M16A1 receiver .. barrel options?

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ThePlato

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Gentlemen,

I've tried searching but as of yet I've found nothing. I'm buying a M16A1 parts kit that essentially comes with everything except the lower receiver, disconnector, and barrel.

My question is I've heard that the M16A1 barrel was thinner?.. or something to that effect? Will current production barrels fit? such as a BCM barrel?

Anything else I should be aware of?

Before anyone suggests a brand new production coltbushmasterBCMDPMS... just know that I have a certain fondness for the old M16A1 rifles.. I'll be completing it with a Nodak spud receiver. I'm essentially trying to get this as correct as possible barrel not withstanding.
 
Century was building theirs with 1/9 twist barrels on old Colt parts, you might look on their website to get an idea, but i have no doubt you can fit a barrel easily.
 
Any Ar15 barrel will fit.
The thing is...if you are not a fan of the A1 style upper, you might be able to trade for a barrels upper to someone who is.
 
M16A1 parts kit - I assume you mean a semiauto version. Is that what you mean when you say it comes with no disconnector? Be aware that the selector is different also. The M16 selector works in semiauto configuration, but some owners have had trouble with it. Commercial manufacturers who used the M16 selector changed over to the AR15 selector after a few years. You might want to bear that in mind.

Not sure what the fellow above means about the upper. A1 upper has the older (and less expensive) rear sight. If that's the one you want, keep it.

Any and all M16/AR15 barrels will fit the receiver, the barrel nut will retain it very well. No problem, as long as the Front Sight Base fits.

Be careful of the barrel diameter at the front sight base.
Some barrels are .625" at that location,
most commercial barrels are .750",
and the fat bull barrels are around .940".

Measure your front sight base when you get it. That's the ticket.
 
I'm also doing a retro M16A1 build, but I'm have a heck of a time finding an old A1 pencil barrel. I have all the other parts except for the barrel and a lower, the lower not particularly being a problem.

Sarco has A1 parts kits, but have sold out of barrels.
 
Any AR15 bbl will fit. There's a reason they're called "lego guns."

I looked around for a few minutes and found this bbl, they also offer the A1 birdcage and three prong flash hiders.

I would probably go with a better barrel, and have it turned down by a reputable shop. The only thing out of place would be the .750" FSB.
 
Any AR barrel / upper will work.

The A1 barrel from the 70's was made to be very light weight, and was thin after the chamber, and also thin from the front sight to the muzzle.

When the A2 was developed in the 80's, the military wanted a slightly heavier barrel for improved accuracy, heat dissipation, and stoutness. They also changed the rate of twist from 1/9 to 1/7 to stabilize heavier bullets. This A2 barrel is known as the government profile, and will give you about an 8 pound rifle when built with an A2 stock.

There are plenty of other barrels to select from, lightweight CAR's midlengths, HBAR's, A4's, in lengths from 16" to 24" (shorter bbls are avalilable if you want to get your $200 tax stamp). Anyway, do a little research, to find which fits your needs. A lot of companies offer the heavy barrels HBAR's, just as a caveat, know this will make for a very heavy rifle, around 10 pounds, with a full length barrel, great for competetive shooting, but very heavy for the woods.

Good luck.
 
Got Lead,

Thanks for the input. I'm used to shooting my M1 Garand so heaviness isn't so much an issue. I'll most likely go with a 20 inch government profile barrel. Thank you for all of the input everyone!
 
Well, I built my A1 clone using a complete M16A1 upper when they were around cheap a couple years ago...I love that skinny A1 profile barrel. Makes for a lightweight, accurate rifle.
Building A1 clones is popular with some folks...if the OP is not tied to building an A1, I am sure he could trade his upper.
 
In a similar boat here, I just bought a stripped 20" government profile and sent it off to be recontoured to the A1 profile (.625" gas block/FSB area, .570" ahead of that, slight flare just before the muzzle threads). I found the undrilled non-F marked FSB and skinny barrel handguard cap on gunbroker.

A cheaper route if you're not in too much of a hurry might be to wait until August when Green Mountain will have A1 profile barrels in 1:7 and 1:8 twists.
 
Last edited:
When the A2 was developed in the 80's, the military wanted a slightly heavier barrel for improved accuracy, heat dissipation, and stoutness. They also changed the rate of twist from 1/9 to 1/7 to stabilize heavier bullets.
Click to expand...
1:9 was never a standard M16 bbl twist, if it was used at all. The M16 had a 1:14 twist, M16A1 was 1:12, M16A2 and subsequent variants are 1:7.
 
Buy a kit from WWW.gunthings.com. There kits come with a already parkerized barrel with the FSB already installed. All the other kits come with barrels in the white and require the barrel to be parkerized to match all the other parts. Some kits require you to drill the FSB holes as well. For $100 more you get a ready to go barrel.

Get your lower from NDS and you are good to go.
 
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