Well I was at my local gun shop the other day and I told them I have been looking into m4’s. They had a few, but they were way out of my price range. One of the guys working there said it might be a good idea to build my own. Now I love the thought of this, but I don’t know the first thing about building an m4. I would use the gun for home defense and just to take out to the range on the weekends. I am not a competitive shooter. I would like to build one for around 1k. Nothing fancy, just something that I can do on my own and something that is very dependable. With that said any suggestions? If there are already a lot of posts on this you guys could just give me the links, point me in the right direction, or post some good reading material on this matter. I am in college right now and it’s finals week so I will get to reading them in the next week or so. Thanks guys!
Some of the other guys here can help you out a little more I’m sure… but if you want something for home defense, get something that will be rock solid… I’d look at bravocompanyusa.com and look at complete uppers and bcg (bolt carrier groups) from either BCM (their house brand) or LMT… then you just need a lower + parts kit, furniture and a few other odds and ends and you’ll have a rock solid go to M4…
There are other places to get these parts as well… but no one has them in stock at the moment. You’ll have to be patient if you’re going to build right now…
I just built my first in the last few months so this advise is from a fellow novice.
Assembling a lower reciever is really very simple. The only tools I bought were a roll pin punch, roll pin holder, and a castle nut wrench for the receiver extension. Some use a set of vise grips to press the roll pins in instead of the punches. Regular punches can also be used but may mar the pin a bit (not really a big deal if your building a shooter and not a safe queen ;)). It’s just whatever you prefer. A bit of electrical tape can help protect the finish while you work on the receiver.
I used a book called “Build Your Own AR-15” to guide me through my first lower. It’s got some good information in it but in all honesty, it was written during the assault weapons ban and as such, much of the legal advise that takes up a good portion of the book is dated. Brownells has a video series posted online that walks you through a complete build for an AR-15. Along with the information available on this forum it should provide you with everything you need. Keep in mind that Brownells is using the video in part as a promotional display to sell you tools. I can’t criticize that as it’s an excellent resource and I think it’s very cool they have made it available online. Just remember that many of the tools they show are a matter of convenience or designed for an armorer who is working on many rifles rather than a hobbyist just putting together a couple of rifles.
http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?x=v&p=0&t=1&i=1103
For parts, you will just have to keep an eye out. I was able to find lowers and lower parts kits locally this past weekend. Prices are all over the place but most are high. For a complete upper, I would join up on the e-mail list at Bravo Company and check in often. Pretty much all the parts and tools for my rifle were purchased through Brownells, Bravo Company, G&R Tactical, and Ranier Arms. The lower was purchased locally several months ago at a relatively sane price.
Hey thanks guys. Sorry it took me a while to get back on here. Just finished up all of my tests so now I have some free time. Those links posted were very helpful. Its really lame that these parts are hard to find at the moment. Does anybody know when this stuff should be re stocked? It’s not really a big deal to me right now seeing as I will have to piece the rifle together, but it’s always nice to have the option open. If I recall I can get lowers at my local gun shop they had a few if I’m remembering correctly. But like that first reply stated I definitely want a solid gun that I can always depend on and one that will be shot a lot. I think it would be cool to build my own and have it just the way I like it and then add on some fancy stuff as time goes on. The only two things I can think of that I want on it are a flashlight and maybe a front grip. Other than that I think it will be mostly stock appearing. Are there any good internals to go with(If that’s what you call them) and what exactly is barrel twist? Thanks for the help guys.
http://www.gunnersden.com/index.htm.rifle-barrel-twist-rates.html
What does the rifling twist rate do.
The rate of rifling twist determines the optimum bullet weight for a given caliber and speed of the bullet by applying the proper spin on the bullet to prevent the bullet form yawing and pitching.
Expressed in terms of the number of revolutions per inch of barrel length, this ratio is commonly expressed by designations such as 1:10, 1/10 or 1 in 10 twist, the 1 represents 1 twist, the 10 represents inches of barrel length.
So, a 1 in 10 twist is, 1 complete bullet revolution every 10 inches of barrel length traveled.
How do you know what rifling twist is right.
A good rule of thumb is that the heavier and longer a bullet is, the faster the rifling twist rate needs to be to stabilize it in flight, therefore a lighter shorter bullet needs a slower rifling twist rate to give proper bullet spin for correct flight
Interesting thanks for the reply. What size bullet would be ideal for home defense and just going out to the range and having a good time? Then what twist would work best with this?
Also are bushmaster upper receivers good/durable/reliable? I’m thinking I will go with the 14.5 in barrel and I seem to mostly find 1/9 barrel twist.
55gr FMJ is by far the most common weight, and it’s applicable for both HD as well as plinking. Ballistically speaking, there’s not much noticeable difference between a 1/7 and a 1/9 twist out of a barrel that short. You’ll see 1/12 barrels out there, but they’re usually 20" or 24" and are made for heavier projectiles used in varmints and sniper applications.
BM uppers are just fine, but most of them do not include M4 feed ramps. These aren’t necessary per se, but a lot of guys here like to have them. Also note: if you go with a 14.5" barrel, you’ll have to permanently pin/weld the flash hider to comply with BATFE regulations unless you have the proper paperwork and permit.
yeah I was just reading about having to weld the flash suppressor on. That won’t be to much of a deal. I did find a upper that said it was 14.5 with an a2 birdcage suppressor. Would that make it long enough? What is the difference in the feed ramps?
negative- the standard A2 aint long enough by about a quarter inch. there can be found extended A2 style hiders, if you really like the “service” look, or there’s a multitude of choices like the Vortex and Phantoms. you can even pin on an AAC if you want to add a sound suppressor.
M4 feedramps are where the feedramps extend from the barrel extension into the receiver. normal feedramps dont extend into the receiver.
I didn’t know sound suppressors were legal. I’ll take a look into those other flash suppressors thanks!
check your state laws, but most states it is OK as long as you get the NFA tax stamp from the BATFE (and sometimes Y).
This is 180 degrees right out backwards. Longer twist rates are more suited to lighter bullets, and you need a faster twist to stabilize a heavier projectile.
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So if I got a 1/9 twist what kind of bullet would I want to buy for it?
You don’t want 1/9. I don’t have so much a problem with the twist rate, but the companies that use that twist generally don’t have correct 5.56 chambers (even though they mark them as such).
Use the search feature for “barrel twist rate” in the technical forum, do more reading on this site before you go following the “gun store guy’s” advice. They are generally wrong in the advice they will give you.
alright sounds good. I have done a little bit of reading on the twist rate and I remember reading that 1/7 was the optimal twist rate, but it is incredibly hard to find. I will do more reading on this site though and post when I learn some more.
I’ve tried to use the search feature on a few occasions today and it isn’t working. Guess I’ll try tomorrow.