It weighs 7.35 lbs, 30% more than the 5.65 lbs quoted for the Colt M4:



Both have M4 style handguards, 16.1" barrels cut to the M4 profile (including the light section under the handguards), and removable carry handles.   The only obvious difference in configuration is that my RRA has an A2 stock instead of the Colt's telescopic stock:



But according to the weights of stocks listed on the Maryland AR15 Shooters Site, that should only account for .6 lbs difference (24.5 oz for the A2 versus 15 oz for the telescopic).  So where are the extra 1.1 lbs hiding?

Is Colt making their measurements with or without the carry handle? FWIW, the Hogue grip is a little heavier than the A2 pistol grip and the star selector probably weighs more than the standard selector .

Have you looked under the handguards to see if the barrel is indeed lightweight contour? I know mine was (My RRA barrel) but the R-4 barrels I see on their website now seem to be heavy under the handguards.

Quoted: Both have M4 style handguards, 16.1" barrels cut to the M4 profile (including the light section under the handguards)

Not true, the Wilson R4 barrel that the RRA uses is not true M4 profile. It doesn't have the light section under the hand guard, past the gas block it has the same thickness as a HBAR. At least that's how it is with mine, don't know if they've changed it since last January.

Quoted: Not true, the Wilson R4 barrel that the RRA uses is not true M4 profile. It doesn't have the light section under the hand guard, past the gas block it has the same thickness as a HBAR. At least that's how it is with mine, don't know if they've changed it since last January.

Just to add, my upper was purchased from Rock River Arms at Camp Perry last August (2003) - I don't know if they started off light under the handguards and then went heavy or if mine was just an anomaly.

My RRA upper has an M4 profile barrel, chrome lined no less. I dont find it any heavier than the M4's we have issued in the Army though..

Quoted: Is Colt making their measurements with or without the carry handle?

That's a very good question.  That would account for 9 oz right there.

FWIW, the Hogue grip is a little heavier than the A2 pistol grip

True, although by itself it can't account for 1.1 lbs.

and the star selector probably weighs more than the standard selector .

Ah hah!  Of course!  How could I have overlooked the star selector? It must be the culprit

Have you looked under the handguards to see if the barrel is indeed lightweight contour?

Yes, it truly is light under the handguards.  The chrome-lined post-ban barrels with the press-on fake flash hider are light under the handguards, unlike some of their other "M4" barrels.

Thanks for your input.

I have done a little more research, and the RRA has a heavier bolt carrier.  That probably adds about another  ounce.

Also, I checked Bushmaster's post-ban M4gery:



It is listed as 6.59 lbs, with a 14.5" barrel extended to 16.1" by the permanently attached muzzle break.  Doing some rough math to adjust for the stock (9.5 oz), carrier (1 oz) and Hogue grip (1 oz), I get a figure of  7.3 lbs for the Bushmaster if it were equipped the same as my RRA.  That is close enough to the 7.35 lbs I actually measured for my RRA.  Thus, both Bushmaster and RRA appear to be essentially the same weight and it is the Colt that is so much lighter.

Unless there is some unknown extra-lightweight component in the Colt, it looks like you may be right and Colt may not be including the carry handle.  If that is the case, I would have to say "not cool".  Picturing the weapon in one configuration while quoting a weight for a different configuration without clearly stating the difference strikes me as deceptive.  It makes the Colt seem lighter than it really is.  

Does anyone have an LE6920 in stock configuration, with carry handle, that they can weigh and report?  I'd really like to know if their carbines are truly so much lighter or if Colt is just playing games with the quoted weight.

It weighs 7.35 lbs, 30% more than the 5.65 lbs quoted for the Colt M4:

Not sure where you got a quoted 5.65 lbs for an M4 or who is doing their weighing. Sounds like spin to me. This rifle weighs 6.0 lbs with a 16" pencil barrel, carbine buffer/lightweight stock and fixed A2 sights. Almost every one lies about their sex life, how much money they make, their gas mileage and how much their lightweight AR weighs.

No Colt M4 with the enchanced sliding stock, and removeable carry handle will weight less than this.
You do not state if your RRA barrel is chrome lined or not. The early chrome lined RRA M4 barrels were not light under the handguards. The early unlined barrels were light under the handguards and I have been told the most recent chrome lined RRA M4 barrels are light under the handguards.

I have never seen a RRA M4 barrel that came with the true M4 profile from the factory.

Quoted: I have never seen a RRA M4 barrel that came with the true M4 profile from the factory.

My upper came from the factory as pictured above... I guess stranger things have happend...

Quoted: I have never seen a RRA M4 barrel that came with the true M4 profile from the factory.

When you say "true M4" profile, do you mean correctness of the diameters at different points of the barrel or just "light under the handguards"? Mine came from the Rock River Arms factory store from Commercial Row at Camp Perry this way:



(it did have a press-on fake supressor which was removed and a phantom was permanently attached by Adco/Schuster)

Hey Engineer, How much did ADCO charge total for doing that? I have been wanting to do the exact same thing...

Quoted: Quoted: Both have M4 style handguards, 16.1" barrels cut to the M4 profile (including the light section under the handguards) Not true, the Wilson R4 barrel that the RRA uses is not true M4 profile. It doesn't have the light section under the hand guard, past the gas block it has the same thickness as a HBAR. At least that's how it is with mine, don't know if they've changed it since last January.

Yes it is true:



Now, if you want to say that the cut is not as thin as a real M4's (mine measures 0.645" diameter in the thin section), then that is fine and I am interested in what the true dimension should be.  But otherwise please just accept what I say regarding my RRA.  I don't have an agenda here and I'm not making up lies in support of some ulterior motive.

Quoted: Not sure where you got a quoted 5.65 lbs for an M4 or who is doing their weighing. Sounds like spin to me.

It says so right on the scan of the catalog page I included in my original post.  And thanks to your input and others, it is sounding more and more like nothing but spin to me also.

You do not state if your RRA barrel is chrome lined or not. The early chrome lined RRA M4 barrels were not light under the handguards. The early unlined barrels were light under the handguards and I have been told the most recent chrome lined RRA M4 barrels are light under the handguards.

Yes, it is chrome lined and light under the hand guards.  See my picture of it in the post above.

Why doesn't anyone believe me when I state the barrel is light under the handguards?  Are people so accustomed to trolls posting BS that they can't believe someone would actually look under his handguards before spouting off nonsense about the barrel profile?  (Not a personal attack - I just don't understand why everyone is so skeptical of what I report.)

ETA - Thank you for your information.  I appreciate it.

DM1975, here is ADCO's shop services price list:

www.adcofirearms.com/shopservices.cfm

Thanks.. yeah I have seen this but was wanting some clarity on the cost. There was a big thread on this not too long ago but I never realy go the answer I wanted, thats why I ask. I also sympathyze with you on people here second guessing your every thought on a post. I asked a simple question the other day on aluminum buttstocks and the very first post I got was "you dont realy want aluminum, you want plastic" I can not stand someone telling me what I want or dont want.

Quoted: Thanks.. yeah I have seen this but was wanting some clarity on the cost. There was a big thread on this not too long ago but I never realy go the answer I wanted, thats why I ask. I also sympathyze with you on people here second guessing your every thought on a post. I asked a simple question the other day on aluminum buttstocks and the very first post I got was "you dont realy want aluminum, you want plastic" I can not stand someone telling me what I want or dont want.

It was a total of $70 for the job. It's normally $60 to cut and pin on a flash supressor (eg A1/A2) but there's an extra charge of $10 for pinning on a phantom as there has to be some prep work done to the flash supressor.

Quoted: Yes it is true: img.photobucket.com/albums/v384/zrxc77/M4_profile.jpg Now, if you want to say that the cut is not as thin as a real M4's (mine measures 0.645" diameter in the thin section), then that is fine and I am interested in what the true dimension should be.  But otherwise please just accept what I say regarding my RRA.  I don't have an agenda here and I'm not making up lies in support of some ulterior motive.

You know, if you knock out that extra sling swivel on the FSB, you can save another few ounces!

Thanks... That is exactly what I wanted to know.

Quoted: You know, if you knock out that extra sling swivel on the FSB, you can save another few ounces!

You laugh, but I was thinking exactly that.  Once the ban expires and I get a collapsable stock and a sling, I will remove one, the other, or both of those sling swivels depending on what sling I get.  Sure, the swivels don't weigh much, but if they aren't serving a purpose why not not save a couple of ounces?

I did look up the weights on Colt's website, and it appears that the catalog scan may have listed the weight for the wrong model.  On the website Colt lists the weight of the 14.5" model LE6921 as being 5.65 lbs and the weight of the 16.1" model LE6920 as being 5.95 lbs.   Thus, the catalog may contain a typo that listed the weight of the LE6921 for the LE6920.  

However, based on the weight Tman reported and comparative analysis with other manufacturers, I still suspect that even the weights on Colt's website don't include the carry handle.  Add 9 ounces of carry handle to the 5.95 lbs weight of the LE6920 as listed on the website and you get 6.5 lbs.  That is more in line with all the other weight information I can find.


ETA - Thanks for everyone's input.  I feel a better about my RRA now.  When I first saw 5.65 lbs listed for the equivalent Colt I couldn't believe my RRA was so much heavier and I wanted to know what was different (wrong with it?) so I could make it lighter.  But now I see that my RRA really isn't much heavier after all - just a couple of ounces here and there for little things like the grip, bolt carrier and sling swivels

Quoted: Almost every one lies about their sex life, how much money they make, their gas mileage and how much their lightweight AR weighs.

I think you are on to something there, Tman.  CZ claims that their CZ 452 .22 LR Training Rifle weighs 5.3 lbs.  The actual weight of mine is 6.5 lbs.  That's not even close...

And before everyone chimes in and tells me my scale is wrong, it isn't.   I've double-checked it against known weights and it is fine.  

I had the barrel of my RRA R-4 turned down by ADCO.  With the weapon empty, and wearing the A2 removable sights the gun weights in at exactly 6.5 pounds.  It is amazing the difference after the work done by ADCO.  The gun is more balanced as well, not at all muzzle heavy.  Balance is more in the area of the mag-well.  

Do you have a 14.5" barrel with permanently attached muzzle device, or a 16.1" barrel?  What kind of stock do you have?

I had the same question when I built my RRA mid-length.  I haven't found anything, other than Colt's website, to support that their fully-assembled rifles are really that light.  I assumed they must be weighing them without the carry-handle.  

My RRA mid-length with turned down barrel, ARMS #40 BUIS, hogue grip, and Cav Arms C1 stock weighs just over 6.5 lbs empty.

Quoted: Quoted: Quoted: Both have M4 style handguards, 16.1" barrels cut to the M4 profile (including the light section under the handguards) Not true, the Wilson R4 barrel that the RRA uses is not true M4 profile. It doesn't have the light section under the hand guard, past the gas block it has the same thickness as a HBAR. At least that's how it is with mine, don't know if they've changed it since last January. Yes it is true: img.photobucket.com/albums/v384/zrxc77/M4_profile.jpg Now, if you want to say that the cut is not as thin as a real M4's (mine measures 0.645" diameter in the thin section), then that is fine and I am interested in what the true dimension should be.  But otherwise please just accept what I say regarding my RRA.  I don't have an agenda here and I'm not making up lies in support of some ulterior motive.

Ditto, RRA has had M4 type barrels go out with the M4 Gov't profile under the handguards and some with the HBAR profile under the handguard.  They do not show this in their catalog and I believe they did'nt exactly know what was going on either.  I bought two M4 type barrels from them at different times and recieved two different ones!  One HBAR and one Gov't profile.  Go figure?

Quoted: Quoted: I have never seen a RRA M4 barrel that came with the true M4 profile from the factory. My upper came from the factory as pictured above...

The upper picture above is not the correct M4 profile. The angle and lenght of the taper is wrong. If you have ever seen a Colt M4 brl you know what i mean.

I am around Colt M4's every day. It might not be perfict but it is a far cry from an Hbar..

I know it does not show the taper under the handguards but here is a real M4 next to mine...

Yes, that does show a little less steel in the profile, particularly around the chamber area.  Another couple of ounces.  Good picture.  Thanks Troy.  

Now, can anyone explain to me why the later "light under the handguard" government profiles are heavy in front of the FSB?  I once read here that this was done in order to make the barrel more resistant to abuse from soldiers using rifles in ways they aren't intended to be used.  Is that correct?  What abuse were they concerned with?  Using the barrel as a pry bar?  Is there any other advantage to the heavier barrel forward of the FSB?

Quoted:  Is there any other advantage to the heavier barrel forward of the FSB?

Supposedly testing showed if that section was heavy it kept its accuracy longer (when heated) than with the lighter A1 profile.

Note if you want to compute the weight of your rifle there is an Excel spreadsheet (in beta form) in the Documents section of www.MD-AR15.com in the Technical Documents folder.  First page lists the weight of a wide variety of components and accessories, second page has a worksheet to add up the weight.

Detachable carry handle is 0.6 lbs not 0.9 lbs.  I have compared a RRA M4 profile (from the original LEGP) to a Bushmaster M4 profile side by side and the RRA is a bit beefier (translating to a couple of extra ounces).  Also note if you have the fixed telestock that weighs significantly more than a real telestock (due to the longer receiver extension and the heavier buffer).

FYI the military lists the 14.5" M4 at 6lbs 7oz w/o magazine or sling.  That includes the 0.6lbs detachable carry handle.  This is covered in the -23 on page 1-4.2

Quoted: Supposedly testing showed if that section was heavy it kept its accuracy longer (when heated) than with the lighter A1 profile.

Interesting.  I guess I don't fully understand how barrel accuracy degrades with temperature.  I always assumed that the primary cause of accuracy degradation in the short term - neglecting accelerated throat erosion due to higher temperatures - was barrel warping and bore expansion.   And I would guess that warping and expansion in the long, thin section of the barrel under the handguards would dominate any warping and expansion effects, rendering the thickness of the barrel forward of the FSB somewhat moot.

Note if you want to compute the weight of your rifle there is an Excel spreadsheet (in beta form) in the Documents section of www.MD-AR15.com in the Technical Documents folder.  First page lists the weight of a wide variety of components and accessories, second page has a worksheet to add up the weight.

Yep, there's lots of great information at www.MD-AR15.com.  I haven't used the worksheet, but I have perused the tables of  component weights there on more than one occasion.

Detachable carry handle is 0.6 lbs not 0.9 lbs.

Correct.  I was quoting the weight in ounces, not pounds -> 9 ounces = 0.6 pounds.

FYI the military lists the 14.5" M4 at 6lbs 7oz w/o magazine or sling.  That includes the 0.6lbs detachable carry handle.  This is covered in the -23 on page 1-4.2

Excellent.  More confirmation that the weight quoted by Colt is, as Lumpy put it, apparently influenced by the result of illicit substance abuse...

Thanks for your input, Forest.

Quoted: Yep, there's lots of great information at www.MD-AR15.com.  I haven't used the worksheet, but I have perused the tables of  component weights there on more than one occasion.

Thanks for the kind words on the site.

However I should ponit out - the weight tables that are in the Tech Data section (the HTML sheet) is going away soon.  I need that resource for another article I'm putting together.

I've got a spreadsheet in the documents section that not only has all the information that used to be posted on the webpage - but LOTS and LOTS more (and it is easier to update).  This spreadsheet will be replacing the online page in less than a month.

Thanks for the detailed explanation, Troy.  

Would you and Forest say this is a reasonable summary of barrel profile/weight/accuracy tradeoffs?

1.  All else being equal, the thicker the barrel the more accurate it is.
2.  The chamber and muzzle have more effect on overall barrel accuracy than the middle of the barrel.
3.  In order to reduce weight but still maintain accuracy, the designers of the A2 and similar profiles made the barrel thinner in the middle where accuracy is affected least and left the barrel thicker at the ends where accuracy is affected most.

I concur with Troy's statements.

Thanks guys.   Both Troy and Forest answering on my thread:  I am honored.

Please let me clarify my first summary point.  I wasn't trying to say that a thick diameter by itself makes a barrel accurate.  In other words, I didn't mean to imply that you could take a bad barrel with an out-of-spec chamber, worn throat, inconsistent rifling and nicked crown and make it accurate simply by wrapping more steel around all that junk.  

What I meant was that if you took two good barrels, both with the same good quality chamber, throat, rifling and crown and made one thicker than the other, then the thicker one would be more accurate than the thinner one because it would be more resistant to the barrel whip as Troy described, even when the barrel is cold.  

I concluded this for two main reasons.  First, varmit rigs are designed for accuracy and every one that I have seen has had a thick bull barrel.  I thought varmit rigs aren't typically used with high rates of fire that would appreciably heat the barrel.  Thus, I assumed that even for a cold barrel thicker is more resistant to barrel whip and thus more accurate.  

Second, I imagined a barrel so thin that it can just barely contain the propulsive forces within.   This barrel would be as weak when cold as the hot barrel on the verge of failure that Troy postulated.  Thus, it would be subject to the same accuracy degrading barrel whip on the very first shot.  Granted, this is an extreme and unrealsitic case, but it illustrates the point.  And I concede that there is a point of diminishing returns beyond which adding additional thickness won't yield any significant improvements in accuracy.

Does this make sense?