itself has little to do with accuracy.

 

[Bartholomew Roberts]

ARs are very option-rich. If there is a design you can think of, there is someone out there who will make it. The question is usually whether they will make it for the price you want to pay.