Building my First AR-15

[parabelum]

1/7 twist is great for heavier bullets, as stated previously. I do think that you really need a longer barrel still (20") to see a substantial difference though over 1/9.

If possible and budget permits, I'd suggest a chrome lined barrel.
It will be easier to clean and won't get hot as quickly, so your accuracy will be improved. You will also have a longer barrel life.

If I was building, the right barrel would be my biggest investment next to properly staked bcg.

[Pawpaw]

1/7 twist is great for heavier bullets, as stated previously. I do think that you really need a longer barrel still (20") to see a substantial difference though over 1/9.

If possible and budget permits, I'd suggest a chrome lined barrel.
It will be easier to clean and won't get hot as quickly, so your accuracy will be improved. You will also have a longer barrel life.

If I was building, the right barrel would be my biggest investment next to properly staked bcg.

I have to disagree with the part I highlighted in red, based on personal experience.

My Colt 16" pencil-barrel 1/7 rifle is most accurate with Fiocchi 77gr HPBT ammo. With that ammo, I can hit at will out to 500 yards. One day I was at the range with a friend who brought his brand new Olympic Arms rifle with a 1/9 twist 16" barrel. I was helping him try several different loads to find out what his rifle liked best. He tried my Fiocchi and was getting good results at 100 yards, but couldn't seem to hit the target at 200 yards. It turned out that the rounds were losing stability somewhere just past 100 yards and tumbling. We found a couple of keyhole strikes down low where the bullets had probably hit the ground and skipped into the target. After that, he aimed very high with 5 more rounds and then went back to smaller bullets. On the next cease fire, we found a couple of hits from the Fiocchi... all keyhole strikes.

I personally (YMMV) won't have a non-chromed barrel on an AR. The #1 problem with the M-16 when it was first introduced in Viet Nam was the lack of a chrome lined barrel and chamber. When the rifle was the least bit dirty, corrosion would set in and cause extraction issues in the middle of a firefight. I realize not many of us live in a jungle environment, but I want that extra protection just in case.

[parabelum]

I thought that Olympic barrels were not chrome lined, Colt barrels are. If so, I can imagine how the first few rounds irrespective of distance would be close, and then as they both heat up, non-chrome lined barrel would heat up faster, get messy faster and be drastically less accurate.

20" barreled AR, assuming it is chrome lined and quality, should be very close in accuracy when compared to a 16" 1/7 counterpart. In 16" 1/7 you get 2.29 turns roughly, compared to 2.22 turns from a 20" 1/9. Now, is it better to have 1/9 20" bull barrel, chrome lined, then 16" 1/7....?

But yes, I'd spend few extra dollars and get a good quality chrome lined barrel for sure.

[couzin]

The #1 problem with the M-16 when it was first introduced in Viet Nam was the lack of a chrome lined barrel and chamber. When the rifle was the least bit dirty, corrosion would set in and cause extraction issues in the middle of a firefight. I realize not many of us live in a jungle environment, but I want that extra protection just in case.

Not really, the first versions (not talking about the AR15 model) of the m16 / xm16e1 (with fa) were being shipped without cleaning kits because colt proclaimed it was a self-cleaning rifle. A delivery problem with powder types caused the fouling. Rifles that had proper cleaning kits did not have near the jamming problems the others did. The m16a1 was the masterful fix.

[Pawpaw]

The #1 problem with the M-16 when it was first introduced in Viet Nam was the lack of a chrome lined barrel and chamber. When the rifle was the least bit dirty, corrosion would set in and cause extraction issues in the middle of a firefight. I realize not many of us live in a jungle environment, but I want that extra protection just in case.

Not really, the first versions (not talking about the AR15 model) of the m16 / xm16e1 (with fa) were being shipped without cleaning kits because colt proclaimed it was a self-cleaning rifle. A delivery problem with powder types caused the fouling. Rifles that had proper cleaning kits did not have near the jamming problems the others did. The m16a1 was the masterful fix.

Close, but not quite. Colt never said the rifle was self cleaning. That was the Army not wanting to "waste money" on a rifle they saw as a temporary solution.

The Self-Cleaning Gun

With the purchase and distribution of more than 85,000 AR-15 rifles in Vietnam, there was not a single .22 caliber cleaning kit, operator’s manual or chamber or bore cleaning brush available. As recalled by Gene Stoner, the Army had no intention of buying the rifle so the government did not want to waste money on cleaning kits and manuals. The AR-15 was supposed to be an “interim” solution until they could get the SPIW (Special Purpose Individual Weapon) finalized and fielded. Therefore, the gun was touted as being self-cleaning. Troops were instructed that it was not necessary to perform any cleaning or maintenance on their weapons prior to going out on patrol or on a mission. Due to lack of reasonable maintenance guns would be fouled, firing thousands of rounds without cleaning. By not cleaning, the humidity and other environmental factors, the gun was even more prone to corrosion in the barrel and chamber. With the lack of availability of cleaning supplies, operator manuals and maintenance training, rifles were found to be in unserviceable condition in the hands of infantry soldiers. Many soldiers in the early part of the Vietnam War received training on the M14 rifle in basic training and when they arrived in Vietnam they were issued an M16. They received no instruction on operation and maintenance. With the introduction of Ball propellant, the fouling became more of a problem without maintenance

Many corners were cut to save money. Much of that, including the lack of chrome lining, was due to McNamara’s “Wiz Kids”, who were focused on numbers and understood nothing about small arms.

If you'd like a more complete picture, take a look at this article which lays out the conclusions of the Ichord Hearings.

http://www.smallarmsreview.com/display. ... icles=1735

Failure to Extract

Failure to extract problems were due to the bolt unlocking sooner due to the change-over from IMR to Ball powder. There was still high residual pressure in the chamber and the cartridge cases did not have sufficient time to contract to be easily removed from the chamber. Thus, the extractor would slip off the rim or shear part of the rim off leaving the fired cartridge case in the chamber. To clear this malfunction, often the bolt would be closed again and the cartridge would come out of the chamber. If you compounded this malfunction with a corroded and pitted chamber, the cartridge case would become lodged in the chamber and have to be pounded out with a cleaning rod. This was by far the most serious of any malfunctions of the M16 in Vietnam. Chrome plating the chamber cured the extraction ill. The next major improvement to extraction took place in the 1970s with the addition of the rubber extractor spring buffer, which greatly increased extractor force. This particularly helped carbines that had a much higher cyclic rate.

[jason812]

The reason the 16" and shorter barrels went to 1:7 twist has to do with velocity. At a lower velocity due to barrel length and 1:9 twist the bullet isn't spinning fast enough to stabilize the heavier bullets. Slower muzzle velocity equals a slower bullet RPM given the same twist of the barrel. A 1:9 out of a 20" barrel will most likely stabilize a 75gr bullet but it seems 68-69 is about perfect.

[remanifest]

Thank you all very much for the advice so far. I'm pretty well settled on a Ballistic Advantage Modern Series 16" with a 1:7 twist. It seems like a quality barrel based on the specs you all mentioned that I should be looking out for.

The Palmetto State Armory barrels being manufactured by FN really intrigue me though - reading lots of opinions has taught me that FN produces great quality the vast majority of the time.

While the Daniel Defense looks like a great product, I think it's probably out of range for my budget.

I especially appreciate the information on vendors, and the tips on what to look out for.

Does anyone have recommendations for gas systems to match the above linked barrel?

[remanifest]

Depends - do you prefer the gas-block which includes the traditional, triangular F-type front sight or do you want a sleeker look eg. pop-up iron sights?

Traditional would work fine for me.

[remanifest]

After doing some research on gas systems specifically, I'm strongly considering spending little extra cash for a piston system. While I understand direct impingement works perfectly fine, and is a reliable system, the fact that my upper parts will be cleaner as a result of using a piston system is very nice.

No matter how clean I am, it will ease my mind to know that I'm putting the gases somewhere that will localize the crud, and save me time in maintenance.

Any thoughts?

[parabelum]

Unless you are planning on shooting full auto, or more then 300 rds per range trip I'd stick with DI. My DI LMT will go few houndred rounds on mediocre ammo before I break it up, spray some balistol and wipe it down, then go again.

I've never owned a piston ar so I can't speak to their performance or reliability.

[maverick2076]

You might look at http://www.joeboboutfitters.com/...i have ordered from them a few times. The first time I almost didn't. I said to myself, "am I REALLY gonna buy something from an outfit that calls themselves 'Joe Bob Outfitters'?!" But their service has been outstanding! I ordered my 9mm carbine barrel and got a confirmation that the order was being picked about two hours later and then next day, I had tracking on it. They made me a return customer...

EDITTED TO ADD:
The above mentioned barrel was discounted because the vendor of that particular barrel got a lot in that had their markings etched as opposed to rolled. They were selling the whole lot for $30 less. I could care less that the logos aren't the way the company wanted them to be. The barrel itself was QC'd just like the regular run. Sometimes Joe Bob has some really, really good deals...

I second Joe Bob. I've bought lots of parts from them. I think I bought the same 9mm barrel as you!

[LTUME1978]

Sharing my experiences. I have never owned a piston gun. My DI rifles have all worked very well. I reload my own ammo with the exception of some IMI 262 Mod 1 ammo that I shoot (I can't build a load that shoots as accurately or as fast as this stuff does). I use quality powders in my reloads (H335, Varget, Ramshot Tac). The rifles are also well lubricated with a good synthetic oil (Royal Purple or Mobil 1). I have gone a couple of thousand rounds without breaking down for a good cleaning (it was well lubricated during all of that shooting) and have had no failures to function/see no signs of wear. When I did break it down, the rifle was amazingly clean (wipe down and lube). I still have not cleaned the bore on that rifle and have seen no degradation in accuracy.

I have a Colt, a LMTs and an Aero Precision. They are all 1 in 7 twist. I have no issues getting my 55 grain reloads to shoot very well in those barrels. When I got my first M4 (LMT), I shot some Lake City 55 grain ammo through it and the groups typically ran near 2.5 to 3 inches. I did not know if it was the rifle or the bullet weight. It appears that the issue was with the Lake City ammo as once I started reloading, groups improved considerably. I have not tried any other manufacture's ammo to see how it shoots.