What is this?

--Terry--

--Terry--

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Hi,

I'm quite new to AR and black rifles, but I have just ordered an RRA mid-length, and am still waiting for "my precious" to arrive.

When I look at pictures of RRA carbines online, I found that some of them have a "link" on the side of the lower receiver, right above the trigger position, but some of them don't have this.

Could anybody tell me what is that?

And by the way, what is the difference between "chrome lined barrels" and "chrome moly barrels"? I know that chrome moly is an extra tough steel, but is it more superior to a chorme lined barrel? Or is it actually not as good?

The RRA carbine I bought had the chrome moly barrel, and I have no idea whether it is a good thing or not.

Thanks in advance for all answers.

Here are the pictures (it is not my gun):

Lower1.jpg


IMG_0839.jpg
 
I'm not sure it's for accuracy - they're anti-walk pins - so they don't 'walk out' of the holes.

Useless, in my experience. If they REALLY prevented the pins from falling out (and if that's really a problem in the 'real world' ie: combat), they would have them on ALL issue weapons.
 
Chrome-moly is the barrel steel. I would guess almost ALL AR barrels are made of chromoly of some sort.

Chrome lined barrel/chamber - this is actually a lining that's 'applied' to the chamber and or barrel for a few reasons. Essentially, it makes it somewhat easier to clean (well, with corrosive anyway), and last longer. Chrome is harder than the chromoly steel of the barrel.

SOME would say an unchromed chamber/bore is more accurate, but it would be so slight as to be insignificant in an AR.

If possible, I would go chrome lined.
 
"...what is the difference between..." A chrome lined barrel is literally what it says. A barrel lined with chrome. A chrome lined barrel supposedly lasts longer.
Chrome moly(short for chromium molybdenum) is a type of steel alloy. There's two type of alloy. 4140 and 4150. The latter is more expensive and is used only by FN, Colt and Bushmaster.
 
Terry for what its worth, I just got back today from popping the cherry on my new RRA mid-length with Chrome barrel and chamber. Very glad to have it and it works like a charm. No issues in the 150 plus rounds I fired today(spent most of the day shooting shotgun, somewhere near 700 rounds with a couple buddies.) The action is smooth out of the box and getting smoother. I do notice a slight reduction in recoil or rather impulse with the med-length as compared to my 14.5" carbine.

TDC
 
That's a KNS anti-roll pin. They don't do anything, but give those that like to pretend their life is on the line that their equipment won't fail.
 
Thanks again, guys.

I looked at RRA's web site, and saw that the price difference between a Chrome Moly barrel and a Chrome lined barrel is just US$40. A tiny small difference in cost.

If chrome lined barrels are just better, why didn't they just chrome line all of their barrels, just like what STAG does?

I don't get it.
 
koalorka said:
That's a KNS anti-roll pin. They don't do anything, but give those that like to pretend their life is on the line that their equipment won't fail.
Click to expand...

Or have a well used gun where the pins actually walk out...;)
I have them in my work gun and two civie guns (one Canada and one US). I like them - but unless your gun has loose FC pins its not a necessity.

Barrel steel as per TDP is actually 4150 CMV (which I have been told means has a percentage of Vandium) its more expensive than either 4140 and 4150 - but has a higher strenght when hot (i.e. less likley to blow your gun up in massive amounts of full auto)

IMHO if you dont want a Chrome lined gun get a SS barrel. I dont see a point in a non Chrome lined 4140 or 4150 barrel. Chrome lining is down to a point that its easily possible to get a submoa barrel.
 
They are anti-rotation, not anti-walk.

canucklehead said:
I'm not sure it's for accuracy - they're anti-walk pins - so they don't 'walk out' of the holes. Useless, in my experience. If they REALLY prevented the pins from falling out (and if that's really a problem in the 'real world' ie: combat), they would have them on ALL issue weapons.
Click to expand...

Shazam was correct.
They are anti-roll, but were intended not for accuracy but to reduce wear on the receiver - especially with full-automatic fire - caused by rotation of the pins.

In the U.S., where private machine-gun numbers have been frozen, registered machine-gun lowers are very valuable and this value is still appreciating.

Owners are interested in preserving this value - even as they enjoy shooting them.
 
Some ppl think they need the 'edge' that a non-lined barrel may give them. The sniper rifles I work with never have chrome lined barrels because the chrome supposedly flakes during firing and reduces accuracy. This being said, a sniper rifle barrel has a 5000 round life span and that is on a slow rate of fire. A chrome lined barrel such as our C7 family of rifles has a 12000 round life span and that is on a high rate of fire. So unless you plan on trying to get 3 inch groupings at 2000m, I recommend you go with the chrome lined barrels.
 
For as long as I can remember... I've always competed with Chrome Moly barrels (read : match chambers and hand lapping). I've even had great results with stainless match barrels. (read: more tight chambers). THERE ! Enough said about tight groups.

Back to shooting under service conditions (running and gunning, standing alert to standing, kneeling, squatting, more running and shooting), one does not need a match barrel unless you are sitting on a bench at the 100m range and shooting for tiny groups. I've selected a chrome lined barrel for competition purposes because I can get away without cleaning as often (between 500 and 1000 rds). I've found that chrome lined barrels are very competitive these days. The chrome plating process has been tweaked over the past 20 years to the point that chrome lined barrels are right up there with many match barrels (I did not say ALL match barrels...). If you don't believe me, do a google search on the newer FN SPR barrels... they are all turned from the MAG58 or C6 barrel blanks. No joking... these barrels have been tested with 10G rounds and they are still grouping subMOA. :evil:

So is there much argument ? Not really. Buy what is within your budget and what suits your shooting game. Get out and enjoy your black rifle while we still can.... :rolleyes:
 
KevinB said:
Or have a well used gun where the pins actually walk out...;)
I have them in my work gun and two civie guns (one Canada and one US). I like them - but unless your gun has loose FC pins its not a necessity.
Click to expand...

Damn you and your RL experience ;), I was referring mostly to the Nintendo Force Recon types on AR15.com.
 
Well, I did get the RRA mid length with the Chrome Moly heavy barrel. It has been shooting great in the range.

I don't know about its performance in tactical rifle competition yet, because I have not tried. But now I realize that the heavy barrel is indeed HEAVY, and the carbine is too head heavy to allow a proper single handed grip for mag change.

It seems that I should've got the M4 style instead.
 
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