AR: 20" Barrel vs 16"

MrKalashnikov · 05-30-2017, 04:39 PM

I'm thinking about either building or buying an M16A2 clone with the proper 20" barrel length. I've read & heard over the years that Stoner designed his toy to function at peak performance using that barrel with the 5.56 round.

Seems like everybody & their crazy uncle is pushing the carbine 16" barrel these days. I've never owned an AR with the 20" configuration...maybe now is the time when parts & even whole rifles are so cheap? What say ye?

baboon · 05-30-2017, 05:04 PM

Go for it! Everything I have is 16.25 inches or shorter. I always liked the looks of the Colt LMG with a 20 inch heavy barrel. Way to pricey for me.

CDawg · 05-30-2017, 05:07 PM

Do it. I like my 20" Bushmaster quite a bit. I got it over 20 years ago and it's still one of my favorites. I do find the A2 stock too long for comfort though, so I added an A1 length butt stock. It's an excellent setup. No detachable carry handle, rails etc., etc. ...just a plain old AR15. Mine happened to come with a very good stock trigger and it's extremely accurate with Federal XM193, which is all I use. The barrel is 1 in 9 twist. The 20" creates better velocity, so the XM193 performs correctly (jacket shredding) a bit further out than the 16" barrels. I had an ACOG on it for a while, but moved it onto one of the M4geries. With the 20", I hit very well with just the irons sights. Whenever women have shot that rifle, they've liked it better than any others I have. ...and they hit better with it too.

Railbuggy · 05-30-2017, 05:35 PM

I have assembled five and I am working on number six at this time. My best barrel in the bunch is a 18" 416R Barrel from Faxon, Gov’t / Socom Profile, 5.56 NATO Caliber, Rifle-Length*Gas System with 1:8 twist. I think I paid $179.99 on a sale last year. It came from AIM with a F marked front sight/ gas block. It all depends on what you want it to do. 18" with a 1:8 or 1:9 twist rate is a good all around barrel for different weight boolits. The first M16s had a 20" barrel with a 1:12 twist but didn't do so well shooting tracers and other weight rounds. Most 16" barrels have a quick 1:7 twist to stabilize 55 thru 75gr boolits thru the short barrel. I read that to get the best performance from the 5.56/223 rounds, they need to leave the barrel above 2500fps. With the faster twist rates this can be done with 10.5" barrels and longer. I believe the longer barrels, 18 and 20" have a Muzzle velocity
3,110 ft/s while the 14.5" barrel would do around
2900 ft/sec.

Railbuggy · 05-30-2017, 06:21 PM

Quote from M16 Rifle- Wikipedia

Barrel[edit]
Early model M16 barrels had a rifling twist of 4 grooves, right hand twist, 1 turn in 14*inches (1:355.6*mm) bore - as it was the same rifling used by the .222 Remington sporting round. This was shown to make the light .223 Remington bullet yaw in flight at long ranges and it was soon replaced. Later models had an improved rifling with 6 grooves, right hand twist, 1 turn in 12*inches (1:304.8*mm) for increased accuracy and was optimized for use with the standard U.S. M193 cartridge. Current models are optimized for the heavier NATO SS109 bullet and have 6 grooves, right hand twist, 1 turn in 7 in (1:177.8*mm).[82][83][84][85] Weapons designed to accept both the M193 or SS109 rounds (like civilian market clones) usually have a 6-groove, right hand twist, 1 turn in 9*inches (1:228.6*mm) bore, although 1:8*inches and 1:7*inches twist rates are available as well.

Bluntforce · 05-30-2017, 07:02 PM

My next barrel/upper/rifle will be a 20" with a rifle length gas system. The YouTube

ters have consensus on the 20" barrel length giving the most from the load, longer causing friction, shorter losing performance.

InRangeTV claims 1:7 is too fast for 55 grns. Trigger Time TV claims 1:7 works well for 55 to 82 grns. The 1:9 and slower twists are better for 40 to 55 grns.

The channels I go to for AR oracle pronouncements are InRangeTV, Reid Henrichs, Brent 0331, A Regular Guy and Trigger Time TV.

buzgun · 05-30-2017, 07:24 PM

Im building a M16A4 clone right now......Im using a Faxon 1-8 govt profile 20" barrel with the melonite treatment instead of chrome lined.

I already have this same gun except it has a 20" FN chrome bore with a 1-7 twist and with hot ammo i get muzzle velocity around 3100 -3200 fps...much better than my M4 in velocity and accuracy.......My rifle has a leupold mark-4 10x scope and its so easy to tear the ass out the 10 ring with this thing at 100 yards even with wolf ammo that im building a back-up for shtf.

I seriously love the accuracy of the 20" barrel......i have a extra set of Knights armament A4 RAS rails and im using this as an excuse to build another entire rifle because i like them so much.

Stalky · 06-01-2017, 10:14 PM

As soon as I get the funds GMWILLY will assemble an A1 assy. with my proper GM HYDRAMATIC lowers for old times sake.
Got the Colt triangular handguards and early GI 16 buttstock so I'm about 350$ away from what uncle sugar stuck in my hand.
Just want the rifle I was issued. Legally.
Wouldn't mind the 1 in 14 twist as I don't live in Alaska.
The handguards came from a Colt I owned 15 years ago. The buttstock from Sarco. Not in terrible shape,definitely a 60's military take off.

MrKalashnikov · 06-02-2017, 09:55 AM

I've been browsing the web the last several days looking for deals on 20" AR-15A2 clones...both Windham Weaponry & Bushmaster offer what I'm looking for. Lots of positive reviews for both rifles. I just sold a couple of old bolt guns which had been gathering dust in my safe so I have some extra $$$ to put into this. I'm going to a local funstore today to talk FFL transfer & make a decision.

Stalky · 06-02-2017, 02:02 PM

A repeat.

Stalky · 06-02-2017, 05:02 PM

I have the one for the youngest son,gave one in 300BO to the oldest. A X39 for me and the A1will be last and most expensive. Three prong FH,teardrop FA correct markings.
Could have built at least two or more but what the hey?
Money left over goes to ammo.

baboon · 06-02-2017, 06:02 PM

Quote:

Originally Posted by MrKalashnikov

I've been browsing the web the last several days looking for deals on 20" AR-15A2 clones...both Windham Weaponry & Bushmaster offer what I'm looking for. Lots of positive reviews for both rifles. I just sold a couple of old bolt guns which had been gathering dust in my safe so I have some extra $$$ to put into this. I'm going to a local funstore today to talk FFL transfer & make a decision.

Windham would be my choice over Bushmaster/Remington.

Sanders · 06-02-2017, 06:05 PM

Quote:

Originally Posted by baboon

Windham would be my choice over Bushmaster/Remington.

Same here. Windham is the old Bushmaster founding crew. Bushmaster is the new Remington/Freedom Group conglomerate.

MrKalashnikov · 06-02-2017, 06:40 PM

Yeah it's my first choice too. A few more bucks than Bushmaster but I've always heard good stuff about their builds.

Bluntforce · 06-03-2017, 01:42 AM

Weight vs. twist. Length/bearing surface is the determining factor according to these Ruger guys.

https://www.youtube.com/watch?v=cNF5pdAf8bs

05-30-2017, 04:39 PM	#1
MrKalashnikov Deplorable Join Date: May 2008 Location: Behind The Iron Curtain Posts: 8,053	AR: 20" Barrel vs 16" I'm thinking about either building or buying an M16A2 clone with the proper 20" barrel length. I've read & heard over the years that Stoner designed his toy to function at peak performance using that barrel with the 5.56 round. Seems like everybody & their crazy uncle is pushing the carbine 16" barrel these days. I've never owned an AR with the 20" configuration...maybe now is the time when parts & even whole rifles are so cheap? What say ye?

05-30-2017, 05:07 PM	#3
CDawg slug Join Date: Aug 2010 Location: Florida Posts: 12,270	Do it. I like my 20" Bushmaster quite a bit. I got it over 20 years ago and it's still one of my favorites. I do find the A2 stock too long for comfort though, so I added an A1 length butt stock. It's an excellent setup. No detachable carry handle, rails etc., etc. ...just a plain old AR15. Mine happened to come with a very good stock trigger and it's extremely accurate with Federal XM193, which is all I use. The barrel is 1 in 9 twist. The 20" creates better velocity, so the XM193 performs correctly (jacket shredding) a bit further out than the 16" barrels. I had an ACOG on it for a while, but moved it onto one of the M4geries. With the 20", I hit very well with just the irons sights. Whenever women have shot that rifle, they've liked it better than any others I have. ...and they hit better with it too. __________________ "Don't fight a battle if you don't gain anything by winning" Erwin Rommel A Chief Petty Officer shall not drink. However, if he should drink he shall not get drunk. If he should get drunk, he shall not stagger. And if he should stagger, he shall not fall. And if he should fall, he will fall in such a manner as to cover up his rank so that passersby will think he is an officer.

05-30-2017, 05:35 PM	#4
Railbuggy Senior Member Join Date: Dec 2009 Location: Taylor Creek,Ohio Posts: 7,279	I have assembled five and I am working on number six at this time. My best barrel in the bunch is a 18" 416R Barrel from Faxon, Gov’t / Socom Profile, 5.56 NATO Caliber, Rifle-Length*Gas System with 1:8 twist. I think I paid $179.99 on a sale last year. It came from AIM with a F marked front sight/ gas block. It all depends on what you want it to do. 18" with a 1:8 or 1:9 twist rate is a good all around barrel for different weight boolits. The first M16s had a 20" barrel with a 1:12 twist but didn't do so well shooting tracers and other weight rounds. Most 16" barrels have a quick 1:7 twist to stabilize 55 thru 75gr boolits thru the short barrel. I read that to get the best performance from the 5.56/223 rounds, they need to leave the barrel above 2500fps. With the faster twist rates this can be done with 10.5" barrels and longer. I believe the longer barrels, 18 and 20" have a Muzzle velocity 3,110 ft/s while the 14.5" barrel would do around 2900 ft/sec. __________________ Im not a wannabe,Im a has-been. We already lost the war. You are the resistance.

05-30-2017, 07:02 PM	#6
Bluntforce slug Join Date: Dec 2007 Location: Allturd State Posts: 21,865	My next barrel/upper/rifle will be a 20" with a rifle length gas system. The YouTube ters have consensus on the 20" barrel length giving the most from the load, longer causing friction, shorter losing performance. InRangeTV claims 1:7 is too fast for 55 grns. Trigger Time TV claims 1:7 works well for 55 to 82 grns. The 1:9 and slower twists are better for 40 to 55 grns. The channels I go to for AR oracle pronouncements are InRangeTV, Reid Henrichs, Brent 0331, A Regular Guy and Trigger Time TV. __________________

05-30-2017, 07:24 PM	#7
buzgun slug Join Date: Apr 2006 Posts: 25,638	Im building a M16A4 clone right now......Im using a Faxon 1-8 govt profile 20" barrel with the melonite treatment instead of chrome lined. I already have this same gun except it has a 20" FN chrome bore with a 1-7 twist and with hot ammo i get muzzle velocity around 3100 -3200 fps...much better than my M4 in velocity and accuracy.......My rifle has a leupold mark-4 10x scope and its so easy to tear the ass out the 10 ring with this thing at 100 yards even with wolf ammo that im building a back-up for shtf. I seriously love the accuracy of the 20" barrel......i have a extra set of Knights armament A4 RAS rails and im using this as an excuse to build another entire rifle because i like them so much. __________________ Better Dead than Red

05-30-2017, 05:04 PM	#2
baboon slug Join Date: Feb 2010 Location: Out by the lake in central Texas Posts: 18,306	Go for it! Everything I have is 16.25 inches or shorter. I always liked the looks of the Colt LMG with a 20 inch heavy barrel. Way to pricey for me.

05-30-2017, 06:21 PM	#5
Railbuggy Senior Member Join Date: Dec 2009 Location: Taylor Creek,Ohio Posts: 7,279	Quote from M16 Rifle- Wikipedia Barrel[edit] Early model M16 barrels had a rifling twist of 4 grooves, right hand twist, 1 turn in 14inches (1:355.6mm) bore - as it was the same rifling used by the .222 Remington sporting round. This was shown to make the light .223 Remington bullet yaw in flight at long ranges and it was soon replaced. Later models had an improved rifling with 6 grooves, right hand twist, 1 turn in 12inches (1:304.8mm) for increased accuracy and was optimized for use with the standard U.S. M193 cartridge. Current models are optimized for the heavier NATO SS109 bullet and have 6 grooves, right hand twist, 1 turn in 7 in (1:177.8mm).[82][83][84][85] Weapons designed to accept both the M193 or SS109 rounds (like civilian market clones) usually have a 6-groove, right hand twist, 1 turn in 9inches (1:228.6mm) bore, although 1:8inches and 1:7*inches twist rates are available as well.

06-01-2017, 10:14 PM	#8
Stalky Senior Member Join Date: Jul 2014 Posts: 8,076	As soon as I get the funds GMWILLY will assemble an A1 assy. with my proper GM HYDRAMATIC lowers for old times sake. Got the Colt triangular handguards and early GI 16 buttstock so I'm about 350$ away from what uncle sugar stuck in my hand. Just want the rifle I was issued. Legally. Wouldn't mind the 1 in 14 twist as I don't live in Alaska. The handguards came from a Colt I owned 15 years ago. The buttstock from Sarco. Not in terrible shape,definitely a 60's military take off.

06-02-2017, 09:55 AM	#9
MrKalashnikov Deplorable Join Date: May 2008 Location: Behind The Iron Curtain Posts: 8,053	I've been browsing the web the last several days looking for deals on 20" AR-15A2 clones...both Windham Weaponry & Bushmaster offer what I'm looking for. Lots of positive reviews for both rifles. I just sold a couple of old bolt guns which had been gathering dust in my safe so I have some extra $$$ to put into this. I'm going to a local funstore today to talk FFL transfer & make a decision.

06-02-2017, 02:02 PM	#10
Stalky Senior Member Join Date: Jul 2014 Posts: 8,076	A repeat.

06-02-2017, 05:02 PM	#11
Stalky Senior Member Join Date: Jul 2014 Posts: 8,076	I have the one for the youngest son,gave one in 300BO to the oldest. A X39 for me and the A1will be last and most expensive. Three prong FH,teardrop FA correct markings. Could have built at least two or more but what the hey? Money left over goes to ammo.

06-02-2017, 06:40 PM	#14
MrKalashnikov Deplorable Join Date: May 2008 Location: Behind The Iron Curtain Posts: 8,053	Yeah it's my first choice too. A few more bucks than Bushmaster but I've always heard good stuff about their builds.

06-03-2017, 01:42 AM	#15
Bluntforce slug Join Date: Dec 2007 Location: Allturd State Posts: 21,865	Weight vs. twist. Length/bearing surface is the determining factor according to these Ruger guys. https://www.youtube.com/watch?v=cNF5pdAf8bs

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