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View Full Version : AR 15: National Match Barrel vs Gov Profile


DanThaMan1776
July 28, 2010, 08:44 AM
Chances are I am going to sell my carbine length AR 15 so I may afford a rifle length AR 15. My carbine is a RRA and I love it to death because it simply works and works well. That said, I wish to go RRA again and am looking seriously at their National Match (http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=226) models.

I handled one in the Gshop yesterday and have fired one at my range before. Naturally, the weight is a little discouraging. My carbine is HBAR as well, but since it's only 16 inches It isn't so bad. The 20 inch tube, however, makes a big difference. So my attention got diverted to the standard government profile barrel model.

I am looking for the good accuracy (MOA) and will likely be shooting a LOT some days for appleseed and some carbine classes I take (ironic, i know). So my concern is: will the gov. profile barrel "overheat" and string shots much like the older Mini 14s are known for?

What are the pros/cons for a HBAR on an AR 15?

thanks a lot, DanThaMan

thesheepdog
July 28, 2010, 08:55 AM
Depends on what era GOv profile you're looking at getting. The A4 profile is much like that of a national match barrel, just a tad lighter. The A2 has a lighter profile, unless it's specified otherwise.

http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=225

Here is one that would probably fit what you need, and save some weight. It's over a pound lighter than the RRA NM, but still wears the HBAR.

I don't recommend lighter profile barrels. Especially with the .223/5.56 round heating up barrels pretty quick.
Your only other option would be to get a medium profile .75 OD, which is better than GOv profiles, but not as good as the HBARS.

The only thing you lose with an HBAR, is lightweight. Still the HBAR A4 is lighter than most guns out there.

emcon5
July 28, 2010, 09:11 AM
Why don't you keep what you have and just buy a new upper in whatever configuration you want?

Great thing about the AR platform, it is modular.

riverwalker76
July 28, 2010, 09:39 AM
In my opinion you are trying to compare apples to oranges.

The HBAR barrels usually have a 1:8 or 1:9 twist rate and are 20" barrels.

The Gov't Profile Barrels are 1:7 twist rate and have 16" & 20" barrel options.

I have never had any problems with the Gov't Profile barrels. Most of them are chrome lined, but some are not depending on the maker. To be honest ... the only thing that makes the 16" class barrels 'Government Profile' is the addition of the grooves in the barrel for the M203 grenade launcher option. Some A2 class rifles also have the bayonet lug below the front site, but not all A4s do. I know ... it's kind of confusing.

The HBAR barrels are heavier and bulkier than the Gov't barrels.

HBAR barrels are not necessarily more accurate than the Government Profile barrels. I have found the 1:7 twist (gov't profile) to be just right for me. I can shoot the heavier 77 gr. SMK & 75 gr. Hornady HPBT Match bullets with ease and good accuracy.

tirod
July 28, 2010, 09:40 AM
The incremental increase in accuracy isn't going to be easily measurable. It's quite possible that adding a free float tube to the carbine would be as good. Ammo selection and testing could add more, as would handloading to discover the optimum round and overall length.

All that can tighten groups a lot more than swapping to an unknown upper and starting all over again. For the money, you can improve what you have and still keep the handy length. Unless competition rules require a 20" barrel, I'd stick with what you have. The result will be a better understanding of what really works to make it more accurate.

For example, installing a better grade barrel, no chrome, nitrided, mid length gas and a comp should yield a slightly softer shooting carbine with less recoil and pressure. It would look almost the same, have no M203 cuts, and the barrel installer could improve on accuracy by squaring the receiver, proper barrel nut torque, a free float tube, and having a higher quality barrel with less restrictions - they air gauge them and select the best ones for precision. "Loose" barrels go in the low buck bin for a cheaper assembly.

At that point a Wilson Tactical Trigger Unit would be even more icing on the cake, without breaking the bank. Match aperature sights or an optic would be even better.

$600 probably wouldn't cover all that, but a swap to a NM rifle could be arguably less accurate in comparison. Without the skilled assembly, they are just NM by the collection of parts they represent, not because someone tuned them over months shooting it at the range.

Now we'll get all sorts of 3 shot group pics from "Texas Sharpshooters" claiming their off the shelf NM rig gets 1/4MOA out of the box . . .

All I have to say is, if it's not ten shot groups for Mean Radius, it's not statistically accurate enough for military acceptance. But that's another discussion.

riverwalker76
July 28, 2010, 09:44 AM
If you get a new trigger unit ... go with Geissele. They are 10 X better than the competition, but not a lot of people know about them.

darkgael
July 28, 2010, 09:51 AM
What are the pros/cons for a HBAR on an AR 15?

I can't think of any cons for an HBar. Mine shoots sub-moa groups at 100 yards. Beyond 100, I have not gone.
The 1-8 twist stabilizes the Sierra 77s.
Weight - I don't have to walk around with mine and so I added lead to the buttstock and fore end to bring it up to 12lbs.
Pete

azredhawk44
July 28, 2010, 10:11 AM
Dan:

The NM RRA is heavy, because it is a competition upper. While you might shoot it in the "service rifle" class of competition in High Power if you chose to, it is in no way a service rifle. It has free-floated handguards (which a service rifle does not), it has either 1/4 or 1/2 MOA adjustments (which a service rifle does not), and there are lead weights in the forward handguard to deliberately make the rifle heavier. Many high power shooters even fill the buttstock with more lead weights, and the result is a rifle that was designed to weigh about 7-8 pounds, hitting the scales over 16 pounds.

I've got a generic Del-Ton A2 upper with a 1:9 twist 20" government profile barrel. No free-float, 1MOA sights, no lead to add weight to it. She's a shooter. I've never benched it to shoot for sub-MOA groups. But, it is well under 4MOA from prone as long as I do my part. On a good day, I can manage 2MOA with it from prone. The only change I've made to it is a NM front sight, which is merely a thinner front sight blade than a GI front sight blade.

Frankly, it's pretty load-agnostic. It shoots well with any .223 load I drop in there. Right now, I'm running a bunch of Midway bulk 55gr FMJ's and IMR 4895 and routinely getting 3MOA from prone, sometimes a bit better.

I can shoot 75gr match ammo from it with no evidence of keyholing or instability. I've never shot 77's though, and I hear that 75's may work in some 1:9 guns but not 77's.

I've yet to get my hands on a good supply of 69gr match bullets, which would be the ideal projectile for a 1:9 barrel for accuracy.

With an un-floated barrel and slinging up into it, I've never seen my shots walk from heat and repeated shooting. I HAVE seen them walk from getting fatigued and having inconsistent sling tension. A free-floated barrel will not suffer from sling tension problems, and the heavier it is, the longer it takes for groups to walk.

However: ALL rifles will walk their impact as they heat up. Heavy barrels do this more slowly, then they also reverse-walk more slowly since they retain more thermal energy and cool more slowly. Thin barrels do it quickly, and then cool quickly back to the original POA.

The AR is designed to shoot 12-15 rounds per minute. Stay under that rate of fire, and you'll be happy with the performance of either a match rifle or an M4 clone in regards to accuracy.

emcon5
July 28, 2010, 10:14 AM
The bigger advantage of a proper NM upper is not necessarily the barrel itself, it is the float tube under the handguards that lets you sling up without putting pressure on the barrel.

Also, if he is using Irons, it will be easier to shoot well with the longer sight radius on the rifle. I expect this will be the largest advantage.

Now we'll get all sorts of 3 shot group pics from "Texas Sharpshooters" claiming their off the shelf NM rig gets 1/4MOA out of the box . . .

How about 10 shots, prone and slung?

http://thefiringline.com/forums/attachment.php?attachmentid=61776&stc=1&d=1280333556

Off the shelf Armalite NM upper, Jewell trigger and handloads.

Bartholomew Roberts
July 28, 2010, 10:19 AM
So my concern is: will the gov. profile barrel "overheat" and string shots much like the older Mini 14s are known for?

No, not even close to a Mini-14 in terms of point of impact shifting as it heats up.

However, a government profile barrel is going to be a little more susceptible to the point of impact shifting (compared to an HBAR) when you are slung up due to the less rigid barrel.

What are the pros/cons for a HBAR on an AR 15?

Pros: Slightly better heat management and slightly better rigidity.
Cons: About a half pound heavier and most of that weight in front of the barrel nut.

If you are going to shoot NRA High Power (which Appleseed is more closely related to IMO), then an HBAR is the way to go. For practical use, the government profile is a better choice.

The A4 profile is much like that of a national match barrel, just a tad lighter. The A2 has a lighter profile, unless it's specified otherwise.

I'm a bit confused here. In the military, the M16A4 uses the same barrel profile as the M16A2. On RRA's website, regardless of A2 or A4, they only offer 20" barrels in the HBAR profile or the Varmint (even heavier) profile. Am I missing a detail?

thesheepdog
July 28, 2010, 10:35 AM
I'm a bit confused here. In the military, the M16A4 uses the same barrel profile as the M16A2. On RRA's website, regardless of A2 or A4, they only offer 20" barrels in the HBAR profile or the Varmint (even heavier) profile. Am I missing a detail?

I always thought-from looking at A4 uppers-that the A4 came with an HBAR, not a A2 profile. My mistake.

tirod
July 28, 2010, 10:46 AM
Emcon, nice target. Range? Mean Radius?

If the NM free float tube was aluminum, I'd buy it. Not the way that game is shot. At least it relieves sling tension, which on all my issue M16's forced me to quit using the sling as I was taught in .22 International and bare hand it. I forgot that at Camp Clark, MO one year and nearly ran out of sight in ammo chasing the zero.

Sling swivels off the barrel is a finesse point precision shooters know will create an improvement, but it's not limited to a NM rifle. It works on all the ARs.

emcon5
July 28, 2010, 01:18 PM
It was 100 yards. I didn't measure it, but the rifle is certainly more capable than I am.

Pretty sure all the CMP legal float tubes are steel, because most of the people who want them like the extra weight.

DanThaMan1776
July 28, 2010, 01:34 PM
All that can tighten groups a lot more than swapping to an unknown upper and starting all over again. For the money, you can improve what you have and still keep the handy length. Unless competition rules require a 20" barrel, I'd stick with what you have. The result will be a better understanding of what really works to make it more accurate.

This September In Waterman, IL, Appleseed is hosting a shoot specifically and only for Rifleman (myself :cool:). The range will be 600 yards :eek: so I need that 20 inch barrel to fling the 69 gr HP Match rounds I have that distance accurately... If the sight radius was all I wanted I would just throw a medium length gas system on there.

I think the general consensus is that the HBAR is the way to go for accuracy shooting and voluminous shooting. That will be what I use it for most of the time. However, for the occasional varmint hunt or camping expedition, I will be lugging this bad boy around. Honestly, I'm a young and fit college student and don't think it'll be a problem.. however the heaviest rifle I've ever carried on my back for a long distance was a 12 gauge pump which weighed 8.5 lbs. I might be being naive in thinking I won't mind the weight of a 20 inch HBAR... I'm not sure. Anyone done this?

emcon5
July 28, 2010, 01:49 PM
At 600 yards, you really don't want 69s. You want 80s.

DanThaMan1776
July 28, 2010, 02:16 PM
I see guys do 600 yards with 69s all day

emcon5
July 28, 2010, 02:36 PM
I see people putting $3000 worth of 24" rims on mid 1980s Caprice Classics all day too, doesn't mean it is smart.

thesheepdog
July 28, 2010, 02:47 PM
I might be being naive in thinking I won't mind the weight of a 20 inch HBAR... I'm not sure. Anyone done this?

The Marines do it every day! :) Well, they're A4's with Gov profile barrels weigh less, but they have grenade launchers, and other things attached as well, making the gun about as heavy as a NM, or more.

I am sure you will get used to it, if not, go to the gym, and beef up a bit.

DanThaMan1776
July 28, 2010, 03:11 PM
The Marines do it every day! Well, they're A4's with Gov profile barrels weigh less, but they have grenade launchers, and other things attached as well, making the gun about as heavy as a NM, or more.

I am sure you will get used to it, if not, go to the gym, and beef up a bit.

Excellent point. I was just thinking that most serviceman, including my buddies in the army, tell me that every ounce is felt and they try and shave as much as possible. But I guess I won't have 40 pounds of gear on my back, or attachments on my rifle either.

And nicely said, these protein bars just don't do the job unless I fulfill my half of the bargain :D

HiBC
July 28, 2010, 04:15 PM
I will suggest you look at a DMR barrel.Try looking at White Oak's site.It is sort of a fluted Hbar.You can get an assembled YH upper on sale at Midway right now fot about $110 and a YH lightweight free float forend is not much more.

Bartholomew Roberts
July 28, 2010, 04:30 PM
The range will be 600 yards so I need that 20 inch barrel to fling the 69 gr HP Match rounds I have that distance accurately...

Not sure about your environmental conditions; but in standard conditions, my ballistics calculator is showing the Sierra 69gr as supersonic out to 650yds assuming a muzzle velocity of 2,600fps - which should be doable out of a 16" barrel.

Just something to think about; but 16" barrels will still reach out there a ways.

HiBC
July 28, 2010, 05:01 PM
I get 2780 through the chronograph wit my 16 hbar using a 69 gr MK or Nosler and Varget.Checking the reticle elevation @500 meters I put 20 rds in a group I could cover with my hand (Yes,bench)
But.it is true competitors single load 80 gr bullets for longer ranges.
I find the 69's a good compromise.

DanThaMan1776
July 29, 2010, 12:26 PM
The 20 inches can only help.. and the rifle length sight radius is even better than medium length

emcon5
July 29, 2010, 01:12 PM
Still think you should be looking at this page, rather than the one you linked.

http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=268

But.it is true competitors single load 80 gr bullets for longer ranges.Really a shame the guy making LRP magazines quit making/selling them. Really an elegant solution to shooting 80gr loads through a magazine. Too bad DPMS bought them and screwed them up bad enough to stop making them. http://www.midwayusa.com/viewProduct/?productNumber=112114

I think Federal is making a load with the 77 Sierra Matchking, that would be my first choice if 80s were not an option.

Scorch
July 29, 2010, 01:25 PM
I own a RRA NMA4 rifle and use it in ODCMP Service Rifle matches. I am very pleased with it, and would buy another if I were looking to replace this one.

Since you ask how the rifle would work for Service Rifle Match (as opposed to NRA High Power Match), I will answer the question as they apply to ODCMP Service Rifle rules. This may come in handy for information. Service Rifle rules begin on page 21.
http://www.odcmp.com/Competitions/Rulebook.pdf

The NM RRA is heavy, because it is a competition upper.
The RRA NM rifles use the same configuration receivers as a standard-issue rifle, they are no heavier. They use a heavier barrel under the handguard. The result is a slightly heavier rifle overall (1.5 lbs heavier). You may be noticing the different point of balance in the rifle, since all of the weight difference is in front of the receiver.
While you might shoot it in the "service rifle" class of competition in High Power if you chose to, it is in no way a service rifle.
The RRA NM rifle has a standard service rifle configuration, as required by ODCMP rules. It has a standard buttstock, standard receiver, standard handguards, standard muzzle brake. However, it has several refinements, and is manufactured to extremely close tolerances. Some of the refinement are NM trigger (4.5# minimum pull, as required), NM barrel (heavier under the handguard but appears standard when the handguards are in place), NM sights (1/4 MOA adjustments).
It has free-floated handguards (which a service rifle does not),
The RRA NM rifle has free-float handguards (as opposed to a fre-float tube forend) and uses standard configuration A2 handguards mounted on a steel frame that allows the forend to be free-floated. FWIW, a free-float tube forend would place you in Target Rifle class.
it has either 1/4 or 1/2 MOA adjustments (which a service rifle does not),
The RRA NM rifle has 1/4 MOA sights mounted on a service rifle "carry handle" sight bridge. The difference between the 1/2 MOA and 1/4 MOA sights is the adjustable sight hood, which is eccentric to permit the smaller adjustments by rotating the sight hood.

Flip-up sights or optical sights are not allowed in ODCMP Service Rifle matches.
and there are lead weights in the forward handguard to deliberately make the rifle heavier.
Absolutely not. This would eliminate you from the ODCMP Service Rifle class and move you to Target Rifle class.
Many high power shooters even fill the buttstock with more lead weights, and the result is a rifle that was designed to weigh about 7-8 pounds, hitting the scales over 16 pounds.
Absolutely not allowed under ODCMP Service Rifle rules.
a Wilson Tactical Trigger Unit would be even more icing on the cake
The RRA NM rifles come with an excellent trigger.
At 600 yards, you really don't want 69s. You want 80s.
I shoot Hornady 68 gr MBTHP bullets in my rifle. I do not have any issues shooting 600 yds (I generally shoot in the mid-90s). People who shoot the heavier bullets for 600 yds do not necessarily have an advantage, except in their mind.

nbkky71
July 29, 2010, 01:46 PM
Read your CMP rulebook...

The CMP rules make no such mention of weight limits in the general or specific service rifle rules (CMP rules 6.1 and 6.2). Aside from the rules covering the trigger and gas system, the rules governing service rifles pertain to the exterior profile of the rifle, not the interior.

However, CMP rule 6.3.1 (3) states that as-issued rifles must conform to original weight specifications.

Also, the CMP has no "target class". You may be confusing this with the NRA service rifle/match rifle classes.

emcon5
July 29, 2010, 02:10 PM
Interesting, first time I heard the claim that adding weight to a rifle was not legal for CMP competition, and I can't find anything in the rules that would seem to back up that claim (except under the "as-issued" rules). Granted, I haven't competed actively for a few years, but I know a lot of people who shot black rifles who used stick-on wheel weights under their handguards and a lead wedge in the butt stock compartment to help balance the rifle.

Here is the rear one:
http://www.sinclairintl.com/.aspx/pid=34319/Product/Martin_AR_15_Rear_Wedge_Weight#

Can you please point out the section in the rules that says this would not be legal.

People who shoot the heavier bullets for 600 yds do not necessarily have an advantage, except in their mind.

Drift at 600 yards with a 10mph full value wind.
69 @ 2700fps 55in
77 @ 2650fps 46in
80 @ 2550fps 41in

If you say so.

emcon5
July 30, 2010, 01:27 PM
Stumbled across this ad this morning:

http://www.calguns.net/calgunforum/showthread.php?t=326209

P-990
July 30, 2010, 05:53 PM
Drift at 600 yards with a 10mph full value wind.
69 @ 2700fps 55in
77 @ 2650fps 46in
80 @ 2550fps 41in

If you say so.

And the 80 can be pushed to 2700-fps muzzle velocity, though a couple hundred feet per second doesn't make as much of a drift difference as a bullet with higher BC.

The added weights are 100% okay in Service Rifle competition. I think my rifle once passed tech at Camp Perry at about 16 pounds. And all of the match prepped M-14s/M1As and M-1 Garands are heavier than issued as well.

To the OP, big difference between a National Match prepped rifle, a basic HBAR and a carbine. If NRA match competition is your aim, get the NM rifle. For fun and carbine/tactical matches, get the carbine.