RRA Entry Tactical Inspection (8/07)

AR/M4 AR Technical Discussion
1

Highlights from an initial acceptance inspection of an officer’s Rock River Arms carbine. Photos included below are of anomalous items, or items of particular common interest. Photos copyright by me, all rights reserved.

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Manufacturer: Rock River Arms
Type: Carbine
Model: “Entry Tactical”, p/n Unknown
Serial Number: CM63###

Lower Receiver:

 RRA OEM two-stage match trigger, semi-automatic fire control group. Mil dim receiver, hammer, pivot, and takedown pins. Drain hole in magazine fence. Hex bolt in grip screw. Grip is rubber Hogue-type, RRA branded.

Buttstock Group:

 Common RRA type. Commercial dim receiver extension. Circumferentially larger and longer (3/4") than mil dim. 6-position. End of extension cut at angle. Buttstock plastic. Form of current mil type . Loose fit. Receiver extension (castle) nut unstaked. Standard carbine buffer, correct weight.

Upper Receiver:

 Flat top w/ rail addressing (T-numbers). Detachable RRA “tactical carry handle” supplied. Extended feedramp file-cut post anodizing. Ramps uneven.

Bolt Carrier Group:

 Unmarked bolt. Extractor spring assembly 4-coil spring with black insert. Carrier key bears small rectangular indents for staking with no material intrusion on carrier key screws. Bolt carrier includes shrouded firing pin and semi-auto rear tang.

Barrel Assembly:

 16” barrel. Marked “202” under hand guards. Coding indicates barrel is 4140 chrome-moly steel, unlined, R4 (M4-type) profile, 1/9 twist. M4-type step on barrel. Heavy profile under hand guards. A2-type flash hider installed and timed correctly. Forged traditional front sight assembly, unmarked. Sling swivel installed with rivet. Side-mount sling swivel assembly installed. Front sight base installed with straight pins. Barrel extension cut for extended feedramps prior to parkerizing. Handguards M4-dim, plastic, single pair of black heatshields.

Gauging:

 Passes pertinent gauges.

Other:

 None

Function Testing / Live Fire:

 Officer reports 500-600 rounds successfully fired in static slow-fire exercises to measure accuracy with previously installed variable power scope. Officer reports no problems. Additional live-fire pending. Verification of compatibility with NATO duty ammunition pending.

Required corrections:

 Replace supplied match-type fire control group with standard single-stage fire control group. Stake carrier key screws. Stake receiver extension nut to receiver end-plate. Replace grip screw with slotted screw.

Recommendations:

 Conditional approval. Return for inspection following live fire test, and 90 day intervals thereafter.

END
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2

These are the old style RRA feedramps.
Current production appear to be actually machined with an endmill or similar cutter.
The new style are an improvement for sure.

3

I’m glad to hear RRA stopped dremeling the ramps. Notice I’m not calling them M4 ramps.

4

Just FYI, I read the other day on TOS’s RRA forum where their rep stated that they do not consider them M4 ramps.

I previously asked this same individual why they did not machine cut their ramps prior to annodizing, and the response I got was pretty much that it’s just how they do it and they aren’t getting any back with problems for the way they cut thier ramps so they weren’t changing them. I too am glad that they have gone to machining them, maybe they’ll start doing it before annodizing too.

FWIW, I have a 16" middy RRA that ADCO built for me during the ban. It has standard rifle ramps, not dremeled ramps. It has run without an issue so far. I’ll be taking it to Pat’s clas in Dec. We’ll see how it does there.

-RD62

5

I quit using “M4” except as it applies to the mil M4. Where it’s a useful descriptor, I’ll use M4-type, M4-like, etc.

I like “extended feed ramp”. Most will know what you’re talking about, and it’s more correct than calling something M4 that isn’t.

Bushmaster calls theirs “M2” ramps. No explanation as to what their M2 specification is.

I would rather see them uncut, period, than cut poorly. They can be corrected, of course, but why should it even be left at issue?

6

Skintop, you need to stop pissing all over everybody’s beloved rifles on TOS. You need to remember that reason and evidence are not often well accepted.

7

I know, I know. Is there a 12-step program?

“But…but…but…the fit and finish is great!”

“But…but…but…mine is fine! Not a single jam in 150 rounds!”

The chips fall where they do, for better and worse.

8

It’s a useful reality check. Not saying RRA, BM, or even DPMS rifles are crap, but people need to stop kidding themselves that it works “good enough”. Evaluate what is wrong with it and fix all you can, better yet get a new, quality rifle, but just because you bought from other brands doesn’t mean your gun is automatically crap, but if you want to trust it you must put it through its paces and fix anything you can, even if you don’t NEED it on the static range. Skintop, keep it up, I just hope that those on TOS actually want to improve their equipment, instead of claiming it “works just fine”. I’m taking the steps now, learning about what’s good and fixing what I have, I may not have bought a Colt, but gosh darnit, that’s not gonna keep me from making my gear as reliable as I can. I just hope others are willing to learn instead of denying the facts.

9

I couldn’t have said that better! You have echoed my sentiments exactly. Thats why I have been doing the same. Replacing what I can (like my new Bravo Co BCG) and doing all I can for the rest til such time as I can upgrade it too (like properly staking my castle nut and bolt carrier key on my now back-up RRA BCG).

Thanks Skintop for the reports please keep these inspections coming and keep us posted on any failures you come across as well.

-RD62

10

Any reason why the two-stage trigger group was replaced?

11

Not skintop, but probably because they have a tendency toward unreliability (we had another one poop the sheets in class yesterday)

From a doctrine standpoint, a “match” trigger makes no sense. It is a carbine, not a sniper rifle, and while it makes the press nicer it would be hard to see any downrange improvement, and at the expense of reduced reliability.
There are some that are getting better to be sure, but i consider them Money Transfer Units- your money goes to someone else w/o viable benefit on yout part.

12

You’re right as usual. The RRA is unsat for any meaningful task. In no uncertain terms.

13

I had a surplus RRA two stage trigger when I put together my carbine. It had roughly 3500 rounds + a crapload of dry fire cycles on a yellow glass rifle when it came off that gun.

Since going on a carbine it’s had another 1600 rounds through it and still reliable. I think I’ll keep it on just to determine its breaking point.

Yep, it’s a sample of one, and it in no way becomes a wholesale endorsement of RRA two stage triggers in general.

14

We also had a competitive shoother in this same class (Memphis PD) that had a RRA trigger in his gun that ran well.
For his purposes, it made sense. For a service grade gun, it doesen’t.
Most stuff works. Some doesn’t. I’m not sure i want a sometimes performer on a gun i need.
Your choice, your consequences.

15

I just love the “jam” word when describing a malfunction.

“Jam goes on bread son.”

C4

16

Range day this morning.

After restaking the carrier keys with a P-MOACKS a new problem emerged. Following insertion, the carrier met substantial resistance at the point the key screws entered the receiver. A quick check of the receiver and carrier finds nothing abnormal. Same result upon reinsertion. This time, I forced the carrier forward and found the same resistance throughout carrier travel into battery. Removed, repeated. Signs of friction were then found in the upper corresponding with the sides of the carrier key base.

I double checked the carrier key. Straight and true. No excess material displaced. No apparent issue.

Time for a parts swap. BCGs from 2 Colts, 2 Bushmasters, and 1 DPMS were available. The problem BCG inserts easily and travels smoothly in all other guns. The BCGs from those guns insert easily and travel smoothly in the RRA, but with less play. Aha.

I found a file on my multi-tool and cleaned up the sides of the key, and voila.

Diagnosis: Stacking tolerances between the receiver and the minimal material displacement caused by the restaking.

Noteworthy: The 2 BM and DPMS carrier had been done with the same P-MOACKS in identical fashion. Almost two dozen others haven’t produced the same issue, either.

Thereafter, the RRA fired a few hundred rounds of exercises and COFs without issue.

17

Interesting. This would leave me to believe that the RRA upper receiver was on the tight side (maybe out of spec?). This must be why RRA doesn’t stake their keys. :slight_smile:

C4

18

T’would seem so, esp when you can drop the same carrier into other guns without a problem.

I’ve been told that the tighter tolerances in the RRAs are not flaws, but a feature. :frowning:

19

Yes, I have heard this as well. I also hear that they have the best fit/finish of any AR as well. This is a very important feature when selecting a fighting weapon.

C4